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PM6685 & PM6685R

Contents

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3. 5 T K2A T Kos Oh BAV99 e on R35 REED pes Be p Ds C10 R42 cum cte 4 1 10n 15 100 jon 15uF 6 3V TP26 1P27 0 5 2pF 47 15 2 18pF p 5 Batis a R1 R2 R3 R4 R5 R2
4. O J4 J3 ES 2 ES Ee E EE 12 E re S G s EE RE E B E ES 2 RES R159 19 1 J5 lt for E m E EE ERE J3e D L10 o o o o 40 39 5 BE Ej Ej ss s s 210 a 5 29 612 Ala fl C63 E 5 css 8160 aa ERES e 209 8179 cos Li 94 C90 2 M o rz R148 e 1 J17 J30 8195 51 5 Fl RIGI U13 H J29 8194 E C65 RI63 802 Utt o ti C95 8165 J18 I E h D9 R167 U14 27 i ix Eme 2 5 9 L 853 B MS em 8 E B 020 E B amp U41 U43 al 8 RI90 E 1281 8129 39 40 8175 am D6 EB 5 5 s 16 C64 4 gleg S Fo 21 27 Elus 1 U36 fee
5. m 12VREG BATT 5ECL Y J23 piy 124 4 9 Oscillator STD OPT 4 2 3 Oscillator selection jo C107 1 2 Eciz5 selection 100nF R209 4 rer 9 R296 R297 560 10 9 220 220 111 n 1 E C109 B2 10 9 M9 8 1 T BLM21A102S R298 2 cm _ on 4030 10A gt 2 032 033 100nF WEAR 15uF 6 3V BFS17 BFS17 4 E 100 47 ics e u29 R300 AN gt 3 10pF RTCX2 8 RTCX1 Lai VBAT counter ALARM 7 R304 F2 45 R301 R302 120 MTCXO pHi HL 100 100 5 48 1 EXTREF OUTMUX 22 12MHz XH veok NTREF 42 1 V REFO 40 2ECL 2ECL R217 RE R303 R51 100 vouta SS 5ECL 1127 2 7K A V REFA VOUTB 59 5ECL 11 5M lt V REFA 719 gt V REFB INTP1 88 Pe L se V REFB INTP2 90 R 100nF R208 R218 88 INTS1 SXA 5ECL 100 Notused 680 ss mrez 0177 FIN 4 FIN kadi
6. CSIB gt U30A gt 4 1 amp gt U31A 5V 20 U32A ________ DB1 a 8 vin DB2 2 po oo 18 HZ En ren VREF a l E i R269 C145 al 44 8 04 o ART D21 220 390pF t 80 087 15 05 Q5 54 AD amp BAVAS R270 R271 SH DB8 12 gps ADS 8 2K 820 CS DB9 D7 al 2 a She 0 0 15 i25 RS ADC1061 4 HC573 ls BFT92 7 Q28 2 U44D 22 47 1 Not Used cue 10 t HC125 R274 e 100 R275 i D22 Bavo Bis Il amp l 22 2 2K A V savas R276 HC125 929 2 BFS17 1 1 R277 33K U30D 5J 33K 1 it amp HCo0 U44A 3 HC125 U44B CSIA gt HC125 SA vi L 2 amp U35A 4 22 U36A DB1 12 8 vN 082 18 2400 DB3 Di VREF vrer JvreF 084 16 402 i 085 15 sj 35 026 R2
7. Drawings amp Diagrams 8 7 This page is intentionally left blank 8 8 Drawings 8 Diagrams Amplifier amp Trigger Level DACs PCB 1 Sheet 3 5
8. J32 5 2V E BC807 25 1 J7 STANDBY 7 4 x t s 3 R124 J22 R121 100K R 1 p 10K ic oa n z HEF4013BT 9 10 4 UNIT 13 oN 2 D13 4 gt 14 R146 BAV99 R123 R125 15K 16 100K 100K 3 18 R122 C35 Has t 5 DISABLE STANDBY 012 U 12V 1o RME 7 BC8478 4 Con20 012 470n R127 BAvee 1 i D6 1N4003 200 L at UA 2 1 a 2 i DISCONNECT IF BATTERY OPTION OTS m LM2940CT 12 INSTALLED 33uF 63V J21 m gt osn gt H2VREG BATT Br 15 r EXT DC eu 2 12V ON REAR SB140 220uF 50V 0 J31 s I PANEL OPTIONAL FAN R56 1 J LLL 500 58140 u42 R55 D10 4 a Q5 ge BCP51 LM317T in SB140 Q6 D20 R156 R157 BC847B BZX79 B5V6 SZ 22K esik R53 R54 To Rubidium 22 560 Power J3 F1 1 6 7 T 19 R148 I 4 gt DAE u39 TP16 15V amp 9 4 TP28 C64 10uH 270uF 1 719 4 1 TP15 09 18 5V K5A ces YvY 4 I 4 1 8 4 1 gt gt 100n AAA 5 10uH t ae 10mH 2KBP08 42 C83 PF C74 c75 mim C76 J15 15uF 6 3V 2 cn C72 mm 33uF
9. bent 15 to lock zi Replacement Parts Mechanical Parts 7 5 Main Board Pos Description Part No 227 CHOKE 452 3 5X6MM BANDAD 80ohm at 100MHz 5322 157 61928 CRYSTAL 12 000 MHz SMD MA 406 2422 543 01353 B2 CRYSTAL 10 MHz HC 49U 13 5322 242 82118 CI CAPACITOR TRIM 0 5 2 pF 300V 5322 124 80335 C10 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C100 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C101 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C102 CAPACITOR 33 pF 5 50V 0805 2222 861 15339 C103 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C104 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C105 CAPACITOR 6 80 UF 20 16V 6 0X3 2 MOLD 5322 124 10687 C106 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C107 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C108 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C109 CAPACITOR 22 pF 5 50V NPO 0805 5322 122 32658 Cll CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C110 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C111 CAPACITOR 15 UF 20 6 3V 6
10. BLM21A1028 T 8 8 8 e z z 5 2V 19 5 cot 82 ju 92 1478 ccos 99 0228 82 238 4208 ees 89 VUE 89 0260 092 ze N gt _ gt 15uF 6 3V wmm gt HC573 100nF gt 16973 T oonF 2 55257 ton gt 276512 90 ton 29 HC138 Beat 59 100 gt HC10 1O0nF 15uF 6 3V w 100nF U 12V u 12v e e 12VREG BATT gt gt gt 12VREG BATT Drawings amp Diagrams 8 5 Main PCB Component layout A Q O O O O O O OO x K3 O O O O O O Bottom View 8 6 Drawings amp Diagrams ounter Circuits 1 sheet 2 5
11. FLAT PIN 2 8mm E184 8 LESA SN BAND J15 CONNECTOR 2 POL F095 SINGLE ROW J15 CONNECTOR 2POL F095 JUMPER GREY J16 CONNECTOR 2POL F095 JUMPER GREY J16 CONNECTOR 3 POL F095 SINGLE ROW D22 D24 D26 J17 CABLE ASSY J18 CONNECTOR 40 POL LOW PROFILE HEADER J19 CONNECTOR 16 POL TMH 108 01 L DW J21 CONNECTOR 2POL 095 JUMPER GREY J21 CONNECTOR 3 POL F095 SINGLE ROW 122 CONNECTOR 2POL F095 JUMPER GREY 122 CONNECTOR 3 POL 095 SINGLE ROW J23 CONNECTOR 2POL F095 JUMPER GREY J23 CONNECTOR 3 POL F095 SINGLE ROW 124 10 22 03 2101 4030 10 125 CONNECTOR 2POL F095 JUMPER GREY J25 CONNECTOR 3 POL F095 SINGLE ROW J29 CONNECTOR 2POL F095 JUMPER GREY 129 CONNECTOR 3 F095 SINGLE ROW J3 FLAT PIN 2 8mm E184 8 LESA SN BAND J30 CONNECTOR 2POL F095 JUMPER GREY J30 CONNECTOR 3 POL F095 SINGLE ROW J32 CONNECTOR 20 POL LOW PROFILE HEADER 14 FLAT PIN 2 8mm E184 8 LESA SN BAND J5 FLAT PIN 2 8mm E184 8 LESA SN BAND J6 FLAT PIN 2 8mm E184 8 LESA SN BAND J7 CONNECTOR 2 POL F095 SINGLE ROW 19 FLAT PIN 2 8mm E184 8 LESA SN BAND KI RELAY REED 5V PRMA 15157 3790 K2 RELAY REED 5V PRMA 15157 3790 K3 RELAY REED 5V PRMA 15157 3790 K4 RELAY 2 5 SV IA 2pol 14X9X5m KS RELAY 2p V23042 A1003 B101 alt A2303 LI CHOKE 220 UH 10 NL453232T 221K L10 FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm 111 FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm 5322 130 32076 SOT23 5322 130 34337 SOT
12. After 15 year of operation For 19 year add lt 3x 10719 Table 5 1 5 2 Preventive Maintenance Stability of timebase oscillators A user can accept a maximum of 3 Hz deviation on the 10 MHz frequency of the oscillator This results in 3 Acceptable error 3 x107 10 x10 The aging and temperature factors can be selected from the table on page 5 2 The value of the aging factor is correctly selected from the table when the calculation of MTBRC results in 1 to 30 days use 24h 1 to 12 months use month or over 1 year use year e g 43 days or 17 months or 0 8 years Example The user has the same requirements as in the example above The counter has a PM9691 oscillator Look up information about 9691 in the table on page 5 2 The results will be the following Relative Frequency deviation caused by Ambient temperature deviation within 0 to 50 C reference point at 23 C Less than 3 10 Aging year Less than 1 5 107 Use the MTBRC formula with the above values This gives a MTBRC of maximum 3x107 3x10 15x107 NOTE When recalibrating the reference crystal oscillator will be compensated only for frequency deviation caused by aging 1 8 year When to Replace the Fan PM6685R only To maintain the high reliability of a counter used in around the clock applications you must replace the fan every
13. INTERNAL CONTROLS IGNALS 8 DIS PLAY Levd 5 MICROCO MPUT ER KERNEL Level 4 MICROCONTROLLER Level3 OSCLLATOR Level 2 POWE RSUPPLY Level 1 Fig 5 1 Functional levels The troubleshooting strategy for the PM6685 is an integrated part of the overall service strategy for the instrument This instrument is hi erarchically designed in different levels and troubleshooting can be performed in any design level if the lower levels are OK It is there fore important to disconnect all options at the beginning ofthe trou bleshooting procedure Power Supply TP22 7 J16 20 5 2 23 5 TP21 12V ES Load peloeuuoD peloeuuoosId TP17 7 TP15 5 Nuts 2 P16 15 Fig 5 2 Test points trimmers for the power supply Connect the counter to line power Set the counter to STAND BY mode Check that the voltage between J9 and J10 is in the range of 90 to 260 VAC see Fig 5 2 Check that the input voltage to the power module U39 be tween pin 1 and pins 4 and 5 on the bottom side of the PCA is 120 to 375 VDC Move the jumper J16 to the DISCONNECT position Check the STAND voltages after the power module 039 Use for instance the screen around the input amplifier as ground connection
14. R117 R116 R115 1 PADS pADit 100K 100K 100K NC gt LADA H AD4 8 AD12 BUTOI Paps i Laos 1 L AD13 I LADS 8 D ADS 8 LAD14 WRH 2 LAD7 19 LAD7 118 AD15 BU101 gt 27C256 270256 43256 43256 2 2 BU101 gt 28 80101 NC BU101 T 5 BU101 48V 1 u BU101 10107 10109 der 412 Lena 114 5 BU101 10N 10N 10N 10N 10N 10N 10N 10N 10N 10N 10N GND BU101 GND BU101 0 GND 4 BU101 G H 1 J K M N 5 Drawings amp Diagrams 8 17 This page is intentionally left blank 8 18 Drawings 8 Diagrams Chapter 9 Appendix How to Replace Surface Mounted Devices Most of the components in this instrument are mounted on the sur face ofthe board instead of through holes in the board These compo nents are not hard to replace but they require another technique If you do not have special SMD desoldering equipment follow the in structions below Fig 9 4 Attach the IC to the pad with the solder Fig 9 1 Heat the leads and push a thin aluminum sheet Fig 9 5 Solder all leads with plenty of solder don t worry between the leads and the PC board about short circuits at this stage Fig 9 2 When removed clean the pads with desoldering Fig 9 6 Remove excessive solder with desoldering braid braid Fig 9 3 Place solder on the pad Fig 9 7 a strong magnifying glass to make sure there
15. en en ons eu mU m mU en m ENTER V AUX ARM FREQA FREQC RATIOAE RATIO C A PWIDTHA DUTYFA STA STO REMOTE EXTREF CHECK FILTER 150MQ Illi AUTO LEVEL A SENSITIVITY SRQ LO BAT OVERLOAD HOLD NULL OFFSET TRIG Fig 2 1 Text on the display Internal Self Tests The different built in test routines invoked by the power on test can also be activated from the front panel as follows Enter the Auxiliary Menu by pressing AUX MENU Select the test submenu by pressing DATA ENTRY up or down Enter the test menu by pressing the ENTER key Selections for internal self tests are TEST ALL Test 2 to 5 in sequence TEST RO ROM TEST RA RAM TEST LOGIC Measuring Logic TEST DISP Display Test Use DATA ENTRY up down to select TEST ALL then press ENTER C N If any fault is detected an error message appears on the dis play and the program halts If no faults are detected the program returns to measuring mode Keyboard Test The keyboard test verifies that the counter responds when you press any key To check the function behind the keys see the tests further on in this chapter Press the keys as described in the left column and look on the display for the text as described in the second column Some keys change more text on the display than described here The display text men tioned her
16. 38 vccN MTIME 2 R52 R305 R306 T m 8219 VCCB cvi 81 220 220 R220 330K 50 Voce 98 CARRY 71 veco 2 Not used VCCG 82 Tp28 R97 R307 GNDA 2 R254 CARRY2 1 035 GNDB BFS17 BFS17 GNDC 39 Not used GNDE c2 iss GNDD3 GI wx GNDD2 R309 GNDD1 st p l GNDD4 82 GNDG 83 47 s4 pa4 GET gt Leet 55 pa5 gt R311 R312 120 A INT 100 100 HOLD 5ECL 68 B2 5ECL Cip RO 1 5 m J 1 2ECL 2ECL m AT gt gt AR 0 7 or 5ECL 179 L A8 22 n e R313 FH 100 BURST gt 4 s apo R101 R315 100nF aL CSASIC 21 cs AD1 1 47k 820 70180 U25B ALE AD2 R331 ECL Tuer WRL ADE R317 R318 4 WRH AD4 os 220 220 gt 1 DE BSR12 BSR12 ALE 5 HLDA ADE AR7 5M QDMA M HC32 E R330 ton 22K U25D 47 038 039 U25C hw BFS17 BFSI7 il baa 47 lt 24b 43 5ECL lt H Hs epe WRL 02 0 em R325 gt 18 47 C122 HC32 2 1 n je A HC32 680 R235 R319 R320 100331 120 56 56 47 L 57370 R329 R326 R327 120 100 100 123 R321 R322 47 10 10 d 2ECL 2ECL R328 2 4 127 H L12 2ECL 21 0182 j i 5V 1 100nF 400nF BLM21A1028 5ECL Loi 2 2uF 6 3V C125 T R244 R245 82 Y R241
17. m 531 8 4 a M C202 0201 ba 10n 10n 53054 PCF8576 Drawings amp Diagrams 8 15 GPIB Unit PM9626B Component layout GPIB board Type 5 2V GND 5 _ 74HC32 7 14 NE532D 4 on 77 71 74HC00 14 39 1 74HC573 20 74HC573 20 27C256 1 32 1 12 17 26 BuO 27 256 1 32 1 12 17 26 16114 43256 28 TE x 1C447 2 5 g m 75161 20 5 5 3 5 74HC573 20 IC113 74HC86 14 4 5 6 8 9 FINE ECT o CU 115 10109 12106 C115 SK404 10101 12442 C108 10110 C4106 4031 100 48430 03 8 16 Drawings amp Diagrams GPIB Unit PM9626B F G H J K L M N
18. 5 ANALOG OUT euo 11 GPIB CONNECTOR BASIC BOARD mun mad 1K SHIELD BU103 BU101 FULL SCALE ADJUST 10 8109 R110 tt 1 T Be 0102 100 100 id BU101 16101 ad 10N 10105 EO mud R105 TOON BU103 C 47K TOK 52570 BU103 E poi gt 10117 17 mier E sone REN 5 10N I R106 id ZERO jo FC BU103 ADJUST 1 A 5 2V Buros A INSTALLED BU101 52V SHIELD AGND Bo NDAC BU103 GPIBINT Jol 254 BUI ot BU103 GET DAV BU101 BU103 CLOCK gt MH BU101 Ho BU101 wot BU101 DIO1 RESET GPIB BU101 3 2o d IC101 4 BU103 21 CSB291A DIO3 CSGPIB BU103 HC32 4o DIO4 RAMROND 83 igit BUIOS B BU101 12106 12 n Bars CSGPIBADR li 005 AE i BU103 BU101 0106 BU103 ADO 1101 ADI 8U103 BU101 Diog AD2 8U103 L BU101 181920212223 AD3 GND BU101 BU103 Abi NOT MOUNTED NOT MOUNTED 10110 IC111 16112 5 m 0 RAM BU101 AL 9 3208 ADE BU101 AD7 set MS BU101 K101 y aal ABS A TON BU101 32767 32768 ti AD9 BKO BU101 5 i 5 4 AD10 AD10 t Hi A4 Vs 2 i BU101 105 1015 L__ 012 zA e 9 HC573 4 I SK101 aD Dell AD13 2EN Le en A2 02 27 AD14 014 Sauce 2c 42SK191 BU101 1 2C4 UPROG 962 i 1 9 3 80101 s pADO wit S ADO 1 ADB R114 R113 R112 ARD 1ooK 100K 100K Ap1 AD1 LADS
19. 0116 Full Scale U114 0115 0113 U106 Fig 6 6 Trimmers for the GPIB interface m Setup PM6685 Input A 50 AC Manual trigger levels LF synthe Amplitude 1 Vpp sizer Period 1000 01 Hz square wave Table 6 10 Connect the counter to line power Switch on the counter Press PRESET then press ENTER Connect the DMM to the BNC output of the analog output Activate the analog output Select AUX MENU Press DATA ENTRY UP DOWN keys until the display reads ANALOG OUT Press ENTER Press DATA ENTRY UP DOWN keys to select ON Press ENTER Press DATA ENTRY UP DOWN keys to until the display reads 1 0 V Press ENTER Connect the LF synthesizer to the A input of the counter The counter should read 1000 0xxxxx Hz m Adjustment Adjust the trimmer ZERO see Fig 6 6 until the output volt age is 0 V 1 mV Set the LF synthesizer to 999 90 Hz 1 Vpp square wave The counter should read 999 9xxxxx Hz Adjust the trimmer FULL SCALE see figure 6 6 until the output voltage is 4 980 V 3 mV Set the LF synthesizr to
20. 24 i oE CSRLY pus R19 an L R73 R74 R78 R79 1K Not 5429 10K 10K 10K 10K CSDAC R75 UTA R87 WRL gt 4 34 124 1 5V T T T 45D AB 3 2 R71 uc 400 482 3 5X6MM BLM21A102S AR 0 7 gt C56 C59 60 cei 1 1 629 10n 10n 100nF 5uF 6 3V 5 10K 100nF 50 100K 1 t 4 1 DACMUX 1 Luis f A 100K 10K 123 so DAGAIDACB m gt 24v 51 40 10n 10p uea 4 B 02 n 482 3 5X6MM 52 R89 HD lt 02 4 W 2 R15 pet D3 AGND on e 24 JL ba U5B 16 D5 Ab LE Ee L NESH W C51 C52 C54 C126 50 1 A RFBA 3 BC807 25 Tin 10n Ton 10n 10n 2 2uF 6 3V 4 BO A USA VREFA R81 R85 R86 BCOM QUIA 22 5320 6 B1 2 RFBB CO VREFB ccom 3 gt 29 10K 10K et C26 R116 R117 R118 NES32D PM7258 10 fe 15K 47 47 T weas R82 TRIG LEVEL DAC S 1 amp 555 1 4 BLM21A102S 5 1 DAC RANGE REFERENCE 10K 5 NE532D 100 552 5 R72 R83 NE532D 5 C30 m 4 10K BLM21A102S 100K SN gt 4 4 52 pd R84 USD 5 55 le 100K w 4S2 3 5X6MM R57 R60 R63 R66 657 i amp 15K 47K 6 8K 4 7K 10n P anon 45 C47 10 104 ni 10n 10n 10n 100nF 15uF 6 3V 10K 5 2 022V 1 0 s9v C28 R90 Md aL 164 5V 10n 68
21. JE E Ee 6 Fa 2 c185 EN R19 820 SID zs R3 _ H GND 5 2150 2151 4 alls 2 E E B E a 212 Gb o 229 R30 52 us Dell SS B AB ce s lee Us 7 Reg 221 E I ces ces Bl 013 E E GN B E C136 B Z ea 8 91 S 50 mg ms L5 81 107 Q r E EB U Ji eee rea cs Jusl R39 244 n 8 Ug B EU E TE 1 ne IE END ue 115 Real 259 S 3 4 IS L Eb R i Rn E E E SRE BE pie O Re s C1 24 E sje R8 pue m E Le3 Lei RE C Em LE mE Em 024 027 Ral a EX 051848 feeb 5 Rene ES B R lea IS Rs SIRI 2 CI3e 5 24 r r e gm ke 5 lt rr 5 J Cied amp ji C Top View 8 4 Drawings amp Diagrams Control Logic PCB 1 sheet 1 5 12MHZ gt gt GET R159 10K u10 SENSE RESET RESIN REF GND R160 TL7705B 390 C88 2 2uF 6 3V Un TO GPIB XTAL1 8 XTAL2 Reser CPU CLKOUT EA NMI WRIWRL AGND BHE WRH VREF RD VPP ALE ADV READY INST BUSWIDTH ACH
22. R247 R248 10K C427 R249 122 126 savas gt P VES i 4 1 24 015 BNC Coax uso 52N PFG16A 7 900 BLM21A1028 External vec C186 16121 in 47 R252 C120 016 t a Traay TORE cine 8928 99 Rabe rear panel R253 BAV99 5 33pF 1K 560 T J27 100 6 8p MAX961 C130 4 4 100 e Internal db 1 reference R243 R258 A 10007 rar panel 24V X 2ECL BNC Coax R22 BLM21A1028 R259 40 680 C431 C18 av c184 R260 100nF 100nF I fa _BFG16A 47 TI D17 BYD17G us BAV99 ENA EXT REF gt L14 1 P SEGL 2 2uF 6 3V AAA 21 1025 c133 vola 019 1 C136 R261 R262 wan 0152 BAV99 BLM21A102S wama TSuF 6 3V 100 190 C135 35 256 116 DH 1 56 2 5N DAY R263 als TE 128 ni BLM21A1028 BNC Coax 38 28 H External 1K V La R264 reference d mes 2 UE 88 ws HET gt input R267 S9 MR 5ECL rear panel t t t t D 5M U27C R266 JL 4 pO gt vl BLM21A1028 ge 20 26 4 Q C139 C140 C141 142 C143 100331 bz w 75ALS176D 100 5144 563 ton 10n 100nF 100nF gt gt in 9 R268 Not Used uel R L 1K 100381 E 5ECL
23. D LL A 777777 R149 R155 p 4 U21A amp Q17 Fan A for ON STBY control amp OCXO PM6685R on J31 Fig 4 10 Power Supply Hardware Functional Description 4 9 m Function The three DC voltages from the power module are used for generating the following four supply voltages in the counter 5 V Regulated 3 V from the power module is used directly 5 2 V 7 is used with regulator U43 127 15 is used with regulator 041 7 V Stabilized 12 V is used with regulator U21A and 017 The following supply voltage is used for a special purpose 12 This voltage comes directly from the 12 V regulator U41and will be present as soon as the power cord is connected regardless of the po sition ofthe ON STANDBY switch It is used forthe ON STANDBY control logic and for supplying an optional OCXO in STANDBY to avoid the long warm up time otherwise needed to obtain maximum accuracy At stand by the four main supply voltages are switched off but as described above some parts of the instrument should not be diconnected Therefore the power module will never be switched off The PM6685 has consequently only a secondary power switch A relay K5 disconnects the load on the 5 V and 5 2 V at stand by Because the
24. 11515 Part Number 4822 502 11713 5322 502 13553 4822 502 11691 5322 502 13552 5322 502 13641 5322 502 30703 4822 530 80173 O 6 O O LT d O E up El M 7 4 Replacement Parts Mechanical Parts TT p Pos Description 182 184 190 200 201 202 Spring washer kba 4 3 St fz din137 Lock washer yt4 3 St fz din6798a Nut m6m 04 st fzb Receptacle 140825 2 2 8X0 8 Protect sleeve 2 8mm N 94610 transp pa Cable clip reel srb 2 5T m4 VER up END PPE a gn Ga Es dd t HEEL T 4 a Part Number 4822 530 80076 4822 530 80083 4822 505 10326 5322 268 10275 5322 321 40117 5322 358 50107 1 1 A Ur La D Y
25. 4822 051 10569 4822 051 10562 4822 051 51002 4822 051 10561 4822 051 10159 4822 051 10105 5322 117 12497 4822 051 56801 5322 117 10969 4822 051 52204 5322 130 10682 4822 051 51804 4822 051 52204 5322 117 12497 5322 117 12505 5322 117 12506 5322 116 80447 4822 051 51003 4822 051 56801 5322 117 10034 4822 051 10829 OLOR c cR x c Rc cp X Ko iu c E c c c c c ad pe Pos Description R245 RESISTOR 3 90 1 125W 100PPM 1206 R247 RESISTOR 820 ohm 1 125W 100PPM 1206 R248 RESISTOR 680 ohm 196 125W 100PPM 1206 R249 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R25 RESISTOR 470 kohm 190 125W 100PPM 1206 R251 RESISTOR 1 00 kohm 196 0 125W 100PPM 1206 R252 RESISTOR 100 ohm 196 125W 100PPM 1206 R253 RESISTOR 560 ohm 1 0 125W 100PPM 1206 R254 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R255 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R258 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R259 RESISTOR 680 ohm 1 125W 100PPM 1206 R26 RESISTOR 470 1 125W 100PPM 1206 R260 RESISTOR 47 ohm 196 0 1W 100PPM 0805 R261 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R262 RESISTOR 10 0 ohm 1 0 125W 100PPM 1206 R263 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 R264 RESISTOR 220 0 ohm 1 125W 100PPM 1206 R265 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 R266 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 R267 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R268 RESISTOR 1 00 kohm 196 0 125W 100PPM 1206 R269 RESISTOR 220 0 ohm 1 125W 100PPM 1206 R27 RESISTOR
26. 5322 214 91033 4031 100 62820 5322 130 82201 5322 381 11136 5322 255 41228 4031 100 62720 4822 502 30081 5322 122 34098 5322 122 34098 5322 130 81921 7 12 Replacement Parts Front Board HAUT qe Pos Description Part Number D202 LED 3mm Yellow 590nm 4822 130 30953 4 8MCD 10mA P204 Connector 40 POL TMH 120 01 L DW 5322 265 51295 R201 Resistor 220 k 196 125W 100PPM 4822 051 52204 1206 R204 Resistor 10 0 Q 1 0 125W 1206 4822 051 10109 R205 Resistor 10 0 2 1 0 125W 1206 4822 051 10109 R206 Resistor 10 0 2 1 0 125W 1206 4822 051 10109 R207 Resistor 10 0 2 1 0 125W 1206 4822 051 10109 U201 IC PCF8576T VSO56 5322 209 11129 U202 IC PCF8576T VSOS6 5322 209 11129 6x TORQUE 3 Ncm TIGHTEN THIS SCREW FIRST TO GUIDE LCD HOLDER F ORIENTATION MARK FOR LCD ww o NS _ 0 0 00 H __ 1 IX IX IX Dum Pos BU101 BU103 C101 C102 C103 C104 C105 C106 C107 C108 C109 C110 C111 C112 C113 C114 C115 C116 C117 C118 IC101 IC103 IC106 IC107 IC108 IC109 IC109 IC111 IC113 IC114 IC115 IC116 IC117 R101 R102 R103 R104 R105 R106 R107 R108 R109 R110 R111 R112 R113 GPIB Interface PM9626B D 79 35 IC Socket 40 DIL Lock Washer YT3
27. 63V Capacitor 47 nF 10 250V Capacitor 330 nF 20 250V Capacitor 100 uF 20 35V Capacitor 220 pF 20 200V Capacitor 100 pF 5 63V Capacitor 22 pF 5 63V Capacitor 4 7nF 10 63V Capacitor 4 7nF 10 63V Capacitor 100 nF 10 63V Capacitor 100 nF 10 63V Capacitor 100 nF 10 63V Capacitor 470 uF 20 35V 2M Capacitor 470 uF 20 35V 2M Capacitor 10000 uF 20 6 3V Capacitor 1 nF 5 63V Capacitor 100 nF 10 63V Capacitor 100 nF 10 63V Capacitor 100 nF 10 63V Capacitor 220 pF 20 200V Diode 7A BYW29 200 Diode 7 5A MBR760 60V Diode 7A BYW29 200 Diode 0 2A BAV23 200V Diode 0 35 W BZX84 C8V2 Diode BYV26E DOD57 Diode 0 35 W BZX84 C18 Diode 0 2A BAV23 200V Diode 0 35 W BZX84 C18 Diode 0 35 W BZX84 C18 Diode 0 35 W BZX84 C8V2 Diode 0 2A BAV23 200V Resistor 82 KQ 1 125W Resistor 82 1 125W Resistor 270 1 125W Resistor 10 0 1 0 125W Resistor 2 20 kQ 1 125W Resistor 1 00 1 0 125W Resistor 1 80 1 125W Resistor 3 90 1 125W Resistor 47 1 125W Resistor 220 1 125W Resistor 10 0 1 0 125W Resistor 10 0 1 0 125W Resistor 10 0 Q 1 0 125W Resistor 10 0 1 0 125W Resistor 10 0 kO 1 0 125W 9 8 Replacement Parts Replacement Parts Part Number 5322 255 41313 5322 255 41314 4822 122 31746 4822 122 31746 5322 126 13129 4822 122 31981 4822 122 31981 4822 122 31981 4822 122 33496 4822 122 33496 4822 121 41676 5322 121 44222 5322 124 40852 5322 126 13129 4822
28. INTREF OUTMUX MPCLK PH VCCB GNDB VCCC GNDC 9 3 voca 5 VCCX 9 5 PG RTCX1 RTCX2 ALARMN VBAT sw CNTS uM le CY2 SB SA oa 52225908 556 GNDG lt VREFAD lt RES L lt NTP lt INTP2 rs INTS2 FIN PCL MTIME gt 5 V REFA VOUTA V REFA V REFB VOUTB V REFB VCCE GNDE VCCF GNDF wo uzzzoor eozz 22222 5 METERS 22 EE EEE 3383085 gd Fig 4 11 Counter ASIC block diagram CNTS Two 32 bit binary counters count external events or keep track of the time Interpolator This block is not used at present MCTRL The different events in the measurement cycle of the ASIC are timed by this block MPI This is the microprocessor interface block The bus width is 16 bits ADO to ADIS Interrupts to the microprocessor are generated at INT GET The GET signal from an optional GPIB interface can control the start of a measurement m External Interpolator The X POLATOR unit is connected directly to the internal interpolator in the ASIC It is used for increasing the time resolution beyond the limits set by the reference clock period of 100 ns An er ror pulse is generated in the SYNC block Its width is determined by the difference between an external event on an input channel and the next clock pulse This pulse controls a current generator charging a capacitor When the pulse has expired the voltage across the
29. R137 R138 R139 R14 R140 R141 R142 R143 R144 R145 R146 R147 R148 R149 R15 R150 R151 R152 R153 R154 R155 R158 R159 R16 R160 R161 R162 R163 R164 R165 RESISTOR 4 7 kohm 1 0 125W 100PPM 1206 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 120 ohm 190 0 125W 100PPM 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 RESISTOR 15 0 kohm 1 125W 100PPM 1206 RESISTOR 47 ohm 190 0 1W 100PPM 0805 RESISTOR 47 ohm 190 0 1W 100PPM 0805 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 120 ohm 190 0 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 1 00 Mohm 1 0 125W 100PPM 1206 RESISTOR 1 50 kohm 1 0 125W 100PPM 1206 RESISTOR 470 ohm 196 125W 100PPM 1206 RESISTOR 120 ohm 1 0 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125
30. REF 5 m m m m m nooo m E nooo jam m o m m Fig 2 2 Connect the output of the signal generator to the HF input of the counter Required Test Equipment Suggested Specification HF signal generator 3 3 GHz Table 2 8 Test equipment for 3 0 GHz HF input Connect the output of the signal generator to the HF input of the counter Connect the 10 MHz REFERENCE OUT of the generator to the REFERENCE IN at the rear panel of the counter Setting for the counter after Preset Function FREQ C EXT REF Generate a sine wave in accordance with the following table Verify that the counter counts correctly The last digit will be unstable Frequency Amplitude Pass Fail MHz mVRMS dBm 100 300 20 21 2500 10 27 2700 20 21 3000 100 7 Table 2 7 Sensitivity of the PM9624 HF input Performance Check Options 2 5 This page is intentionally left blank 2 6 Performance Check Options Chapter 3 Disassembly The terms in the following figure are used in all descriptions in this manual Front Bottom Fig 3 1 Designations us
31. ROM IC112 RAM and R118 are not mounted IC107 IC108 are address latches and IC101 IC106 and IC117 use the latched address to gener ate chip select and chip enable signals for internal use on the GPIB board Fig 4 16 Analog output 4 14 Hardware Functional Description m Analog Out The result on the display can be converted to an analog signal by means of a pulse width modulated PWM signal from the micro processor The signal is filtered attenuated offset adjusted inte grated and buffered by IC103 and supporting passive components to give an analog DC level between 0 and 4 98 V with a resolution of 20 mV The analog output has a separate analog ground connected to the cabinet HF Input You can add an optional prescaler This HF input is mounted on the main board to the right of the input amplifier It is connected to J19 where there are three pins reserved for ID coding Preparations have thus been made for other prescalers with different prescaling factors m Prescaler 3 0 GHz PM9624 This prescaler cannot be repaired at a local workshop It must be sent to the factory for repair The prescaler consists of the following parts Limiter The limiter consists of a 6 dB attenuator and a PIN diode at tenuator to achieve constant input amplitude to the amplifiers Amplifier Five amplifier stages are divided into three blocks One block consists of one amplifier Two b
32. iG gE 1154 UE RIE E E U42 J7 O e 28 eleg R B e E r e e I f E J31 5 L 32 ABI ma a 8 a C l SE SBE Els 55 8 ExT 2 G 125 ale U4 873 874 el R53 R54 R56 880 L3 Lo ol E o Ra 05 85 e ka C77 Bs n 5 5 A P al 8013 fg RES 5247 124 BIg m RES a o E p 035 p 03 als sl gg 2523 5 R86 R79 Q c g 25118 029 E m Elsa E B SEES ma SIRI R77 n an E prep ge Jeo e S E Bm S E E 030 824 ane R69 589 276 el 51 158 159 cis 160161 148 cs asi Suse 18293 2121 E o D uo Eg El ma B s g Be Reg cud Sg L14 135 lt 18 D TN R318 E R306 R2971 930 031 166 Re06 R198 2 R E RI 2263 R70 Raa 1 praka 039513 sr des 03 kokan Ti Res SJ R Re ug ceg 176563 EL F e Re Do4 8 EI u9 Reed 2169 104 819 4 good LASIS n Lo jc x I Tum RIR BE ERE 8279 P E Je8 C46 RI ja R284 R275 R37 R92 R38 ug 4 R93 L _ BE HE n Teel 67 R33 R91 fee 1 c186 BG
33. 0 1250 R45 Resistor 1 00 1 0 1250 R46 Varistor 95V 95VRMS4 1J R47 Resistor 4 70 1 125W R48 Resistor 10 0 1 0 125W R49 Resistor 22 0 1 125W R50 Potentiometer 1 20 R51 Resistor 3 30 1 125W R52 Resistor 8 20 k2 1 125W R53 Resistor 470 1 125W R54 Resistor 470 1 125W R55 Resistor 2 7 5 0 25W R56 Resistor 100 Q 1 0 125W R57 Resistor 47 1 125W R58 Resistor 270 Q 1 125W TOI Transformer 001 IC ref 2 5V TL431I D 508 002 Optocoupler CNX82A V02 Transistor 0 50 BC807 25 V03 Transistor 0 50 A BC817 25 V04 Transistor 0 50 A BC817 25 V05 Transistor 0 50 A BC817 25 06 Transistor 0 50 A BC817 25 V07 Transistor 0 50 A BC817 25 VOS Transistor 0 50 A BC807 25 Part Number 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51003 4833 051 10478 4822 051 51003 4822 051 51004 4822 051 51004 4822 051 10109 4822 051 51002 4822 051 10278 4822 051 10278 4822 051 10278 4822 051 51002 4822 051 10109 5322 116 80426 5322 116 80426 4822 051 51002 5322 116 80426 5322 116 80426 4822 051 51002 5322 116 21222 5322 116 80445 4822 051 51003 5322 116 80435 4822 101 10792 4822 051 53302 4822 051 10822 5322 116 80447 5322 116 80447 4822 051 10278 5322 116 80426 5322 116 80448 4822 051 10271 5322 148 20035 5322 209 62422 4822 130 10025 5322 130 60845 4822 130 42804 4822 130 42804 4822 130
34. 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm CHOKE 482 3 5X6MM BANDAD 80ohm at 100MHz FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2A R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2A R 0 6ohm CHOKE 452 3 5X6MM BANDAD 80ohm at 100MHz FILTER EMI BLM21A102SPT Z 1Kohm 0 2A R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2A R 0 6ohm CHOKE 452 3 5X6MM BANDAD 80ohm at 100MHz FILTER EMI BLM21A102SPT Z 1Kohm 0 2A R 0 6ohm CHOKE 452 3 5X6MM BANDAD 80ohm at 100MHz CHOKE 10mH B82722 J2102 N1 LA CHOKE 10 00uH NEWPORT 18R103 CHOKE 10 00uH NEWPORT 18R103 CHOKE 33uH TSL0809 330K 1R2 TRANSISTOR 513 03A20V SOT23 TRANSISTOR 0 5 BC807 25 45V SOT23 TRANSISTOR 0 5A BC817 25 45 SOT23 TRANSISTOR BC847B 1A45V SOT23 TRANSISTOR BFG97 15V 50223 TRANSISTOR BC847B 1A45V SOT23 TRANSISTOR BC857B 1A45V SOT23 TRANSISTOR BC847B 1A45V SOT23 TRANSISTOR 0 5A BC817 25 45 SOT23 TRANSISTOR 25 MA BFR92A 20V SOT23 TRANSI NPN SMD BFG16A SOT223 1 5GHz 1W TRANSI NPN SMD BFG16A SOT223 1 5GHz 1W TRANSISTOR BFT92 25MA 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR BFT92 25MA 15V SOT23 TRANSISTOR 7 05A 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR 7 05A 15V SOT23 TRANSISTOR BSRI2 0 1A 15V SOT23 TRANSISTOR BSRI2 0 1A 15V SOT
35. 0X3 2 MOLD 5322 124 11418 C112 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C113 CAPACITOR 82 pF 5 50V NPO 0805 2222 861 15829 C114 CAPACITOR 100 pF 5 50V NPO 0805 2222 861 15101 C115 CAPACITOR TRIM 3 10 pF TZBX4Z100BB110 5322 125 50306 C116 CAPACITOR 47 pF 5 50V NPO 0805 2222 861 15479 C117 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C118 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C119 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C12 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C120 CAPACITOR 10 pF 5 50V NPO 0805 2222 861 15109 C121 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C122 CAPACITOR 680 pF 20 63V NPO 1206 4822 126 12075 C123 CAPACITOR 47 pF 5 50V NPO 0805 2222 861 15479 C124 CAPACITOR 100nF 20 25V X7R 0805 5322 126 13638 C125 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD 5322 124 10685 C126 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C127 CAPACITOR 1 nF 20 50V X7R 0805 5322 122 34123 C128 CAPACITOR 82 pF 5 50V NPO 0805 2222 861 15829 C129 CAPACITOR 6 8 pF 5 50V NPO 0805 2222 861 15688 C13 CAPACITOR 47 pF 5 50V NPO 0805 2222 861 15479 C130 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C131 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C132 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD 5322 124 10685 C133 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C134 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C135 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C136 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD 5322 12
36. 1 0 0 0 0 3 2 3 9 0 1 0 1 1 0 0 0 3 5 4 3 1 0 0 1 1 0 0 0 4 0 4 7 1 0 1 1 1 1 0 0 4 1 5 0 1 0 1 0 1 1 1 0 Table 6 8 NOTE There are also oscillators that do not have DIP switches If this is the case then the trimmer potenti ometer alone covers the whole adjustment range Reference Oscillators 6 5 Other Options HF Input 3 0 GHz PM9624 Fig 6 5 Test points and trimmers for the 3 0 GHz HF input NOTE Before beginning any adjustments the HF input must have been in operation for at least one minute to let it reach normal operating temperature m Setup PM6685 Function FREQ C Signal gener Frequency 800 25 MHz ator Amplitude 5 9 0 5 mVrms Table 6 9 Connect the counter to line power Switch on the counter Press PRESET then press ENTER Connect the signal generator to the HF input m Adjustment Turn the potentiometer R61 see Fig 6 5 fully counterclock wise Check that the GATE indicator stops blinking Turn R61 slowly clockwise until the GATE indicator starts blinking The input frequency 800 25 MHz will now be displayed To verify the 3 0 GHz HF input a sweep frequency synthesizer is needed Also refer to Chapter 2 Performance Check Options Prescaler 6 6 Other Options GPIB Interface PM9626B TE E BU103 080102 010 2 3
37. 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 124 10455 2222 037 90074 2222 037 90074 2222 861 15109 5322 122 34098 2222 037 90074 5322 122 34098 5322 122 34098 5322 122 34098 5322 124 11418 5322 124 11418 5322 122 32658 5322 122 32658 5322 126 13638 5322 124 10685 2222 861 15101 5322 122 34098 2222 861 15101 5322 124 11418 5322 124 11418 5322 126 13638 5322 126 13638 5322 126 13638 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 130 32076 5322 130 81917 Pos Description Part No D12 DIODE 0 10 A BAV99 SOT23 5322 130 34337 D13 DIODE 0 10 A BAV99 SOT23 5322 130 34337 D14 DIODE 0 10 A BAV99 SOT23 5322 130 34337 015 DIODE BYD17G 400V 1 5 0087 9338 122 40701 D16 DIODE 0 10A BAV99 SOT23 5322 130 34337 D17 DIODE BYD17G 400V 1 5A SOD87 9338 122 40701 D18 DIODE 0 10A BAV99 SOT23 5322 130 34337 D19 DIODE 0 10A BAV99 SOT23 5322 130 34337 D2 DIODE 0 10A BAT18 35V 1PF SOT23 D21 DIODE 0 10A BAV99 DIODE 0 10A BAV99 D23 DIODE 0 10A BAV99 DIODE 0 10A BAV99 D25 DIODE 0 10A BAV99 DIODE 0 10A BAV99 D3 DIODE 0 10A BAV99 D4 DIODE 0 10A BAV99 D5 DIODE 0 10A BAV99 D6 DIODE 1A 1N4003 200 D7 DIODE 1A SB140 40V D8 DIODE 1A SB140 40V D9 BRIDGE RECTIFIER 2KBP08 2A 800V F1 FUSE HOLDER 011 656 5X20mm F1 FUSE 1 6A 5X20 T FST034 3119 SOLDERING LUG 10 0X15 21 CU SN
38. 42804 4822 130 42804 4822 130 42804 5322 130 60845 This page is intentionally left blank Replacement Parts 9 9 Power Supply Component layout TOP SIDE 9 10 Replacement Parts Power Supply dq 001 cuva or ort a LORI LIK CON L 1808 i L Le OI oa s ANA gt 001 l jeu oUm ca La Br X 85 5 N NE ssull eet k 4 90 so uva EWEX L Z0d NOOL Kt K MOOI 3001 B WE c T TA 8ID 459000001 z fo 01 i cel el NOT xof 11 CODEN c ny ru doc 3 i Tm gt d assenar ANLE Arf 301 NO EE To 00 6 MARL ou i ser T o 4 K em 92 ga 24 SA KI gt D NOOL ASENA 5 oo 710 ce 000 16 MA ilm 002 8 gt Kt TOL Replacement Parts 9 11 PM6685R Introduction A Rubidium timebase is now available for the PM6685 Frequency counter This oscillator cannot be retrofitted in the standard version ofthe PM6685 Due t
39. 5 60 1 125W 100PPM 1206 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 560 ohm 194 125W 100PPM 1206 RESISTOR 15 0 ohm 195 125W 100PPM 1206 RESISTOR 1 00 Mohm 1 6 0 125W 100PPM 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 680 ohm 194 125W 100PPM 1206 RESISTOR 330 kohm 1 125W 100 1206 RESISTOR 220 kohm 1 125W 100PPM 1206 SENSOR TEMP KTY82 120 RESISTOR 180 kohm 1 125W 100 1206 RESISTOR 220 1 125W 100 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 47 ohm 196 0 1W 100PPM 0805 RESISTOR 120 ohm 196 0 1W 100PPM 0805 RESISTOR 470 kohm 1 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 680 ohm 1 0 125W 100 1206 RESISTOR 18 0 kohm 1 125W 100PPM 1206 RESISTOR 82 ohm 196 125W 100PPM 1206 Part No 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 5322 116 82262 4822 051 52202 4822 051 52202 4822 051 51003 4822 051 51003 4822 051 53301 4822 051 51003 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 51003 4822 051 56803 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 52203 4822 051 10569 4822 051 10569 4822 051 10569 4822 051 51003 4822 051 51003 5322 117 12506 5322 117 12506 4822 051 54702 4822 051 51003 4822 051 51001 4822 051 10822 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 10561 4822 051 52202
40. 51003 5322 116 82261 5322 117 12505 5322 117 12505 4822 051 51002 4822 051 10121 4822 051 51003 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51002 4822 051 10105 4822 051 51502 4822 051 54701 4822 051 10121 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 10121 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 53301 5322 116 82261 4822 051 52202 5322 116 30457 4822 051 52201 4822 051 51501 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 52201 4822 051 53301 5322 117 12506 4822 051 51003 4822 051 51501 4822 051 53901 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 Ro Rc c c c Gc c c qc p c KOS d ama A Das R166 R167 R168 R169 R17 R170 R171 R172 R173 R174 R175 R176 R177 R178 R179 R18 R180 R181 R182 R183 R184 R185 R186 R187 R188 R189 R19 R190 R191 R193 R194 R195 R196 R197 R198 R199 R204 R211 R217 R218 R244 RESISTOR 100 kohm 1 0 125W 100 1206 RESISTOR 100 kohm 195 0 125W 100PPM 1206 RESISTOR 100 kohm 195 0 125W 100PPM 1206 RESISTOR 100 kohm 195 0 125W 100PPM 1206 RESISTOR 27 0 ohm 196 125W 100PPM 1206 RESISTOR 2 20 1 125W 100PPM 1206 RESISTOR 2 20 kohm 1 125W 100PPM 1206 RESISTOR 10 0 ko
41. 55682 5322 209 60424 5322 209 71802 9322 187 55682 5322 209 60424 5322 209 71553 5322 693 22828 4822 209 62803 5322 209 14477 Ap A AA Am ld iii Su amo Sua Suk uku 1 3 1 8 3 c ae Re Pos Description 041 041 041 043 043 043 U44 05 050 U6 U7 U8 09 INSULAT PLATEP TO220 CLIP Sil Pad 400AC CLAMP TO220 IC 12V LM2940CT 12 TO220 INSULAT PLATEP TO220 CLIP Sil Pad 400AC CLAMP TO220 IC 1 50 ALM337T 220 IC CMOS 74HC125 SMD 8014 IC 532 DUAL SO 8 IC COMP MAX961 SOS 4 5ns IC 532 DUAL SO 8 532 DUAL 50 8 AD96687BP 20 IC DIG ECLIPS MC10E104 5322 466 61813 5322 401 11257 4822 209 62085 5322 466 61813 5322 401 11257 5322 209 81236 9337 569 90701 5322 209 71553 9322 194 34682 5322 209 71553 5322 209 71553 4822 201 62795 4822 209 31775 Z m m Z Parts Main Board 7 11 201 C202 D201 Description Connector row SG0 25x100x6 0x3 0 LCD Display LCD bezel Backlight LED Window LCD LED spacer LEDS1E 3 01 for led Rubber keypad Screw RX PT Z 2 28X8 FZB Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 LED 3 mm HLMP 1300 red gt 929 9 INSIDE GREEN PROTECTIVE FOIL MATTE OUTSIDE WHITE PROTECTIVE FOIL Front Board Part Number 5322 267 70294
42. C53 C54 C55 C56 C57 C58 C59 C6 C60 C61 C62 C63 C64 C65 C66 C67 C68 C69 C73 C74 C75 C76 C77 C78 C79 C8 C80 C81 C82 C83 C85 C86 C87 C88 C89 C9 C90 C91 C92 C93 C94 C95 C96 C97 C98 C99 D10 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 1 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 15 UF 2095 6 3V 6 0X3 2 MOLD CAPACITOR 2 20 nF PME289MA4220MR04 CAPACITOR 2 20 nF PME289MA4220MR04 CAPACITOR 270 uF 20 SMG 400V 25X45 CAPACITOR 100 nF 20 250V CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 68 uF 2
43. Circuit Descriptions m Bus Interface A simple method to check the most fundamental functions of the in terface is to send the standardized query message IDN and check the response string Setup Make sure you have access to a PC with GPIB capability Check that there is a program installed that can send simple commands entered via the keyboard and that can receive and display the response strings Connect the GPIB connectors of the counter and the PC by means of a standard GPIB cable Set the address switches on the counter the five rightmost ones seen from the rear so that their binary weight corre sponds to the wanted decimal value between 0 and 30 Send the command to the counter and observe the re sponse string See the programming manual for more information on the response format and contents You can also try the command OPT to get a listing of in stalled options except OCXO If you find a fault continue with traditional troubleshooting tech niques and replace defective circuits Try to exercise the address data bus by writing small program loops Look for stuck nodes with an oscilloscope Safety Inspection Test After Repair General Directives After repair in the primary circuits make sure that you have not re duced the creepage distances and clearances Before soldering bend component pins on the solder side of the board Replace insulating guards and pla
44. Press ENTER twice Set the measuring time to 10 s Connect the 10 MHz reference to the input A of the counter Adjustment procedure Remove the seal from the front panel Adjust the potentiometer beyond the seal until the display reads 0 5 Hz or less Check that the value is stable over time more than 30 min utes Cover the CALIBRATION ADJUSTMENT hole on the front panel with a relevant seal if necessary Replacement Parts Pos Description Part Number x Cover incl front part 5322 447 92194 P Fan 282203101327 R Text plate kit 403110062440 R Rear plate 4031100 53930 P AI Power supply 5322 214 91268 P DI LED HLMP 1300 red 5322 130 81921 L1 Toroid 5322 526 10545 L2 Toroid 5322 526 10545 L3 Toroid 5322 526 10545 PI P3 Cable kit 403110061530 P RI Potentiometer 1 5322 101 11298 R2 Resistor 3 83 1 0 5 W MRS25 4822 050 23832 NOTE The rubidium time base unit A2 must be sent to a Fluke service center for repair Follow the exchange procedure 9 14 Replacement Parts
45. STANDBY logic in the power supply UV Counter EPROM ASIC E r amp Data Bus LCD Drivers Fig 4 12 Microcomputer circuits block diagram 4 12 Hardware Functional Description The STAND BY button is connected to the ON STANDBY logic in the power supply The LOCAL PRESET button is connected directly to input pin 24 on the microcontroller U11 Pressing this button sends an interrupt to a special handler in the SW Rear Panel Unit The rear panel contains the following connectors INPUTS External reference input D REF IN BNC External arming input E EXT ARM BNC Power supply inlet including EMI filter OUTPUTS Internal reference output G 10 MHz OUT BNC If a GPIB interface is installed in the device it is mounted on the rear panel and connected to the main board with a flat cable Besides the normal standard GPIB connector this optional unit also has a BNC connector capable of outputting an analog representation of any three consecutive digits on the display There is also a 6 SPST DIP switch on this unit for setting the default GPIB address p o sns ON 168 42 1 IEEE 488 IEC 625 INT ER FACE OFF ADDRESS SH 1 T5 RI ANALOG OUT RL DG 071 E2 PRIMARY FUSE INSIDE OPM9621 906 9628 85 C BATTERY 1 6 BTLINE P M9623 PM9 678 P M9697 stupa m OpPM9624 990 12 24
46. There are also a number of ground pads on the PCB available for this purpose Test Points Voltage TP15 5 10 V 10 mV TP16 14 8 V to 21 V TP17 12 5 V to 7 5 V TP21 12 V 0 5 V Table5 4 Standby voltages NOTE If this vollage does not meet the above mentioned spec and if it is not possible to adjust it the output resistances of the module must be checked To verify the Power Module proceed as follows If the primary fuse is broken there is a short circuit in the primary circuits Use a DMM and try to locate the fault by resistance measurements Disconnect L and check the resistance between pin 1 and pins 4 and 5 on the power module The DMM should not show a short circuit Put 1 6 back Check that the DC voltage between pin 1 and pins 4 and 5 on the power module is about V2 times the input AC voltage If not use traditional troubleshooting tech niques to locate the fault Remove the power cable from the counter Measure the resistances according to the table below Test Pins Resistance GND and TP15 5 V 100 GND TP16 15 V 21 5 GND and TP17 7 V 270 Table 5 5 Output resistances If one of the above mentioned measurements shows 0 remove L7 L8 and L9 and use conventional troubleshoot ing techniques to isolate the fault Measure the resistances according to the
47. USF 1 e 12 ee M 4 4 8 888 z 97 usc usc u2B usc 482 3 5X6MM R59 R58 R61 R62 R64 R65 R67 R68 gt gt fa Not used 120 220 Notused 1k 10K 2 2K _ Notused 215100 NES32D apup za Most gom 27665 096687 C37 C38 ca cao i e 10E104 PER 100nF 10n 6 8u 16V Lp 52 5 2 5 2L Drawings amp Diagrams 8 9 This page is intentionally left blank 8 10 Drawings 8 Diagrams ower Supply PCB 1 sheet 4 5
48. all necessary initialization at power up It also does the power up tests See Power On test in chapter 2 The Handlekeyboard procedure controls all user input output via the front panel except displaying the measurement results The PresetDevice procedure reprograms the complete device when the PRESET key has been pressed in local mode It aborts pending measurements The ExecuteGpibCommands procedure executes GPIB commands and if a query is received it starts the response formatter and sends the requested data to the GPIB interface If the display is switched on the results are also displayed The RestartMeasurement procedure aborts pending measure ments the measure loop will later continue to measure This is mainly used when the RESTART key is pressed The Measure procedure is the measurement control loop that is used in local mode It sends its result to the display The ParseGpibInputData procedure parses the GPIB messages found in the input buffer and sends executable statements to the ExeceuteGpibCommands procedure The input of data to the input buffer from the external GPIB interface is fully controlled in inter rupts These interrupts are always enabled so the new data bytes can be stored in the input buffer while parsing commands This ParseGpibInputDat is also executed in interrupt Software Functional Description 4 15 Test Routines Test Routines via AUX MENU Key The test routines are the routines accessible
49. are no short circuits or unsoldered leads 9 2 How to Replace Surface Mounted Devices Electrostatic discharge Almost all modern components have extremely thin conductors and metal oxide layers If these layers are exposed to electrostatic dis charge they will break down or perhaps even worse be damaged in a way that inevitably will cause a breakdown later on The lectro tatic Discharge ESD sensitivity of MOS and CMOS semiconductors have been known quite a while but nowadays bipolar semiconduc tors and even precision resistors are ESD sensitive Consider therefoe all components pc boards and sub assemblies as sensi tive to electrostatic discharge The text below explains how you can minimize the risk of damage or destroying these devices by being aware of the problems and learning how to handle these compo nents ESD sensitive options are packed in conductive containers marked with the symbol to the leftl Never open the container unless you are at an ESD protected work station Use a wrist strap grounded via a high resistance Use a grounded work mat on your work bench Never let your clothes come in contact with ESD sensitive equipment even when you are wearing grounded wrist strap Never touch the component leads Never touch open connectors Use ESD safe packing materials Use the packing material only once Keep paper and non conductive plastics etc away from your work bench These may block the discharg
50. capaci tor is A D converted and the value is added to the result There are two interpolators one for the start event and one for the stop event They are calibrated over the possible error pulse range to allow for any aberrations from the theoretical linear behavior Oscillator Circuits m CPU Oscillator The microcontroller U11 is clocked at 12 MHz The crystal is connected to the XTAL inputs of the microcontroller m Reference Oscillators A 10 MHz crystal oscillator is used as the reference for the measur ing logic If a stable external 10 MHz reference is available it can be connected to REF IN on the rear panel and selected by means of the EXT REF button on the front panel In addition to the standard crystal oscillator there are two optional oven controlled crystal oscillators OCXO to choose from Standard The uncompensated standard oscillator consists of the crystal B2 C109 C113 C115 R209 and R211 C115 is used for manual adjust ment of the frequency when the calibration tolerance has been ex ceeded The active circuitry is built into the ASIC U29 and is accessi ble via the pins marked X1 and X2 OCXO If one of the OCXOs is mounted the standard oscillator has to be in activated by moving the jumpers J23 and J25 to their alternative po sition These oscillators are connected to J24 and are self contained Hardware Functional Description 4 11 units with facilities for coarse and fine adjustment They
51. high speed integrated comparators and USB plus a separate trigger level circuit connected to the comparators at pins 9 and 13 via resistors R87 and R88 The trigger level circuits which are described later generate a DC level in the range of approximately 1 6 V This covers a dynamic range of 6 4 V since the input signal is divided by a factor of 2 before it reaches the comparator The counter is provided with adjustable hysteresis i e it is control lable via the front panel or GPIB The circuitry for setting the hyster esis consists of the resistor network R91 to R96 supplied with 5 V and 5 2 V It is connected to the latch enable inputs of the compara tor pin 5 and 7 for Comparator I and pin 17 and 15 for Comparator II The input signal is fed to both comparators the outputs of which are used for setting resetting the Flip Flop U9 m Buffer Stage Before the signal is fed further into the ASIC U29 it has to be level shifted by a buffer stage The negative ECL logic levels 0 9 V to 1 7 V from U9 pins 17 and 18 are converted to a single ended signal with CMOS logic levels 5 V to 0 V The buffer is a differential amplifier consisting of the two transistors Q32 and Q33 whose bases are fed differentially from the two com parator outputs Resistor R304 serves as a current generator that is switched alternately to the two collector resistors R296 and R297 Trigger Level Circuits The trigger lev
52. m Secondary circuits For secondary circuits see Chapter 5 Repair Power Supply Safety Inspection and Test After Repair m General Directives After repair in the primary circuits make sure that you have not re duced the creepage distances and clearances Before soldering component pins must be bent on the solder side of the board Replace insulating guards and plates VI Gate W3 pin7 RC 3 2 1 Fig 9 10 Typical curves of the power supply Safety Components Components in the primary circuits are important to the safety of the instrument and may be replaced only by components obtained from your local Fluke organization Check the Protective Ground Connection Visually check the correct connection and condition and measure the resistance between the protective lead at the plug and the cabinet The resistance must not be more than 0 5 Q During measurement the power cord should be moved Any variations in resistance shows a defect Calibration Adjustments Required Test Equipment Type Performance DMM 3 5 digits Table 9 3 Required Test Equipment Preparation WARNING Live parts and accessible terminals which can be dangerous to life are always exposed inside the unit when it is connected to the line power Use extreme caution when handling testing or adjust ing the counter Before beginning the calibration adjustments power up t
53. sec ond year For part time and low ambient temperature use you can ex tend this service interval to 6 10 years or more Additional informa tion can be found in Chapter 9 Appendix Preventive Maintenance 5 3 Troubleshooting General Quick Troubleshooting The PM6685 is a highly integrated Frequency counter with dedicated LSI counter circuits and microcontrollers that control the complete units The microcontroller can help you locate faulty parts by run ning test programs and generating stable signal patterns on t he bus If microcontroller does not work or the fault is in a part of the counter that cannot be accessed by the microcontroller tradi tional troubleshooting must be performed Where to Start After reading the safety instructions continue with this chapter for troubleshooting and repair instructions When you have fixed the in strument always do the Safety Inspection and Test after Repair as described later in this Chapter Then do the checks in Chapter 2 Per formance Check Recalibrate if required by following the adjustment instructions in chapter 6 Calibration Adjustments Logic Levels The PM6685 contains logic of four families The levels for these families are listed in the following table Positive Negative CMOS TTL ECL ECL Supply voltage 5 V 5 2 5 5 Signal ground OV OV 0 OV Input voltage High gt 3 9 V gt 11 gt 4 gt 2V Low VIL 3
54. switched off within lt 6 minutes after connection to line power Connect a 10 MHz reference signal to input A of the counter Select FREQUENCY A measurement Select 1 s measuring time Check that the displayed frequency is 10 00000000 MHz 1 LSD lt 6 minutes after connection to line power Functional Description The oscillator is supplied with 24 V from the extra power supply The oscillator generates a stable 10 MHz output frequency from a 20 MHz Voltage Controlled Crystal Oscillator VCXO whose fre quency is locked to the atomic standard resonance frequency of the rubidium atom see Fig 9 14 Frequency multiplier Synthesizer x Detector Rubidium Gol l lamp MN Rubidium cell 20 MHz Voltage tunable Feedback DC correction Quartz Oscillator be electronics voltage VCXO Servo 10 MHz output Fig 9 14 Block diagram showing the principle of Rubidium Atomic Standard A microwave signal that is derived from the VCXO tunable oscillator is applied to rubidium vapor contained within a heated glass cell Light from a rubidium lamp is passed through the cell and illluminates a photo detector causing current to flow in the detector As the applied microwave signal approaches the frequency that cor responds to the ultra stable rubidium atomic resonance frequency the rubidium light entering the glass cell is absorbed by
55. table below Test Pins Resistance 10 11 and 13 14 150 2 8 and 9 1 5 6 and 7 270 Table 5 6 Output resistances If the resistances deviate considerably from the values in the table the complete power module must be replaced Move jumper J16 to the CONNect position Connect the power cable to the counter Switch the counter ON Check the POWER ON voltages Test Points Voltage TP23 5 06 V 30 mV TP20 5 2 V 50 mV TP22 7 V 100 mV Table 5 7 Power on voltages NOTE the 5 V voltage is outside the specification all other levels will be wrong since they are based on the 5 V level If you find any fault continue with traditional troubleshooting tech nigues and replace defective circuits Also refer to Power Supply in Chapter 4 Circuit Descriptions Troubleshooting 5 5 Oscillator SS J27 Optional OCXO 5 Coarse adjust mm Fine adjust E O 924 D O ey U29 A 81 31 923 025 MN Optional oscillator EI Standard oscillator m C115 Fig 5 4 Trimmers for the reference frequency oscillators m Standard Oscillator Be sure the jumpe
56. the STAND BY LED that is fed by the uninterruptible 12 V 5 V also indirectly controls the fan in the PM6685R Itisa 12 V DC fan that operates only if 12 V is on An NTC resistor serving as a 4 10 Hardware Functional Description temperature sensor controls the speed by applying a variable refer ence voltage to the fan voltage regulator U42 Counter ASIC The main part of the counting logic is integrated in a CMOS ASIC specially designed for the Fluke MultiFunction Counter series There are also analog blocks included in the 100 pin QPF package MUX The MUX block is a switchboard for incoming and internal signals involved in the measuring process Some signals are divided by 2 to make it possible to measure higher frequencies The trigger slope is controlled by the MUX block as well A trigger edge detector senses the presence or absence of comparator pulses and controls the trigger level DAC s in the TLDAC block These functional units form an es sential part of the Auto Trigger System OSC The oscillator block generates selects and distributes the reference clock for the circuit The active semiconductors ofthe standard oscil lator are included in this block The crystal is connected to pins X1 and X2 A TCXO or OCXO is connected to X2 only An external ref erence clock is connected to EXTREF The PWM signal generated at OTRIM controls the frequency ofthe reference oscillator after exter nal integration PG
57. the power module from the main PCA and check the resistance between pin 1 and 4 on the transformer see Fig 9 9 If the DMM shows a short circuit the fault is proabably a broken transistor V01 Put the power module back Connect the counter to the line power via an insulating trans former with separate windings Set the counter to STAND BY mode Check that the voltage between J9 and J10 is in the range of 90 to 260 VAC Check that the DC voltage between pin 1 and 4 on TOI is about V2 times the input AC voltage If not use traditional faultfinding techniques to locate the fault Disconnect the secondary load by moving the jumper J16 to its alternative position Check the STAND voltages according to Table 9 2 Test points Ground Voltage 003 pin 11 8 12 003 pin 8 10 to 13 5 V 003 pin 14 003 pin 8 5 0 V V01 source U03 pin 8 10 mV 002 pin 1 Amplifier Screen 18 2 U01 pin 1 Amplifier Screen 4 4 V TP15 Amplifier Screen 5 1 V TP16 Amplifier Screen 14 8 V to 21 V TP17 Amplifier Screen 12 5 V to 7 5 TP21 Amplifier Screen 12 V 20 5 Table 9 2 Stand by voltages Restore the jumper J16 to its normal position Check the waveforms in Fig 9 10 at the corresponding testpoints in Fig 9 9 to verify the primary circuits Use the heat sink of V01 as ground NOTE U01 and U03 are located at the bottom side of the PCA
58. the rubidium va 99 gt 90 to LINE I J3 260 2 j t 1 SAFETY EARTH 5 FILTER C 910 gt 14 AUXPOWER A1 SUPPLY P2 por to an increased extent causing a decrease in the photo detector current This darkening effect is used to generate an error signal which permits continuous regulation of the quartz crystal oscillator output frequency thereby locking it to the frequency of the atomic standard Calibration Adjustments NOTE Before Calibration Adjustment the Rubidium time base must have been in operation for more than 24 hours Required Test Equipment Type Performance Model 10 MHz reference lt 1x10710 Calibrated Rubidium oscillator or Cesium atomic standard Table 9 5 Required test equipment Setup Connect the counter to the line power Press PRESET then ENTER Press AUX UNIT 1 D1 UNLOCKED ES RUBIDIUM 2 B OSCILLATOR 33 TYPE LPRO FREQ 1 24 ADJUST R1 2 25 7 20 pe QNO 27 28 R2 29 3 83k P1 2C p1l M 23 N 24V 4 G4 24V 5 210 Fig 9 13 Wiring diagram showing the interconnections between the Rubidium timebase its power supply and the PCA Calibration Adjustments 9 13 Select NULL by pressing A V
59. the start up voltage to the control cir cuit U03 U03 outputs a frequency of 120 kHz on OUT pin 10 to the switch transistor V01 When the switch transistor has started U03 will be supplied from the transformer 01 pin 3 via the diodes 009 Every switch pulse causes a voltage drop over the resistors R35 R37 and R55 This voltage feeds the SENSE input pin 5 of the control circuit U03 When the voltage has reached the internal reference level in 003 the switch transistor V01 is turned off VOS is a blanking transistor that will compensate for high transients generated by the transformer T01 The internal sawtooth generator RC pin 7 in 003 is connected to the SENSE input via V03 to compensate for low load The regulated 5 V is sensed by 001 and adjusted by R50 The out put of 003 is connected to the VF input pin 3 of 003 via the optocoupler U02 The VREF pin pin 14 outputs a reference voltage of 5 V DC m Secondary circuits For secondary circuits see Chapter 4 Circuit Descriptions Power Supply 02 pin 2 D01 gt 02 pin 7 D04 P01 pin 1 P01 pin485 R24 R27 SENSE RG VREF 4 T01 R31 R32 p09 V01 E 2 pin 5 8 6 P02 pin 1 4 8 amp 9 gt 2 pin 3 Fig 9 8 Power supply module primary c
60. via the AUX MENU key Refer to the PM6685 Operators Manual Power On Tests At power on some tests are automatically performed If any of these tests fails an error message is displayed and the instrument is halted Pressing the LOCAL PRESET key makes the device continue inde pendently ofthe detected error but without performing the next tests in the start up sequence The following tests actions are performed Write 001 to internal test pins Pulse all microcomputer i o ports twice Write 0 1 on display Write 0 1 2 on display and 010 on test pins Test mC internal RAM error Err mC amp halt Write 0 1 2 3 to display and 011 on test pins Test mC timer error Err mC amp halt Write 0 1 2 3 4 on display and 100 on test pins Test main board RAM error Err ra amp halt Write 0 1 2 3 4 5 to display and 101 to test pins Test ASIC error Err 5 amp halt Write 110 on test pins Check display light all segments for 2 s Clear Display Perform GPIB RAM test if GPIB is installed error Err ra amp halt Write 111 on test pins final value Clear display and start normal measurement procedure 4 16 Software Functional Description Chapter 5 Calibration To maintain the performance of your counter we recommend that you calibrate your instrument every year or more often if greater time bas
61. warm up period of 48 hours To check the accuracy of the oscillator you must have a calibrated reference signal that is at least five times as stable as the oscillator that you are testing see the following table Press the PRESET key then press the ENTER key to set your counter in the Default setting Performance Check Short Form Specification Test 2 3 Connect the reference to input A Check the readout against the accuracy requirements of your application m Acceptance Test As an acceptance test the following table gives a worst case figure after a 30 minute warm up time All deviations that can occur in a year are added together Oscillator Frequency readout Suitable refer Pass ence Fail Standard 10 00000000 MHz PM9691 120 Hz PM9691 10 00000000 MHz 1 Hz PM6685R PM9692 10 00000000 MHz PM6681R 20 25 Hz Table 2 5 Acceptance test for oscillators m Acceptance Test PM6685R To fully test the accuracy of the PM6685R a reference signal of ex tremely high stability is needed Examples of such references are Cesium Atomic references or transmitted signals from a nationally or internationally traceable source like the GPS satellites Recommended Test Equipment Type Stability Model 10 MHz refer lt 1x10 910R with satellite contact dur ence ing the last 72 hours Test Procedure Connect the counter to the line po
62. 0 input impedance Frequency A measurements m Adjustment The oscillator has a voltage controlled adjustment range This range 15 divided into five fixed steps set via DIP switches a trimmer to fine tune the control voltage CRYSTAL OSCILLATOR MODEL xxxxxxx FREQ 10 MHz SIN Trimmer for fine tuning Switches for coarse adj Fig 6 4 Adjusting the optional oscillator frequency Normally the range of the trimmer should be sufficient to compen sate for the aging that occurs during at least two years of operation Fine adjustment Adjust the trimmer to better than 10 MHz 0 2 Hz PM9691 10 MHz 0 05 Hz PM9692 i e 20 resp 5 in the last two digits on the PM6681R PM6685R display If this adjustment is OK reassemble the counter Coarse adjustment Make this adjustment only if the trimmer range is insufficient to ad just the oscillator Remove the tape from the DIP switch Adjust the trimmer to its mid position about 12 turns from ei ther end position Read the frequency on the PM6681R PM6685R Nominal 10 000000 MHz If the frequency is too low set the DIP switches to the next higher voltage range If the frequency is too high set the DIP switches to the next lower voltage range Trimmer range V DIP switch number 1 on 0 off 1 2 3 4 5 6 7 8 26 34 0 0 0
63. 0 6 3 V SOLID AL CAPACITOR 33 uF 20 63 RADIAL 2M 6 3x11 CAPACITOR 33 uF 20 63V RADIAL 2M 6 3x11 CAPACITOR 10 pF 5 50V NPO 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 33 uF 20 63 RADIAL 2M 6 3x11 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 22 pF 5 50V NPO 0805 CAPACITOR 22 pF 5 50V NPO 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD CAPACITOR 100 pF 5 50V NPO 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 pF 5 50V NPO 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 15 UF 2095 6 3V 6 0X3 2 MOLD CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 DIODE 0 10A BAT18 35V SOT23 DIODE IA 58140 40V DO41 Part No 5322 122 34098 5322 122 34098 5322 122 34098 5322 126 13638 5322 122 34098 5322 124 11418 5322 122 34098 5322 122 34098 5322 122 34098 5322 124 10685 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 126 13638 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34123 5322 126 13638 5322 124 11418 5322 121 43756 5322 121 43756 5322 124 80334 2222 336 20104 5322 122 34098 5322 122 34098 5322 122 34098 5322
64. 0 0 125W 100PPM 1206 POTENTIOMETER 100 kohm 3304X 1 104 7 10 Replacement Parts Main Board Part No 4822 051 52201 5322 117 12505 5322 117 12505 5322 101 10841 4031 002 27090 5322 117 12497 5322 117 12497 4822 051 10569 5322 117 12506 5322 116 82264 4822 051 52202 4822 051 52201 4822 051 52201 4822 051 10569 5322 116 80447 4822 051 10569 4822 051 10109 4822 051 10109 5322 117 12505 5322 117 12505 5322 117 12497 5322 117 12497 4031 002 27090 5322 117 12506 5322 100 11143 5322 117 12505 5322 117 12505 5322 117 10034 4822 051 54701 4822 051 54701 4822 051 51502 4822 051 51002 4822 051 10106 4822 051 52204 5322 117 12505 4822 051 52201 4822 051 10159 5322 117 12497 5322 116 80448 5322 117 12505 4822 051 51501 4822 051 51501 4822 051 10829 5322 117 12497 4822 051 52204 4822 051 10828 4822 051 52702 4822 051 52202 4822 051 10561 4822 051 10561 4822 051 53901 5322 116 82261 4822 051 10121 5322 116 80448 4822 051 54702 4822 051 52201 4822 051 10682 4822 051 51002 4822 051 51003 4822 051 54702 4822 051 52202 5322 101 10841 4822 051 10121 5322 101 10841 E fa Lc cM i d cL a P m c f f c e ci a Pos Description R71 RESISTOR 100 kohm 196 0 125W 100PPM 1206 R72 RESISTOR 100 kohm 1 0 125W 100PPM 1206 R73 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R74 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R75 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R76 RESISTOR 10 0 kohm 196 0 125W 10
65. 00 k 1 1 8W 100PPM 1206 Resistor 100 k 1 1 8W 100PPM 1206 Part Number 5322 267 10004 5322 255 44217 4822 530 80082 5322 502 21489 5322 502 21644 4822 530 80173 5322 321 61341 5322 267 60148 5322 122 34098 5322 122 34098 5322 122 34098 4822 122 33575 4822 122 33496 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 5322 124 10455 4822 209 63475 5322 209 71553 5322 209 71802 5322 209 60424 5322 209 60424 5322 255 41141 5322 209 51853 9322 106 65682 9322 023 60682 5322 209 81807 5322 209 81842 5322 209 60424 5322 209 71562 5322 116 80446 5322 116 80446 4822 051 54702 5322 101 11095 4822 051 51003 4822 051 53301 5322 100 11143 4822 051 53302 4822 051 51001 4822 051 51001 4822 051 51002 4822 051 51004 4822 051 51004 Ene e gs uv uuu uuu nr DA pm io R114 R115 R116 R117 SK101 D Resistor 100 k 1 1 8W 100PPM 1206 Resistor 100 k 1 1 8W 100PPM 1206 Resistor 100 k 1 1 8W 100PPM 1206 Resistor 100 k 1 1 8W 100PPM 1206 DIP switch 6 p 206 6 RAST Part Number 4822 051 51004 4822 051 51004 4822 051 51004 4822 051 51004 5322 277 21125 Replacement Parts GPIB Interface PM9626B 7 13 This page is intentionally left blank 7 14 Replacement Parts GPIB Interface PM9626B Chapter 8 Drawings 8 Diagr
66. 05 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 470 nF 10 25V X7R 1210 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 2090 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 6 80 UF 20 16V 6 0X3 2 MOLD CAPACITOR 3 3 pF 0 25pF 50V NP0 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 Part No 5322 122 34098 5322 124 11418 5322 124 11418 5322 126 13638 5322 126 13638 5322 124 11418 5322 126 13638 5322 126 13638 5322 126 13638 5322 126 13638 5322 124 10685 5322 122 34098 5322 124 11418 5322 126 13638 5322 126 13638 5322 122 34098 5322 122 34098 5322 126 13638 5322 126 13638 5322 124 10685 5322 122 34098 5322 126 13638 5322 126 13638 5322 126 13638 5322 126 13638 5322 126 13638 5322 126 13638 5322 122 34098 5322 126 13638 5322 122 34098 5322 126 13638 5322 126 13638 5322 126 13638 5322 124 11418 5322 124 11418 5322 122 34098 2222 809 05217 5322 122 34123 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 2222 861 15109 2222 861 15109 5322 122 34098 5322 122 34098 5322 126 13638 5322 126 14081 5322 126 13638 5322 122 34098 5322 122 34098 5322 122 34098 5322 122 34098 4822 126 12549 5322 126 13638 5322 126 13638 5322 122 34098 5322 124 10687 2222 861 15338 5322 126 13638 5322 122 34098 Pos Description C42 C44 C45 C46 C47 C48 C49 C5 C50 C51 C52
67. 0PPM 1206 R77 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R78 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R79 RESISTOR 10 0 kohm 196 0 125W 100PPM 1206 R8 RESISTOR 120 ohm 1 0 125W 100PPM 1206 R80 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R81 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R82 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R83 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R84 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R85 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R86 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 R87 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R88 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R89 RESISTOR 68 ohm 1 125W 100PPM 1206 R9 RESISTOR 120 ohm 1 0 125W 100PPM 1206 R90 RESISTOR 68 ohm 1 125W 100PPM 1206 R91 POTENTIOMETER 100ohm CVR 4A 101 R92 RESISTOR 8 20 kohm 196 125W 100PPM 1206 R93 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R94 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R95 RESISTOR 3 30 kohm 196 125W 100PPM 1206 R96 RESISTOR 1 80 kohm 196 125W 100PPM 1206 R98 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R99 RESISTOR 100 ohm 1 0 1W 100PPM 0805 Ul IC OP AMP CA3140AM CA3140 AM BIMOS 508 010 TL7705BCD SMD LOW VOLT DETECT U11 IC MICROP N80C196KB10 U12 IC PROM 24LC16B 16 I2C SMD 08 U13 PC74HC574T 5020 014 IC PC74HC573T 5020 015 IC PC74HCOT 50 14 016 IC PC74HC573T 5020 017 IC PC74HC573T 5020 018 IC PC74HC2IT 5014 019 PC74HCOOT 5014 02 PC74HC574T 5020 020 PC74HCI38T 016 021 NE532D DUAL 50 8 022 IC S
68. 100 01 Hz 1 Vpp square wave The counter should read 100 0xxxxxx Hz Check that the output voltage is 500 mV 5 mV Chapter 7 Replacement Parts Introduction Standard Parts Electrical and mechanical replacement parts can be obtained through your local Fluke organization or representative However many of the standard components can be obtained from other local suppliers Before purchasing or ordering replacement parts check the parts list for part number value tolerance rating and description Ifthe value ofthe physical component differs from what is described in the parts list you should always replace the part with the same value as originally mounted Standard parts are unmarked or marked with 5 in the column of the parts lists Special Parts In addition to standard electronic components the following special components are used 7 2 Replacement Parts Introduction Components that are manufactured or selected by the manufac turer to meet specific performance requirements Components that are important for the safety of the instrument Both types of components may be replaced only by components ob tained through your local Fluke organization NOTE Physical size and shape of a component may af fect the performance of the instrument particularly at high frequencies Always use direct replacements un less it is known that a substitute will not degrade the performance o
69. 122 31765 4822 122 32482 4822 122 31784 4822 122 31784 4822 122 33496 4822 122 33496 4822 122 33496 5322 126 13131 5322 126 13131 5322 124 80821 4822 122 31746 4822 122 33496 4822 122 33496 4822 122 33496 5322 126 13129 5322 130 32328 5322 130 83602 5322 130 32328 5322 130 33764 5322 130 80255 4822 130 60815 5322 130 80212 5322 130 33764 5322 130 80212 5322 130 80212 5322 130 80255 5322 130 33764 4822 051 10829 4822 051 10829 4822 051 10271 4822 051 51003 5322 116 80434 4822 051 51002 4822 051 10182 5322 116 80443 5322 116 80446 5322 116 80436 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 P P Pos Description R17 Resistor 10 0 1 0 125W R18 Resistor 10 0 1 0 125W R19 Resistor 10 0 1 0 125W R20 Resistor 10 0 1 0 125Q R24 Resistor 100 1 0 125W R25 Resistor 100 1 0 125W R26 Resistor 100 1 0 125W R27 Resistor 100 1 0 125W R28 Resistor 10 0 1 0 125W R29 Resistor 4 7 10 0 25W R30 Resistor 10 0 1 0 125W R31 Resistor 100 1 0 125W R32 Resistor 100 1 0 125W R33 Resistor 10 0 Q 1 0 125W R34 Resistor 1 00 1 0 125W R35 Resistor 2 7 5 0 25W R36 Resistor 2 7 5 0 25W R37 Resistor 2 7 Q 5 0 25 W R38 Resistor 1 00 1 0 125W R39 Resistor 10 0 2 1 0 125W R40 Resistor 100 Q 1 0 125W R41 Resistor 100 Q 1 0 125W R42 Resistor 1 00 1 0 125W R43 Resistor 100 Q 1 0 1250 R44 Resistor 100 Q 1
70. 158 segments that are multiplexed with a ratio of 2 1 Two parallel and synchronized LCD drivers U201 and U202 are used They are connected with a serial bus to the microcomputer on the main board The clock frequency of the drivers is approxi mately 140 kHz set by R201 The VLCD pin is connected to GND on the main board The LCD is provided with a backlight an LED array integrated into one component Its current consumption is set by the resistors R204 R207 The backlight dissipates approximately 1 5 W 4 4 Hardware Functional Description Keyboard Main Board Keyboard amp Display Board AD0 AD7 LOCAL PRESET SCL SDA Fig 3 Keyboard scanning The front panel pushbuttons are connected in a matrix The scanning signals HO to H3 come from the main board If a push button is pressed and to H3 is high one of the output signals VO to V7 will be high The STAND BY ON and LOCAL PRESET buttons are not part of the scanning but are connected directly to the main board The front unit is fixed to the main board unit with three screws The electrical connection is made with a 40 lead flat cable to the main board Main Board Introduction Components not necessary for explaining the function are omitted from the figures in this chapter For the complete set of components see the circuit diagrams in Chapter 8 Drawings and Diagrams Input Amplifier The input amplifier has
71. 2 R23 e 4 4 at 100 470K 220K 220K AK m usc 1 Re 02 839 R100 C20 1 amp pia 68K R24 R27 AN 10M JK 02 ATOK 470K 3 3pF zy BFRe2A AD96687BP EIS R44 Ring MiniCoax 3 4 4 013 100 REED R25 BFG97 R50 A REED 470K R36 A 1 K3A 470 47 K4B KAA la R28 BAV99 Q3 8 2 5 24 470K A ha BFS17 R105 4 i R26 alle 1K 1 1 R19 470K 52 22K R92 220uH T 82K R7 R9 R13 R15 HH R40 R41 5 2 4 24 120 120 120 120 150 47 220 R46 R49 1 R20 150 100 c31 8 2K R34 10n pa R33 k ne 4 4 R91 R93 R8 R10 R12 R14 Ris 10K 4 Q4 100 47 R98 120 120 120 120 150 1 1 18K 5 2 ha BFR93A I 10n Not used 5 2 c19 199 7 10n 10n 10n T 1 10n 4 4 05 R94 UE ble R37 saves 10n 47 10n EN L I al amp amp R11 DAN At 100 10E104 JL 210 Tae 014 R47 R48 15 R95 150 82 10n 3 3K R29 R32 R38 TE R99 22K 470K 1K in 21 Not used M R96 1 8K 98 U9B 1 R30 52 2 2 1 470K 2 5 3 amp R109 42 E S 7 100 02104 021 TE 066 C68 R31 10 bus 10 K3B in iook REED REED REED i2 E T i USA 1 L g L lt i q a 2 i amp 6 c22 C24 4 AD96687BP 10n 10n 10n 10n 108104 R110 R112 d R114 R106 R107 100 100 100 100 100 JL 21 24 24
72. 2 ST FZ DIN6798A Screw MRT KOMBI 3X08 STFZ Screw MRT KOMBI 3X10 STFZ Spring Washer KBA 3 2 ST FZ DIN137 Cable Assy Connector 24pin 57LE 20240 7700D35G Capacitor 10 nF 20 50 X7R 0805 Capacitor 10 nF 20 50 X7R 0805 Capacitor 10 nF 20 50 X7R 0805 Capacitor 220 pF 5 50V NPO 0805 Capacitor 100 nF 10 63V X7R 1206 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 10 nF 20 50V X7R 0805 Capacitor 68 uF 20 6 3V SOLID AL IC PC74HC32T 5014 IC NE532D DUAL SO 8 IC PC74HCOOT 014 IC PC74HC573T SO20 IC PC74HC573T SO20 IC socket 32pin P N 213 032 602 IC PROM PM9626B IC SRAM TC55257DFL 85L SOP28 32Kx8 IC DIG UPD7210D IEC BUS GPIB CONTROLLER IC SN75160AN IC SN75161AN IC 74 573 5020 IC PC74HC86T SO 14 Resistor 47 k 1 1 8W 100PPM 1206 Resistor 47 k 1 1 8W 100PPM 1206 Resistor 4 7 k 1 1 8W 100PPM 1206 Potentiometer 1k 3304X 1 102E Resistor 10 k 1 1 8W 100PPM 1206 Resistor 330 1 1 8W 100PPM 1206 Potentiometer 10 k 25 0 1W 3304X 1 103 Resistor 3 3 k 1 1 8W 100PPM 1206 Resistor 100 1 1 8W 100PPM 1206 Resistor 100 1 1 8W 100PPM 1206 Resistor 1 k 1 1 8W 100PPM 1206 Resistor 1
73. 23 TRANSISTOR BFS17 05A 15V SOT23 TRANSISTOR BFS17 05A 15V SOT23 TRANSI HE SMD BFR93A 35mA 12V SOT23 TRANSISTOR BCP51 1 5A 45V SOT223 TRANSISTOR BC847B 1A45V SOT23 TRANSISTOR 0 5A BC807 25 45V SOT23 RESISTOR 47 ohm 1 0 125W 100PPM 1206 RESISTOR 120 ohm 1 0 125W 100PPM 1206 RESISTOR 27 ohm 196 0 1W 100PPM 0805 Replacement Parts Main Board Part No 2422 549 43133 2422 535 94048 2422 549 43133 2422 549 43133 2422 549 43133 2422 549 43133 2422 549 43133 2422 549 43133 5322 157 61928 2422 549 43133 2422 549 43133 2422 549 43133 5322 157 61928 2422 549 43133 2422 549 43133 5322 157 61928 2422 549 43133 5322 157 61928 5322 157 70143 2422 536 00061 2422 536 00061 5322 157 53568 4822 130 60686 5322 130 60845 4822 130 42804 4822 130 60511 4822 130 63069 4822 130 60511 5322 130 60508 4822 130 60511 4822 130 42804 5322 130 60647 9340 022 10701 9340 022 10701 5322 130 44711 5322 130 40781 5322 130 40781 5322 130 44711 5322 130 40781 5322 130 40781 5322 130 40781 5322 130 40781 5322 130 40781 5322 130 44743 5322 130 44743 5322 130 40781 5322 130 40781 5322 130 60705 5322 130 62639 4822 130 60511 5322 130 60845 5322 116 80448 4822 051 10121 4031 002 27090 x Pos Description R101 R105 R106 R107 R108 R109 RII R110 R111 R112 R113 R115 R116 R117 R118 R119 R12 R121 R122 R123 R124 R125 R126 R127 R128 R129 R13 R130 R131 R132 R133 R134 R135 R136
74. 23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 SOT23 5322 130 34337 DO41 4822 130 31878 DO41 5322 130 81917 DO41 5322 130 81917 5322 130 50474 4822 256 30139 4822 253 30024 4031 100 58390 5322 267 10004 5322 290 34064 5322 265 44074 5322 263 50101 5322 263 50101 5322 290 60445 5322 321 60669 5322 265 41051 5322 265 41013 5322 263 50101 5322 290 60445 5322 263 50101 5322 290 60445 5322 263 50101 5322 290 60445 5322 265 64028 5322 263 50101 5322 290 60445 5322 263 50101 5322 290 60445 5322 290 34064 5322 263 50101 5322 290 60445 5322 265 51296 5322 290 34064 5322 290 34064 5322 290 34064 5322 265 44074 5322 290 34064 5322 280 20489 5322 280 20489 5322 280 20489 5322 280 20514 5322 280 60557 5322 157 61918 2422 549 43133 2422 549 43133 Replacement Parts Main Board 7 7 Pos Description L12 L13 L14 1 15 L16 L17 L18 L19 L2 L20 L21 L22 L23 L24 L25 L3 L4 L5 L6 17 L8 L9 Ql 010 012 Q13 014 015 016 017 02 Q24 Q27 Q28 Q29 Q3 Q30 Q31 Q32 Q33 Q34 Q35 Q36 Q37 Q38 Q39 Q4 Q5 Q6 Q7 RI RIO R100 7 8 FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm CHOKE 4 70uH 5 LOHINAR7J FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm 0 2 R 0 6ohm FILTER EMI BLM21A102SPT Z 1Kohm
75. 2506 4822 051 52201 Replacement Parts Main Board c A c PI c c c c c c Acc a 0 A c cc o d RED t 7 9 Pos Description R306 R307 R309 R31 R310 R311 R312 R313 R314 R315 R316 R317 R318 R319 R32 R320 R321 R322 R323 R325 R326 R327 R328 R329 R33 R330 R331 R34 R35 R36 R37 R38 R39 R4 R40 R41 R42 R43 R44 R45 R46 R47 R48 R49 R5 R50 R51 R53 R54 R55 R56 R57 R58 R6 R60 R61 R63 R64 R65 R66 R67 R69 R7 R70 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 47 ohm 1 0 1W 100PPM 0805 POTENTIOMETER 100 kohm 3304X 1 104 RESISTOR 27 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 56 ohm 1 125W 100PPM 1206 RESISTOR 120 ohm 1 0 1W 100PPM 0805 RESISTOR 820 ohm 190 125W 100PPM 1206 RESISTOR 2 20 kohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 1 125W 100PPM 1206 RESISTOR 470 kohm 190 125W 100PPM 1206 RESISTOR 56 ohm 1 125W 100PPM 1206 RESISTOR 10 0 ohm 196 0 125W 100PPM 1206 RESISTOR 10 0 ohm 196 0 125W 100PPM 1206 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 27 ohm 1 0 1W 100PPM 0805 RESISTOR 120 ohm 1 0 1W 100PPM 0805 POTENTIOMETER 10 kohm 3304X 1 103 RESIST
76. 3 Drawings amp Diagrams How to read the diagrams 8 2 Appendix How to Replace Surface Mounted Devices 9 2 Electrostatic discharge 9 3 ipae bue wr wa hare 9 4 Power Supply Switchmode Module 9 5 Circuit Descriptions 9 5 ed Reba edhe os 9 6 Calibration Adjustments 9 7 Replacement 9 8 6685 9 12 Introduction nd EE RARES 9 12 P rformance Check Pak ee beds 9 12 Functional Description 9 12 Calibration Adjustments 9 13 Replacement Parls 9 14 This page is intentionally left blank Chapter 1 Safety Instructions WARNING These servicing instructions are for use by qualified personnel only To reduce the risk of electric shock do not perform any servicing other than that specified in the Operating Manual unless you are fully qualified to do so Authorized service and calibration of this instrument is available through your Fluke representative See address at the end of this manual Read this chapter carefully before you check adjust or repair an in strument Caution and Warning Statements You will find specific warning and caution statements where neces sary throughout the manual CAUTION Indicates
77. 300 MHz bandwidth and is of the split band type It contains four main stages the signal adaptation stage the im pedance converter stage the comparator stage and the buffer stage m Signal Adaptation This part of the amplifier contains 50 impedance selector 1 11 attenuator Voltage limiter 50 Q 1 MQ Impedance Selector R22 R23 Fig 4 4 Impedance selector and 1X 11X attenuator The 50 Q or 1 impedance modes are selected by relay 50Q is selected via the resistors R7 to R17 if the relay is closed 1 is Trigger level Comp LP filter selected if the relay is open Depending on selected attenuation the 1 MQ input impedance is determined by different combinations of resistors Inx attenuation mode K2 is closed and K3 is open the impedance is determined by resistor network R22 to R28 Inx attenuation mode K2 is open and K3 is closed the same net work as in the x case is involved plus the resistors R3 to R5 and R18 to R20 The input capacitance in parallel with 1 MQ is 24 pF at x attenua tion and 12 pF atx attenuation The series resistor R1 immediately after the selector serves both as current limiter together with the voltage limiter see below and as impedance matching resistor The resistor also improves the Volt age Standing Wave Ratio VSWR of the amplifier input x1 x11 Attenuator The x attenuator consists of a resistive l
78. 4 11418 C138 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C139 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD 5322 124 11418 C14 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C140 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 41 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C142 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C143 CAPACITOR 100 nF 20 25V X7R 0805 5322 126 13638 C145 CAPACITOR 390 pF 5 50V NPO 0805 4822 122 32636 C146 CAPACITOR 10 pF 5 50V NPO 0805 2222 861 15109 C148 CAPACITOR 470 pF 1 63V NPO 0805 5322 126 14051 C149 CAPACITOR 22 pF 5 50V NPO 0805 5322 122 32658 C15 CAPACITOR 10 nF 20 50V X7R 0805 5322 122 34098 C150 CAPACITOR 390 pF 5 50V 0805 4822 122 32636 C151 CAPACITOR 10 pF 5 50V NPO 0805 2222 861 15109 C153 CAPACITOR 470 pF 1 63V NPO 0805 5322 126 14051 C154 CAPACITOR 22 pF 5 50V NPO 0805 5322 122 32658 7 6 Replacement Parts Main Board Pos Description C155 C156 C157 C158 C159 C16 C160 C161 C162 C163 C164 C165 C166 C167 C168 C169 C17 C170 C171 C172 C173 C174 C175 C176 C177 C178 C179 C18 C180 C181 C182 C183 C184 C185 C186 C19 C2 C20 C21 C22 C23 C24 C25 C26 C27 C28 C29 C30 C31 C32 C33 C34 C35 C36 C37 C38 C39 C4 C40 Cal CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD C
79. 470 kohm 1 125W 100PPM 1206 R270 RESISTOR 8 20 kohm 1 125W 100PPM 1206 R271 RESISTOR 820 ohm 1 125W 100PPM 1206 R272 RESISTOR 2 20 1 125W 100PPM 1206 R273 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R274 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R275 RESISTOR 2 20 kohm 1 125W 100PPM 1206 R276 RESISTOR 33 0 1 125W 100PPM 1206 R277 RESISTOR 33 0 1 125W 100PPM 1206 R278 RESISTOR 220 0 ohm 1 125W 100PPM 1206 R279 RESISTOR 8 20 kohm 1 125W 100PPM 1206 R28 RESISTOR 470 kohm 1 125W 100PPM 1206 R280 RESISTOR 820 ohm 1 125W 100PPM 1206 R281 RESISTOR 2 20 1 125W 100PPM 1206 R282 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R283 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R284 RESISTOR 2 20 1 125W 100PPM 1206 R285 RESISTOR 33 0 1 125W 100PPM 1206 R286 RESISTOR 33 0 1 125W 100PPM 1206 R287 RESISTOR 0 ohm JUMPER RC 01 1206 R288 RESISTOR 68 ohm 1 125W 100PPM 1206 R288 RESISTOR 33 0 ohm 195 125W 100PPM 1206 R289 RESISTOR 220 ohm 1 0 1W 100PPM 0805 R29 RESISTOR 22 0 kohm 1 125W 100PPM 1206 R290 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R291 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R292 RESISTOR 0 ohm JUMPER RC 01 1206 R293 RESISTOR 330 ohm 1 125W 100PPM 1206 R294 RESISTOR 27 ohm 196 0 1W 100PPM 0805 R295 RESISTOR 270 ohm 1 125W 100PPM 1206 R296 RESISTOR 220 0 ohm 1 125W 100PPM 1206 R297 RESISTOR 220 0 ohm 1 125W 100PPM 1206 R298 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R3 RESISTOR 4
80. 5 V 15V lt 1 lt 0 8 Output voltage High VoH 214 V gt 1 V 24349 V 242 7 V Low VOL lt 3 3 V 1 7 V lt 0 05 lt 0 4 V Bias ref voltage VBB 3 7 V 1 3 V Table 5 2 Logic levels 5 4 Troubleshooting Required Test Equipment To test the instrument properly using this manual you will need the equipment listed below The list contains specifications for the criti cal parameters Type Performance DMM 3 5 digits Oscilloscope 300 MHz 2 channel Signal generator 3300 MHz Power supply 12 V 2 A BNC BNC 50 2 cables RG 58 Table 5 3 Required test equipment PROM Identification There are two different PROMs in the PM6685 one on the main PCB containing the instrument firmware the other on the optional GPIB board containing the interface bus firmware They have labels with version designation of the traditional form Vx yz where x y and z are digits The last digit can be followed by a single letter The version numbers do not have to coincide except for the last letter So the combination Vr stE and Vu vwE is valid whereas Vr stE and Vu vwF is not Operating Conditions Power voltage must be in the range of 90 to 260 VAC Introduction GPIB Level 10 INPUT AMPLIFIE R Levd 9 D ACONVERTERS Levd 8 MEASURING LOGIC Level7 KEY BOARD Level6
81. 63V Tr 33uF 63V m 2 2nF 2 2nF POWER MODULE 10n 10n 10n 10n 4 T A T 4 4 4 4 4 R155 Ris4 R153 R152 R151 R150 R149 330 220 220 220 220 220 220 To Rubidium 14 ESE m SAFETY EARTH SIGNAL GROUND R130 R131 R132 R133 R134 R135 R136 R137 R139 R140 R141 R142 R143 R144 R145 220 220 220 220 220 220 220 220 220 220 220 220 220 220 330 1 2 R128 1 5K TP20 C82 15uF 6 3V R198 R196 43 R129 52 4 7K 120 REGA H 470 KSB d 1 U21A x 13 Ir T D 52 Mu LM337T BCB17 25 120 UH2V NE532D 5 6K U40A z U21B 4 82 uzic SZ gt 7 C104 R207 C105 HEF4013BT NE532D al gt 5 10n 1K P C106 xl Ton HEF4013BT NE532D Drawings amp Diagrams 8 11 This page is intentionally left blank 8 12 Drawings 8 Diagrams Interpolators PCB 1 sheet 5 5
82. 70 kohm 1 125W 100PPM 1206 R30 RESISTOR 470 kohm 196 125W 100PPM 1206 R300 RESISTOR 47 ohm 1 0 1W 100PPM 0805 R301 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R302 RESISTOR 100 ohm 1 0 1W 100PPM 0805 R303 RESISTOR 27 ohm 196 0 1W 100PPM 0805 R304 RESISTOR 120 ohm 1 0 1W 100PPM 0805 R305 RESISTOR 220 0 ohm 1 125W 100PPM 1206 Part No 4822 051 53902 5322 116 82264 4822 051 56801 5322 117 12505 5322 116 80447 4822 051 51002 4822 051 51001 4822 051 10561 4822 051 51003 5322 117 12497 5322 117 12497 4822 051 56801 5322 116 80447 5322 117 12505 5322 117 12497 4 4 4 4 4 4 4 4 4 4 4 4 4 4 822 051 10109 4822 051 51002 822 051 52201 822 051 51002 822 051 51002 5322 117 12497 822 051 51002 822 051 52201 5322 116 80447 822 051 10822 5322 116 82264 822 051 52202 5322 117 12505 5322 117 12497 822 051 52202 822 051 53303 822 051 53303 822 051 52201 822 051 10822 5322 116 80447 5322 116 82264 822 051 52202 5322 117 12505 5322 117 12497 4822 051 52202 4822 051 53303 4 4 4 4 4 4 4 4 4 822 051 53303 822 051 10008 822 051 10689 4822 051 10339 031 002 22010 822 051 52203 5322 117 12497 5322 117 12505 822 051 10008 4822 051 53301 4031 002 27090 822 051 10271 822 051 52201 822 051 52201 5322 117 12505 5322 116 80447 5322 116 80447 5322 117 12505 5322 117 12497 5322 117 12497 4031 002 27090 5322 117 1
83. 78 C150 i4 8 1D4 55 gave 11220 390 tj 9 46 0 ADE rd pao 65 DB9 247 H ADS L NT H amp 5V lt cs U34B ADC1061 4 e j d HC573 n 2 s BFT92 amp 2 22K 47 10 RS Pd 100 C154 R284 T 2 l D24 1 L BAV99 T 225 220 ou Hco0 BAV99 as BFS17 4 R286 33k 33K 12 5 ne amp 43 HC00 5 120 R287 12V gt 1 gt 12 0 BLM21A102S ussc EX R288 gt NE532D TORRE C155 10n m R289 220 R290 AREE L18 100 m 5ADC NE532D C162 C163 BLM21A1028 Wii 100nF foo T 22uF 6 10n 47 C156 C157 88 uate C158 159 88 9358 ctet Wmmm 15UF 6 3V 15uF 6 3V 7958 ADC1061 100nF 100nF gt 5 ADC1061 100nF 100nF e R292 t E E 169 10n Lig ge U388 gt D gt 5J 5 2 R294 z z amp amp BLM21A1028 tH 27 89 99 82 u32B 99 c112 88 u44E 2 2 2 2 2 4 85 ton 156 55 ion SO hcs73 ton 26 125 que 0166 C168 NE532D C170 C171 mm 0172 n 15uF 6 3V 167 2 2uF 6 3V 100nF 100nF 0173 R295 100nF 100nF 5 10n 270 Drawings amp Diagrams 8 13 Display amp Keyboard PCB Component layout
84. 88 2 2 uF gives a pulse of ap proximately 30 ms 010 also controls the reset pulse during power up so that the microcontroller will be initiated correctly m Keyboard Scanning Main Board Keyboard amp Display Board ADO AD7 wi U14A Latch a ADO AD7 LOCAL PRESET SCL SDA Fig 4 13 Keyboard scanning The keyboard scanning is done in two modes The first mode is ac tive as long as no button has been detected as depressed Then all out puts of U13A are set high and the latch U14A is read If no button has been depressed all outputs are low This check is done at every timer interrupt in the microcontroller every 25 ms If a button is depressed one of the output bits is high When this event is detected mode two is entered The outputs of U13A must be set high one after the other to find the specific button When found only this button will be checked so other simultaneously depressed buttons will not be recognized The depressed button must stay down for several timer interrupts before action is taken After the button has been rec ognized the timer interrupt SW will be waiting for the button to be released The button must be released for several timer interrupts be fore the keyboard scanning returns to mode 1 Then the search for other activated buttons can be resumed The following three buttons are not scanned in this way The ON button is connected to the ON
85. 911 RAM error 0 1 2 3 0 1 1 Er uC timer er Replace 911 TOT 0 1 2 3 4 1 0 0 RAM error Replace U22 0 1 2 3 4 5 1 0 1 Err ASIC error Replace U29 All seg 1 1 0 ments 1 1 1 JErrrA GPIB RAM Replace U111 on error GPIB board Test OK Table 5 8 Start up test If you find any fault continue with traditional troubleshooting tech niques and replace defective circuits Also refer to Chapter 4 Circuit Descriptions NOTE Check that activity is going on at U11 pin 62 ALE pin 61 RD pin 63 INST and pin 43 READY These pins should not be stuck HIGH or LOW If one or more bits on the AD bus are corrupt the microcontroller uC often reads the same instructions re peatedly When the uC discovers an invalid OP code it will RESET itself and start from the beginning again The uC sets the RESET input low when it resets itself This can be discovered at the RESET input of U11 pin 16 If 5 V to U10 is OK this could be the cause of trouble Input Amplifier m A Input Check DC levels Switch on the counter Press LOCAL PRESET and ENTER Deselect AUTO and set the sensitivity to 1 Vrms Measure the DC voltages according to Fig 5 5 Use the DMM with a 10 resistor in series with the test cable AC levels Connect a 1000 Hz sine wave signal with an amplitude of 1 Vpp to Input A Measure the AC levels according to F
86. A built in pulse generator having the 10 MHz clock as a reference can generate pulses with controllable duration and repetition rate at the OUTPUT connector The level is fixed TTL RTC A real time clock not used at present TLDAC This block contains two 10 bit DAC s generating the trigger levels for the input comparators VOUTA for channel A and VOUTB for channel B An external reference voltage is connected to V REFA and V REFB HO The Hold Off block can manipulate the internal measuring signal X in several ways One operating mode simulates a low pass filter nor mal hold off another mode is used in burst measurements The following blocks SYNC STST CNTS and MCTRL form the actual measuring logic in the ASIC Three types of measurements can be made in this MEAS block Continuous measurements frequency ratio and period average Not used at present Controlled measurements time interval period single pulse width frequency totalize gated totalize start stop and ratio Totalize manual SYNC The SYNC block synchronizes the actual measurement with certain internal or external events like measuring time and arming signals STST The start and or the stop of the measurements are controlled by this block External events can be used to define the exact moments BURST vcco GNDD1 GNDD2 GNDD3 GNDD4 TIME IM REF FREQ PGARM PGTRIG GET x x2 V REFO OTRIM V REFO EXTREF MTCXO
87. APACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 2 20 UF 20 6 3V 3 2X1 6 MOLD CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 15 UF 20 6 3V 6 0X3 2 MOLD CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR TRIM 2 0 18 pF 300V CAPACITOR 1 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 pF 5 50V NPO 0805 CAPACITOR 10 pF 5 50V NPO 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 10 nF 20 50V X7R 0805 CAPACITOR 100 nF 20 25V X7R 0805 CAPACITOR 22 nF 10 200V X7R 1206 CAPACITOR 100 nF 20 25V X7R 08
88. C Setting B 20 mV div 10 1 probe DC Table 6 3 Adjust C2 X1 until both signals on the screen look as alike as possible without any overshoots or undershoots The level displayed on the CRO B channel for Pin 10 of 08 is mately 1 2 Vpp x11 Attenuator m Setup PM6685 Impedance 50 Sensitivity Any level above 2 8 Vrms Pulse generator Amplitude 5 Vpp Period 100 us symmetrical Oscilloscope Time 10 us div Setting A 0 5 V div 50 Q DC Setting 5 mV div 10 1 probe DC Table 6 4 Adjust C1 X11 until both signals on the screen look as alike as possible without any overshoots or undershoots Input Amplifier 6 3 Observe that the level displayed on the CRO B channel for Pin 10 of 08 is now approximately 120 mVpp indicating that the x11 Attenuator has been selected Trigger Levels m Setup PM6685 Impedance 50 2 Sensitivity 10 mV rms Table 6 6 Disconnect all input signals to the counter m Zero levels Channel A Connect DMM to test points TRIG LEVEL COMP I and GND screen Adjust R69 ZERO ADJ COMP I until the DMM reads 0 95 0 05 mV Connect the DMM to test points TP11 TRIG LEVEL COMP II and GNDescreen Adjust R70 ZERO ADJ COMP II until the DMM reads 0 95 0 05 mV Sensitivity m Setup Measure the DC voltage between test po
89. DC 9625 991 10MHz OUT FIN EXT ARM Fig 4 14 Rear panel Hardware Functional Description 4 13 Optional Units GPIB Interface Including Analog Output m GPIB PM9626B 1C101 106 117 1C107 108 Basic board 1C109 110 1C114 115 E connector 1C111 112 IC116 5y MEE Fig 4 15 GPIB interface The GPIB interface controls the communication between the internal microprocessor and the external GPIB bus A 32K extension of the ROM and RAM is placed on the interface board An analog output is also included The PCB is connected to J18 on the main board with a ribbon cable and fixed to the rear panel with two screws Two metal studs at the rear edge of the PCB are inserted in slots on the main board in order to relieve mechanical stress The GPIB control circuit IC113 communicates with the external GPIB bus via the bidirectional bus drivers IC114 and IC115 IC113 is controlled from the microprocessor by writing and reading in the in ternal control registers If IC113 has a message for the microproces sor it uses the GPIB interrupt signal The address switch setting is read by the microprocessor via IC116 A 32K extension of both ROM IC109 and IC110 and RAM IC111 and IC112 is placed on the interface board The circuit board is pre pared for a 16 bit extension but only 8 bits are used IC110
90. Descriptions Block Diagram Description 4 2 General crese das pa buen ELA Rene 4 2 Hardware Functional Description 4 4 FOIE DIE eg or een Er nt sus EO ees 4 4 Main Board 28e 4 5 Rear Panel 2225224 5 onn 4 13 Optional UMIS 4 14 Software Functional Description 4 15 Test Routines 4 16 Repair Preventive Maintenance 5 2 canes hase sae es 5 2 When to Replace the Fan PM6685R Ru mega 5 3 Troubleshooting 5 4 Generals du Bl EL 5 4 Safety Inspection and Test After Repair 5 9 General Directives 5 9 Calibration Adjustments Introduction bor 6 2 Pr paration past 6 2 Power Supply risipi s e dans rema 6 2 Input sex ah em Dre 6 3 Reference Oscillators 6 4 Other Options 6 6 Replacement Parts Introduction 7 2 Mechanical 7 3 Main Board DOR Eb Sub etd 7 6 Front Board anit asus es ne dass 7 12 GPIB Interface 9626 7 1
91. Display and keyboard board IC Type 0201 PCF8576 U202 PCF8576 s218 5221 8216 5219 2202 208 s215 s207 s214 s206 s213 5205 s212 s204 s211 5208 s210 s202 s209 s201 5222 5223 8221 ly D201 E201 8 14 Drawings amp Diagrams Display amp Keyboard PCB 2 U201 DISPDR 13 BP0LZ 1 MAIN BOARD 2 4 v2 V3 V4 V5 V6 edm I 1 1 1 18 I 19 P204 21 P204 23 P204 25 P204 27 P204 29 P204 31 P204 33 P204 9218 FILTER IMP TRIG LVL AUTO SENS SENS 5421 5201 5202 5203 204 205 206 207 208 55 2 gt gt ats o TC TE gt 57 ps 26 MEASRESTART DISPHOLD NULLOFFSET BLANKDIGITS DATAENTRYUP DATAENTRYDN ENTER 12 59 5209 5210 521 S212 S213 5214 5215 VLCD 510 Hi 4 gt s13 P204 FUNCTION FUNCTION MEAS TIME MENU AUX MENU SINGLE 514 RM 8216 S217 218 219 220 221 6 SYNC 91525 2 2 51654 7 R201 6 5175 H2 gt I L 0S 818 P204 220k 519 87 SCL 50441 lt gt SDA 52505 0201 326 STAND 28 5 9274 R BYIND P204 HLMP K150 540 32 0202 1 53048 i YELLO
92. O PO 0 ACH PO 1 ADO P3 0 ACH2 P0 2 AD1 P3 1 8 8 8 ACH3 P0 3 AD2 P3 2 ACH4 P0 4 AD3 P3 3 ACHS PO 5 ADAIP3 A B 8185 8195 887 Ree Ries ACH6 PO 6 5 ACHTIPO 7 AD6 P3 6 ADR gt AD7 P3 7 t P1 0 08 4 0 P14 DATA lt gt Apg p4 1 2 AD10 P4 2 AD11 P4 3 P14 AD12 P4 4 5 AD13 P4 5 AR 0 7 P1 6 AD14 P4 6 P17 AD15 P4 7 AD 0 15 TDX P2 0 HSLO RDX P2 1 HSI 1 lt CARRY1 EXTINT P2 2 HSO 4 HSI 2 CARRY 2 AD 0 15 T2CLKIPL3 lt gt 5 5 m T2RST P2 4 112 PWM P2 5 HSO 0 J13 ALE 26 HSO 1 4 27 HS0 2 RD HS0 3 vss TEST SIGNALS WRL vss vss TMH 108 01 L DW DISABLE STANDBY TO PRESCALER 80C196KB ENA EXT REF E U12A a S LOBATT Fm STAND v IND A1 amp 2 Y as Q15 BC857B ED gt gt csRLY 24LC16B EEPROM R171 R170 22K 22 DACMUX WAITSTATE gt gt BACKLIGHT 2 J17 gt gt csa 27C512 90JC U12B 24LC16B 3e 5 x CSKEYBOARD Y2 va Ya U 12V Y5 Ye gt gt cspac lt STAND gt csasic CSKEYBO CSKEYBOARDIN R161 R162 2163 6164 R165 R166 R167 R168 _ 1 100K 100K 100K LJ 100K L10
93. OR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 18 0 kohm 196 125W 100PPM 1206 RESISTOR 470 ohm 190 125W 100PPM 1206 RESISTOR 470 ohm 190 125W 100PPM 1206 RESISTOR 1 50 kohm 196 0 125W 100PPM 1206 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 10 MOHM 10 0 25W RC 01 1206 RESISTOR 220 kohm 190 125W 100PPM 1206 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 15 0 ohm 196 125W 100PPM 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 47 ohm 1 125W 100PPM 1206 RESISTOR 47 ohm 1 0 1W 100PPM 0805 RESISTOR 150 ohm 190 0 125W 100PPM 1206 RESISTOR 150 ohm 190 0 125W 100PPM 1206 RESISTOR 82 ohm 1 125W 100PPM 1206 RESISTOR 100 ohm 1 0 1W 100PPM 0805 RESISTOR 220 kohm 190 125W 100PPM 1206 RESISTOR 8 2 ohm 10 0 25W RC 01 1206 RESISTOR 2 70 kohm 196 125W 100PPM 1206 RESISTOR 2 20 kohm 196 125W 100PPM 1206 RESISTOR 560 ohm 190 125W 100PPM 1206 RESISTOR 560 ohm 190 125W 100PPM 1206 RESISTOR 390 ohm 190 125W 100PPM 1206 RESISTOR 15 0 kohm 1 125W 100PPM 1206 RESISTOR 120 ohm 1 0 125W 100 1206 RESISTOR 47 ohm 1 125W 100PPM 1206 RESISTOR 4 70 kohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 6 80 kohm 196 125W 100PPM 1206 RESISTOR 1 00 kohm 1 0 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 RESISTOR 4 70 kohm 1 125W 100PPM 1206 RESISTOR 2 20 kohm 196 125W 100PPM 1206 POTENTIOMETER 100 kohm 3304X 1 104 RESISTOR 120 ohm 19
94. PWM signal that is applied to pin 1 on U101 The freguency is approximately 20 Hz but the duty cycle is dependent on several factors like the frequency of the measured sig nal the measurement time and the selected scaling factor The PWM signal is converted to a DC voltage between 0 V and 4 08 V by integration first in a passive RC network R101 C103 R102 C102 and then in an active integrator U103 5 8 Troubleshooting Setup Connect the counter to line power Switch on the counter Press PRESET and then ENTER Connect a DMM to the BNC output BU102 Activate the analog output Select AUX MENU Press DATA ENTRY A W until the display reads ANA LOG OUT Press ENTER Press DATA ENTRY A V to select ON Press ENTER Press DATA ENTRY A V until the display reads 1 0 V Press ENTER Connect a LF synthesizer to Input A on the counter Set the synthesizer to 500 Hz 1 Vpp Read the DMM result The voltage should be 2 49 V 35 mV Minor deviations can depend on the settings of the trimmer potenti ometers for ZERO and FULL SCALE See Chapter 6 Calibration Adjustments for a decription of the procedure to follow Large deviations indicate a fault Trace the signal through the inte gration chain with traditional troubleshooting techniques and replace defective circuits The duty cycle at U101 1 should be 50 Also re fer to GPIB Interface Including Analog Output in Chapter 4
95. Proerammable Frequency Counter 6685 amp PM6685R FLUKE This is complementary service manual covering instruments with manufacturing numbers exceeding 840684 The principal differences are to be found in Chapter 7 and in Chapter 8 due to a major redesign of the main PCB Do not dispose of the previous edition identified by the part number 4822 872 25012 and the publishing date June 1996 You may have to refer to it for information on older instruments as well as options not mentioned here 4822 872 20106 First Edition May 2003 No part of this manual may be copied without the express permission of the copyright owner All product names are trademarks of their respective companies 2003 Pendulum Instruments AB All rights reserved Printed in Sweden 1 2 4 5 Contents Safety Instructions Performance Check General Information 2 2 Recommended Test Equipment 2 2 Front Panel Controls 2 2 Short Form Specification Test 2 3 Rear Input Output 2 4 Measuring Functions 2 4 2 5 Disassembly Removing the Cover 3 2 Reinstalling the 3 2 PM9624 HF 3 2 PM9626B GPIB Interface 3 3 PM9691 or PM9692 Oven Oscillator 3 3 Circuit
96. RAM TC55257DFL 85L SOP28 32Kx8 023 IC PROM PM6685 27C512 023 IC SOCKET 32 POL P N 213 032 602 024 IC PC74HC32T 5014 025 IC PC74HC32T 5014 026 IC CMOS 74HC10 5014 50 14 027 IC DIG ECL 100331QC 3XDFLIP FLOP PCC28 U28 IC BUS TRANSCEIV 75ALS176D SO 8 SMD U29 IC ASIC U3 PC74HC4353T 5020 030 PC74HCOOT 5014 U31 IC OMV ADC 10 ADC1061C1WM 5020 U32 IC PC74HC573T SO20 U34 IC PC74HCOOT 5014 035 IC OMV ADC 10 ADC1061C1WM 5020 U36 PC74HC573T SO20 U38 NE532D DUAL 80 8 U39 POWER MODULE U4 IC 8 BIT PM7528HPC 20 U40 IC HEF4013BT 5014 Part No 4822 051 51004 4822 051 51004 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 10121 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 4822 051 51003 5322 117 12497 5322 117 12497 4822 051 10689 4822 051 10121 4822 051 10689 5322 101 10989 4822 051 10822 5322 117 12505 5322 117 12505 4822 051 53302 4822 051 10182 5322 117 12497 5322 117 12497 9322 114 39682 5322 209 90426 5322 209 52203 9322 186 14682 4822 209 60451 5322 209 60424 5322 209 71563 5322 209 60424 5322 209 60424 5322 209 60437 5322 209 71802 4822 209 60451 5322 209 73178 5322 209 71553 9322 106 65682 5322 209 31776 5322 255 41141 4822 209 63475 4822 209 63475 9337 142 80653 5322 209 33604 5322 209 33171 5322 209 90513 4822 209 62805 5322 209 71802 9322 187
97. S confirm by pressing the ENTER key Press the ENTER key once more The counter does not measure Connect a pulse generator to Ext Arm input Settings for pulse generator single shot pulse amplitude TTL 0 2 and duration 10 ns Apply one single pulse to Ext Arm input The counter measures once and shows 10 MHz on the display Measuring Functions Preparation for Check of Measuring Function is as follows Connect a 10 MHz sine wave signal with 2 0 V pp amplitude via a T piece to Input A Connect a cable from the T piece to Input E Ext Arm at the rear Select the measuring function as in the Selected Function col umn and check that the counter performs the correct measure ment by displaying the result as shown under the Display column in the following table Selected Function Display Pass Fail PRESET DEFAULT ENTER 10 MHz IMP A 50 2 10 MHz 2 Non AUTO 10 MHz PER A 100 ns RATIO A E 1 0000000 PWIDTH A 50 ns TOT A MAN DISPLAY HOLD Start counting DISPLAY HOLD Stop counting DUTY FACT 0 500000 AUTO 0 500000 Table 2 6 Measuring functions check 1 Value depends on the symmetry of the signal 2 Exact value depends on the input signal Options Prescaler This extra HF input PM9624 is easily recognized by its front panel connector Input C type N EXT
98. W S31 IND 204 CQV13 6 C M 36 53461 204 Ed 35 56 AX P204 PCF8576 82 8180179 6751747312 7117069 1686766 651646316261 605915857 5655 545315251 504948 47 4645 4443 22 5V 0 00000000 STAND BY JR204 R205 R206 RU STAND 26 5223 10 10 50 BY c 10 U202 4142 11213 41516 7 8 911011 1213 1415 1617 18 19 20 2122 230405 28 129130131132 133 34 35136 37138 3940 204 DISPDR LOCAL PRESET apo B7 1 7 Locau 38 8224 ad PRESET P204 BP3 17 5118 18 52 BAck P204 L S4 LIGHT 20 A 55 S7 P204 D203 58 TEMP 37 01100 T 59 gt 510 204 511 4 513 21039 CLK 3 P204 ISYNC 15 5V 146121416 30 6 S17 5V OSC S18 P204 519 IC TYPE GND 5V S20 8 19119094 U201 PCF8576 11789 5 10 521 P204 U202 PCF8576 1178910 5 2 GND SCL 23 SDA 525
99. W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 120 ohm 1 0 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 330 ohm 190 125W 100PPM 1206 RESISTOR 15 0 kohm 196 125W 100PPM 1206 RESISTOR 2 20 kohm 1 125W 100PPM 1206 THERMISTOR 16 0 9 20 3 5A 5236 16 RESISTOR 220 0 ohm 1 125W 100PPM 1206 RESISTOR 150 ohm 190 0 125W 100PPM 1206 RESISTOR 220 0 ohm 196 125W 100PPM 1206 RESISTOR 220 0 ohm 1 RESISTOR 220 0 ohm 1 RESISTOR 220 0 ohm 1 RESISTOR 220 0 ohm 1 125W 100PPM 1206 125W 100PPM 1206 125W 100PPM 1206 125W 100PPM 1206 RESISTOR 330 ohm 190 125W 100PPM 1206 RESISTOR 120 ohm 1 0 1W 100PPM 0805 RESISTOR 10 0 1 0 125W 100PPM 1206 RESISTOR 150 ohm 1 0 125W 100PPM 1206 RESISTOR 390 ohm 196 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 RESISTOR 100 kohm 1 0 125W 100PPM 1206 Part No 4822 051 54702 4822 051 51002 5322 117 12497 5322 117 12497 5322 117 12497 5322 117 12497 4822 051 10121 5322 117 12497 5322 117 12497 5322 117 12497 5322 117 12497 4822 051
100. a DC voltage before it is fed to the power mod ule After a line power filter in the power inlet a fuse of 1 6 AT and an NTC resistor protect the power supply The fuse should only blow ifa catastrophic error occurs on the primary side ofthe power supply A short circuit on the secondary side should not affect the primary side To minimize the inrush current to the capacitors at the connec tion of the power cord an NTC resistor R148 is used The resis tance is 15 Q when the resistor is cold but decreases to a few ohms as it is warmed up by the steady state current The AC voltage is rectified in the bridge rectifier D9 and filtered in C64 C65 suppresses noise from D9 L6 and C82 C83 serve as a fil ter at the input of U39 All inputs and outputs of the power module have HF chokes The module is mounted with distance washers on the main board From the module there are three DC voltages outputs One of those is regulated 5 V and the others are unregulated These voltages will vary with input line voltage the current at 5 V and at the unregu lated voltages The output marked 15 will be approximately 18 V and the output marked 7 will be approximately 8 V The outputs are filtered HF is filtered by C70 C73 and LF is filtered by L7 L9 and C74 C76 gt 12 V A L Mains Inlet U3 2 LL E
101. ams How to read the diagrams This chapter contains circuit diagrams and component layout Each diagram has been completed with lists of the ICs used in the unit This list indicates the connections that are not shown in the dia gram such as GND and supply voltages Signals The signals in these units are named after what they do e g LEAD EDGE is used as control current to the leading edge circuits Two different types of arrows are used to mark references for contin ued connection somewhere else in the diagram This arrow is used ifthe reference is directed to a point A1 located on the same page This arrow is used ifthe reference is directed to a point ITA located on another page The example means that the point is on sheet 1 coordinate A1 Circuit symbols The circuit diagrams are computer drawn The symbols conform to the IEC standards These symbols are designed to be logical and easy to read The component number is written above the symbol Inside the symbol at the top is an abbreviated description of the cir cuit s function Pin numbers are written outside the symbol and if it is a complex cir cuit the pin functions are written inside A small circle on a pin indicates that the input output inverts the sig nal The component name is written below the symbol The signal flow through the circuit is always from left to right Resistors capacitors diodes transistors and other components Thes
102. are fixed to the main PCB with two screws The output signal is AC coupled to the X2 pin on U29 via C107 External This input consists of an AC coupled line receiver with Schmitt trig ger function U28 and is protected against excessive voltage excursions by a resistor diode network The output signal from U28 has CMOS logic levels and is connected to the EXTREF pin on the counter ASIC U29 Logic m Microcomputer Circuits Microcontroller The microcomputer circuitry consists mainly of the microcontroller U11 an Intel 16 bit CMOS 80C196 RAM U22A and EPROM U23A The microcontroller is clocked at 12MHz data and ad dress lines ADO to ADIS are shared by means of multiplexing Therefore the addresses are stored in the latches U16A and U17A The ALE signal Address Latch Enable enables the latches UVEPROM The main program is stored in U23A that is mounted in an IC socket making it easy to update and customize the instrument firmware by changing the EPROM EEPROM Front panel settings GPIB address and certain other data that are not changed frequently e g information in the Protected User Data Area are stored in U12A which does not need battery backup Reset Circuit A special reset circuit the power supply supervisor U10 is included in the design If the 5 V supply line becomes lower than 4 5 V the reset output pin 5 goes low and the microcontroller will start over The length of the reset pulse is set by C
103. ated when the total acceptable error and the oscillator specifications are known The total acceptable error is defined as Deviation of reference frequency The high stability oscillators have been built into an oven in Acceptable error order to keep the oscillator temperature as stable as possible Nominal reference frequency Continuous operation is also important for stability After a power interruption the oscillator restarts at a slightly different frequency It will then as time goes on age at an equal rate Model PM6685 PM6685R Option Standard PM9691 PM9692 Timebase type UCXO OCXO OCXO Rubidium Total uncertainty for operating temperature 0 C to 50 C at 20 95 confidence interval 1 month after calibration 12 x 10 3x10 8x 10 Ax 10719 3 months after calibration 12 x 10 4x 107 lt 1 2 x 1078 lt 4 10710 amp 1 year after calibration 12x10 1x10 25x10 lt 4 10779 2 years after calibration lt 1 5 x 10 lt 2 x 107 lt 5 x 1078 6x 10779 Typical total uncertainty for operating temperature 20 C to 26 C at 20 95 confi dence interval month after calibration lt 4x 1079 3x 1078 8x 10 Ix 10779 3 months after calibration 4x 10 lt 4 1078 lt 1 2 x 10 2x 10719 A 1 year after calibration 1076 lt 1 107 lt 2 5 19 lt 2 5x 197 2 years after calibration lt 1 2 x 10 2x10 5x10 5x10
104. cessible terminals which can be dangerous to life are always exposed inside the unit when it is connected to line power Use ex treme caution when handling testing or adjusting the counter Before beginning the calibration adjustments power up the instru ment and leave it on for at least 30 minutes to let it reach normal oper ating temperature Power Supply CAUTION If you adjust the 5 V trimmer you have to adjust the complete instrument m Setup Remove the protective cover above the power module WARNING The heat sink inside the power module is connected to line power Connect the counter to line power Switch on the counter Press PRESET then press ENTER NOTE The backlight must be switched on during the adjust ment of the power module 6 2 Introduction J16 Lum TP20 5 2 STP23 5 TP21 12V c Load pelosuuoD pejoeuuoosiq TP15 5 27 TP16 15 TP17 7 4 Fig 6 1 Test points and trimmer for the Power Supply m Adjustment Connect the DMM to test point TP15 5V and GND see Fig 6 2 Adjust the 5V trim potentiometer inside the power module until the DMM reads 5 10 0 01 V Check that the voltage between the test point TP23 5 V and GND is 5 06 0 03 V Check that the u
105. e Sine up to 10 MHz Power Splitter 50 Q PM9584 02 T piece Termination 50 2 PM9585 Reference oscilla tor 10 MHz 0 1 Hz for standard oscillator Fluke counter with calibrated option PM9691 10 MHz 0 01 Hz for 9691 amp PM9692 Fluke PM6685R or PM6681R 10 MHz 0 0001 Hz for PM6685R Fluke 910R or Ce sium Standard HF signal genera tor 0 5 GHz no presc 3 3 GHz option 10 Pulse Generator 125 MHz Oscilloscope with 350 MHz probes BNC cables 5 to 7 cables Table 2 1 Recommended Test Equipment Two of the cables must have 10 ns difference in delay for ex ample 5 ns and 15 ns 2 2 Performance Check General Information Preparations Power up your instruments at least 20 minutes be fore beginning the tests to let them reach normal operating temperature Failure to do so may result in certain test steps not meeting equipment specifi cations Front Panel Controls Power On Test At power on the counter performs an automatic self test of the fol lowing Microprocessor RAM ROM Measuring circuits Display If a GPIB interface is installed the GPIB address is displayed If there are any test failures an error message is shown Turn on the counter and check that all segments light up on the display and that no error message appears OVERFLOW SINGLE Hz MEMORY BURST
106. e accuracy is required Calibration should be performed with traceable references and instruments at a certified calibration labora tory Contact your local Fluke representative for calibration To know the present status of your instrument test your timer coun ter from time to time The test can be made according to the informa tion in Chapter 2 Performance Check Oscillators The frequency of the reference crystal oscillator is the main parame ter affecting accuracy in a counter The frequency is affected by ex ternal conditions like the ambient temperature and supply voltage but also by aging When recalibrating the reference crystal oscillator is compensated only for deviation in frequency due to aging m Some important points Maintenance The stability indicated for the oscillators is valid within a tem perature range of 0 to 50 C with a reference temperature of 23 C If the timer counter is used in a room temperature of 20 to 30 C the temperature stability of an OCXO will be in creased by a factor of 3 The temperature stability indicated for the standard oscillator is mainly dependent on the ambient temperature When the coun ter is operating there is always an internal temperature increase that will influence the oscillator m Recalibration intervals The Mean Time Between ReCalibration MTBRC is defined as Acceptable error Temperature stability Aging MTBRC MTBRC can be calcul
107. e components are similar to the old fashioned hand drawn sym bols They have their component number above and their value or compo nent name below A resistor contained in a resistor network has a frame drawn around it and one of the pin numbers is written to the left or below it Component numbers R305 is a typical component number The indicates that it is a resistor 3 that it is positioned on the unit 3 and 05 that it 15 the fifth resistor in the component list for that unit Drawings amp Diagrams 8 2 This page is intentionally left blank Drawings amp Diagrams 8 3 Main PCB Component layout
108. e is the text mainly associated with the selected key Key s Display Note Pass Fail STAND BY Display Off Red LED beside the key On ON Backlight on PRESET DEFAULT Default ENTER NO SIGNAL setting EXT REF EXT REF Input A FILTER FILTER 50 2 50 Q NII TTL 2 times SENS Bar graph 2 times 1117710 SENS Bar graph 2 times AUTO AUTO TRIG Other PRESET DEFAULT Default ENTER NO SIGNAL setting MEAS TIME 200 s DATA ENTRY t 500 s DATA ENTRY 1 200 s ENTER NO SIGNAL DISPLAY HOLD HOLD DISPLAY HOLD SINGLE SINGLE FUNCTION lt DUTY FA FUNCTION TOT A MAN FUNCTION gt DUTY FA FUNCTION gt FREQ A AUX MENU RECALL MEAS RESTART NO SIGNAL PRESET DEFAULT Default ENTER NO SIGNAL setting CHECK 10 00000000 Hz Start counting NULL NULL NULL 10 00000000 Hz BLANK DIGITS 10 00000 9Hz 3 times MENU Displays all avail able functions pro cesses and input controls Selected items are blinking Table 2 2 Keyboard Test NOTE For the instrument to respond correctly this test must be carried out in sequence and you must start with the preset power on setting The LSD may vary MENU is not disabled by setting DEFAULT press menu again Short Form Specification Test Sensitivity and Frequency Range Press the PRESET key to set the counter in the defaul
109. e path to ground Electrostatic discharge 9 3 Glossary A ASIC Calibration Adjust ments CSA GaAs GPIB T2C bus IEC 1010 1 151 OCXO P PCA PCB Performance Check PWM TCXO 9 4 Glossary Application Specific Integrated Circuit How to restore an instrument to perform in agreement with its specifications Canadian Standards Association safety stan dard A technique to make very fast IC s using Gallium Arsenide substrate General Purpose Instrumentation Bus used for interconnecting several measuring instruments to a common controller An internal address and data bus for communi cation between microcontroller measuring logic and options International Electrical Commission safety standard Large Scale Integrated circuit Oven Controlled X tal Oscillator Printed Circuit Assembly Printed Circuit Board A procedure to check that the instrument is functionally operational and performs to its specification Must not require opening of cabi net If the instrument passes the check it is con sidered as calibrate Pulse Width Modulation Temperature Controlled X tal Oscillator Power Supply Switchmode Module Circuit Descriptions W Primary Circuits For primary circuits outside the power supply module see Chapter 4 Circuit Descriptions Power Supply The power supply module generates three DC voltages to the sec ondary circuits R24 R27 R31 and R32 give
110. ed in this manual The 6685 is available with a number of options and accessories The labels on the rear panel of the counter identify the options and accessories included If there are no labels the counter contains an uncompensated crystal oscillator and no options The following la bels exist PM9624 3 0 GHz HF input PM9691 High Stability Oven Oscillator PM9692 Ultra High Stability Oven Oscillator PM9626B GPIB Interface The location of these optional parts is illustrated in Fig 3 2 m mma 11 5 GPIB interface Optional oscillator Power Module HF input Main board Front panel Fig 3 2 Location of the boards in the counter 3 2 Disassembly Removing the Cover Removing the Cover WARNING Do not perform any internal service or ad justment of this instrument unless you are qualified to do so WARNING When you remove the cover you will ex pose high voltage parts and accessible terminals which can cause death WARNING Although the power switch is in the off position line voltage is present on the printed cir cuit board Use extreme caution WARNING Capacitors inside the instrument can hold their charge even if the instrument has been sepa rated from all voltage sources Make sure the power cord is disconnected from
111. el circuits generate the trigger voltage levels to the in put comparators The trigger level range is 3 2 V to 3 2 V with a maximum resolution of 0 6 mV The input amplifier attenuation is TP27 Trigger Level gt Input signal R88 Trigger Level L 3 R297 Counter gt circuits Fig 4 8 Comparator flip flop and buffer stages Hardware Functional Description 4 7 approximately 2 times The trigger level circuits generate DC level The trigger level circuits consist of the following that has the same attenuation This means that the output of this cir Resistor network R57 to R68 for generating the reference volt cuit has a range of 1 6 V to 41 6 V with a resolution of maximum ages 0 04 V 0 22 V 0 59 V and 1 6 V 0 3 mV A dual 8 bit DAC is used The DACs only generate voltages between 0 and 1 6 but by using a X2 amplifier and an offset shift Three multiplexers U3 to select one of the levels With this of 50 the voltage range of 1 6 V to 1 6 V is achieved The supply arrangement there is a total trigger level range of voltages to the trigger level circuits are filtered by R and C to prevent 1 6 V to 1 6 V noise originating in the digital circuitry from influencing the trigger A double DAC 04 levels The ground plane under the trigger level circuits is separa
112. epresentative After exchange of the primary circuits perform the safety inspection and tests as described in Chapter 5 Repair m Fuses This instrument is protected by an ordinary 1 6 A slow blow fuse mounted inside the instrument NEVER replace this fuse without first examining the Power Supply Unit Chapter 2 Performance Check General Information WARNING Before turning on the instrument ensure that it has been installed in accordance with the In stallation Instructions outlined in Chapter 3 of the Operators Manual This performance procedure is intended to Check the instrument s specification Be used for incoming inspection to determine the acceptability of newly purchased instruments and recently recalibrated in struments Check the necessity of recalibration after the specified recalibration intervals NOTE The procedure does not check every facet of the in strument s calibration rather it is concerned primarily with those parts of the instrument which are essential for determining the function of the instrument It is not necessary to remove the cover of the instrument to perform this procedure If the test is started less than 20 minutes after turning on the instru ment results may be out of specification due to insufficient warm up time Recommended Test Equipment Type of instru Required Suggested ment Specifications Equipment LF Synthesizer Squar
113. er remove or loosen this screw When the instrument is brought from a cold to a warm environment condensation may cause hazardous conditions Therefore ensure that the grounding requirements are strictly met Power extension cables must always have a protective ground con ductor Indicates that the operator should consult the manual WARNING Any interruption of the protective ground conductor inside or outside the instrument or dis connection of the protec tive ground terminal is likely to make the instrument dangerous Do not in tentionally disrupt the protective grounding Disposal of Hazardous Materials WARNING Disposal of lithium batteries requires spe cial attention Do not expose the batteries to heat or put them under extensive pressure These mea sures may cause the batteries to explode A lithium battery is used to power the nonvolatile RAM in this in strument Our world suffers from pollution so don t throw batteries into your wastebasket Return used batteries to your supplier or to the Fluke representative in your country Line Voltage The instrument can be powered by any voltage between 90 and 265 Vac without range switching This makes it suitable for all nom inal line voltages between 100 and 240 V m Replacing Components in Primary Circuits Components that are important for the safety of this instrument may only be replaced by components obtained from your local Fluke r
114. f the instrument These parts are Recommended Replacement Parts and are marked with an R in the column of the parts lists Components marked with a in the Z column are Production items not kept in replacement parts stock These items can be ordered but the delivery time is longer than for normal replacement parts Pos Description 13 18 20 22 25 34 35 38 39 50 52 53 54 PCA 1 Main board PCA 2 Front board Stand off plastic Textplate kit Rubber keypad Cover and Front panel Rear panel Profile support Profile support Shield cover Shield cover Rearfoot cabinet m 90 Bottom foot cabinet m 90 Bracket cabinet Spring cabinet 1696 lt 9 0696na vz96na 4696 896 4 amp 296 4 8296 92964 12964 SNOILdO TONI 100 ZHNOL 9L LHS 338 JOVAJALNI 929 231 88 3331 L 3 1ddns 1X tas Q3TIV1SNI LON NOUdo Jndlno ANY 8189 wav 1X3 20 2 o ri nos gt 4 EM 298 AR MOJ 3514 1791 Mechanical Parts Part Number 4031 100 65420 4031 100 48250 5322 532 12746 4031 100 62430 4031 100 62720 4031 100 49570 5322 447 31085 5322 460 60542 4031 100 53210 5322 447 91931 5322 462 50459 5322 462 41719 5322 462 41554 5322 401 11422 5322 492 63808 Pos Descriptio
115. he instru ment and leave it on for at least 60 minutes to let it reach normal oper ating temperature m Setup Connect the counter to the line power Switch on the counter Press PRESET then press ENTER TP17 9 0 TP16 J18 Fig 9 11 Test points and trimmer for the power supply m Adjustment CAUTION If you adjust the 5 V trimmer you have to adjust the complete instrument Connect the DMM between TP23 and ground see Fig 9 11 Adjust the 5 V trimmer potentiometer R50 in the power sup ply through the nearest vent in the protective cover until the DMM reads 5 00 0 01 V Check that the unregulated voltage from the power supply at test point TP16 15 is about 18 V Check that the unregulated voltage from the power supply at test points 7 7 is about 8 V Calibration Adjustments 9 7 Pos Description C01 C02 C03 C04 C05 C06 C07 C08 C09 C10 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28 D01 D02 D03 D04 D06 D07 D08 D09 D11 D12 D13 D14 R01 R02 R03 R04 R06 R07 R08 R09 R10 R11 R12 R13 R14 R15 R16 Heat Sink 16 K W T0220 Heat Sink 13 5 K W T0220 Capacitor 1 nF 5 63V Capacitor 1 nF 5 63V Capacitor 220 pF 20 200V Capacitor 33 nF 10 50V Capacitor 33 nF 10 50V Capacitor 33 nF 10 50V Capacitor 100 nF 10 63V Capacitor 100 nF 10
116. hm 1 0 125W 100 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 330 ohm 1 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 68 0 kohm 1 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 22 0 kohm 1 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 RESISTOR 120 ohm 196 0 1W 100PPM 0805 RESISTOR 120 ohm 196 0 1W 100PPM 0805 RESISTOR 4 70 kohm 1 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 100 ohm 1 0 125W 100PPM 1206 RESISTOR 8 20 kohm 1 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100PPM 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 10 0 kohm 1 0 125W 100 1206 RESISTOR 560 ohm 1 125W 100PPM 1206 RESISTOR 2 20 kohm 1 125W 100PPM 1206 RESISTOR 56 ohm 196 125W 100PPM 1206 RESISTOR
117. ig 5 5 Use the oscillo scope and a 10 MQ probe If you find any fault continue with traditional troubleshooting tech niques and replace defective circuits Also refer to Input Amplifiers A and B in Chapter 4 Circuit Descriptions TP27 1 4V TP26 1 4V m 5 4 3V Fig 5 5 Typical voltages input amplifier Troubleshooting 5 7 m Prescaler 3 0 GHz PM9624 See Chapter 2 Performance Check for verification Sensitivity 10 dBm 20 dBm 30 dBm 40 dBm 50 dB mo 2GHz 25GHz Frequency Fig 5 6 Specified and typical sensitivity of input C PM9624 This prescaler cannot be repaired in a local workshop It must be sent to your Fluke representative for repair GPIB Interface and Analog Output O BU103 UBU102 i 0103 U114 U115 Zero U116 4 Full Scale U113 GPIB m U106 Fig 5 7 Component layout GPIB interface m General Remark If the GPIB board is suspected to be faulty be sure the basic instru ment is OK by performing a few functional checks after the ribbon cable has been disconnected from J18 m Analog Output The microcontroller generates a
118. ints TP26 and 27 see Fig 6 2 Adjust R91 SENSE until the DMM reads 10 0 2 mV Offset m Setup PM6685 Impedance 50 2 Sensitivity 10 mVrms Signal generator Amplitude 18 dBm Frequency 50 MHz Table 6 5 Connect the Signal generator to the A input of the counter Press NULL on the counter Decrease the amlitude from the signal generator to 28 dBm Adjust R33 OFFSET A until the counter reads lt 100 Hz If this is not possible adjust 91 SENSE until the counter reads lt 100 Hz NOTE Reinstall the screen shield after making these adjust ments 6 4 Reference Oscillators Reference Oscillators NO X D J27 Optional OCXO Coarse adjust Fine adjust J23 J25 Wl optional oscillator x Standard oscillator m 115 Fig 6 3 Trimmers for the reference oscillator frequency NOTE The standard oscillator is always mounted in the unit even if an optional oscillator is installed You set the jumpers J23 and J25 to select the timebase source that you want to use Standard Oscillator W Setup Connect the counter to line power Switch on the counter Press PRESET then press ENTER Connect the 10 MHz reference to the A input of the counter Pre
119. ircuits Circuit Descriptions 9 5 Troubleshooting m Required Test Equipment To be able to test the instrument properly using this manual you will need the equipment listed in Table 9 1 The list contains specifica tions for the critical parameters Type Performance DMM 3 5 digits Oscilloscope 50 MHz 2 channel Table 9 1 Required test equipment m Operating Conditions Power voltage must be in the range of 90 to 260 VAC WARNING Live parts and accessible terminals which can be dangerous to life are always exposed inside the unit when it is connected to the line power Use extreme caution when handling testing or adjusting the counter 1 o 1 45 0V 003 10 to 13 5V poo 2 01 cm E OI 6 1 002 T01 L aa12 82V 5Vadjust Ld 10m 2m P02 Fig 9 9 Test points and voltages for the power supply 9 6 Repair m Primary circuits CAUTION If you adjust the 5 V trimmer you have to adjust the complete instrument To verify the power supply proceed as follows If the primary fuse is broken there is a short circuit in the pri mary circuits Use a DMM and try to locate the fault by resis tance measurements Remove the cover from the power supply Disconnect
120. istor R36 plus the diodes D2 and D4 to clamp negative voltage The clamp voltage is approxi mately 2 1 V for low frequency signals At high frequency the clamp voltage rises to approximately 2 3 V m impedance Converter Stage The analog signal from the input stage is fed to an amplifier stage where split band technique is used to get good frequency response over a wide range This means that the high frequency contents of the signal are fed to a high impedance AC coupled FET transistor stage Q1 The low frequency contents are fed to a DC coupled oper ational amplifier stage with negative feedback from the output ofthe converter stage buffer The low frequency path handles frequencies up to approximately 5 kHz The high frequency signal is fed to the gate of Q1 The high imped ance at the gate is converted to a low impedance at the source The source is connected to the base of HF transistor Q2 the summing point for the two signal paths To make the FET work well in its active region within the whole dy namic range the FET drain is supplied with 7 V via resistor R42 The low frequency signal is divided by the two resistors R27 and R28 before it is coupled to the input pin 2 of the operational ampli U1 The resistors R37 and R38 at the operational amplifier out put pin 146 center the output swing and capacitor stabilizes the operational amplifier stage The low frequency path goes from the operational amplifier
121. locks consist of two amplifiers each and an AGC control Automatic Gain Control AGC Helps the amplifiers retain a constant output amplitude Dividers Two dividers divide the input signal frequency by 16 Detector Detects whether the level of the input signal is high enough to ensure correct measurement and if not blocks the output sig nal from the prescaler Positive Voltage Regulator Supplies a well regulated voltage to the HF amplifiers Software Functional Description General The PM 6685 software is divided into two main modules the GPIB and DEVICE modules The GPIB fully implements the Message Ex change protocol as described in the IEEE 488 2 1987 standard The DEVICE module is a real time measurement executive that can be interrupted to do other tasks such as handling the keyboard per forming bus commands etc The basic structure of the main module is as follows main PM6685 1 Initialize while TRUE f 1 if BREAKFLAG KEYBOARD 1 HandleKeyboard if BREAKFLAG PRESET f 1 PresetDevice if BREAKFLAG GPIBCOMMAND f 1 ExecuteGpibCommands if BREAKFLAG RESTART 1 RestartMeasurement while not any BREAKFLAG f 1 Measure break flags are set by interrupt driven events either from exter nal functions the GPIB interface or from internal functions timers etc The Initialize procedure does
122. n 56 58 62 63 64 67 68 70 84 90 92 100 102 104 110 122 150 152 156 160 Rubber foot sj 5018 black Tilting support Coax connector Coax connector Soldering tag 9 6X15 15 ms fs Toroid core 30nh rcc9 6 3 4c65 violet Bottom shield BNC holder Mains filter 1a fs3514 1 07 PCA guide for prescaler Stand off nut M3x14 Washer 4 0X10x2 pa6 6 Washer 9 5X13x2 3 plate 25 4 25 4 Insulate plate Shielding strip 610mm 99 210 self adhesive Screw mrt kombi 3x06 stfz Screw mrt kombi 3x08 stfz Screw mrt kombi 4x16 stfz Screw mft tt 3x08 stfzb tx Part Number 5322 462 44434 5322 401 11471 5322 267 10004 5322 265 10264 5322 290 30318 5322 526 10545 5322 447 91829 4031 100 48830 5322 121 42352 5322 401 11347 4031 100 48800 5322 532 52364 4822 532 10222 5322 466 82868 5322 466 61932 5322 466 62077 4822 502 11658 5322 502 21489 5322 502 21491 4822 502 11713 D rg rg Y Uo Uo UU g v x FU UU Replacement Parts Mechanical Parts 7 3 Pos Description Screw mfx tt 3x08 st fz poz Screw mft tt 4x12 stfzb tx Screw mrt tt 3x08 stfzb tx Screw mrt tt 4x16 stfzb tx Screw mft 4x10 st fzb tx Screw rtk ko st3 5X10 stfz Spring washer kba 3 2 St fz din137 161 164 166 168 172 176 180
123. nregulated voltage from the power module at test point TP16 15 V is about 18 Check that the unregulated voltage from the power module at test point TP17 7 V is about 8 V Reinstall the protective cover onto the power module Input Amplifier The instructions in this section are consecutive Do not change a set ting until you are told to do so either in the text or in the tables m Setup Remove the screen shield before performing any adjustments in the input amplifier Connect the counter to line power Switch on the counter Press PRESET then press ENTER TP27 SE E Sense Ag TRIG LEVEL COMP 1 ZERO ADJ I 8 1 26 SENSE 2 Us gg TP11 TRIG LEVEL COMI RI ZERO II ottset 833 X1 C2 5 X11 Fig 6 2 Test points and trimmers for the Input amplifiers Offset Connect the DMM to Pin 10 of U8 and GND screen see Fig 6 2 Pin 1 is marked in the figure and is the middle pin on the side closest to the rear of the unit Alternatively you can use one of the soldering pads of resistor R114 as a test pad as it is connected to Pin 10 This resistor is normally not mounted Adjust R33 OFFSET A until the DMM reads 0 0 0 2 mV Linearity m Setup Press the Waveform Key once This step puts the instrument into the correct mode so
124. o the size ofthe timebase and its power require ments a larger cabinet must be used A fan is needed to keep the temperature to an acceptable level This version is called PM6685R where R stands for Rubidium o Main Supply 1 Aux Power Supply 000000 Le Fig 9 12 Location of the Rubidium Timebase and its power supply 9 12 Introduction Performance Check Required Test Equipment Type Performance Model 10 MHz reference lt 1x10779 Calibrated Rubidium oscillator or Cesium atomic standard Table 9 4 Required test equipment NOTE fully test the accuracy the PM6685R access to an extremely high stability reference signal is needed for example a Cesium atomic reference or a transmit ted signal from a nationally or internationally traceable source Additionally the instrument has to be stabilized for a period of one month The PM6685R is equipped with an LED labelled UNLOCKED When the LED is lit the Rubidium time base is still in its warm up phase and is not yet stabilized Test procedure Connect the counter to the line power Check that the UNLOCK LED is lit Check that the UNLOCK LED is
125. ow frequency divider which reduces the input signal by a factor of 2 and a capacitive high frequency divider The attenuator is formed by the resistors R22 R23 and R24 R26 in parallel with R27 R28 The capacitive part is formed by the variable capacitor C2 in parallel with R22 R23 and the parasitic capacitance across R24 R26 The capacitive attenuator is adjusted via variable capacitor C2 to the same attenuation value as the resistive attenuator The x attenuator also consists of a resistive low frequency divider and a capacitive high frequency divider The resistive part is formed by 1 5 and R18 R20 in parallel with 1 the x attenuator im pedance The capacitive divider is formed by the variable capacitor and the parasitic capacitance at the node where R5 R18 and R22 meet Resistors R2 and R6 improve the frequency response Comp arator Trigger level Comp II Fig 4 5 Input amplifier block diagram 52 e Hardware Functional Description 4 5 Voltage limiter Fom Impedance Attenuator converter stage Fig 4 6 Voltage limiter A voltage limiter that protects the impedance converter against overvoltage is placed between the attenuator and the impedance con verter The voltage limiter consists of resistor R35 and the diodes D1 From Protection circuits C13 and D3 to clamp positive voltage and res
126. power module must always have a load on the regulated voltage seven bleeder resistors R149 R155 are always connected to 5 V via J15 At stand by the counter only needs 15 so a dummy load consisting of R130 R145 15 connected to the power module by means of the relay K5 in order to stabilize the operation of the switchmode converter 5 V controls the switching on off of 12 V and 7 V When 5 V is on Q6 and Q5 will conduct i e 12 V will be on If there is no 5 V Q6 and Q5 will be off thus blocking the 12 V The ON STANDBY logic controls relay K5 which operates as de scribed above It is also possible to open the relay by changing the position of J16 The ON STANDBY logic consists of the RS set reset flip flop U40B that is controlled by the ON STANDBY button on the front panel Pressing STANDBY will apply a high voltage 12 V to the set input The inverting output of the flip flop will be low discon necting K5 via Q14 Pressing ON will give a high voltage 12 V on the reset input The inverting output of the flip flop will be high engaging K5 Inserting the power cord into the power inlet will cause a pulse on the reset input via C35 The microcomputer can disable the ON STAND BY button via Q12 and Q7 This is done in remote mode and during RAM testing A high level on the base of Q12 en ables STAND BY a low level disables it The STAND BY indicator on the front panel is controlled by the 5 V via 016 5 V offlights
127. rom the keyholes PM9691 or PM9692 Oven Oscillator Disconnect the power cable Remove the cover of the counter Remove the two screws A holding the oscillator to the main pca from underneath Press the clip B gently to the front of the counter and lift the oscillator straight up Make sure that jumpers J14 and J15 are set in the correct posi tion When fitting the oscillator make sure that the connector pins fit exactly in the holes in the connector housing Fig 3 5 One of the two screws holding the oven oscillator in place Disassembly PM9626 GPIB Interface 3 3 This page is intentionally left blank 3 4 Disassembly PM9691 or PM9692 Oven Oscillator 4 Circuit Descriptions Block Diagram Description General The PM6685 Frequency Counter consists of three main units Front unit Main board unit Rear panel unit The following options can be added GPIB interface including analog output PM9626B Prescalers 1 3 GHz PM9621 3 0 GHz PM9624 Oven controlled crystal oscillators PM9691 or PM9692 Rack mount adapter PM9622 02 Battery option PM9623 The chassis of the counter consists of a front piece molded in alumi num an aluminum rear panel and two profiled aluminum rods that hold the front and rear panels together This unit can be slid into the aluminum cover of the instrument The front unit con
128. rs J23 and J25 are in the STD position see Fig 5 4 Check that 10 MHz is present at U29 pin 42 Check that 10 MHz is present at the rear panel connector 10 MHz OUT J27 If you find any fault continue with traditional troubleshooting tech niques and replace defective circuits Also referto Chapter 4 Circuit Descriptions Oscillator Circuits m OCXO PM9691 or PM9692 This test can be carried out only ifthe counter is equipped with one of the optional oscillators PM9691 or PM9692 Be sure the jumpers J23 and J25 are in the OPT position see Fig 5 4 Check that 10 MHz is present at U29 pin 42 Check that 10 MHz is present at the rear panel connector 10 MHz OUT J27 These oscillators cannot be repaired in a local workshop They must be sent to the factory for repair Microcontroller Check that 6 MHz is present at U11 pin 65 see Fig 5 3 5 6 Troubleshooting Check that the RESET circuit U10 works properly by moving J30 g gu29 e t 3 Fig 5 3 Test points and jumpers for checking the microcontroller the RESET jumper J29 temporarily to the ON position Ifthe CPU is not running check the state ofthe pins J11 J13 See ta ble below Display JP11 J12 Message Error Action J13 0 1 0 0 1 uC port Replace 011 error 0 1 2 0 1 0 ErUC uC internal Replace
129. ss CHECK NULL and CHECK again The adjustment should preferably be made at an ambient tempera ture of 423 C m Adjustment Adjust C115 STD OSC until the counter reads 10 MHz 5 Hz NOTE Move the two jumpers J23 and J25 back to position OPT if an optional oscillator is installed Oven Controlled Oscillators PM9691 amp PM9692 9691 is adjusted to 10 MHz 0 2 Hz when manufactured PM9692 to 10 MHz 0 05 Hz so there is no need to adjust the fre quency directly after installation These oscillators like any oscillator change frequency because of aging Use the table in the User s Handbook Chapter 11 to calculate when calibration is due The complete specifications can be found in the same manual Chapter 12 Required test equipment Instrument Required specification Model Counter with Rubidium 10 MHz 0 01 Hz Uncer PM6681R or Reference tainty lt 1x10 PM6685R Table 6 7 m Setup Connect the counter to the line power Switch on the counter Set the counter to default settings preset Make the adjustment at an ambient temperature of 23 C if possi ble The oscillator must have been operating continuously for 48 hours before an adjustment Connect the 10 MHz OUT socket of the counter to be adjusted rear panel to the Input A of the PM6681R PM6685R Set up the PM6681R PM6685R Measuring time 0 5 s 5
130. t setting Then confirm by pressing ENTER Turn off AUTO Select IMP A 50 Q and maximum sensitivity Connect a signal from a HF generator to a BNC power splitter Connect the power splitter to your counter and an oscilloscope Set input impedance to 50 2 on the oscilloscope Adjust the amplitude according to the following table Read the level on the oscilloscope The counter should display the correct frequency Frequency Level Pass Fail MHz mVpp mVRMS dBm Input A 1 30 10 27 25 30 10 27 50 30 10 27 150 60 20 21 200 90 30 17 250 150 50 13 300 150 50 13 Table 2 3 Sensitivity of input A at various frequencies Reference Oscillators X tal oscillators are affected by a number of external conditions such as ambient temperature and supply voltage but they are also af fected by aging Therefore it is hard to give limits for the allowed frequency deviation You must decide the limits depending on your application and recalibrate the oscillator accordingly See the Pre ventive Maintenance in the Repair chapter Chapter 5 Oscillator Max tempera Max aging Max aging ture dependence per month per year Standard 2100 Hz 5 Hz 250 Hz PM9691 0 05 Hz 20 1 Hz 20 75 Hz PM9692 0 025 Hz 20 03 Hz 20 2 Rubidium 0 003 Hz 0 0005 Hz 0 002 Hz Table 2 4 Deviation for PM9691 and PM9692 after a
131. tains all functions needed for the user communica tion It is connected to the main board unit with a flat cable and the 4 2 Block Diagram Description molded front unit is fixed to the two profiled aluminum rods with screws The main board unit consists of a PCB mounted on two profiled alu minum rods Most functions such as the following are placed on the main board Input amplifiers with trigger level circuits Power supply Measurement logic Microcomputer circuitry Some outputs such as the trigger levels and probe compensation view outputs are directly mounted on the main board The rear panel unit is of aluminum with a number of mounted con nectors Most of the connectors are soldered directly to the main board The rear panel is fixed to the two profiled aluminum rods with screws INTREF 10 MHz out U29 HF input Counter ASIC External reference Micro Input Amplifier computer Trigger DAC s Ut Local preset gt gt Power supply 90 265 V Fig 4 1 6685 block diagram Block Diagram Description 4 3 Hardware Functional Description Front Unit LCD Drivers gt Backpl 0 f gt 4 Backpl 1 LCD 158 segments 2 1 Multiplex Fig 4 2 Front panel LCD drivers An LCD and two LEDs are used as indicators The LCD is used to show both the measurement result and the state indicators of the in strument setting The LEDs show standby and gating The LCD has
132. ted Two current to voltage converters U6 These circuits convert from the rest of the ground plane and the planes are connected only the current at the IOUT pins of the DACs to a voltage This at the front of the counter signal has a range of 0 V to approximately 1 6 V Two amplifiers U7 with an amplification of X2 to generate a signal with a range of 0 V to 3 2 V Resistors R69 and R70 set the reference voltage to the amplifier to get the 50 offset shift To get exact voltages 0 5 precision resistors are used R73 R75 R78 R79 and R80 R82 R85 R86 The zero adjust of the trigger levels is done with trimmer po tentiometers R69 and R70 connected to the amplifiers in U7 Two low pass filters R87 C29 and R88 C30 Trigger level Comp I R78 R79 07 _ gt R87 Comparator 04 1 26 29 Trigger level Comp 11 R85 R86 U7 gt R88 Comparator Il td C30 Fig 4 9 Trigger level circuits 4 8 Hardware Functional Description Power Supply m General survey The power supply generates four regulated DC supply voltages to the counter as well as some other supply voltages for special purposes The power supply block also contains the ON STANDBY logic The main building block of the power supply is a primary switch mode power module U39 The line power AC voltage 90 V to 265 is rectified to
133. tes Safety Components Components in the primary circuits are important to the safety of the instrument and may be replaced only by components obtained from your local Fluke representative Checking the Protective Ground Connection Visually Check the correct connection and condition and measure the resistance between the protective lead at the plug and the cabinet The resistance must not be more than 0 5 Q During measurement the power cord should be moved Any variations in resistance show a defect Safety Inspection and Test After Repair 5 9 This page is intentionally left blank 5 10 Safety Inspection and Test After Repair Chapter 6 Calibration Adjustments Introduction Required Test Equipment Type Performance DMM Acc 0 02 Res lu V HF synthesizer 3300 MHz Pulse generator 125 MHz 2 ns rise fall time LF synthesizer 50 MHz 20 Vpp Oscilloscope 300 MHz 2 channel Passive probe 10 1 preferably 500 Q or well compensated 10 FET probe 300 MHz Power supply 12 2 Power splitter 50 2 4W Feed through termination 50 9 10 MHz reference Ix10 7 10 MHz reference 1 10 BNC BNC cables Different lengths Screwdrivers Torx 10 amp 20 Table 6 1 Required test equipment For adjustment of PM9691 and PM9692 Oven Oscillators only Note Only calibrated instruments should be used Preparation WARNING Live parts and ac
134. that it switches from x1 Attenuator to x11 Attenuator when the sensitivity is adjusted above 2 8V Connect the pulse generator to the A input of the counter via the power splitter Connect the other output from the power splitter to channel A of the oscilloscope PM6685 Input 50 Q Sensitivity level below 1 V rms Pulse generator Amplitude 5 V pp in 50 Q Period 2 ms symmetrical Oscilloscope Time 200 us div Setting A 0 5 V div 50 Q DC Setting B 20 mV div 10 1 probe DC Table 6 2 NOTE The Pulse Generator with 50 ohm output impedance should be set to 5 Vy when loaded 50 Q so that the level recorded at the CRO A channel equal to the in put to the DUT is 2 5 after going through the split ter NOTE If you are using a 10 x10 CRO probe ensure that its compensation has been correctly adjusted so that incorrect observations of undershoots overshoots are not made Use the probe to connect channel B of the oscilloscope to Pin 10 of U8 Adjust R31 LIN A until both signals look as alike as possi ble NOTE The AC coupling will give the curve a slight tilt x1 Attenuator m Setup PM6685 Impedance 50 Sensitivity Any level below 1 V rms Pulse generator Amplitude 5 Vpp in 50 Q Period 100 us symmetrical Oscilloscope Time 10 us div Setting 0 5 V div 50 2 D
135. the counter Turn the counter upside down Loosen the two screws A at the bottom and the two screws B in the rear feet Grip the front panel and gently push at the rear Pull the counter out of the cover Fig 3 3 Remove the screws and push the counter out of the cover Reinstalling the Cover Gently push the counter back into the cover Turn it upside down Install the two screws A at the bottom Install the two rear feet with the screws B to the rear panel PM9624 HF Input Disconnect the power cable Remove the cover from the counter Disconnect the cable from the mini coax connector A on the HF input Press the clips B apart and lift the HF input pca straight up and out When installing the HF input make sure that the connector pins fit exactly in the holes in the connector housing C Fig 3 6 Removing the HF Input PM9626 GPIB Interface Disconnect the power cable Remove the cover from the counter Loosen the two screws A holding the GPIB interface to the rear panel Disconnect the interface cable from P103 Move the GPIB interface pca toward the front of the counter and lift the pca supports out from the keyholes B on the main PCA Fig 3 4 Loosen the two screws in the rear panel and dis engage the board f
136. to the base of transistor Q3 the collector of which is connected to the base Flip Flop Fig 4 7 Impedance converter 4 6 Hardware Functional Description of transistor Q2 This point is common to the high and low frequency paths A buffer amplifier with high driving capacity is used to get a linear output in the 100 load resistor R106 over a swing of 2 V This am plifier consists of a driver stage Q2 an output stage Q13 and a cur rent generator Q4 From the output of this second amplifier stage the signal is fed back to the op amp pin 3 via the divider chain R29 to R32 The trimmer tentiometer R31 sets the gain of the low frequency path equal to the high frequency gain of about 0 9 Capacitor C5 is connected to oper ational amplifier pins 1 and 8 to achieve stable operation The trimmer potentiometer R33 between pins 1 and 5 on the opera tional amplifier is used for adjusting the offset voltage of the opera tional amplifier The channel A filter connected to the output of the second amplifier stage is a 100 kHz low pass LC filter It consists ofthe coil L1 and the two capacitors C18 and C19 in parallel The filter is controlled by the relay K4 The filter output is connected to the input ofthe comparator stage m Comparator Stage The comparator stage converts the analog signal from the impedance converter stage to a square wave This circuit consists mainly of the
137. wer Check that the UNLOCK indicator turns on and then turns off again within 6 minutes after connecting line power Connect the 10 MHz reference signal to input A of the counter Select FREQUENCY A measurement Select 2 s measuring time Check that the displayed frequency is 10 00000000 MHz 0 05 Hz lt 10 minutes after connection to line power Rear Input Output INT REF Output Connect an oscilloscope to the 10 MHz output on the rear of the counter Use coaxial cable and 50 2 termination The output voltage is sinusoidal and should be above 2 8 VPP EXT REF Input Press the PRESET key then press the ENTER key to set your counter in the Default setting Apply 10 MHz sine to input A equipped with a T piece and to Ext Ref input at the rear terminated with 50 Q Amplitude on 10 MHz signal 200 mVRMS 560 mVpp Press the Ext Ref key The display should show 10 00000000 Hz 5 LSD 2 4 Performance Check Rear Input Output EXT ARM INPUT Press the PRESET key then press the ENTER key to set your counter in the Default setting Select 50 Q input impedance Apply 10 MHz 500 mVnws 1 4 Vpp sine to input A The counter measures and displays 10 MHz Press the AUX MENU key Press the DATA ENTRY UP DOWN keys until the display shows Ar Start confirm by pressing the ENTER key Press DATA ENTRY UP DOWN keys until the display shows PO
138. where incorrect operating proce dures can cause damage to or destruction of equipment or other property WARNING Indicates a potential danger that requires correct procedures or practices in order to prevent personal injury This Timer Counter has been designed and tested in accordance with safety class 1 requirements for Electronic Measuring Apparatus of IEC CENELEC publication EN61010 1 and CSA 222 No 1010 1 and has been supplied in a safe condition This manual contains information and warnings that should be fol lowed by the user and the service technician to ensure safe operation and repair in order to keep the instrument in a safe condition WARNING Opening instrument covers or removing parts except those to which access can be gained by hand is likely to expose high voltages which can cause death The instrument must be disconnected from all voltage sources before it is opened Remember that the capacitors inside the instrument re tain their charge even if the instrument has been disconnected from all voltage sources Grounding This instrument is connected to ground via a sealed three core power cable which must be plugged into socket outlets with protective ground contacts No other method of grounding is permitted for this instrument 1 2 Safety Instructions protective ground lead is connected inside the instrument The ground symbol on the rear panel indicates where the Nev

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