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HP 6255A User's Manual

1. Device 5 50 Pointer Adjustment or Calibration Meter Zero Voltmeter Tracking R63 and R72 R56 R6 or R8 Ammeter Tracking Zero Volt Output Voltage Program ming Current R13 Zero Current Output R25 or R28 5 48 ADJUSTMENT AND CALIBRATION 5 49 Adjustment and calibration may be required after performance testing troubleshooting orrepair and replacement Perform only those adjustments thataffectthe operation of the faulty circuit and no others Table 5 8 summarizes the adjustments and calibrations contained in the following paragraphs 5 50 METER ZERO 5 51 The meter pointer mustrest on the zero cali bration mark on the meter scale whenthe instrument is at normal operating temperature resting in its normal operating position and the instrument Le turned off To zero set the meter proceed as fol lows a Turn on instrument and allow it to come up to normal operating temperature about 20 5 15 Voltage across each diode 0 6 to 0 9 volts Voltage across appro priate filter capacitor Output voltage Positive reference voltage 46 2V Negative reference voltage 6 2V 4 AV Calibration and Adjustment Summary Adjustment or Calibration Current Program ming Current Reference Circuit Line Voltage Ad justment R46 Negative Reference Load Adjustment Replace VR2 Positive Reference
2. Hewiett Packerd France Bureau de vente de Lyon La Saquin Chemin des Mouilles B P 162 F 88130 Ecitly Cedex Tel 78 33 B1 28 Sabie HEWPACK Ecuty Teiex 31 86 17 Hewlett Packard france Bureau da vente de Toulouse P ricantre de la C pidre Chernin da ia Cepi re 20 IM Neige Mira SI 48 11 12 Cabs hewPack gue Telex 530957 Hewlett Packard France La Ligoures Bureau de vente de Marseities Place Roude da Villenueve F 43108 Alx en Provence Tel 42 59 41 02 Gadd IC WPACK MARGN Tetex 410770 Hewlett Packard Franca Sureau de vente de Ke nes 2 Allea de la Bourgnetia B P 1124 F 35100 Rennaa C dex Tek 99 51 42 44 Cable HEWPACK 74912 Telex 740912 Hewlett Packard France Burgau de vente de Strassbourg 18 rue da Canai de ia Mame F 57300 Schiltigheim Tal 88 oF tu 10 83 11 53 Telax 890 Gable HeWPACK STREG Kewiatt Packard France Bureau de vante de Liia Iramaubie P ricentre Rue van Gogh F 59650 Villeneuve d Ascq Tet 20 91 44 25 Telex 16 01 24F tHewiett Packard France Bureau de Van Centre d stares Paris Nord Batiment Amp re Rya ge la Commune de Paris Hewlett Packar GmbH Technisches B ro Rampure Wenderstrasse 23 p 2000 riy i Tet 040 24 13 93 Cadig HEWPACKSA Hamburg Telex 21 63 032 Honn d Hewlett Packard GmbH Technisches 8gro Hanaovar Am Grossmarkt 6 D 30009 Hannover 91 Tet 6511 48 60 31 Taiex 092 3259 Hewlett Packard GmbH
3. North Hollywood California Rockville Maryland Reling Moadaws Ihinais Their complete addresses are listed above Service Only H
4. STABILITY Constant Voltage Less than 0 10 plus 2 5mv total drift for 8 hours after an initial warm up time of 30 minutes at constant ambient con stant line voltage and constant load Constant Current Less than 0 10 plus 4ma total drift for 8 hours after an initial warm up time of 30 minutes at constant ambient constant line voltage and constant load INTERNAL IMPEDANCE AS A CONSTANT VOLTAGE SOURCE l Less than 0 001 ohm from DC to 100 Hz Less than 0 01 ohm from 100 Hz to 1 kHz Less than 0 2 ohm from 1 kHz to 100 kHz Less than 2 0 ohms from 100 kHz to 1 MHz TRANSIENT RECOVERY TIME Less than 50usec for output recovery to within 15 mv following a full load current change in the Output Specifications 1 3 OVERLOAD PROTECTION continuously acting constant current circuit protects the power supply for all overloads in cluding a direct short placed across the termi nals in constant voltage operation The constant voltage circuit limits the output voltage in the constant current mode of operation METERS Each front panel meter can be used as either a 0 50V or 0 5 volt voltmeter or as a 0 1 8 or 0 0 18 amp ammeter OUTPUT CONTROLS Coarse and fine voltage controls and coarse and fine current controls set desired output volt age or current OUTPUT TERMINALS Six five way output posts three per section are provided on the front panel and output terminal strips are located on the rea
5. 804 476 8422 EEN P O Box 105005 450 interstate North Parkway 30 z Tel 404 355 1500 TWX 810 766 4890 Medical Service Only Augusta 30903 Tel Tis 736 0692 P O Box 2103 1172 N Dayis Drive Warner Robins 31098 Tel 912 922 0449 1391Budapost V1 Tel 42 03 38 Telex 22 51 14 ICELAND Medicat Only ing Trading Company inc ryggvag tu P 0 Box 895 IS Reykjavik Tel 1 58 20 1 63 03 Cabla ELDING Reykjavik IRAN Hewiati Packard fran Ltd No 13 Faurteanth St Mit Emad Avenue P E 41 2419 Te 881082 5 Telex 212405 hewp ir IRELAND Hawier Packara Ltd King Deet Lane a Wokingham Baria A 1 SAR Tel 6720 E 47 74 Tee 847178 Tabie Hewpie London HAWAL 2875 So King Street Honoluiu 96826 Tei 808 955 4455 U JNOS 5201 Tollviaw Dr Rolling Meadows 50008 Tei 1312 255 9800 TWX 910 587 2200 INDIANA 7301 North Shadsiand Ave indisnapoiis45250 Taf BYC TWX 810 280 1797 IOWA 2415 Heinz Road lowa City 52240 Tet 319 338 9466 KENTUCKY Madical Only 3901 Atkinson Dr Suite 407 Atkinson Square Louisvilte 40218 Tel 802 456 1573 LOUISIANA DD Sox t449 3229 39 Williams Boulevard Kenner 70053 Te 504 443 6201 MARYLAND 5707 Whitestone Road Baitimore 21207 at 301 944 5400 TWX 719 862 9187 2 Choke Cherry Road Rockviila 20850 Tat 361 948 6370 TWK 710 828 9854 MASSACHUSETTS 32 Hartweii Ava Lexington 02173 Tek 6 JE Desa TWX 710 32
6. Set METER switch to highest current range and turn on supply d Adjust CURRENT control until front panel meter reads exactiy the maximum rated output current e The ripple and noise indication should be less than the following Model 6253A 6284A 6255A 6289A 6281A 6294A mA rms 2 8 5 4 0 5 5 39 TROUBLESHOOTING 5 40 Components within Hewlett Packard power supplies are conservatively operated to provide maximum reliability In spite of this parts within a supply may fail Usually the instrument must be immediately repaired with a minimum of down time anda systematic approach as outlined in succeeding paragraphs can greatly simplify and speed up the repair 5 41 TROUBLE ANALYSIS 5 42 General Before attempting to troubleshoot this instrument ensure that the fault is with the instrument and not with an associated circuit The performance test Paragraph 5 1 0 enables this to be determined without having to remove the instrument from the cabinet 5 43 Once it is determined that the power supplyis at fault check for obvious troubles such as open fuse a defective power cable or an input power failure Next remove the top and bottom covers each held by four retaining screw s and inspect for open connections charred components etc If the trouble source cannot be detected by visualinspec tion follow the detailed procedure outlined in suc ceeding paragraphs Once the defective component has been located by means of vis
7. The following test can be used as an incom ing inspection check and appropriate portions of the testcan berepeated either to check the operation of the instrument after repairs or for periodic mainte nance tests The tests are performed usinga 115Vac 60Hz single phase input power source If the cor rect result is not obtained for a particular check do not adjust any controls proceed to trouble shooting Paragraph 5 41 5 12 CONSTANT VOLTAGE TESTS 5 13 Rated Output and Meter Accuracy 5 14 Voltage Proceed as follows a Connect load resistor across rear output terminals of supply Resistor value to be as foi lows Model 6253A 6255A 6281A 6284A 6289A 6294A Resistance 64 26 1 54 a 26 Den b Connect differential voltmeter across 5 and Sterminals of supply observing correct polar ity c Set METER switch to highest voltage range and turn on supply d Adjust VOLTAGE control s until front panel meter indicates exactly the maximum rated output voltage e Differential voltmeter should indicate maximum rated output voltage within 2 5 3 5 16 Load Regulation 5 15 Current Proceed as follows a Connect test setup as shown in Figure 5 4 leaving switch S1 open b Turn CURRENT controls fully clockwise c Set METER switch to highest current range and turn on supply d Adjust VOLTAGE control s until front panel meter ndicates exactly the maximum rated output current e Differential voltm
8. 1 C2 18 fxd film Oluf 200vdc 4 192P10392 Sprague 56289 0160 0161 i C3 fxd film 0 luf 200vdc 2 192P10492 Sprague 56289 0160 0168 1 C4 7 8 11 13 15 17 NOT ASSIGNED CS fxd film 001p 200vdc 2 192P10292 Sprague 56289 0160 0153 1 C6 fxd elect 20uf 15vdc 30D206G0158B4 Sprague 56289 0180 0300 i C9 fxd elect 4 7uf 35vdc 2 HLAB 09182 0180 0100 l C10 fxd elect 100uf 50vdc 2 HLAB 09182 0180 1852 1 C12 20 fxd elect 490uf 75vdc D38618 HLAB 09182 0180 1888 L C14 fxd elect 1600uf 70vdc 2 HLAB 09182 0180 1895 1 C16 fxd ceramic O5pf 500vdc 2 33C17A Sprague 56289 0150 0052 H Gig fxd elect 15uf 50vdc 2 150D156X0050R2 Sprague 56289 0180 1834 E CR1 5 189 20 30 32 Rect si 200ma 200prv 250mw 18 HLAB 09182 1901 0033 8 CR6 10 12 16 21 28 29 31 33 NOT ASSIGNED 07 4 CR11 18 34 Rect si 3A 200prv 6 MR 1032B Motorola 04713 1901 0416 6 CR17 22 27 Rect si 900ma 200prv 14 1N5059 GB 03508 1901 0327 7 DSI Lamp neonpartofsi ass y Ref HLAB 09182 2140 0244 1 Pl Puse Cartridge 4A 250V 3AG 1 312002 Littlefuse 75915 2110 0055 5 Ol 2 11 SS NPN diff amp si 6 HLAB 09182 1854 0229 6 Q3 5 8 10 12 14 15 SS PNP si i4 2N2907A Sprague 56289 1853 0099 7 Q4 Power PNP si 2 MI 2268 Motorola 04713 1853 0063 2 Q6 7 Power NPN si 4 HLAB 09182 1854 0225 4 Q9 16 SS NPN s 4 4JX16A1014 G E 03508 1854 0071 4 Q13 NOT ASSIGNED Ri fxd ww lKa 5 3w 2 242E1025 Sprague 56289 0813 0001 1 R2 22 23 86 f
9. 19 20 30 32 VR3 VR4 5 Si rectifier 200ma 200prv 1901 0033 1N485B Sylvania Diode zener 4 22V 400mW Motorola 4 3V IW 1902 3070 1902 0797 1N749 1N3824 Motorola Diode zener Table 5 7 Checks and Adjustments After Replacement of Semiconductor Devices Constant voltage CV line and load regulation Zero volt output Constant voltage differential amplifier R6 or R8 Constant current CC line and load reguiation Zero current output Constant current differential amplifier R25 or R28 CV CC load regulation CV transient response Mixer amplifier Q3 Q16 Error amplifiers and driver CV CO load regulation Q4 Q5 Q6 Q7 Series regulator CV CC load regulation Reference circuit line regulation Q8 Q9 Reference regulator Q10 Clamp circuit CC load regulation R63 R72 R56 Meter zero Voltmeter ammeter tracking Meter circuit Q11 Q15 CRI CR2 Limiting diodes CV load regulation CR3 CR4 ORS OR gate diodes and limiting diode CV CC load regulation 5 14 Table 5 7 Checks and Adjustments After Replacement of Semiconductor Devices Continued CR8 CR10 Forward bias regulator CR22 CR27 Rectifier diodes CR34 Protection diode VRI Positive reference voltage VR2 Negative reference voltage Bias voltage Table 5 8
10. Load Adjustment Replace VRI R30 Transient Response minutes b Turn the instrument off Wait two minutes for power supply capacitors to discharge completely c Rotate adjustment screw on front of meter clockwise until the meter pointer is to the left of zero and further clockwise rotation will move the pointer upscale towards zero d Turn the adjustment screw clockwise un til the pointer is exactly over the zero mark on the scale If the screw is turned too far repeat steps c and d e Turn meter adjustment screw counter clockwise about 15 degrees to break contact be tween adjustment screw and pointer mounting yoke but not far enough to move the pointer back down scale If screw is turned too far as shown by the needle moving repeat the procedure The meter is now zero set for best accuracy and mechanical stability 5 52 VOLTMETER TRACKING 5 53 To calibrate voltmeter tracking proceed as follows a To electrically zero meter set METER switchto highestcurrent position and with supply on and no load connected adjust R63 until front panel meter reads zero b Connect differential voltmeter across sup ply observing correct polarity c Set METER switch to highest voltage range and turn on supply Adjust VOLTAGE control until differential voltmeter reads exactly the max imum rated output voltage l d Adjust R72 until front panel meter also in dicates maximum rated output voltage 5
11. Newark N J Drake Mfg Co Harwood Heights Ill Elastic Stop Nut Div of Amerace Esna Corp Union N J rie Technological Products Inc Erie Pa Hart Mig Co Hartford Conn Beckman Instruments Inc Helipot Div Fullerton Calif Fenwal Inc Ashland Mass Hughes Aircraft Co Electron Dynamics Div Torrance Calif Amperex Electronic Corp Hicksville N Y Bradley Semiconductor Corp New Haven Conn Carling Electric Inc Hartford Conn Federal Screw Products Inc Chicago Ill Heinemann Electric Co Trenton N f Hubbell Harvey inc Bridgeport Conn Amphenol Corp Amphenol RF Div Danbury Conn E F Johnson Co Waseca Minn IRC Div of TRW Inc Philadelphia Pa Howard B jones Div of Cinch M g Corp New York N Y Kurz and Kasch Inc Dayton Ohio Kilka Electric Corp Mt Vernon N Y Littlefuse Inc Des Plaines iil Minnesota Mining and Mig Co St Paul Minn Bloomfield N Dialight Corp Minor Rubber Co Inc Malden Mass J W Miter Co Compton Calif 76530 76854 77068 77122 77147 77221 77252 77342 77630 77764 78189 78452 78488 78526 78553 78584 79136 79307 79727 79963 80031 80294 81042 81073 81483 81751 82099 82142 82219 82389 82647 82866 82877 82893 83058 83186 83298 833
12. No 6281A 6294A Variation mVdc 1 24 0 75 g Replace decade resistance with appro priate value resistor in R46 position 5 64 CONSTANT VOLTAGE TRANSIENT RESPONSE 5 65 To adjust the transient response proceed as follows a Connect test setup as shown in Figure 5 8 b Repeat steps a through e as outlined in Paragraph 5 31 c Adjust R30 so that the transient response is as shown in Figure 5 9 SECTION VI REPLACEABLE PARTS 6 1 INTRODUCTION 6 2 This section contains information for ordering replacement parts Table 6 4 lists parts in alpha numeric order by reference designators and provides the following information a Reference Designators Refer to Table 6 1 b Description Refer to Table 6 2 for ab breviations C Total Quantity TQ Given only the first time the part number is listed except in instruments containing many sub modular assemblies in which case the TQ appears the first time the part number is listed in each assembly d Manufacturer s Part Number or Type e Manufacturer s Federal Supply Code Num ber Refer to Table 6 3 for manufacturer s name and address f Hewlett Packard Part Number g Recommended Spare Parts Quantity RS for complete maintenance of one instrument during one year of isolated service h Parts not identified by a reference desig nator are listed at the end of Table 6 4 under Me chanical and or Miscellaneous The former consists of parts belonging to and g
13. Technisches B ro N rnberg br bise 90 rnberg Tel 0911 56 36 83 Telex 0623 860 Hewlett Packard GmbH Technisches amp dro M nchen Eschenstrasse 5 D 85021 Taufkirchen Tel 059 6117 1 Hewtett Packard GmbH Technisches B ro Berlin Kaithstrasse 2 4 D 1000 mE 30 Tel 030 24 90 BS TeigcQ18 3405 hpbin GREECE Kostas Karayantis 8 Omirou Streat Athene 153 Tai 32 30 303 32 37 731 Tsiex 21 59 62 AKAR GR Cable RAKAR ATHENS nalytica Only MIES G Papathanassiou amp Co 47 Marni Street Athens 103 Tel 5522 915 9221 989 Telex 21 5329 INTE GR Cable INTEKNIKA Medical Only Tecknomed Hellas Ltd 52 Skouta Street Athens 135 Tel 3628 972 Talex 21 4693 Cable ETALAK HUNGARY M ITA Mdszerdgy s M r stechnikai Szolgaiata Hewlatt Packard Service B P 300 7 9153 Le Blanc Mesni C dex enin Kit 87 P O Box 241 Tel 01 931 86 50 Hewiett Packard France Bureau de vente de Jordeau Av du Pat Kennedy F 33790 Meriguac Tei 56 97 22 86 GERMANFEDERALREPUBLIG DI Hewlett Packard GmbH Vertnebszentrala Frankfurt Berner Strasse 117 Posttach 580 140 D 66000 Frenne 56 Tel 0611 50 04 Cable ST MPACKSA Frankturt Telex 04 13249 horfm d pewieti Packard GmbH Tachnisches B ro Bobiinge Herre parger Strasse 11 5 7930 ee W rttemberg Tet 07031 667 Cable HEWPACK SE Telex 07265739 bbn Hewlett Packard GmbH Technisches Bare D sseidorf Emanuel Saus Bir 1iSeast
14. binding post maroon 2 HLAB 09182 1510 0040 1 5 Way binding post black 4 DF21BC Superior 58474 1510 0039 1 Cable clamp I D 4 T4 4 Whitehead 79307 1400 0330 i Line cord plug PH151 74 ft l KH 4096 Beldon 70903 8120 0050 1 Spacer captive 4 HLAB 09182 0380 0742 i Strain relief bushing i SR SP 1 Heyco 28520 0400 0013 l Knob 17 64 insert pointer 4 HLAB 09182 0370 0101 i Knob 3 16 insert 4 HLAB 09182 0370 0179 1 Knob 4 insert pointer 2 HLAB 09182 0370 0084 1 Barrier strip 2 HLAB 09182 0360 1234 l Jumper 16 422 13 11 013 Cinch 71788 0360 1143 4 Rubber bumper 4 MB 50 Stockwell 87575 0403 0088 l Fuseholder assembly 1 342014 Littlefuse 75915 1400 0084 l Mica insulator 4 734 Reliance 08530 0340 0174 4 Meter 24 size DUAL SCALE 0 50V 0 1 8A 2 HLAB 09182 1120 1139 1 Bezel 1 6 MOD 2 HLAB 09182 4040 0295 i Spring o 4 HLAB 09182 1460 0720 2 Spacer HEX brass NI PL 4 6x LG HLAB 09182 0380 0716 2 Fastener 1l C8091 632 24B Tinnerman 89032 0510 0275 3 Captive nut 16 CLA 632 2 Pem Eng 46384 0590 0393 4 Captive nut 4 CLA 832 2 Pem Eng 46384 0590 0395 1 Insulator transistor pin 8 HLAB 09182 0340 0166 6 Insulator 8 HLAB 09182 0340 0168 6 Rubber bumper 4 40 72 Stockwell 87575 0403 0086 1 Rubber bumper black duro hard 55 60 2 3066 Stockwel 87575 0403 0085 1 OPTION 07 10 Turn Voltage Control var ww 10Ka 5 10 Turn 2100 1866 Knob R10 Black 0370 0137 OPTION 08 10 Turn Current Control var ww IKa 5 10 Turn 2100 1864 K
15. dA eejel jejejojalol lej jo o 2 o Al A2 A3 A4 AS AGB AT AB A9 S 3 Aid SLAVE NO 2 Figure 3 9 Auto Series Two and Three Units 3 39 PARALLEL OPERATION 3 40 Normal Parallel Connections Figure 3 10 Two or more power supplies can be connected in parallel to obtain a total output current greater than that available from one power supply The total output current is the sum of the output currents of the individual power supplies The output CURRENT controis of each power supply can be separately set The output voltage controls of one power sup ply should be set to the desired output voltage the other power supply should be set for a slightly larger output voltage The supply set to the lower output voltage will act as a constant voltage Source the supply set to the higher output will act 8S 8 Constant current source dropping its output 3 5 Al A2 A3 A4 AS AG A7 AB A9 S GND 5 AIO ejeieiereleiglelelalelele Tele D CIEIEJCIEIETE GND 5 AIO ZLY maven Eit Ai A2 AS A AS A6 AT ABAD Figure 3 10 Normal Parallel Connections voltage until it equals that of the other supply The constant voltage source will deliver only that frac tion of its total rated output current which is neces sary to fulfill the total current demand Al A2 A3 A4 AS AB A AB A9 S GND 5 AIO MASTER Al A2 A3 A4 AS A6 AT AB A9 S GND 5 AIO SLAVE NO 2 Figure 3 11 Auto Parallel Two and T
16. defective shorting Q5 emitter to col lector b Remove short across Q5 and proceed to step 4 Output decreases a Q5 R31 or associated com ponents defective Open Q3 collector lead a Output remains high Check conduction of Q5 by shorting R33 Remove short and proceed to step 5 Output decreases Check turnoff of Q3 by a Output remains high Stage Q3 or Q17 defective Shorting Q3 base to emitter b Remove short and proceed to step 6 Output decreases a Voltage clamp circuit is de fective Remove CR32 anode or cathode Output decreases Reconnect CR32 and pro ceed to step 7 Output remains high On rear terminal board short Output remains high Stage Q1 defective A6 to i Remove short across termi nals Ap and Check R10 for open and R12 R13 for short Output decreases Excessive heat or pressure can lift the copper strip from the board Avoid damage by using a low power soldering iron 50 watts maximum and following these instructions Copper that lifts off the board should be cemented in place with a quick drying acetate base cement having good electrical insulating properties A break in the copper should be TOS by soldering a short length of tinned copper wire across the break Use only high quality rosin core solder when repairing etched circuit boards NEVER USE PASTE FLUX Af
17. is piugged into an appropriate receptacle the in strument is grounded The offset pin on the power cable three prong connector is the ground connec tion 2 19 To preserve the protection feature when operating the instrument from a two contact outlet use a three prong to two prong adapter and con nect the green lead on the adapter to ground 2 20 REPACKAGING FOR SHIPMENT 2 21 To insure sa e shipment of the instrument it is recommended that the package designed for the instrument be used The original packaging material is reusable If it is not available con tact your local Hewlett Packard field office to obtain the materials This office will also furnish the address of the nearest service office to which the instrument can be shipped Be sure to attach a tag to the instrument which specifies the owner model number full serial number and service re quired or a brief description of the trouble SECTION III OPERATING INSTRUCTIONS 3 1 QPERATING CONTROLS AND INDICATORS 3 2 The front panel controls and indicators to gether with the normal turn on sequence are shown in Figure 3 1 HARRISON DC POWER SUPPLY HE V L ETT PACKARD LINE METER PUSH ONAF VOLTAGE CURRENT ST TURN ON SEQUENCE PUSH ON OFF BUTTON AND BUTTON SHOULD LIGHT SET METER SWITCH TO DESIRED VOLTAGE RANGE ADJUST VOLTAGE CONTROL UNTIL DESIRED OUTPUT VOLTAGE 18 INDICATED ON METER SET METER SWITCH DESIRED CURRENT RANGE AND SHORT
18. ment and not the average 3 48 OUTPUT CAPACITANCE 3 49 An internal capacitor connected across the output terminals of the power supply helps to sup ply high current pulses of short duration during constant voltage operation Any capacitance added externally will improve the pulse current capability but will decrease the safety provided by the con stant current circuit A high current pulse may dam age load components before the average output cur rent is large enough to cause the constant current circuit to operate 3 50 The effects of the output capacitor during constant current operation are as follows a The output impedance of the power supply decreases with increasing frequency b The recovery time of the output voltage is longer for load resistance changes c A large surge current causing a high pow er dissipation in the load occurs when the load re sistance is reduced rapidly 3 51 REVERSE VOLTAGE LOADING 3 52 A diode is connected across the output termi nais Under normal operating conditions the diode is reverse biased anode connected to negative ter minal If a reverse voltage is applied to the output terminals positive voltage applied to negative ter minal the diode will conduct shunting current across the output terminals and limiting the voltage to the forward voltage drop of the diode This diode protects the series transistors and the output elec trolytic capacitor G2 M 3 53 REVERSE CURRE
19. onthe face ofthe CRT The magni tude of this resulting noise signal can easily be much greater than the true ripple developed between the plus and minus output terminals of the power supply and can completely invalidate the measure ment 5 22 The same ground current and pickup problems can exist if an RMS voltmeter is substituted in place ofthe oscilloscope in Figure 5 6 However the oscilloscope display unlike the true RMS meter reading telis the observerimmediately whether the fundamental period of the signal dis played is 8 3 milliseconds 1 120 Hz or 16 7 milliseconds 1 60 Hz Sincethe fundamentalrip ple frequency present on the output of an Ze suppiy is 120 Hz due to full wave rectification an os cilloscope display showing a 120 Hz fundamental component is indicative of a clean measurement setup while the presence of a 60 Hz fundamental usually means that an improved setup will result in a more accurate and lower value of measured ripple 5 23 Figure 5 6B shows a correct method of mea suring the output ripple of a constant voltage pow er supply using a single ended scope The ground loop path is broken by floating the supply output Note that to ensure that no potential difference exists between the supply and the oscilloscope it is recommended that whenever possible they both be plugged into the same AC power buss If the Same buss cannot be used both AC grounds must be at earth ground potential 3 24 Eith
20. pullout resistor serves as a trimming adjustment for the programming current flowing through R16 4 25 VOLTAGE CLAMP CIRCUIT 4 26 During constant current operation the con stant voltage programming resistors are a shunt load across the output terminals ofthe power sup ply If the output voltage changed the current through these resistors would tend to change re sulting in an output current change The clamp circuit is a return path for the voltage programming current the current that normally flows through the programming resistors The circuit maintains the current into the constant voltage summing point A6 constant thus eliminating the error due to shunting effects of the constant voltage program ming resistors 4 27 The voltage divider R51 R52 and VR3 back biases CR30 and Q10 during constant voltage operation When the power supply goes into con stant current operation CR30 becomes forward biased by the collector voltage of QlA This re sults in conduction of Q10 andthe clamping of the summing point at a potential only slightly more negative than the normalconstant voltage potential Clamping this voltage at approximately the same potential that exists in constant voltage operation results in a constant voltage across and conse quently a constant current through the pullout re sistor R12 4 28 MIXER AND ERROR AMPLIFIERS 4 29 The mixer and error amplifiers amplify the error signal from the constant volt
21. trols local programming no strapping changes are necessary Ai A2 A A4 AS AG AT A8 A9 S GND 5 AIO A A ME A i7 KU LJ Land kJ wi LJ We LJ AJ RL MONITORING POINTS Figure 3 2 Normal Strapping Pattern 3 7 CONSTANT VOLTAGE 3 8 To select a constant voltage output proceed as follows a Turn on power supply and adjust VOLTAGE controls for desired output voltage output terminals open b Short output terminals and adjust CUR RENT controls for maximum output current allowable current limit as determined by load conditions If a load change causes the current limit to be ex ceeded the power supply will automatically cross over to constant current output at the preset current limit and the output voltage will drop proportionate ly In setting the current limit allowance must be made for high peak current which can cause un wanted cross over Refer to Paragraph 3 46 3 9 CONSTANT CURRENT 3 10 To select a constant current output proceed as follows a Short output terminals and adjust CUR RENT controls for desired output current b Open output terminals and adjust VOLTAGE controls for maximum output voltage allowable volt age limit as determined by load conditions Ifa load change causes the voltagelimit to be exceeded the power supply will automatically crossover to constant voltage output at the preset voltage limit and the output current will drop proportionately In setting the voltage lim
22. voltage or current The voltage or currentranges are selected by the applicable METER switch on the front panel 1 5 Two sets of programming terminals located at the rear of the unit allow ease in adapting to the many operational capabilities of the power supply brief description of these capabilities is given below a Remote Programming The power supply may be programmed from a remote location by means of an external voltage source or resistance b Remote Sensing The degradation in regulation which would occuratthe load because of the voltage drop in the load leads can be reduced by usingthe power supply in the remote sensing mode of operation c Series and Auto Series Operation Power supplies may be used in series when a higher output voltage is required in the voltage mode of operation or when greater voltage compliance is required inthe constant current mode of operation Auto Series operation permits one knob control of the total output voltage from a master supply d Parallel and Auto Parallel Operation The power supply may be operated in parallelwith a similar unit when greater output cur rent capability is required Auto Paralleloperation permits one knob controlof the total output current from a master supply e Auto Tracking Ihe power supply may be used as a master supply having controlover one or more slave supplies that furnish various voltages for a System 1 6 SPECIFICATIONS 1 7 Det
23. watts and 2 6 amperes 2 15 CONNECTIONS FOR 230 VOLT OPERATION Figure 2 1 TRANSFORMER PRIMARY CONNECTED FOR H5VOLT OPERATION NOTE CONNECTIONS BETWEEN 50 851 548 55 ARE MADE WITH COPPER ON THE PRINTED CIRCUIT BOARD THESE CONNECTIONS MUST BE REMOVED FOR 230V OPERATION THE CONNECTIONS ON THE PRINTED CIRCUIT BOARD MUST BE BROKEN AND A SEPARATE EXTERNAL CONNECTION MADE BETWEEN POINTS 50 amp 55 TRANSFORMER PRIMARY CONNECTED FOR 230 VOLT OPERATION Figure 2 1 Primary Connections 2 16 Normally the two primary windings of the in put transformer are connected in parallel for opera tion from 115 volt source To convert the power supply to operation from a 230 volt source the power transformer windings are connected in series as follows a Unplug the line cord and remove the unit covers b Break the copper between 54 and 55 and also between 50 and 51 on the printed circuit board These are shown in Figure 2 1 and are labeled on copper side of printed circuit board C Add strap between 50 and 55 d Replace existing fuse with 2 ampere 230 volt fuse Return unit to case and operate normally 2 17 POWER CABLE 2 18 To protect operating personnel the National Electrical Manufacturers Association NEMA rec ommends that the instrument panel and cabinet be grounded This instrument is equipped with a three conductor power cable The third conductor is the ground conductor and when the cable
24. 1 26982 27014 28480 28520 28875 31514 31827 33173 35434 37942 42190 43334 44655 46384 47904 49956 55026 56289 58474 58849 59730 61637 63743 Use Code 71785 assigned to Cinch Mfg Co Chicago HL 24655 General Radio Co Table 6 3 Code List of Manufacturers Continued MANUFACTURER Delco Radio Div of General Motors Corp Kokomo Ind Atlantic Semiconductors Inc Asbury Park N J Fairchild Camera and Instrument Corp Semiconductor Div Transducer Plant Mountain View Calif Daven Div Thomas A Edison Industries McGraw Edison Co Orange N I Signetics Corp Sunnyvale Calif Bendix Corp The Navigation and Control Div Teterboro N J Electra Midland Corp Mineral Wells Texas Fansteei Metallurgical Corp No Chicago fll Union Carbide Corp Electronics Div Mountain View Calif UID Electronics Corp Hollywood Fla Pamotor Inc Pampa Texas General Electric Co Schenectady N Y General Electric Co Lamp Div of Con sumer Prod Group Nela Park Cleveland Ohio West Concord Mass LTV Electrosystems Inc Memcor Com ponents Operations Huntington Ind Dynacool Mfg Co Inc Saugerties N Y National Semiconductor Corp Santa Clara Calif Palo Alto Calif Kenilworth N J Hewlett Packard Co Heyman Mfg Co IMC Magnetics Corp New Hampshire Div Rochester N H SAE Advance Packaging Inc Santa Ana Calif Ramona Cali
25. 1 Output Impedance Test Setup b Set METER switch to highest voltage range and turn CURRENT controlsfully clockwise and turn on supply c Adjust VOLTAGE control s until front panel meter reads 20 volts d Set AMPLITUDE control on Osciliator to 10 volts Bi and FREQUENCY control to i kHz e Record voltage across output terminals of the power supply Eo as indicated on AC voltmeter f Calculate the output impedance by the following formula Zout EoR Ein Eo Eg rms voltage across power supply output terminals R 1000 Ein 16 volts o The output impedance Zout should be less than 0 01 ohm h Using formula of stepf calculate output impedance at frequencies of 10kHz 100kHz and 1MHz Values should be less than 0 05 ohm 0 5 ohm and 5 ohms respectively 5 34 CONSTANT CURRENT TESTS 5 35 Load Regulation To check the constant cur rent load regulation proceed as follows a Connect test setup as shown in Figure 5 4 b Turn VOLTAGE control s fully clockwise c Set METER switchto highestcurrent range and turn on supply d Adjust CURRENT control until front panel meter reads exactly the maximum rated output cur rent e Read and record voltage indicated on differential voltmeter f Short out load resistor Ry by closing switch S1 g Reading on differential voltmeter should not vary from reading recorded in step e by more than the following Mode No 6253A 6284A 6255A 6289A
26. 13211 Tel 315 455 2486 1 Crossways Park West Woodbury 11797 Tet 516 921 0300 TWX 510 221 2183 NORTH CAROLINA 5805 Roanne Way Graenaboro 27405 Tel 819 852 1800 OHIO Pi aeg Only xd 300 1313 t Kemper Rd Cincinnatl 45428 Tei 513 571 7400 18500 Spraque Road Cleveland 44130 Tel 216 243 7390 TWX 810 423 9420 330 Progress Rd Dayton 45449 Tat 513 859 6202 1041 eripe Parkway Coiumbus 43229 Tek 14 Hye 1041 OKLAHOMA PI Box 32008 5301 N Merian Avenue Okiahoma City 73112 Tel 405 721 0 4110 S 100th E Avenue Grant Bl g Tuiss 74145 Hewlett Packat Espa ola S A Av Rarndn y Cas 1 Editicio Sevilia pianta 9 Seville 5 Tet 64 44 SA Hewie amp Packard ES ea Albie il il Tet 23 03 06 23 B2 36 Hewlett Packard Espa ola S A C Ramon Gordillo t ed fate AR Tel prend 3 18 544261 13 58 SWEDEN Mewlett Packard Sverige AB Enighetsvigen 3 Pack 5 16 Bromma 20 Tel ker 730 05 50 Telex 10721 Cable MEASUREMENTS Stockhatm Hewiett Packar Sverige AB Frotalisgatan 3G 5 421 52 Vastra Fr unda Tei 030 49 G9 0 Telex 10721 via Bromma office SWITZERLANO Hewlett Packard Schwaiz AG Zbschorstrass 20 ED Box 307 CH 8952 Sehlieren turich Tei 01 7305240 Telex SE th Cable H Geesen Schweiz AG Chateau Bloc t9 CH 1219 e Li ma Tek 022 96 Talex 27333 Cable HEWPA SYRIA Ganaral Electronic Inc Nui Basha Ahnaf Ebn Kays S
27. 15 1 R35 fxd comp 2004 5 iw 2 EB 2015 A B 01121 0686 2015 i R36 fxd ww 5004 5 10w 2 HLAB 09182 0811 1909 1 R39 fxd met film 1 21Ka 4190 1 8w 2 Type CEA T O LRC 07716 0757 0274 i R40 57 60 62 fxd met film 90042196 1 8w 8 Type CEA T O ILR C 07716 0757 1099 2 R41 fxd comp 12Ka 5 iw 2 EB 1235 A B 01121 0686 1235 1 R42 fxd comp 6 8K 5 iw 2 EB 6825 A B 01121 0686 6825 i R43 fxd met film 4224 1 iw 2 Type CEB T O ER C 07716 0698 4590 1 R44 fxd comp 47Ka 5 iw 2 EB 4735 A B 01121 0686 4735 i R45 fxd comp 5 IKa 45 iw 2 EB 5125 A B 01121 0686 5125 i R46 fxd comp 100Ka 5 iw 2 EB 1045 A B 01121 0686 1045 d R47 fxd comp 470 5 lw 2 EB 4715 A B 01121 0686 4715 1 R49 fxd ww 9004 5 15w 2 HLAB 09182 0811 0957 i R50 fxd comp 104 5 iw 2 EB 1005 A B 01121 0686 1005 1 R51 fxd comp 30Ka 5 2 EB 3035 ALB 01121 0686 3035 1 R52 fxd comp 22K 45 iw 2 EB 2235 A B 01121 0686 2235 1 R53 fxd comp 3Ka 5 Zu 2 EB 3025 A B 01121 0686 3025 i R54 fxd ww 0 664 C T 45 20w 2 HLAB 09182 0811 1818 i R56 var ww IKa Modify 3 Type 110 F4 GETS 11236 2100 0391 1 R58 59 fxd met film 100n 1 1 8w 4 Type CEA T O LRC 07716 0757 0401 d R61 fxd met film 47 5Kn 1 1 8w 2 Type CEA T O TRG 07716 0757 0457 l R66 67 fxd met film 3 40Ka 41 za 4 Type CEB T O LRG 07716 0698 4642 l R68 69 fxd met film 3654 1 iw 4 Type CEB T O LRC 07716 0757 0723 1 R70 71 75 85 fxd met film 3K 1 1 8w 8 Type CEA T O ILR C 07
28. 2 0 1 1 2 watt S00pf 50 wVdc Range 0 500K Accuracy 0 1 plus 1 ohm Make before break contacts NOTE Measure transient response Power supply load resis tors Measure current calibrate meter cc ripple and noise Measure impedance Measure impedance Calibrate programming current Calibrate programming current Measure impedance Measure programming coefficients See Figure 5 8 See Parts List R54 R55 A A satisfactory substitute for a differential voltmeter is to arrange a reference voltage source and nuli detector as shown in Figure 5 3 The reference voltage source is ad justed so that the voltage difference between the supply being measured and the refer ence voltage will have the required resolution for the measurement being made The voltage difference will be a function of the null detector that is used Examples of sat isfactory null detectors are Ze 419A null detector a dc coupled oscilloscope utilizing differential input or a 50mV meter movement with a 100 division scale For the latter a 2mV change in voltage will result in a meter deflection o four divisions 5 2 CAUTION Care must be exercised when using an electronic null detector in which one input terminal is grounded to avoid ground loops and circulating currents POWER SUPPLY UNDER TEST REFERENCE VOLTAGE SOURCE Figure 5 3 Differential Voltmeter Substitute Test Setup 5 10 PERFORMANCE TEST 5 11
29. 281A 253A 6284A 6255A 62894 Figure 5 8 Transient Response Test Setup LOADING TRANSIENT UNLOADING TRANSIENT Figure 5 9 Transient Response Waveforms 5 32 Programming Speed This measurement is made by monitoring the output voltage with an os cilloscope while rapidly changing the remote pro gramming resistance For up programming the re mote resistance is varied from zero ohms to the val ue that will produce maximum output voltage and for down programming ther mote resistanceis var ied from the value that wili produce maximum output voltage to zero ohms To check the up programming speed make the connections indicated in Figure 5 10 for down programming simply remove RI AL A3 A4 A5 AG A7 AB S GND 5 AIO ejsaieiareleielelalaiele c Of Els O O VERTICAL a INPUT t t OSCILLOSCOPE HSV 60 HZ MERCURY WETTED RELAY MODEL 6255A 6284A 6289A Figure 5 10 Constant Voltage Programming Speed Test Setup The load resistance is included for up programming and removed for down programming to present the worst possible conditions for the supply to reach the programmed voltage Refer to Application Note 90 Power Supply Handbook for further details on remote programming speed To check the program ming speed proceed as follows 1 Restraptherear barrier stripas indicated in Figure 5 10 Note that the jumper between S and A10 is removed This disconnects the output capacitor C20 to i
30. 29280 Tel 803 782 6493 TENNESSEE 8914 Kingston Pika Knoxville 37922 Tel 815 523 0522 3027 Vanguard Dr Director s Plaza Moinpnis 38131 Tal 01 346 6370 JS gdical Service gniy pu 615 244 Dun TEXAS 4175 North Mesa Suite C413 i Paso 79902 Tel 915 533 3555 P O Box 1270 201 E Arapako Ad Richardson 75080 Toi 214 231 8101 UNITED ARAB EMIRATES Emitac Lig P O Box 1651 Sharjah Tal 247213 Telex 8136 MITAC SH Cable EMITAC SHARJAH UNITED KINGDOM Hewiett Packar Lid Xing Street Lane GB Winnersh Wokingham Berks AG11 SAR Tel 8734 78 47 74 Cable Hewpte Landon Felex 847178 9 Hewlett Packard Ltd Trataigar House Navigation Road Aitrincthiam Cheshire WAt4 INU el 081 928 6422 Telex 568068 Hawiett Packard Ltd Lygon Court Heraward Rise ee Roag Hates ost Midlands 862 850 Tel 021 50 9917 Telex 339100 Hewlett Packard Lid Wedge House 799 London Road aB Maren CSR Surrey Tek 5 EH Za Tmiex 946625 Hewlett Packard itd 0 Wesley t Caatieford Yorks WFIU 1AE Toi 0977 550038 Teiax 557955 Hewiott Packard Lit 1 Wallace Way 58 Hitchin Hertfordshire 564 OSE Tel 0462 31111 Talex 82 59 81 Hewlet Packard Lit 2C Avonbeg Industrial Estate Long Mie m Acad bii Tel Duba 514322514224 Telex 30439 USSA Hewlett Packard Reprasentative Office USSR Pokrovsky Boulevard 4 17 xw 12 000 Telex 7825 hewpa su YUGOSLAVIA Iskra Standard Hewlett
31. 30 83385 83501 Table 6 3 MANUFACTURER Cinch City of Industry Calif Oak Mfg Co Div of Oak Electro Netics Corp Crystal Lake Ill Bendix Corp Electrodynamics Div No Hollywood Calif Palnut Co Mountainside N J Patton MacGuyer Co Providence RL Phaostron Instrument and Electronic Co South Pasadena Calif Philadelphia Steel and Wire Corp Philadelphia Pa American Machine and Foundry Co Potter and Brumfield Div Princeton Ind TRW Eiectronic Components Div Camden N J Resistance Products Co Harrisburg Pa Illinois Tool Works Inc Shakeproof Div Elgin Ill Everlock Chicago Inc Chicago Ill Stackpole Carbon Co St Marys Pa Stanwyck Winding Div San Fernando Electric Mfg Co Inc Newburgh N Y Tinnerman Products Inc Cleveland Ohio Stewart Stamping Corp Yonkers N Y Waldes Kohinoor Inc 1 10 4 NY Whitehead Metals Inc New York N Y Continental Wirt Electronics Corp Philadelphia Pa Zierick Mfg Co Mt Kisco N Y Mepco Div of Sessions Clock Co Morristown N J Bourns Inc Riverside Calif Howard Industries Div of Msl Ind Inc Racine Wisc Grayhill inc La Grange Ill International Rectifier Corp El Segundo Calif Columbus Electronics Corp Yonkers N Y Goodyear Sundries amp Mechanical Co Inc New York N Y Airco Speer Electronic Components i Du Bois Pa Sylvania Electric Products Inc Electronic Tube Div Receiving Tube Operations Emporium Pa Switch
32. 45 Iw 2 GB 6225 0689 6225 l R3 fxd met film 1 21Kn 1 1 8W 2 Type CEA T O 0757 0274 l R4 fxd met film 7 5Ka 1 1 8W 2 Type CEA T O 0757 0440 l R5 var ww l0Ka 5 2 2100 1854 1 R6 fxd ww lKa 45 3W 2 24251025 0813 0001 1 R7 fxd comp 22a 5 W 2 EB 2205 0686 2205 l R8 fxd met film 1964 1 1 8W 2 Type CEA T O 0698 3340 i Tl Transformer Pulse 2 5080 7122 1 Diode zener 6 19V 5 2 1902 0049 4v Diode zener 2 37V 45 2 1902 3002 2 MISCELLANEOUS Heat Sink CR4 5000 6229 Insulator CR4 0340 0462 2 Mica Washer CR4 2190 0709 2 fxd elect luF 50Vdc Cable Clamp Bushing Potentiometer R5 Nut Hex R5 Label Information Crowbar Adj Printed Circuit Board Assembiy includes Components Modified Front Panel Includes Components 6255A A 2 30D105G050BA2 0180 0108 1400 0330 1410 0052 2950 0034 7124 0389 bol PIE 06255 60003 DC POWER SUPPLY FROM INBOARD SIDE OF R54 BIAS VOLTAGE FROM COLLECTOR OF Q7 d R5 IOK ADJUST CR4 CIRCUIT PATENTS APPLIED FOR LICENSE TO USE MUST BE OBTAINED IN WRITING FROM HEWLETT PACKARD CO HARRISON DIVISION Figure A 1 Model 6255A and 6289A Overvoltage Protection Crowbar EUROPE NORTH AFRICA AND MIDDLE AUSTRIA Hewlett Packard Gas m D H Mandelskai 52 0 29 Cette HEWPAK Vienna Telex 75923 hewpak BELGIU Hewiett rs Senelux AN 5 Avenue du Coi Vert t Groenkeaagiaan B 117D Brussels Tei 023 580 0047 672 2240 Ca
33. 54 AMMETER TRACKING 5 55 To calibrate ammeter tracking proceed as follows a Connect test setup shown on Figure 5 4 leaving switch S1 open b Turn VOLTAGE controlfully clockwise and set METER switch to highest current range c Turn on supply and adjust CURRENT con trols until differential voltmeter reads 1 0Vdc d Adjust R56 until front panel meter indi cates exactly the maximum rated output current 5 56 CONSTANTVOLTAGE PROGRAMMING CURRENT 5 57 To calibrate the zero volt programming accu racy proceed as follows a Connect differential voltmeter between 5 and S terminals b Short out voltage controls by connecting jumper between terminals A6 and lt 5 c Rotate CURRENT controls fully clockwise and turn on supply d Observe reading on differential voltmeter e If it is more positive than 0 volts shunt resistor R6 with decade resistance box f Adjustdecade resistance until differential voltmeter reads zero then shunt R6 with resistance value equal to that of the decade resistance g If reading of step dis more negative than 0 volts shunt resistor R8 with the decade resist ance box h Adjust decade resistance until differen tial voltmeter reads zero then shunt R8 with resis tance value equal to that of the decade box 5 58 To calibrate the constant voltage programming current proceed as oo a Connect a 0 1 watt resistor between terminals 5 and Ap on rear barrier strip Resistor value to be a
34. 6 6904 EAST ITALY Hewlett Packard italiana S p A Via Amerigo Vespucci 2 Casella postale 3645 20124 Milano Tel 02 6251 10 lines Cable Milano Telex 32046 Hewlet Packard Haliana S p A Via Pellizzo 9 1 35100 Padova Tei 049 AS 48 B6 Telex 41612 Hewpacki Hewiet Packard AME p A m A ep ead lini 1 e cst 54 Bh fi Telex 61514 Cable HEWPACKIT Roma Hewlett Packard italiana S p A Corso Giovanni Lanza 94 1 10133 Torino Tel 011 682245 659308 MedicailCaiculators Only Hewlett Packard italiana S p A Via Principe Nicoia 43 G C 1 951295 Catania Tel 895 37 05 04 Hawiett Packard italiana S p A Via Amerigo Vespucci 9 1 80142 Napoti Tat 081 33 77 11 Telex 61 51 4 Via Rom Hewlett Packard Italiana 5 p A Via Masi 9 8 1 40137 Boiogna Tel St 30 78 87 JORDAN Mauashar Cousins Ca P O Box 1387 Ammen Tek 24907 39907 Telex SA8GO 30 1456 Cable MOUASHERCO KUWAIT Al Khaldiya Trading A Contractin atat Kuwait Tek42 4910 41 1726 Taiex 2481 Arety xt Cable VISGOUN LUXEMBURG Packar Benalux Avenue du Col Vert 1 Tel 102 672 22 40 aie ALOBEN Brussels Telex 23 494 MOROCCO Doia 81 rug Karatchi Casablanca Tek 22 41 82 87 Telex 23054 22833 Cable MATERIO gerop 190 Blvd Srahim Roudani Casablanca Tal 25 16 75 25 90 99 Telex 23 728 GEREP CASA Cog 2 2 Agadir B P 356 Casablanca Tek 27 GE m Telex 21 Cable COGED
35. 6299A Trip Voltage Rangg 2 5 23V 2 5 44V 2 5 10V 2 5 23V 2 5 44V 2 5 65V 30 106V To prevent transients from falsely tripping the crowbar the trip voltage must be set higher than the power supply output voltage by the following margin 4 of the output voltage plus Y The margin represents the minimum crowbar trip setting for a given output voltage the trip voltage can always be set higher than this margin OPERATION 1 Turn the CROWBAR ADJUST fully clockwise to set the trip voltage to maximum 2 Set the power supply VOLTAGE control for the desired crowbar trip voltage To prevent false crowbar tripping the trip voltage should exceed the desired output voltage by the following amount 4 of the output voltage plus 2V 3 Slowly turn the CROWBAR ADJUST ccw until the crowbar trips output goes to OV or a small positive voltage 4 The crowbar will remain activated and the output shorted until the supply is turned off To reset the crowbar turn the supply off then on 5 If the CROWBAR must be completely disabled remove the lead attached to the CROWBAR ADJUST potentiometer R5 DPR MPB 3 A 1 l Replaceable Parts MFR HP DESCRIPTION MFR PART NO CODE PART NO Ci C2 fxd mica 510uF 500Vdc i RCMISES11 0140 0047 CR1 CR3 Diode Si 200mA 200prv 6 1901 0033 6 CR4 SCR 7 4A 100prv 2 C20A 1884 0031 2 Ol 2 SS NPN Si 4 2N3417 1854 0087 4 R1 fxd met film 10 1 1 8W 2 Type CEA T O 0757 0346 i R2 xd comp 6 2Ka
36. 716 0757 1093 2 R72 var ww 250 Modify 2 Type 110 F4 G T By 11236 2100 0439 1 R73 fxd met film 7504 2195 1 8w 2 Type CEA T O LRO 07716 0757 0420 1 R74 fxd met film 9 09K4 41 V 8w 2 Type CEA T O LR C 07716 0757 0288 i R80 fxd comp 33Ka 5 w l EB 3335 A B 01121 0686 3335 l R81 83 fxd ww 1204 5 75w 6 Type 6BR 37 Hx 73978 0811 1971 2 Si Switch pilot lite red ON OFF SPDT H 54 61681 26AIH Oak 87034 3101 0100 1 2 Switch meter 2 HLAB 09182 3100 1910 i T1 Power transformer 2 HLAB 09182 9100 1838 1 VRI 2 Diode zener 6 2V 4 iN821 N A Elect 06486 1902 0761 4 VR3 Diode zener 4 22V 400MW 2 HLAB 09182 1902 3070 2 VR4 5 Diode zener 4 3V lw 4 HLAB 09182 1902 0797 4 Outrigger chassis H C 1 HLAB 09182 5000 6090 PC Board bracket 1 B 1 HLAB 09182 5000 6088 Transformer bracket right H O 5950 5271 1 HLAB 09182 5000 6087 Transformer bracket left 1 C 5950 5271 1 HLAB 09182 5000 6183 Front panel l HLAB 09182 06255 60001 Cover 2 D 1 HLAB 09182 5000 6089 Outrigger cover i Cl HLAB 09182 5000 6091 Angie guard 2 B 5950 5221 1 HLAB 09182 5020 5540 6255A Reference Mfr Part Desianator Description nti or Type P C Board assembly includes components 2 HLAB 09182 06255 60021 Printed circuit board blank 2 HLAB 09182 5020 5598 Chassis assembly right l D 5950 5249 1 HLAB 09182 5060 6129 Chassis assembly left 1 D 5950 5249 1 HLAB 09182 5060 6130 Sink assembly heat 1 5950 5233 1 HLAB 09182 5606 6128 5 Way
37. CIR CUIT OUTPUT TERMINALS ADJUST CURRENT CONTROLS FOR DESIRED OUTPUT CURRENT REMOVE SHORT AND CONNECT LOAD TO OUTPUT TERMINALS FRONT OR REAR Figure 3 1 Front Panel Controls and Indicators 3 3 OPERATING MODES 3 4 The power supply is designed so that its mode of operation can be selected by making strapping connections between particular terminals on the terminal strip at the rear of the power supply The terminal designations are stenciled in white on the power supply above their respective terminals Al though the strapping patterns illustrated in this section show the positive terminal grounded the operator can ground either terminal or operate the power supply up to 300Vdc off ground floating The following paragraphs describe the procedures for utilizing the various operational capabilities of the power supply A more theoretical description concerning the operational features of this supply is contained in Application Note 90 DC Power Sup piy Handbook which may be obtained from your local Hewlett Packard field sales office 3 1 3 5 NORMAL OPERATING MODE 3 6 The power supply is normally shipped with its rear terminal strapping connections arranged for Constant Voltage Constant Current local Sensing local programming single unit mode of operation This strapping pattern is illustrated in Figure 3 2 The operator selects either a constant voltage or a constant current output using the front panel con
38. IR NETHERLANDS Hewlett Packard Benelux RV Van Hguvan Goedhartlaan 121 P G Box 687 Nt Amstelveun 1134 Tai 020 47 26 21 Cable PALOBEN Amsterdam Telex 13 216 hepa nl MICHIGAN 23855 Research Drive Fermi Hitls 48024 Tai 313 476 6400 724 West Centre Ava Kalamazoo 49002 Tai 608 323 8362 MINNESOTA 2400 N Price Ave St Paui 55113 Tel 612 636 0700 MISSISSIPPI 322 N Mart Plaza Jackaon 39206 Tal 6013 982 9363 MISSOURI 11131 Colorado Ave Kansas City 54137 Tei 816 763 8000 TWX 910 771 2087 1024 Execulive Parkway St Louis 63141 Tet 314 878 0200 NEBRASKA Medical Oni 7571 Mercy Road Suite 0 Omaha 68106 Tal 402 392 0948 NEVADA Las Vegas Tel 7023 736 6610 NEW JERSEY A gz Rd 07652 ba rest 1285 5600 TWX 710 990 4951 Crystal Brook Professional Guiding Route 3 Estontown 07724 Tei 201 542 1384 NEW MEXICO P O Box 11634 Station E 11300 Lomas Blvd N E Tet 505 292 1330 TWX 910 989 1185 NORWAY Hewiett Packard A S Osterdalen 18 P O Box 34 N 1345 Gsteraas Fak 02 3717 80 Telex 16621 hanas R POLAND Biuro tnformaci Terh icznej Hewlett Packard ul Stawki 2 6P 90 959 Warszawa Tei 33 25 88 39 57 A3 Teiex 85 24 53 hepa pi UNIPAN Biuro Obslugi Technicznej 91 447 Warszaw p Newelska D Poland zak ady brani Sprzetu Medyczni Plac ARE Paryskiej 007 Ladt Tel 334 41 237 83 Telex 886881 PORTUGAL T
39. NT LOADING 3 54 Active loads connected to the power supply may actually deliver a reverse current to the power supply during a portion of its operating cycle n external source cannot be allowed to pump current into the supply without loss of regulatiom and pos sible damage to the output capacitor To avoid these effects it is necessary to preload the sup ply with a dummy load resistor so that the power supply delivers current through the entire operating cycle of the load device SECTION IV PRINCIPLES OF OPERATION REFERENCE REGULATOR CIRCUIT POWER TRANSFORMER RECTIFIER AND FILTER NOTE SERIES REGULATOR MIXER AND ERROR me BIAS VOLTAGE CONSTANT CURRENT INPUT CIRCUIT CURRENT SAMPLING RSESISTOR AMPLIFIER CONSTANT VOLTAGE INPUT CIRCUIT m DENOTES VOLTAGE Figure 4 1 4 1 OVERALL BLOCK DIAGRAM DISCUSSION 4 2 The power supply as shown on the overall block diagram on Figure 4 1 consists of a power transformer a rectifier and filter a series regu lator the mixer and error amplifiers an OR gate a constant voltage input circuit a constant current input circuit a reference regulator circuit a bias supplv and a metering circuit 4 3 The input line voltage passes through the power transformer to the rectifier and filter The rectifier filter converts the AC input to raw DC which is fed to the positive terminal via the regulator and current sampling resistor network The regulato
40. Packart Miosiceva 38 Vil 81000 tjubtana Tet 31 58 79 32 16 74 Telex 31583 SOCIALIST COUNTRIES NOT SHOWN PLEASE CONTACT Hewiatt Packard Ges m b ondes 52 P O Box A 1205 Viana Austria Tet 0222 35 16 21 1027 Cable HEWPAK Vieang MEDITERRANEAN AND MIDDLE EAST COUNTRIES NOT SHOWN PLEASE CONTACT Hewlett Packard S A Mediterranean and Middie East Operations 35 Kolowotroai Street Platia Kefallaricu GR Kifissia Athens Greece Te B080337 359 429 Cabie HEWPACKSA Athens FOR OTHER AREAS NOT LISTED CONTACT Hawiatt Packard S A 7 rue du Bois du Lan P O Bax CH 1217 Meyrin 2 Geneva Switzerland Tel 022 82 70 36 Cable GES Geneva P O Box 428t8 10835 Harwin Dr Mouston 77036 Tel 713 776 6400 Lubbock Medical Sarvice only Tel 806 799 4472 205 Biliy Mitchell Road an Antonio 78228 Tek 512 434 8241 UTAH 2150 Soui 3270 Wes Streel Salt Lake Clty 84119 Tai BOT 972 4711 VIRGINA P O Box 12778 No 7 Koger Exec Centar Suite a E Norfolk 23502 Tai oe AB1 4025 5 P O Box 9659 2814 Hungary Springs Road Richmond 23228 Tek 804 285 3431 WASHINGTON Bellefieid Office Pk 208 t14th Ave SE Bp ovue 98004 Tek 206 454 3971 TWX 910 443 2446 WEST VIRGINIA bedrest t Day hari Tek 1304 345 1646 WISCONSIN 9004 West Lincoln Ave West Allis 53227 Tel 4141 541 0550 FOR US AREAS NOT LISTED Contact the regional olfice nearest you Atlanta Georgia
41. R10 A and B have been adjusted so that the supply is yielding the desired output voltage Purther assume that the output voltage instanta neously rises goes positive due to a variation in the external load circuit 4 11 Note that the change may be in the form of a slow rise in the output voltage or a positive going AC signal An AC signal is coupled to summing point A6 through capacitor Cl and a DC voltage is coupled to A6 through R10 4 12 The rise in output voltage causes the voltage at A6 and thus the base of Q1A to decrease go negative QIA now decreases its conduction and its collector voltage rises The positive going er ror voltage is amplified and inverted by Q3 and fed to the bases of series transistors Q6 and Q7 via emitter followers Q5 and O4 The negative going input causes Q6 and Q7 to decrease their conduc tion so that they drop more of the line voltage and reduce the output voltage to its original level 4 13 If the external load resistance is decreased to a certain crossover point the output current in creases until transistor Q2A begins to conduct During this time the output voltage has also de creased to a level so that the base of QIA isata high positive potential With QIA in full conduc tion its collector voltage decreases by the amount necessary to back bias OR gate diode CR3 and the supply is now in the constant current mode of op ration The crossover point at which constant current operation commence
42. Semiconductor Characteristics Page No 5 12 5 14 Checks and Adjustments After Replace ment of Semiconductor Devices Calibration and Adjustment Summary LIST OF ILLUSTRATIONS 1 DC Power Supply l Primary Connections 1 Front Panel Controls and Indicators 2 Normal Strapping Pattern 3 Remote Resistance Programming Constant Voltage 3 4 Remote Voltage Programming Constant Voltage 3 5 Remote Resistance Programming Constant Current 3 6 Remote Voltage Programming Constant Current 3 7 Remote Sensing 3 8 Normal Series Connections 3 9 Auto Series Two and Three Units 3 10 Normal Parallel Connections 3 11 Auto Parallel Two Units 3 12 Auto Tracking Two and Three Units 4 1 Overall Block Diagram Page No iv 2 1 3 1 3 1 3 2 3 2 GA i gt CO cee i Dei WW CO W CO CO CO i E c oot o p i e iid Figure 4 2 Simplified Schematic 4 3 Voltmeter Connections Simplified Schematic d 4 4 Ammeter Connections Simplified Schematic 5 1 Front Panel Terminal Connections 5 2 Output Current Measurement Technique 5 3 Differential Voltmeter Substitute Test Setup 5 4 Output Current Test Setup 5 5 Load Regulation Constant Voltage Test Setup CV Ripple and Noise Test Setup CV Noise Spike Test Setup Transient Response Test Setup Transient Response Waveforms Constant Voltage Programming Speed Test Setup Output Impedance Test Setup CC Ripple and Noise Test Setup Servicing Printed Wirin
43. Table 5 3 b Noisy programming resistor R10 C CRI CR2 leaky d Check R1 R12 R13 and C2 for noise or drift e Stage Q1 defective Check 6 2Vdc reference voltage Table 5 3 Poor stability Constant Current a b Noisy programming resistor R16 c CR5 CR34 C19 C3 leaky d Check R18 R19 R20 R21 R54 and R55 for noise or drift e Stage Q2 defective Poor transient recovery a Check R30 and CS Refer to adjustment procedure Paragraph 5 64 Table 5 3 Reference Bias and filtered DC Troubleshooting Meter Meter Normal Normal Common Positive Vdc Ripple P P Cause VRI Q8 Q9 24 AV C10 CR22 CR23 T1 4 4 VR4 28V 625 3A C12 CR24 5 3V 6255A CR25 T1 12V 6281A 28V 6284A 53V 6289A 80V 6294A 38V 6253A i Gi4 G16 62V 6255A CR26 CR27 21V 6281A R49 T1 38V 6284A 62V 6289A 90V 6294A Table 5 4 Low Output Voltage Troubleshooting sep ation Ro _ Probable Cause Se Turn the VOLTAGE control fully clockwise and disconnect the load To eliminate the constant cur Output increases Stage Q2 defective rent circuit as a cause of the malfunction remove CR4 cath ode or anode lead Output remains low b Reconnect CR4 and proceed to step 3 Check conduction of Q6 and Output remains low a Op Q7 CRI11 or associated Q7 by connecting a jumper be parts defective tween Q4 emitter 22 and R 4 base 18 QOutput increa
44. Test 5 3 3 3 Operating Modes 3 1 5 12 Constant Voltage Tests 5 3 3 5 Normal Operating Mode 3 1 5 34 Constant Current Tests 5 7 3 7 Constant Voltage 3 1 5 39 Troubleshooting 5 9 3 9 Constant Current 3 1 5 41 Trouble Analysis 5 9 3 11 Connecting Load 3 2 5 46 Repair and Replacement 5 14 3 14 Operation of Supply Beyond 5 48 Adjustment and Calibration 5 15 Rated Output 3 2 5 50 Meter Zero 5 15 3 16 Optional Operating Modes 3 2 5 52 Voltmeter Tracking 5 16 3 17 Remote Programming 5 54 Ammeter Tracking 5 16 Constant Voltage 3 2 5 56 Constant Voltage Programming 3 24 Remote Programming Current 5 16 Constant Current 3 3 5 59 Constant Current Programming 3 30 Remote Sensing 3 3 Current 5 16 3 35 Series Operation 3 4 5 62 Reference Circuit Adjustments 5 17 3 39 Parallel Operation 3 5 5 64 Constant Voltage Transient 3 42 Auto Tracking Operation 3 6 Response 5 17 3 45 Special Operating Considerations 3 6 VI REPLACEABLE PARTS ia wn 6 1 3 46 Pulse Loading 3 6 6 1 Introduction 6 1 3 48 Output Capacitance 3 6 6 4 Ordering Information 6 1 3 5 Reverse Voltage Loading 3 7 3 53 Reverse Current Loading 3 7 APPENDIX BE ri edd Sahl anite e cre A 1 Li TABLE OF CONTENTS CONTINUED Tab l i Specifications 5 1 Test Equipment Required 5 2 Common Troubles 5 3 Reference Bias and Filtered DC Troubleshooting 5 4 Low Output Voltage Troubleshooting LIST OF TABLES Page No 1 3 5 2 319 Table 5 5 High Output Voltage Troubleshooting Selected
45. UND CURRENT Is PRODUCES 60 CYCLE DROP IN NEGATIVE LEAD WHICH ADDS TO THE POWER SUPPLY RIPPLE DISPLAYED ON SCOPE POWER SUPPLY CASE OSCILLOSCOPE CASE B A CORRECT METHOD USING A SINGLE ENDED SCOPE OUTPUT FLOATED TO BREAK GROUND CURRENT LOOR TWISTED PAIR REDUCES STRAY PICKUP ON SCOPE LEADS POWER SUPPLY CASE OSCILLOSCOPE CASE Tr T O VERTICAL 4 INPUT C A CORRECT METHOD USING A DIFFERENT AL SCOPE WITH FLOATING INPUT GROUND CURRENT PATH IS BROKEN COMMON MODE REJECTION OF DIFFERENTIAL INPUT SCOPE IGNORES DIFFERENCE IN GROUND POTENTIAL OF POWER SUPPLY 8 SCOPE SHIELDED TWO WIRE FURTHER REDUCES STRAY PICK UP ON SCOPE LEADS Figure 5 6 CV Ripple and Noise Test Setup 5 21 Ripple and Noise Measurements Figure 5 64 shows an incorrect method of measuring p p ripple Note that a continuous ground loop exists from the third wire of the input power cord of the supply to the third wire of the input power cord of the oscil loscope via the grounded power supply case the wire between the negative output terminal of the power supply and the vertical input of the scope and the grounded scope case Any ground current circulating in this loop as a result of the difference in potential Eg between the two ground points causes anIR drop whichisin series withthe scope input This IR drop normally having a 60Hz line frequency fundamental plus any pickup on the un shielded leads interconnecting the power suppiy and scope appears
46. Variation mVdc 0 183 0 265 Model No 6281A 6294A Variation mVdc 0 5 0 35 5 36 Line Regulation To check the line regulation proceed as follows a Utilize test setup shown in Figure 5 4 leaving switch S1 open throughout test b Connect variable auto transformer be tween input power source and power supply power input c Adjust auto transformer for 105Vac input d Turn VOLTAGE control s fully clockwise e Set METER switch to highest current range and tum on supply f Adjust CURRENT controls until front panel meter reads exactly the maximum rated output cur rent g Read and record voltage indicated on dif ferential voltmeter h Adjust variable auto transformer for 125 Vac input i Reading on differential voltmeter should not vary from reading recorded in step g by more than the following _ Model No 6253A 6284A 6255A 6289A Variation mVdc 0 183 0 265 Model No 62814 62944 Variation mVdc 0 15 0 35 5 37 Ripple and Noise Most of the instructions pertaining to the ground loop and pickup problems associated with constant voltage ripple and noise measurement also appiytothe measurement of con stant current ripple and noise Figure 5 12 illus trates the most important precautions to be observed when measuring the ripple and noise of a constant current supply The presence of a 120 cycle wave form on the oscilloscope is normally indicative of a correct measurement method A wavesha
47. Voltage b Check the regulation characteristics of Zener diode VRI as follows 1 Connect differential voltmeter across VR1 2 Connect appropriate load resistor Ry given in Figure 5 4 across 4 and output terminals 3 Perform steps b through f of Paragraph 5 16 4 If the differential voltmeter reading varies by more than 0 5mV replace VRI c Ensure that supply is not in constant current operation under loaded conditions To prevent this condition turn CURRENT control fully clockwise a Improper measuring technique refer to Paragraph 5 3 Poor load regulation Constant Current b Check the regulation characteristics of Zener diode VR2 as follows 1 Connect differential voltmeter across VR2 2 Connect appropriate load resistor Ry given in Figure 5 4 across 4 and output terminais 3 Perform steps b through f of Paragraph 5 35 4 If the differential voltmeter reading varies by more than 0 5mV replace VR2 c C19 C20 and CR34 leaky d Check clamp circuit Q10 CR30 VR3 and CR32 e Ensure that supply is not crossing over into constant voltage operation To prevent this condition load the supply and turn the VOLTAGE control fully clockwise Oscillates a Check C5 open Adjustment of R30 refer to Paragraph 5 64 i b Check R21 and C3 in current input circuit Poor stability Constant Voltage a Check 6 2Vdc reference voltage
48. acceptable for measur ing spikes a differentialoscilloscope is necessary Purthermore the measurement concept of Figure 5 60 mustbe modified if accurate spike measure ment is to be achieved 1 As shown in Figure 5 7 two coax cables must be substituted for the shielded two wire cable 2 Impedance matching resistors must be included to eliminate standing waves and cable ringing and the capacitors must be connected to block the DC current path POWER SUPPLY TOR OSCILLOSCOPE CASE T CONNECTO CASE O Oluf OT VERTICAL 1 5 INPUT VERTICAL INPUT AE T CONNEC TOR doi son TERMINATION Figure 5 7 CV Noise Spike Test Setup 3 The length of the test leads outside the coaxiscriticaland mustbe keptas shortas possi ble the blocking capacitor and the impedance matchingresistor should be connected directly from the inner conductor of the cable tothe power supply terminals l 4 Notice that the shields of the power sup ply end ofthe two coax cables are notconnected to the power supply ground since such a connection would giverise to a ground current path through the coax shield resulting in an erroneous measurement 5 The measured noise spike values must be doubled since the impedance matching resistors constitute a 2 to attenuator 6 The noise spikes observed onthe oscillo scope should be less than 0 5mV p p 5 30 The circuit of Figure 5 7 can also be used for the normal measurement of low frequency
49. age or constant current input circuit to a level sufficient to drive the series regulator transistors Tbe emitter bias potential for mixer amplifier Q3 is established by the emitter follower Transistor Q3 receives the error voltage input from either the constant voltage or constant current circuit via the OR gate diode CR3 or CR4 that is conducting at that time Diode CR3 is forward biased and CR4 reversed biased during constant voltage operation The reverse is true during constant current operation 4 30 The RC network composed of C5 and R30 is an equalizing network which provides for high fre quency rolloff inthe loop gain response in order to stabilize the feedback loop Emitter follower tran sistors O4 and Q5 are the error amplifiers serving as the driver and predriver elements respectively for the series regulator Transistor Q4 together with diode R17 provides a low resistance dis charge path for the output capacitance of the power supply during rapid down programming 4 31 REFERENCE CIRCUIT 4 32 The reference circuit is a feedback power supply similar to the main supply It provides stable reference voltages which are used through out the unit The reference voltages are all de rived from smoothed DC obtained from the full wave rectifier CR22 and CR23 andfilter capacitor C10 The 6 2 and 6 2 voltages which are used in the constant voltage and current input circuits for comparison purposes are developed acr
50. aiectra Empresa T cnica de Equipamantos El ctricas 5 2 14 Rua Rodel d a Fonsaca 103 a bica er Tet Kei Se 0 72 Cat TELECTRA Lisbon Taiex 12598 Medical oniy Mundiater bred Mundial de Comercio IR P G Box 2761 Avenida Antonlo Augusto a fouar 138 P Tel Ve E 21317 Telex 15591 muntar p Cabla INTERCAMBIO Lee RUMANIA Hawielt Packard Raprazentanta d n Baicescu 16 Bucurestt Tei 15 80 23 13 88 85 Telex 10440 ER U C intreprinderea Pantry intretineraa Si Repararaa utlajelor qe Calcul Soul Prof Dimitrie Pompei 6 Bucuresti Sectorul Z Tel 88 20 70 B8 P 40 88 67 98 Telex 118 SAUDI ARABIA Modern Elactronic Establishment Head Office PA e 1228 Baghdadiah Street dedds Tei 27 m Telax 40035 Cable ELECTA JEDDAH Modern Etactronic Establishment Branch P O Box 2728 ren Taf 62536766232 Taha RAQUFCO Modatn Elactronic Establishment Sranch RO Box E Al Khoba Tel 41573 44813 Telex 87644 OTESTA Cable ELECTA AL KHOBAR SPAIN Hewiett Packard Espa ola S A SE Jt EA Tei E E 25 2 40 lines Telex 2 hewlett Ad pif SA Miianesado 21 23 t Barca ona t Tab 3 203 6200 45 fines Telex 52803 hpbe e 18 Wen Drive Cruces 86001 Ta WE 526 2484 TAX 910 9983 0550 NEW YORK 6 Automation Lane computa GA D SE 458 1550 TWX 110 444 4961 850 Perinton Hill Office Park Fal 14450 Tel 1716 223 9950 TWX 510 253 0092 5858 East Motor Road Syracusae
51. ailed specifications for the power supply are given in Table 1 1 NOTE Since both sections of this supply are identical only one section will be discussed throughout the remain ing portions of this manual All descriptions illustrations tests and adjustments apply equally to both sections of the supply 1 8 OPTIONS 1 9 Options are factory modifications ofa stand ard instrument that are requested by the customer The following options are available for the instru ment covered by this manual Where necessary detailed coverage of the options is included through out the manual Option No 07 08 08 i0 11 Description Voltage 10 Turn Pot A single con trol that replaces both coarse and fine voltage controls and improves output settability Standard item on Model 6258A power supplies Current 10 Turn Pot A single con trol that replaces both coarse and fine current controis and improves output settability Voltage and Current 10 Turn Pot Consists of Options 07 and 08 on the same instrument Chassis Slides Enables convenient access to power suppiy interior for maintenance purposes internal Overvoltage Protection Crowbars This option includes two crowbar circuits one for each power suppiy within the 6253A or or 6255A Each crowbar protects delicate loads by monitoring the out put voltage and firing an SCR that shorts the output when the preset trip voltage is exceeded The circuit board
52. ampere output the differential ampli fiers are quickly driven into saturation limiting the current through the meter to a safe value Figure 4 3 Voltmeter Connections Simplified Schematic CURRENT SAMPLING RESISTOR S SERIES REG Figure 4 4 Ammeter Connections Simplified Schematic 4 40 Figures 4 3 and 4 4 show the meter connec tions when the METER section of 82 is in the higher voltage and current range positions respec tively For the sake of simplicity some of the actual circuit components are not shown on these drawings With the METER switch in the higher voltage range position 2 the voltage drop across R59 is the input to the meter amplifier and the meter indicates the output voltage across the 8 and S terminals For low output voltages 52 can be switched to the low voltage position 1 result ing in the application of a larger percentage of the output voltage drop across R59 and R60 to the meter amplifier 4 6 4 41 As illustrated in Figure 4 4 with the METER switch in the high current position 3 the voltage drop across R58 is applied to the meter amplifier and the meter indicates the output current which flows through the sampling resistor network For low values of output current the METER switch can be setto position 4andthe voltage drop across R57 and R58 is applied to the meter amplifier SECTION V MAINTENANCE 5 1 INTRODUCTION 5 2 Upon receipt of the power supply the per form
53. ance check Paragraph 5 10 should be made This check is suitable for incoming inspection If afault is detected inthe power supply while making the performance check or during normal operation proceed to the troubleshooting procedures Para graph 5 41 After troubleshooting andrepair Para graph 5 46 perform any necessary adjustments and calibrations Paragraph 5 48 Before returning the power supply to normal operation repeat the performance check to ensure that the fault has been properly corrected and that no other faults exist Before doing any maintenance checks turn on pow er supply allow a half hourwarm up and read the general information regarding measurement tech niques Paragraph 5 3 5 3 GENERAL MEASUREMENT TECHNIQUES 5 4 The measuring device must be connected acrossthe sensingleads ofthe supply or as close tothe output terminals as possible when measuring the output impedance transient response regula tion or ripple of the power suppiy in order to achieve valid measurements A measurement made across the load includes the impedance ofthe leads to the load and such lead lengths can easily have an impedance several orders of magnitude greater than the supply impedance thus invalidating the measurement 5 5 The monitoring device should be connected to the 8 and S terminals see Figure 3 2 or as shown in Figure 5 1 The performance characteris tics should never be measured on the front terminals if the l
54. asset A Ee ad E RY EE Valuetronics international je 1 800 552 8258 MASTER COPY DC POWER SUPPLY DPR SERIES MODEL 6255A OPERATING AND SERVICE MANUAL FOR SERIAL NUMBERS 7F0651 7F0850 Por Serial Numbers Above 7F0850 Check for inclusion of Change Page 100 Locust Avenue Berkeley Heights New Jersey 07922 HP Part No 06255 90002 Printed June 1967 TABLE OF CONTENTS n Page No Section Page No U GENERAL INFORMATION ene 1 1 EI We PRINCIPLES OF OPERATION 4 1 i 1 Description 1 1 4 1 Overall Block Diagram e 1 6 Specifications 1 1 Discussion A 4 1 1 8 Options 1 1 4 5 Simplified Schematic 4 2 1 10 Instrument Identification 1 2 4 8 Detailed Circuit Analysis 4 3 1 13 Ordering Additional Manuais 1 2 4 9 Feedback Loop 4 3 r INSTALLATION 2 1 HE as bi era ENT EC No 2 1 Initial Inspection 2 1 i pun SE Seen 2 3 Mechanical Check fi ser AG 2 5 Electrical Check 2 1 4 20 Constant Current Input 2 7 Installation Data 2 1 ECM ka 2 4 Tonon 2 1 4 25 Voltage Clamp Circuit 4 4 211 Rack Mounting 2 1 4 28 Mixer and Error Amplifiers 4 4 2 13 Input Power Requirements 2 1 4 31 Rererenes REM ilie A 4 34 Meter Circuit 4 5 2 18 Connections for 230 Voit Operation 2 1 duod eer ee 20 V A 3 ORA res ps 2 20 Repackaging for Shipment 2 2 5 3 General Measurement ao OPERATING INSTRUCTIONS s 3 1 Techniques 5 4 3 1 Operating Controls and 5 8 Test Equipment Required 5 1 Indicators 3 1 5 10 Performance
55. ble PALOGEN Brussels Telex 23 494 patobe dru CYPRUS Xypronics 18 Gregorios Xenapoulas Street P G Box 1152 Nicosia Yol 45628 28 Cable Kygtonics Pandehis Telex 3018 CZECHOSLOVAKIA Yyvoiova 2 Provozni Zak adna Vyrkymnych tstavu v Sechovicich CSSR 25097 Bechovice u Prahy Tei BG 93 4t Telex 121333 Institute of Medical Bionics Vyskuenny Ustav Lakatskaj Bioniky Jedlove 6 08 88346 Bratisfava Kramare Tak A253 Telex 93229 DDR Entwicklungslabor der TU Dresden Peng Meinsberg 908 730 Waidheim Meinsberg Tei 37 667 Taiax 538741 Export Contact AG Zuerich Guenther Forgber Schlageistrasse 13 1040 Berlin Tel 42 74 12 Telex 111588 DENMARK Hewlett Packard AS Datavei 52 OX 3460 Birkarod Tet 02 8 68 40 Tabie HEWPACK AS alex 37489 hpas dk Hewlett Packard A S Nayeryei 3 Ce 9600 Sikeborg k 06 82 71 58 Talex 37409 hpas dk Sabie HEWPALK AS GER LEA international Engineering Associates 24 Hussein Hegazi Street Kasr ei Aini Cairo Tei 23 829 Talex 2067 Cable INTENGASSO Mohamed Sami Arain Sami Amin Trading Office 18 Abdel Aziz Gawish Ahbdine Cairo Tel 24932 fable SAMITRO CAIRO FINLAND Hewiatt Packard OY Nahkahousunt 2 0 Box 6 SF 00211 Helsinki 21 Tal en 5923001 Sabla HEWPACKOY Helsinki Telex 12 1563 HEWPA SF FRANCE Hewtett Packard France Quartier dg Courtaboeut Baile Postale No 6 F te cn 907 leg ege Tel Cable E Orszy Telex 600046
56. craft Inc Chicago Ill Metals and Controls Inc Control Products Group Attleboro Mass Research Products Corp Madison Wis Rotron Inc Woodstock N Y Vector Electronic Co Glendale Calif Carr Fastener Co Cambridge Mass Victory Engineering Corp Springfield Bendix Corp Electric Power Div Eatontown N Herman H Smith inc Brooklyn N Y Central Screw Co Chicago Ill Gavitt Wire and Cable Div of Amerace Esna Corp Brookfield Mass 83594 83835 83877 84171 84411 86684 86838 87034 87216 87585 87929 88140 88245 90634 90763 91345 91418 91506 91637 91662 91929 92825 93332 93410 94144 94154 94222 95263 95354 95712 95987 96791 97464 97702 98291 98410 98978 99934 Code List of Manufacturers Continued MANUFACTURER ADDRESS Grant Pulley and Hardware Co West Nyack N Y Burroughs Corp Electronic Components Div Plainfield N I U S Radium Corp Morristown N J Yardeny Laboratories Inc New York N Y Arco Electronics inc Great Neck N Y TRW Capacitor Div Ogallala Neb RCA Corp Electronic Components Harrison N T Rummel Pibre Co Newark N J Marco amp Oak Industries a Div of Oak Electro netics Corp Anaheim Calif Philco Corp Lansdale Div Lansdale Pa Stockwell Rubber Co Inc Philadelphia Pa Tower Olschan Corp Bridgepo
57. ds between the power suppiy and the load Remote sensing is accomplished by utilizing the strapping pattern shown in Figure 3 7 The power supply should be turned off before changing strap ping patterns The leads from the S terminals to the load will carry less than 10mA of current and it is not required that these leads be as heavy as the load leads However they must be twisted or shielded to minimize noise pick up CAUTION Observe polarity when connecting the sensing leads to the load AL A2 A3 A4 AS AG A7 AS AS 5 GND 5 AIO EE AG WE AW Figure 3 7 Remote Sensing 3 32 Note that it is desirable to minimize the drop in the load leads and it is recommended that the drop not exceed 1 Volt per lead if the power supply is to meet its dc specifications If a larger drop must be tolerated please consult a Hewlett Packard field representative NOTE Due to the voltage drop in the load leads it may be necessary to readjust the current limit in the remote sensing mode 3 33 The procedure just described will result in a low dc output impedance at the load If a low ac impedance is required it is recommended that the following precautions be taken a Disconnect output capacitor C20 by dis connecting the strap between A9 and 3 b Connect a capacitor having similar char acteristics approximately same capacitance same voltage rating or greater and having good high fre quency characteristics ac
58. e comparison amplifier of the slave sup ply thus controlling the s ave s output The master must have the largest output voltage of any power supply in the group must be the most positive sup ply in the example shown on Figure 3 12 3 44 The output voltage of the slave is a percent age of the master s output voltage and is deter mined by the voltage divider consisting of Ry or Ry and Ry and the voltage control of the slave supply Rp where Eg EMRp Rx Rp Turn on and turn off of the power supplies is controlled by the master Remote sensing and programming can be used al though the strapping patterns for these modes show only local sensing and programming In order to maintain the temperature coefficient and stability Specifications of the power supply the external re sistors should be stable low noise iow temperature less than 30ppm per 9C resistors 3 45 SPECIAL OPERATING CONSIDERATIONS 3 46 PULSE LOADING 3 47 The power supply will automatically cross over from constant voltage to constant current oper ation or the reverse in response to an increase over the preset limit in the output current or volt age respectively Although the preset limit may be y set higher than the averageoutput current or voltage high peak currents or voltages as occur in pulse loading may exceed the preset limit and cause crossover to occur If this crossover limiting is not desired set the preset limit for the peak require
59. ecifications 3 16 OPTIONAL OPERATING MODES 3 17 REMOTE PROGRAMMING CONSTANT VOLTAGE 3 18 The constant voltage outputofthe power sup ply can be programmed controlled from a remote location if required Either a resistance or voltage Source can be used for the programming device The wires connecting the programming terminals of the supply tothe remote programming device should be twisted or shielded to reduce noise pick up The VOLTAGE controls on the front panel are dis abled according to the following procedures 3 19 Resistance Programming Figure 3 3 In this mode the output voltage will vary at a rate deter mined by the programming coefficient 200 ohms per Volt for Models 62534 6255A 6281A 6284A and 6289A or 300 ohms per Volt for Models 62944 and 62995 The output voltage will increase 1 Volt for each 200 ohms or 300 ohms added in series with the programming terminals The programming coeffi cient is determined by the programming current This current is factory adjusted to within 2 of 5mA for Models 6253A 6255A 62815 6284A and 6289A or 2 of 3 3mA for Models 6294A and 6299A If greater programming accuracy isrequired it may be achieved by changing resistor R13 A A2 A3 A4 AS AG AT AB A9 GND 5 AIO A i ay ARA k FAL PROGRAMMING Re RESISTOR Remote Resistance Programming Constant Voltage Figure 3 3 3 20 The output voltage of the power supply should be zero Volts 20 millivol
60. effects of any common mode signal introduced because of the difference in the AC potential between the power Supply case and scope case Before using a dif ferential input scope in this manner however it is imperative that the common mode rejection ca pability of the scope be verified by shorting to gether its two input leads at the power supply and observing the trace on the CRT If this trace is a straight line the scope is properly ignoring any common mode signal present If this trace is not a straight line then the scope is not rejecting the ground signal and must be realigned in accordance with the manufacturer s instructions until proper common mode rejection is attained 5 27 To check the ripple and noise output pro ceed as follows a Connect the oscilloscope or RMS volt meter as shown in Figures 5 6B or 5 6C b Turn the CURRENT control fully clockwise and adjust VOLTAGE control until front panel meter indicates maximum rated output voltage C The observed ripple and noise should be less than 200uV RMS and imV an 5 28 Noise Spike Measurement When a high fre quency spike measurement is being made an in strument of sufficient bandwidth must be used an oscilloscope with a bandwidth of 20 MHz ormore is adequate Measuring noise with an instrument that has insufficient bandwidth may conceal high fre quency spikes detrimental to the load 5 29 The test setups illustrated in Figures 5 6A and 5 6B are generally not
61. el or auto parallel operation if one sup ply is turned on before the other Diodes CR18 and CR19 perform a similar function for Q7 4 16 CONSTANT VOLTAGE INPUT CIRCUIT 4 17 The circuit consists of programming resistor R10A and B and a differential amplifier stage Ql and associated components Transistor Q1 con sists of two transistors housed in a single package The transistors have matched characteristics min imizing differential voltages due to mismatched stages Moreover drift due to thermal differen tials is minimized since both transistors operate at essentially the same temperature 4 18 The constant voltage input circuit continu ously compares a fixed reference voltage with a portion of the output voltage and if a difference exists produces an error voltage whose amplitude and phase is proportional to the difference The error output is fed back to the series regulator through an OR gate andthe mixer error amplifiers The error voltage changes the conduction of the series regulator which in turn alters the output voltage so thatthe difference betweenthe two in put voltages appliedtothe differentialamplifier is reduced to zero The above action maintains the output voltage constant 4 19 Stage Q1B of the differential amplifier is connected to a common 8 potential through im pedance equalizing resistor R5 Resistors R6 and R8 are used to zero bias theinput stage offsetting minor base to emitter voltage difference
62. ence Designators Continued vacuum tube neon bulb photocell etc zener diode socket integrated cir cuit or network Description Abbreviations manufacturer modular or modified mounting nano 107 normally closed normally open nickel plated ohm order by description outside diameter pico 10712 printed circuit potentiometer peak to peak parts per million peak reverse voltage rectifier root mean square silicon single pole double throw single pole single throw small signal slow blow tantulum titanium volt variable wirewound Watt Table 6 3 Code List of Manufacturers MANUFACTURER ADDRESS Jamaica N Y New Bedford Mass ZBY Sales Co Inc Aerovox Corp Sangamo Electric Co S Carolina Div Allen Bradley Co Litton Industries inc Beverly Hills Calif TRW Semiconductors Inc Lawndale Calif Texas Instruments Inc Semiconductor Components Div Dallas Texas RCL Electronics Inc Manchester N H Amerock Corp Rockford Ill Sparta Mfg Co Dover Ohio Ferroxcube Corp Saugerties N Y Fenwal Laboratories Morton Grove Ill Amphenol Corp Broadview Ili Radio Corp of America Solid State and Receiving Tube Div Somerville N J G E Semiconductor Products Dept Syracuse N Y Compton Calif Pickens S C Milwaukee Wis Eldema Corp Transitron Electronic Corp Wakefield Mass Pyrofilm Resistor C
63. er a twisted pair or preferably a shield ed two wire cable should be used to connect the output terminals of the power supply to the vertical input terminals of the scope When using a twist ed pair care must be taken that one of the two wires is connected to the grounded input terminal of the oscilloscope When using shielded two wire it is essential for the shield to be connected to ground at one end only so that no ground current will flow through this shield thus inducing a noise signal in the shielded leads 5 25 To verify that the oscilloscope is not dis playing ripple that is induced in the leads or picked up from the grounds the 4 scope lead should be shorted to the scope lead at the power supply terminals The ripple value obtained when the leads are shorted should be subtracted from the actual ripple measurement 5 26 In most cases the single ended scope method of Figure 5 6B will be adequate to elimi nate non real components of ripple and noise so that a satisfactory measurement may be obtained However in more stubborn cases it may be nec essary to use a differential scope with floating in put as shown in Figure 5 60 If desired two single conductor shieided cables may be substi tuted in place of the shielded two wire cable with egual success Because of its common mode re jection a differential oscilloscope displays only the difference in signal between its two vertical input terminals thus ignoring the
64. ern 9 4000 Dusseldort Yet Gan 975 Telex 085 88 533 hp d UNITED STATES ALABAMA PO Box 4207 8290 Whitesburg Dr Huntsvii a 35802 Tel 205 861 4531 8933 E Rosbuck Siva Sirmingham 35206 Tel 205 B36 2203 2 ARIZONA 2338 E Magnolia St Phoenix 85034 Tel 802 244 1381 2424 Kasi Aragon Rd Tucson 85726 Tet 602 89 4683 ARKANSAS Medica Service Only 8 0 Box 5646 Brady States Little Rock 72235 Tet E54 375 1844 CALIFORNIA 1430 East Qrangethorge Ava Fulterton 32631 Tei 7141 870 1000 3939 Lankershim Boulevard North Hollywood 91604 Fak 213 877 1282 TWX 910 499 2871 5400 Wost Rosecrans Blvd P O Box 2105 World Way Posta Canter Los Angelos aa Tel 213 070 7800 TWX See Les Ang Tei 213 Krk K 3003 Scott Boulevard Santa Clara 95050 e 408 249 7090 TWX 310 238 0518 Ridgecrest Tel m 446 6165 46 W North Market Blvd Sacramenio 95034 Tat 916 929 7222 9608 Aero Oriva P O Box 23393 Sen Diego 92123 Tal 714 279 3200 Farzana Tat 213 705 3344 COLORADO Tek 903 771 3458 CONNECTICUT Ne Tek 203 489 6551 TwX 710 455 2000 FLORIDA P O Box 24210 2797 N W Send Street Ft Lauderdale 33309 Tel 305 973 2600 4428 Emerson Street unit 108 tt Jacksonvilie 32297 Tek 904 725 5333 P O Box 13910 8177 Laka Eitenor Dr Oriando 32809 Tet 305 859 2900 PO Bax 12826 Suite S Bidg 1 Offices Park orth Pensacola 32575 Tek
65. eter should read 1 0 amp We 0 02 Vde POWER SUPPLY UNDER TEST DIFFERENTIAL LOAD RESISTOR VOLTMETER CURRENT SAMPLING RESISTOR RESISTANCE OHMS MODEL No RESISTANCE OHMS Move wo ER Figure 5 4 Output Current Test Setup To check constant voltage load regulation proceed as follows a Comnnecttest setup as shown in Figure 5 5 b Turn CURRENT controls fully clockwise c Set METER switch to highest current range and turn on supply d Adjust VOLTAGE control s until front panel meter indicates exactly the maximum rated output voltage l e Read and record voltage indicated on dif ferential voltmeter f Disconnect load resistors g Reading on differential voltmeter should not vary from reading recorded in stepe by more than the following Model No 6253A 6284A 6255A 6289A Variation mVdc i6 6 Model No 6281A 6294A Variation mVdc 5 x8 5 17 Line Regulation To check the line regulation proceed as follows POWER SUPPLY UNDER TEST MODEL NO RESISTANCE OHMS 62534 6284A 6255A 6289A 628IA LOAD RESISTORS DIFFERENTIAL VOLTMETER Figure 5 5 Load Regulation Constant Voltage Test Setup a Connect variable auto transformer between input power source and power supply power input b Turn CURRENT controls fully clockwise c Connect test setup shown in Figure 5 5 d Adiustvariable auto transformer for 105 Vac input e Set METER switch to highest voltage ra
66. f Owensboro Ky Chicago Ill Budwig Mfg Co G E Co Tube Dept Lectrohm Inc Da Mallory amp Co Inc Indianapolis Ind Muter Co Chicago Ill New Departure Hyatt Bearings Div General Motors Corp Sandusky Ohio Ohmite Manufacturing Co Skokie Ill Penn Engr and Mfg Corp Doylestown Pa Polaroid Corp Cambridge Mass Raytheon Co Lexington Mass Simpson Electric Co Div of American Gage and Machine Co Chicago Ill Sprague Electric Co North Adams Mass Superior Electric Co Bristol Conn Syntron Div of FMC Corp Homer City Pa Philadeiphia Pa New York N Y Thomas and Betts Co Union Carbide Corp Ward Leonard Electric Co Mt Vernon N Y ADDRESS Globe Union Inc james Millen M g Co inc MANUFACTURER ADDRESS Amperite Co inc Beemer Engrg Co Belden Corp Bud Radic Inc Union City N J Fort Washington Pa Chicago Ill Willoughby Ohio Cambridge Thermionic Corp Cambridge Mass Bussmann Mfg Div of McGraw amp Edison Co St Louis Mo CTS Corp Elkhart Ind I T T Cannon Electric Inc Los Angeles Calif Centralab Div Milwaukee Wis General Cable Corp Cornish Wire Co Div Williamstown Mass Coto Coil Co Inc Providence R I Chicago Miniature Lamp Works Chicago ill Cinch Mfg Co and Howard B Jones Div Chicago Ill Dow Corning Corp Midland Mich Electro Motive Mfg Co Inc Willimantic Conn Brooklyn N Y General Instrument Corp
67. g Boards 5 14 s 15 w W Ui UT Cn C i t oon i a 3 R Cn Cn Cn it re CO o S es DC Power Supply ri Typical DPR Se Figure 1 1 SECTION I GENERAL INFORMATION l l DESCRIPTION 1 2 This power supply Figure 1 1 is completely transistorized and suitable for either rack or bench operation It is a dual supply consisting of two in dependently controlled sections both identical to each other Each section is a well regulated Con stant Voltage Constant Current source that will furnish full rated output voltage at the maximum rated output current or can be continuously adjusted throughout either output range The front panel CURRENT controls can be usedto establishthe out putcurrentlimit overload or short circuit when the Supply is used as a constant voltage source andthe VOLTAGE control s can be used to establish the voltage limit ceiling when the supply is used as a constant current source Each section will auto matically crossover from constant voltage to con stant current operation and vice versa if the output current or voltage exceeds these preset limits i 3 Each supply has both front and rear terminals Either the positive or negative output terminal may be grounded or the power supply can be operated floating atup to a maximum of 300 volts off ground 1 4 Each section has its own front panel meter and operating controls The meters are of the mul tiple range type and can measure output
68. ges and their nominal magnitudes with an input of 115 VAC 4 7 Diode CR34 connected across the output SERIES REGULATOR OR GATE CR3 CR4 SAMPLING CONSTANT RESISTOR VOLTAGE ERROR PULLOUT AMPLIFIER RESISTOR 04 5 REFERENCE REGULATOR 08 09 MIXER AMPLIFIER Q3 016 6 2V RIS CONSTANT CURRENT PULLOUT RESISTOR A4 CURRENT INPUT CIRCUIT Q2 CURRENT CONTROLS CURRENT CIRCUIT Q1 0l2 014 VOLTAGE INPUT CIRCUIT QI VOLTAGE CONTROLS Simplified Schematic 4 2 terminals of the power supply is a protective de vice which prevents internal damage that might occur if a reverse voltage were applied across the output terminals Output capacitor C20 is also connected across the output terminals when the normal strapping pattern shown on Figure 4 2 is employed Note that this capacitor can be removed if an increase in the programming speed is desired Under these conditions capacitor C19 serves to insure loop stability 4 8 DETAILED CIRCUIT ANALYSIS Refer to over all schematic diagram at rear of manual 4 9 FEEDBACK LOOP 4 10 The feedback loop functions continuously to keep the output voltage constant during constant voltage operation and the output current constant during constant current operation For purposes of this discussion assume that the unit is in con stant voltage operation and that the programming resistors
69. hree Units 3 41 Auto Parallel The strapping patterns for Auto Parallel operation of two power supplies are shown in Figure 3 11 Auto Parallel operation permits equal current sharing under all load con ditions and allows complete control of output cur rent from one master power supply The output cur rent of each siave will be approximately equal to the master s regardless of the load conditions Because the output current controls of each slave are operative they should be set to maximum to avoid having the slave revert to constant current operation this would occur if the master output current setti g exceeded the slave s Ai A2 A3 AA A5 AG A7 AB A9 S GND S AIO CH A GOYA MASTER eje ISTA a 3 T8 Be e P o Al A2 A3 A4 AS A6 A7 A8 A9 S GND t S AIO SLAVE Ai A A3 A4 AS AG AT A8 A9 GND 5 AIO elalalglelgiale LLLA l elelelglelelg cC WW MASTER t TUT CZEKZEEKCWNCLU U Ai A2 A3 A4 AS AB AT A8 A9 5 GND 5 AIO SLAVE NO I Ry da EEEEEEEEEEEEEEE Al AZ A3 A4 AS A6 AT ZA dde E S AiO SS qq NO 2 Figure 3 12 Auto Tracking Two and Three Units 3 42 AUTO TRACKING OPERATION See Figure 3 12 3 43 The Auto Tracking configuration is used when it is necessary that several different voltages re ferred to a common bus vary in proportion to the Setting of a particular instrument the control or master A fraction of the master s output voltage is fed to th
70. it allowance must be made for high peak voltages which can cause unwanted crossover Refer to Paragraph 3 46 3 11 CONNECTING LOAD 3 12 Each load should be connected to the power supply outputterminals using separate pairs ofcon necting wires This will minimize mutual coupling effects between loads and willretain full advantage of the low output impedance of the power supply Bach pair of connecting wires should be as shortas possible and twisted or shielded to reduce noise pickup if shield is used connect one end to power supply ground terminal and leave the other end unconnected 3 13 1f load considerations require that the output power distribution terminals be remotely located from the power supply then the power supply out put terminals should be connected to the remote distribution terminals via a pair of twisted or shielded wires and each load separately connected to the remote distribution terminals For this case remote sensing should be used Paragraph 3 20 3 14 OPERATION OF SUPPLY BEYOND RATED OUTPUT 3 15 The shaded area on the front panel meter face indicates the amount of output voltage or current thatis available in excess ofthe normal rated out put Althoughthe supply can be operated in this shaded region without being damaged it cannot be guaranteed to meet all of its performance specif ications However if the line voltage is main tained above 115 Vac the supply willprobably op erate within its sp
71. ith resistance value equal to that of decade box 5 61 To calibrate the constant current programming current proceed as follows a Connect power supply as shown in Figure 9 4 b Remove strap between A3 and A4 leaving A4 and A5 iumpered c Connect a 0 1 watt resistor between Al and AS Resistor value to be as follows Model No 6253A 6284A 6255A 6289A Resistance l1 5Ka 750a Model No 6281A 6 294A Resistance IKa 0 IKa d Connect decade resistance box in place of R19 e Set METER switch to highest current range and turn on supply f Adjust the decade resistance so that the differential voltmeter indicates 1 0 x 0 01 Vdc g Replace decade resistance with appro priate value resistor in R19 position 5 62 REFERENCE CIRCUIT ADJUSTMENTS 5 63 Line Regulation To adjust the line regula tion capabilities of the instrument proceed as fol lows a Connect the differential voltmeter be tween 5 common and 33 positive b Connect variable voltage transformer be tween supply and input power source c Adjust line to 105 Vac d Connect decade resistance in place of R46 e Turn on suppiy and adjust VOLTAGE con trol s for maximum rated output voltage f Adjust decade resistance so that voltage indicated by differential voltmeter does not change more than the following as input line voltage is varied from 105 to 125Vac Model No 6253A 6284 62554 6289A Variation mVdc 0 95 0 81 Model
72. le 5 2 includes the symptoms and prob able causes of many possible troubles If either high orlow output voltageis a symptom there are two methods of isolating the fault The first is a simplified procedure that involves only measuring voltages the second is a more thorough approach requiring that transistor stages be opened or shor ted Both methods are described as follows 1 First the reference bias and filtered dc voltages as given in Table 5 3 should be checked Then the voltage levels at critical points base and collector in the feedback loop should be measured and compared to the normal voltages given on the overallschematic diagram atthe rear of the manual This method of troubleshooting a feedback loop is notalways conclusive a better method is described in 2 2 First measure the reference bias and filtered dc voltages as given in Table 5 3 Then drive each stage in the feedback loop into conduc tion or cutoff by either shorting or opening the pre vious stage as indicated in Tables 5 4 or 5 5 Common Troubles To prevent this condition turn Table 5 2 Common Troubles Continued Symptom Probable Cause Poor line regulation a Improper measuring technique refer to Paragraph 5 3 b Check reference circuit voltages Table 5 3 C Check reference circuit adjustment Paragraph 5 62 Poor load regulation a Improper measuring technique refer to Paragraph 5 3 Constant
73. ming terminals Al and A5 should open at any time during this mode the output current will rise to a value that may damage the power sup ply and or the load To avoid this possibility connect a resistor across the programming terminals having the value listed below Like the program ming resistor this resistor shouid be of the iow noise low temperature coef ficient type Model 6253A 6284A 6255A 6289A 6299A Resistance 1 5Ka 750a Model 6281A 62944 Resistance IKa 3 28 Voltage Programming Figure 3 6 In this mode the output current will vary linearly with changes in the programming voltage The program ming voltage should not exceed 1 2 Volts Voltage in excess of 1 2 Volts will result in excessive power dissipation in the instrument and possible damage Ai A3 A4 AS A6 A7 AS AG S GND 5 AIO ej EE A REFERENCE VOLTAGE Remote Voltage Programming Constant Current Figure 3 6 3 29 The output current will be the programming voltage divided by 1 ohm The current required from the voltage source will be less than 25 micro amperes The impedance matching resistor Ry should be approximately 500 ohms if the temperature coefficient and stability specifications of the power supply are to be maintained 3 30 REMOTE SENSING See Figure 3 7 3 31 Remote sensing is used to maintain good regu lation at the load and reduce the degradation of reg ulation which would occur due to the voltage drop in the lea
74. ncrease the programming speed A minimum amount of output capacitance C19 is permanentiy wired to the output and should not be removed because the supply could oscillate under certain load conditions The programming speed in creases by afactor of from 10 to 100 when the out put capacitor C20 is removed 2 Connectthe relay oscilloscope and pro gramming resistor Rpas illustrated in Figure 5 10 Select the value of the programming resistor that will produce maximum output voltage of the supply This value is obtained by multiplying the program ming coefficient 200 ohms volt 300 ohms volt for Model 6294A by the maximum rated output voltage of the supply 3 A mercury wetted relay is employed to rapidly switch the programming resistance from zero to maximum at a 60 Hz rate Other automatic switching devices can be used however a hand operated switch connected across the programming resistor is notadequate because the resulting one shot displays are difficult to observe on most os cilloscopes 4 The time T required for the output volt age to change from zero volts to maximum rated out put or from maximum rated output to zero should be less than 10 milliseconds 9 33 Output Impedance To check the output im pedance proceed as follows a Connect test setupas showninFigure 5 11 VOLTMETER VOLTMETER hp403B hp4038 INDICATES Eo 4 INDICATES Ein POWER SUPPLY OSCILLATOR UNDER TEST hp 200 CD 100 CHM Figure 5 1
75. nge and turn on supply f Adjust VOLTAGE control s until front panel meter indicates exactly the maximum rated output voltage g Read and record voltage indicated on dif ferential voltmeter h Adjust variable auto transformer for 125Vac input i Reading on differential voltmeter should not vary from reading recorded in step g by more than the following Model No 6253A 6284A 6255A 6289A Variation mVdc 4 6 Mode No 6281A 6294A Variation mVdc 2 75 8 5 18 Ripple and Noise Ripple and noise measure ment can be made at any input AC line voltage combinedwith any DC output voltage and loadcurrent within rating 5 19 The amountofripple and noise thatis present on the power supply output is measured either in terms of the RMS or preferably peak to peak value The peak to peak measurement is particularly im portant for applications where noise spikes could be detrimental to a sensitive load such as logic circuitry The RMS measurement is not an ideal representation ofthe noise since fairly high out put noise spikes of short duration could be present in the ripple and not appreciably increase the RMS value 5 20 The technique used to measure high frequency noise or spikes on the output of a power supply is more critical than the low frequency ripple and noise measurement technique therefore the former is discussed separately in Paragraph 5 28 POWER SUPPLY CASE OSCILLOSCOPE CASE A INCORRECT METHOD GRO
76. nob R16 Black 0370 0137 OPTION 09 10 Turn Voltage and Current Controls R10 var ww l0Ka 5 10 Turn 2 HIAB 09182 2100 1866 i R16 var ww IKa 45 10 Turn 2 HLAB 09182 2100 1864 Knob R10 amp R16 Black 4 HLAB 09182 0370 0137 l OPTION 10 Chassis Slides Slides CTS 120 E6 Gen Devices 06666 1490 0870 Spacer 2 HLAB 09182 06253 00001 Reference Mfr Part Designator Description Quantity or Type OPTION 11 Overvoltage Protection Crowbar See Appendix A for Parts List OPTION 13 3 Digit Decadial Voltage Control var ww l0Ks 5 10 Turn 2100 1866 Decadial 1140 1120 OPTION 14 3 Digit Decadial Current Control var ww IKa 596 10 Turn 2100 1864 Decadial 1140 0020 OPTION 28 230Vac 10 input Fuse 1A 250V 312 001 Littlefuse 75915 2110 0001 6255A 6 8 APPENDIX A Option 11 Overvoltage Protection Crowbar DESCRIPTION This option is installed in DC Power Supplies 6253A 6255A 6281A 6284A 6289A 6294A an 6299A and tested at the factory It consists of a printed circuit board screwdriver type front panel potentiometer and six wires that are soldered to the main power suppiy board The crowbar monitors the output voltage of the power supply and fires an SCR that effectively shorts the output when it exceeds the preset trip voltage The trip voltage is determined by the setting of the CROWBAR ADJUST control on the front panel The trip voltage range is as follows 6253A 6255A 6281A 6289A 6294A
77. ns 5 78 TEST EQUIPMENT REQUIRED 5 9 Table 5 1 lists the test equipment required to perform the various procedures described in this Section Table 5 1 Test Equipment Required REQUIRED USE RECOM MENDED CERE CHARACTERISTICS MODEL Differential Sensitivity l1mV full scale min Measure DC voltages Ze 3420 See Note Voltmeter Input impedance 10 megohms min calibration procedures Variable Range 90 130 volts Equipped with Vary AC input m Voltage voltmeter accurate within 1 volt Transformer AC Voltmeter Accuracy 2 Sensitivity lmV full Measure AC voltages and 403B scale deflection min ripple Oscilloscope Sensitivity 100uV cm Differential Display transient response Ki 140A plus 1400A input waveforms plug in 1402A plug in for spike measurements only Oscillator Range 5 Hz to 600 kHz Accuracy Impedance checks de 200 CD 2 Output 10Vrms DC Voitmeter Accuracy 1 Input resistance Measure DC voltages Ze 412A Repetitive Load Switch Resistive Loads Current Sampling Resistor Resistor Resistor Resistor Resistor Capacitor Decade Resistance Box 20 000 ohms volt min Rate 60 400 Hz 2usec rise and fall time Values See Paragraph 5 14 and Figure 5 4 X596 75 watts 6253A 6284A 0 33 6255A 6289A 0 66n 6281A 0 Za 6294A la lKa 41 2 watt non inductive 100 ohms 5 10 watt Value See Paragraph 5 59 x0 196 1 2 watt Value See Paragraph 5 6
78. o Inc Cedar Knolls N J Arrow Hart and Hegeman Electric Co Hartford Conn ADC Electronics Inc Harbor City Calif Caddell amp Burns Mfg Co Inc Mineola N Y Hewlett Packard Co Palo Alto Div Palo Alto Calif Motorola Semiconductor Prod Inc Phoenix Arizona Westinghouse Electric Corp Semiconductor Dept Youngwood Pa Ultronix Inc Grand Junction Colo Wakefield Engr Inc Wakefield Mass General Elect Co Electronic Capacitor amp Battery Dept irmo S C Bassik Div Stewart Warner Corp Bridgeport Conn IRC Div of TRW Inc Semiconductor Plant Lynn Mass Amatom Electronic Hardware Co Inc New Rochelle N Y Beede Electrical Instrument Co Penacook N H General Devices Co Inc Indianapolis ind Semcor Div Components Inc Phoenix Arizona Robinson Nugent Inc New Albany Ind Torrington Mig Co West Div Van Nuys Calif Transistor Electronics Corp Minneapolis Minn 6 2 MANUFACTURER ADDRESS Westinghouse Electric Corp Electronic Tube Div Elmira N Y Fairchild Camera and Instrument Corp Semiconductor Div Mountain View Calif Birtcher Corp The Los Angeles Calif Sylvania Electric Prod Inc Sylvania Electronic Systems Western Div Mountain View Calif IRC Div of TRW Inc Burlington Plant Burlington lowa Continental Device Corp Hawthorne Calf Raytheon Co Components Div Semiconductor Operation Mountain View Calif Breeze Corporations Inc Union N J Reiiance Mica Cor
79. oad is connected across the rear terminals Note that when measurements are made at the front terminals the monitoring leads are connected at not B as shown in Figure 5 1 Failure to connect the measuring device atA willresultin a measure ment that includes the resistance of the leads be tween the output terminals andthe point of connec tion 9 6 For output current measurements the current sampling resistor should be a four terminal resis OUTPUT TERMINAL MONITOR HERE merem Figure 5 1 Front Panel Terminal Connections tor The four terminals are connected as shown in Figure 5 2 in addition the resistor should be of the low noise low temperature coefficient less than 30ppm C type and should be used at no more than 5 of its rated power sothat its temper ature rise will be minimized CURRENT SAMPLING TERMINALS EXTERNAL LOAD TO UNGROUNDED TO GROUNDED TERMINAL OF SAMPLING POWER SUPPLY RESISTOR LOAD TERMINALS TERMINAL OF POWER SUPPLY Figure 5 2 Output Current Measurement Technique 5 7 When using an oscilloscope ground one ter minalofthe power supply and then ground the case of the oscilloscope to this same point Make cer tain that the case is not also grounded by some other means Power line Connect both oscillo Scope input leads tothe power supply ground termi nal and check that the oscilloscope is not exhibi ting aripple or transient due to ground loops pick up or other mea
80. od is imprac tical use method shown below Thisis especially applicable for circuit boards without eyelets 1 Clip lead as shown below 2 Bend protrudingieads upward Bend lead of new APPLY CLIP component SOL DER HERE around pro truding lead Apply solder using a pair of long nose pliers as a heat sink ARANNANEKEANARKORENA aS trp sosss This procedure is used in the field only as an alternate means of repair It is not used within the factory Figure 5 13 Servicing Printed Wiring Boards 5 13 5 46 REPAIR AND REPLACEMENT Specialcharacteristics of selected semiconductors If the device to be replaced is not listed in Tabie 5 47 Before servicing a printed wiring board refer 5 6 the standard manufacturers part number listed to Figure 5 13 Section VI of this manual contains in Section VI is applicable After replacing a semi a list of replaceable parts Before replacing a semi conductor device referto Table 5 7 for checks and conductor device refer to Table 5 6 which lists the adjustments that may be necessary Tabie 5 6 Selected Semiconductor Characteristics Suggested No Matched differential ampli fier NPN Si Planar 70 min hpg ic 1 ma VG 5V Ico 0 01ua Vebo 5V Reference Designator Ql 2 ii 1854 0229 2N2917 G E NPN Power hrf 35 min Q Ic 4A VCE 4V Q6 7 16 1854 0228 2N3055 R C A CR1 5
81. oss temperature compensated Zener diodes VR1 and VR2 Resistor R43 limits the current through the Zener diodes to establish an optimum bias level 4 33 The regulating circuit consists of series reg ulating transistor O9 and error amplifier Q8 Out put voltage changes are detected by Q8 whose base is connected to the junction of a voltage divider R41 R42 connected directly across the supply Any error signals are amplified and inverted by Q8 and applied to the base of series transistor Q9 The series element then alters its conduction in the direction and by the amount necessary to maintain the voltage across VRl and VR2 constant Resistor R46 the emitter resistor for Q8 is connected in a manner which minimizes changes in the reference voltage caused by variations in the input line Output capacitor C9 stabilizes the regulator loop 4 34 METER CIRCUIT 4 35 The meter circuit provides continuous indica tions of output voltage or current on a single multi ple range meter The meter can be used either as a voltmeter or an ammeter depending upon the position of the METER switch 2 on the front panel of the supply This switch also selects one of two meter ranges on each scale The meter circuit consists basically of a selection circuit switch 82 and asso ciated voltage dividers stable differential amplifier stages Q11 O12 and O14 and the meter move ment 4 36 The selection circuit determines which volt age divider is connec
82. ound proceed as described in the Claim for Damage in Shipment section of the warranty page at the rear of this manual 2 3 MECHANICAL CHECK 2 4 This check should confirm that there are no broken knobs or connectors that the cabinet and panel surfaces are free of dents and scratches and that the meter is not scratched or cracked 2 5 ELECTRICAL CHECK 2 6 The instrument should be checked against its electrical specifications Section V includes an in cabinet performance check to verify proper instrument operation 2 7 INSTALLATION DATA 2 8 The instrument is shipped ready for bench operation It is necessary only to connect the instrument to a source of power and it is ready for operation 2 9 LOCATION 2 10 This instrument is air cooled Sufficient space should be aliotted so that a free flow of cooling air can reach the sides and rear of the instrument when it is in operation It should be used in an area where the ambient temperature does not exceed 509C 2 11 RACK MOUNTING 2 12 This instrument is full rack size and can be easily rack mounted in a conventional 19 inch rack panel using standard mounting Screws 2 13 INPUT POWER REQUIREMENTS 2 14 This power supply may be operated from either a nominal 115 volt or 230 volt 50 400 cycle power source The unit as shipped from the fac tory is wired for 115 volt operation The input power required when operated from a 115 volt 60 cycle power source at fuli load is 235
83. p Brooklyn N Y Sloan Company The Sun Valley Calif Vemaline Products Co Inc Wyckoff N J General Elect Co Minia ture Lamp Dept Cleveland Ohio Nylomatic Corp Norrisville Pa RCH Supply Co Vernon Calif Airco Speer Electronic Components Bradford Pa Hewlett Packard Co New jersey Div Rockaway N J General Elect Co Semiconductor Prod Dept Buffalo N Y General Elect Co Semiconductor Prod Dept Auburn N Y C amp K Components Inc Newton Mass Burndy Corp Norwalk Conn Wagner Electric Corp Tung Sol Div CTS of Berne Inc Chicago Telephone of Cal Inc So Pasadena Calif IRC Div of TRW Inc Boone Plant Boone N C Bloomfield N T Berne Ind General Instrument Corp Rectifier Div Philadelphia Handle Co Inc Camden N J U S Terminals inc Cincinnati Ohio Hamlin Inc Lake Mills Wisconsin Clarostat Mfg Co Inc Dover N H Thermalioy Co Dallas Texas Hewlett Packard Co Loveland Div Loveland Colo Cornell Dubilier Electronics Div Federal Pacific Electric Co Newark N Newark N J Generai Instrument Corp Semicon ductor Prod Group Hicksville N Y Fenwal Elect Framingham Mass Corning Glass Works Electronic Components Div Raleigh N C Use Code 28480 assigned to Hewlett Packard Go Palo Alto California 16758 17545 17803 17870 18324 19315 19701 21520 22229 22753 23936 24446 24455 2468
84. panel VOLTAGE control on the master The master Supply must be the most positive supply of the series The output CURRENT controls of all series units are operative and the current limit is equal to the lowest control setting If any output CURRENT controls are set too low automatic crossover to constant current operation will occur and the out put voltage will drop Remote sensing and pro gramming can be used however the strapping ar rangements shown in the applicable figures show local sensing and programming 3 38 In order to maintain the temperature coeffic ient and stability specifications of the power supply the external resistors Rx shown in Figure 3 should be stable low noise low temperature co efficient less than 30 ppm per degree Centigrade resistors The value of each resistor is dependant on the maximum voltage rating of the master sup ply T he value of Rx is this voltage divided by the voltage programming current of the slave supply 1 Kp where Kp is the voltage programming coef ficient The voltage contribution of the slave is determined by its voltage control setting A A2 A3 A4 AS A6 A7 AB A9 S GND S AIO BEER KL LJ LU LOAD Ai A2 A3 A4 AS A6 AT AB Yi elelee a LL kJ LU Lists LJ A U LU Ai A2 A3 A4 AS AG A7 A8 AS S GND tS AIO ejeiejareleleleisleleleigiaie fue Ts LOAD Ry Po Al A2 A A4 AS AG ATXAB AD AE S AIO E SLAVE NO Rx2 DAC sza JT
85. pe having 60 Hz as its fundamental component is typically as Sociated with an incorrect measurement setup 5 38 Ripple and Noise Measurement To check the ripple and noise proceed as follows a Connect the oscilloscope or RMS voit meter as shown in Figures 5 12B or 5 120 Ct POWER SUPPLY CASE OSCILLOSCOPE CASE A INCORRECT METHOD GROUND CURRENT Ig PRODUCES 60 CYCLE DROP IN NEGATIVE LEAD WHICH ADDS TO THE POWER SUPPLY RIPPLE DISPLAYED ON SCOPE POWER SUPPLY CASE OSCILLOSCOPE CASE kK Q x TWISTED PAIR LENGTH OF LEAD BETWEEN Rr AND OUTPUT TERMINAL OF POWER SUPPLY MUST BE HELD TO ABSOLUTE MINIMUM B A CORRECT METHOD USING A SINGLE ENDED SCOPE OUTPUT FLOATED TO BREAK GROUND CURRENT LOOP TWISTED PAIR REDUCES STRAY PICKUP ON SCOPE LEADS POWER SUPPLY CASE OSCILLOSCOPE CASE SHIELDED TWO WIRE X LENGTH OF LEAD BETWEEN Ry AND GROUNDED OUTPUT TERMINAL OF POWER SUPPLY MUST BE HELO TO ABSOLUTE MINIMUM C A CORRECT METHOD USING A DIFFERENTIAL SCOPE WITH FLOATING INPUT GROUND CURRENT PATH IS BROKEN COMMON MODE REJECTION OF DIFFERENTIAL INPUT SCOPE IGNORES DIFFERENCE IN GROUND POTENTIAL OF POWER SUPPLY amp SCOPE SHIELDED TWO WIRE FURTHER REDUCES STRAY PICKUP ON SCOPE LEAD MODEL 6253A 62554 628IA 6284A 6289A 6294A Rq OHMS 0 33 1 0 66 Ry OHMS 6 26 0 20 0 33 0 66 L 6 26 CC Ripple and Noise Test Setup Figure 5 12 b Rotate the VOLTAGE control fully cw c
86. r part of the feedback loop is made to alter its conduction to maintain a constant out put voltage or current The voltage developed 4 1 FEEDBACK PATH DENOTES CURRENT FEEDBACK PATH METER CIRCUIT Overall Block Diagram across the current sampling resistor network is the input to the constant current input circuit The constant voltage input circuit obtains its input by sampling the output voltage of the supply 4 4 Any changes in output voltage current are detected in the constant voltage constant current input circuit amplified by the mixer and error am plifiers and applied to the series regulator in the correct phase and amplitude to counteract the change in output voltage outputcurrent The refer ence circuit provides stable reference voltages which are used by the constant voltage current in put circuits for comparison purposes The bias supplyfurnishes voltages which are used through out the instrumentfor biasing purposes The meter Circuit provides an indication of output voltage or current for both operating modes 4 5 4 6 CR22 d o 08 7 1 ON OFF SWITCH Figure 4 2 SIMPLIFIED SCHEMATIC A simplified schematic of the power supply is shown in Figure 4 2 It shows the operating controls the ON off switch the voltage and cur rent programming controls R10 and R16 Figure 4 2 also shows the internal sources of bias and reference volta
87. r of the chassis All power supply output terminals are isolated from the chassis and either the positive or negative terminals may be connected to the chassis through a separate ground terminal located on the output terminal strip ERROR SENSING Error sensing is normally accomplished at the front terminals if the load is attached to the front or at the rear terminals if the load is attached to the rear terminals Also provision is included on the rear terminal strip for remote sensing REMOTE PROGRAMMING Remote programming of the supply output at ap proximately 200 ohms per volt in constant voltage is made available at the rear terminals In con stant current mode of operation the current can be remotely programmed at approximately 500 onms per ampere COOLING Convection cooling is employed The supply has no moving parts SIZE 3 12 Hx 14 V2 D x 19 W mounted in a standard 19 relay rack Easily rack WEIGHT 28 lbs net 35 lbs shipping FINISH Light gray front panel with dark gray case POWER CORD A three wire five foot power cord is provided with each unit SECTION II INSTALLATION 2 1 INITIAL INSPECTION 2 2 Before shipment this instrument was inspec ted and found to be free of mechanical and electri cal defects As soon as the instrument is un packed inspect for any damage that may have oc curred in transit Save all packing materials until the inspection is completed If damage is f
88. ripple and noise simply remove the four terminating resistors andthe blocking capacitors and substitute a higher gain verticalplug inin place of the wide band plug in required for spike measurements Notice that with these changes Figure 5 7 becomes a two cable version of Figure 5 6C 5 31 Transient Recovery Time To check the transient recovery time proceed as follows a Connect test setup shown in Figure 5 8 b Turn CURRENT controls fully clockwise c Set METER switch to highest current range nd turn on supply d Adjust VOLTAGE control s until front panel meter indicates exactly the maximum rated output voltage e Close line switch on repetitive load switch setup f Adjust 25K potentiometer until a stable display is obrained on oscilloscope Waveform should be within the tolerances shown in Pigure 5 9 output should return to within 15mV of original value in less than 50 microseconds OSCILLOSCOPE hp 140A POWER SUPPLY UNDER TEST CONTACT PROTECTION NETWORK duf 4090Y SI SW NOTE 3 NOTES THIS DRAWING SHOWS A SUGGESTED METHOD OF BUILDING A LOAD SWITCH HOWEVER OTHER METHODS COULO B USED SUCH AS A TRANSISTOR SWITCHING NETWORK MAXIMUM LOAD RATINGS OF LOAD SWITCH ARE 5AMPS 500V 250W NOT 2500W USE MERCURY RELAY CLARE TYPE HGP 1002 OR W E TYPE 2768 3 USE WIRE WOUND RESISTOR OI H REPETITIVE LOAD SWITCH NOTE 1 RESISTANCE OHMS MODEL No RESISTANCE OHMS X 6
89. ross the load using short leads 3 34 Although the strapping patterns shown in Fig ures 3 3 through 3 6 empioy local sensing note that it is possible to operate a power supply simul taneously in the remote sensing and Constant Voit age Constant Current remote programming modes 3 35 SERIES OPERATION 3 36 Normal Series Connections Figure 3 8 Two or more power supplies can be operated in series to obtain a higher voltage than that available from a single suppiy When this connection is used the output voltage is the sum of the voltages of the in dividual supplies Each of the individual supplies must be adjusted in order to obtain the total output voltage The power supply contains a protective diode connected internally across the output which protects the supply if one power supply is turned off while its series partner s is on Al A2 A3 A4 AS A6 A AB A9 S GND t rS AIO elelalalelalalsizialelalalaie y e e d 8 5 8 3 5 4 8 0 e d 3 Ai A2 A3 A4 A5 AG A7 AB A9 S GND 5 AiO Figure 3 8 Normal Series Connections 3 37 Auto Series Connections Figure 3 9 The Auto Series configuration is used when it is desir able to have the output voltage of each of the series connected supplies vary in accordance with the setting of a control unit The control unit is called the master the controlled units are called slaves At maximum output voltage the voltage of the slaves is determined by the setting of the front
90. rouped by individual as semblies the latter consists of all parts not im mediately associated with an assembly 6 3 ORDERING INFORMATION 6 4 To order a replacement part address order or inquiry to your local Hewlett Packard sales office see lists at rear of this manual for addresses Specify the following information for each part Model complete serial number and any Option or special modification J numbers of the instrument Hewlett Packard part number circuit reference des ignator and description To order a part not listed in Table 6 4 give a complete description of the part its function and its location Tabie 6 1 Reference Designators assembly miscellaneous blower fan electronic part capacitor fuse circuit breaker jack jumper diode relay device signal L inductor ing lamp meter 6 1 Table 6 1 Table 6 2 plug transistor resistor switch transformer terminal block thermal switch z ampere alternating current assembly board bracket z degree Centigrade z card coefficient composition z cathode ray tube center tapped z direct current z double pole double throw z double pole single throw electrolytic encapsulated farad degree Farenheit z fixed germanium Henry Hertz z integrated circuit inside diameter incandescent kilo 103 milli 1073 mega 106 micro 1079 metal Refer
91. rt Conn Cutler Hammer Inc Power Distribution and Control Div Lincoln Plant Lincoln Il Litton Precision Products Inc USECO Div Litton Industries Van Nuys Calif Gulton Industries Inc Metuchen N United Car Inc Chicago Ill Miller Dial and Nameplate Co El Monte Calif Chicago Ill Attleboro Mass Dale Electronics Inc Columbus Neb Elco Corp Willow Grove Pa Honeywell Inc Div Micro Switch Freeport I Whitse Inc Schiller Pk TH Sylvania Electric Prod Inc Semi conductor Prod Div Woburn Mass Essex Wire Corp Stemco Controls Div Radio Materials Co Augat inc Mansfield Ohio Raytheon Co Components Div ind Components Oper Quincy Mass Wagner Electric Corp Tung Sol Div Livingston N J Southco Inc Lester Pa Leecraft Mfg Co Ino L I C N Y Methode Mfg Co Rolling Meadows Ill Bendix Corp Microwave Devices Div Weckesser Co Inc Amphenol Corp Amphenol Controls Div Janesville Wis Industrial Retaining Ring Co Irvington N J IMC Magnetics Corp Eastern Div Westbury N Y Sealectro Corp Mamaroneck N Y ETC Inc Cleveland Ohio international Electronic Research Corp Burbank Calif Boston Mass Franklin Ind Chicago Ill Renbrandt Inc Reference Desianator ipti i Mfr Stock No RS NOTE ALL ELECTRICAL COMPONENTS HAVE DUPLICATED QUANTITIES EXCEPT THOSE MARKED WITH AN C1 fxd elect 4 7uf 50vdc 2 150D475X9050B2 Sprague 56289 0180 1731
92. s are factory installed within the supply The Crowbar Adjust controls are mounted on the front panel to permit convenient adjust ment Trip Voltage Range 6253A 6255A 2 5 to 23V 2 5 to 44V Trip Voltage Margin The minimum crowbar trip setting above the desired operating output voltage to prevent false crowbar tripping is 4 of the output voltage setting 42V Refer to Appendix A for complete details Option No Description 13 Three Digit Graduated Decadial Volt age Control Control that replaces coarse and fine voltage controls per mitting accurate resettability l Three Digit Graduated Decadial Cur rent Control Control that replaces coarse and fine current controls per mitting accurate resettability A 28 Rewire for 230V AC Input Supply as normally shipped is wired for 115VAC input Option 28 consists of recon necting the input transformer for 230V AC operation i 10 INSTRUMENT IDENTIFICATION l 11 Hewlett Packard power supplies are identified by a three part serial number tag The first part is the power supply model number The second partis the serial number prefix which consists of num ber letter combination that denotes the date of a significant design change The number designates the year and the letter A through L designates the month January through December respectively The third part is the power supply serial number l 12 If the serial number prefix on your power sup ply does no
93. s follows Model 6253A 6284A 6255A 6289A 6281A 6294A Resistance 4Ka 8Ko 1 5Ka JL Da p b Disconnect jumper between A6 and A8 leaving A6 and A7 jumpered on rear terminal bar rier strip c Connect a decade resistance in place of R13 d Connect a differential voltmeter between 8 and S and turn on supply e Adjust decade resistance box so that dif ferential voltmeter indicates maximum rated output voltage within the following tolerances Model No 6253A 6284A 6255A 6289A Tolerance Vdc 0 4 0 8 Model No 5281A 6294A Tolerance Vdc 0 15 1 2 f Replace decade resistance with resistor of appropriate value in R13 position 5 59 CONSTANT CURRENT PROGRAMMING CURRENT 5 60 To calibrate the zero current programming ac curacy proceed as follows a Connect differential voltmeter between 8 and S terminals b Short out current controls by connecting jumper between terminals Al and AS c Rotate VOLTAGE control s fully clockwise and turn on supply d Observe reading on differential voltmeter e If it is more positive than 0 volts shunt resistor R25 with a decade resistance box f Adjust decade resistance until differen tial voltmeter reads zero then shunt R25 with re sistance value equal to that of decade resistance g If reading of step d is more negative than 0 volts shunt resistor R28 with decade resistance h Adjust decade resistance until differential voltmeter reads zero then shunt R28 w
94. s in QL The base of Q1Ais connectedto a summing point at the junction of the programming resistor and the current pullout resistor R12 Instantaneous changes in output voltage result in an increase or decrease in the summing point potential QlAis then made to conduct more or less in accordance with the summing point voltage change The re sultant output error voltage is fed back to the series regulator via OR gate diode CR3 and the remaining components of the feedback loop Re sistor Rl in series with the base of QIA limits the current through the programming resistor during rapid voltage tum down Diodes CRI and CR2 form a limiting network which prevent excessive voltage excursions from over driving stage Q14A Capacitors C1 and C2 shunting the programming resistors increase the high frequency gain of the input amplifier Resistor R13 shunting pullout resistor R12 serves as a trimming adjustment for the programming current 4 20 CONSTANT CURRENT INPUT CIRCUIT 4 21 This circuit is similar in appearance and op eration to the constant voltage input circuit It consists basically of the current programming re sistors R16A and B and a differential amplifier stage Q2 and associated components Like transistor Q1 in the voltage input circuit Q2 con sists of two transistors having matched charac teristics that are housed in a single package 4 22 The constant current input circuit continu ously compares a fixed reference
95. s is determined by the setting of CURRENT control R16 The operation of the feedback loop during the constant current op erating mode is similar to that occuring during constant voltage operation except that the input to the differential amplifier comparison circuit is ob tained from the current sampling resistor network 4 14 SERIES REGULATOR 4 15 The series regulator consists oi transistor stages Q6 and Q7 see schematic atrear of manual Transistor Q6 is the series element or pass transis tor which controls the output Transistor Q7 to gether with shunt resistors R81 R82 and R83 are connected in a manner which minimizes the power 4 3 dissipated in series transistor Q6 The bias voltage for Q7 is developed across zener diode VR5 The The conduction of Q7 will decrease as the collector to emitter voltage of Q6 approaches the voltage developed across the biasing diodes At low out put voltages Q7 is completely cutoff and all of the load current flows through the shunt resistors The voltage that is dropped across Q7 and the shunt resistors reduces the voltage dropped across Q6 thus diminishing its power dissipation The reli ability of the regulator is further increased by mounting the shunt resistors outside the rear of the cabinet so that the internal components are operated under lower temperature conditions Diode CR11 connected across Q6 protects itfrom reverse voltages that could develop across it dur ing parall
96. ses Remove jumper and procee to step 4 Check turnoff of O4 by short Output remains low Q4 CR17 R38 defective ing Q5 emitter to base Output increases Remove jumper and proceed to step 5 Check turnoff of Q5 by short Output remains low Q5 R31 or associated com ing Q3 emitter to collector ponents defective Qutput increases Remove short across Q3 and proceed to step 6 Table 5 4 Low Output Voltage Troubleshooting Continued Check conduction of Q3 by a Output remains low Stage Q3 or Q16 defective shorting QIA emitter to col lector b Output increases Remove short and proceed to step 7 Remove CR32 anode or cath ode lead a Output increases a Voltage clamp circuit is de fective i b Output remains low b Reconnect CR32 Stage Q1 defective Check R10 C1 for short and R12 R13 for open Table 5 5 High Output Voltage Troubleshooting Turn the VOLTAGE control to approximately mid range and disconnect the load If the output voltage should rise to an excessive value with the VOLTAGE control turned ccw the control could be damaged a Q6 Q7 CR11 R23 R27 R34 defective Check turnoff of Q6 and Q7 Output remains high by shorting collector of Q5 to emitter of Q4 b Remove short across Q4 and proceed to step 3 b Output decreases Check conduction of Q4 by Output remains high Q4 CR17 R38
97. t agree with the prefix on the title page of this manual change sheets are included to up date the manual Where applicabie backdating information is given in an appendix at the rear of the manual 1 13 ORDERING ADDITIONAL MANUALS 1 14 One manual is shipped with each power sup ply Additional manuals may be purchased from your local Hewlett Packard field office see list at rear of this manual for addresses Specify the model number serial number prefix and stock number provided on the title page Table 1 1 INPUT 105 125 210 250 VAC single phase 50 400 cps QUTPUT Two independent outputs each of which can be set at 0 40 volts 0 1 5 amps LOAD REGULATION Constant Voltage Less than 0 01 plus 2mv for a full load to no load change in output current Constant Current Less than 0 01 plus 250ua for a zero to maximum change in output voltage LINE REGULATION Constant Voltage Less than 0 01 plus 2mv for any line voltage change within the input rating Constant Current Less than 0 01 plus 250ua for any line voltage change within the in put rating RIPPLE AND NOISE Constant Voltage Less than 200uv rms Constant Current Less than S00ua rms TEMPERATURE RANGES Operating 0 to 509C Storage 20to 85 C TEMPERATURE COEFFICIENT Constant Voltage Less than 0 02 plus 500uv per degree Centigrade Constant Current Less than 0 02 plus 0 8ma per degree Centigrade
98. ted to the differential ampli fier input When the METER section of 82 is in one of the voltage positions the voltage across divider R59 R60 and R61 connected across the output of the supply is the input to the differen tial amplifier 4 37 When S2 is in one of the current positions the voltage across divider R56 R57 and R38 is the input to the differential amplifier Note that this divider is connected across the sampling re sistot network The amplified output of the differ ential amplifier is used to deflect the meter 4 38 The differential amplifier is a stable device having a fixed gain of ten Stage Q11B of the am plifier receives a negative voltage from the appli cable voltage divider when 82 is in one of the voltage positions while stage Ql1l is connected to the S common terminal With S2 in a current position stage QLIA receives a positive voltage from the applicable voltage divider while stage Q11B is connected to the S terminal The differ ential output of the amplifier is taken from the collectors of Q12 and Q14 Transistor Q15 is a constant current source which sets up the proper bias current for the amplifier Potentiometer R63 permits zeroing of the meter 4 39 The meter amplifier contains an inherent current limiting feature which protects the meter movement against overloads For example if METER switch 2 is placed in the low current range when the power supply is actually deliver ing a higher
99. ter soldering clean off any excess flux and coat the repaired area with a high quality electrical varnish or lacquer When replacing components with multiple mounting pins suchastube sockets electrolytic capa citors and potentiometers it will be necessary to lift each pin slightly working around the components several times until it is free WARNING If the specific instructions outlinedinthe steps below regarding etched circuit boards without eyelets are not followed extensive damage to the etched circuit board will result 1 Apply heat sparingly to lead of component 2 Reheat solder in vacant eyeletand quickly tobe replaced If lead of component passes insert a small awlto cleaninside of hole through an eyelet Tf hole does in the circuit not have an ZOE oe board apply eyelet in 2 heat on com sert awlor ponent side a 57 drill of board If from con lead of com S ductor side ponent does of board not pass through an eyelet apply heat to conductor side of board 4 Hold partagainst board avoid overheating 3 Bend clean tinned lead on new part and and solder leads carefully insert Apply heat to compo through eyelets or RZE nent leads on correct holes in board side ot board as explained in step 1 ee ssss saenqsdaussssnsesononss ROUTERS oe 3 In the event that either the circuit board bas been damaged or the conventional meth
100. the constant current output of the supply The CURRENT controls on the front panel are disabled according to the following procedures 3 26 Resistance Programming Figure 3 5 In this mode the output current varies at a rate determined by the programming coefficient 200 ohms per Amp for Modei 6281A 500 ohms per Ampere for Models 6253A 6255A 6284A and 6289A and 1000 ohms per Ampere for Models 6294A and 6299A The program ming coefficient is determined by the Constant Cur rent programming current 2mA for Models 62534 6255A 6284A and 6289A 5mA for Model 62814 1mA for Model 6294A and 1 33mA for Model 6299A This current is adjusted to within 10 at the factory If greater programming accuracy is required it may be achieved by changing resistor R19 as outiined in Section V BI A2 A3 A4 AS A6 A AB A9 S GNO S AIO eleieieleleigielelaielelalal l PROGRAMMING RESISTOR Figure 3 5 Remote Resistance Programming Constant Current 3 27 Use stable low noise low temperature coef ficient less than 30ppm C programming resistors to maintain the power supply temperature coefficient and stability specifications A switch may be used to set discrete values of output current A make before break type of switch should be used since the output current will exceed the maximum rating of the power supply if the switch contacts open during the switching interval 3 3 AU TION if the program
101. treet P D Box 5781 Damascua Tek 33 24 m Telex 11215 Cabie ELECTROBOR DAMASDUS Madicai Personal Calculator only Sawah amp Co Place Azm B P 2308 Damascus Tal 16 367 19 697 14 268 Telex 11304 SATACO SY Canis SAWAH DAMASCUS Suteman Hilak EL M awi PO Box 2528 Mamoun Bitar Street 56 58 DamascusTel 11 46 63 Telex 15270 Cable HILAL DAMASCUS ola S A r G Ganeva TUNISIA Tunisie Electronique 31 Avenus de la Liberte Tunis Tei 280 t44 Corema 7 1er Av de Carthage Tunia Tei 253 821 Telex 12319 CABAM TN TURKEY TEKNIM Company Lid Riza Sah Pahlevi Caddesi No 7 rige Ankara Tek 275800 Telex iss TKNM TR Medical only EMA Muhendistik Xoltextit Sirkati Madiha Eldem Sokak 41 6 Yukse Caddasi Ankara Tei 17 56 22 Cable MATRADE Ankara Anaiyticat any Yiimta Ozyure Milli Mudafaa Cad 18 8 XN Ankar Tel 25 t QS 17 80 26 Telex 42576 OZEK TR Cable OZYUREK ANKARA OREGON 17890 SW Lower Boones Ferry Road Tuaietin 27062 Tek 503 620 3356 _ PENNSYLVANIA 111 Zeta live Pittsburgh 15238 Tai 412 762 0400 1021 Bth Avenue King of Prussia industrial Park King of Prussia 19406 Tal Tus 285 7000 TWX 540 680 2670 PUERTO ACO Howiett Packard inter Americas Puarto pe Branch Office Catia 272 Edif 203 Utg Country Club Carolina 60924 Tai 909 762 7255 Telex 345 0514 SOUTH CAROLINA P G Box 6442 6941 0 N Trenholm Aoad Columbia
102. ts when zero ohms is con nected across the programming terminals If a zero ohm voltage closer than this is required it may be achieved by changing resistor R6 or R8 as described in Paragraph 5 59 3 21 To maintain the stability and temperature co efficient of the power supply use programming resistors that have stable low noise and low temperature less than 30 ppm per degree Centi grade characteristics A switch can be used in conjunction with various resistance values in order to obtain discrete output voltages The switch should have make before break contacts to avoid momentarily opening the programming terminals during the switching interval 3 22 Voltage Programming Figure 3 4 Employ the strapping pattern shown on Figure 3 4 for Al A2 A3 A4 AS AG AT AB A9 9 GND S AIQ elelelelelei lelaiaie ic il G i 2 CIT C SSES Rx REFERENCE L VOLTAGE e Figure 3 4 Remote Voltage Programming Constant Voltage voltage programming in this mode the output volt age will vary in a 1 to 1 ratio with the programming voltage reference voltage and the load on the pro gramming voltage source will not exceed 25mA 3 23 The impedance matching resistor Ry for the programming voltage source should be approximately 500 ohms to maintain the temperature and stability Specifications of the power supply 3 24 REMOTE PROGRAMMING CONSTANT CURRENT 3 25 Either a resistance or a voltage source can be used to control
103. ual inspection or trouble analysis correct it and re conduct the per formance test If a component is replaced refer to the repair and replacement and adjustment and cali bration paragraphs in this section 5 44 A good understanding of the principles of op eration is a helpful aid in troubleshooting and it Table 5 2 Low output or no output voltage High output voltage High ripple 9 Probable Cause Refer to Table 5 3 then 5 4 Refer to Table 5 3 then 5 5 Check operating setup for ground refer to Paragraph 5 18 If output floating connect Inf capacitor between output and ground Check for excessive internal ripple refer to Table 5 3 Ensure that supply is not in constant current operation under loaded conditions CURRENT control fully clockwise Check for low voltage across C14 C12 or C10 is recommended that the reader review Section IV of the manual before attempting to trouble shoot the unit in detail Once the principles of operation are understood logical application of this know ledge used in conjunction with the normal voltage read ings shown on the schematic and the additional procedures given in the following paragraphs should suffice to isolate a fault to a component or small group of components The normal voltages shown on the schematic are positioned adjacent to the applicable test points identified by encircled num bers on the schematic and printed wiring boards 5 45 Tab
104. voltage with the voltage drop across the current sampling resistors R54 and R55 Ifa difference exists the differen tial amplifier produces an error voltage which is proportional to this difference The remaining components in the feedback loop amplifiers and series regulator function to maintain the drop across the current sampling resistors and conse quently the output current at a constant value 4 23 Stage Q2B is connected to a common 5 po tential through impedance equalizing resistor R26 Resistors R25 and R28 are used to zero bias the in put stage offsetting minor base to emitter voltage differences in Q2 Instantaneous changes in out put current on the positive line are felt at the cur rent summing point and hence the base of Q2A Stage Q2A varies its conduction in accordance with the polarity of the change at the summing point The change in Q2A s conduction also varies the conduction of Q2B due to the coupling effects of the common emitter resistor R22 The error voltage is taken from the collector of Q2B and fed back to the series regulator through OR gate diode CR4 and the remaining components of the feedback loop The error voltage then varies the conduction of the regulator so that the output current is main tained at the proper level 4 24 Resistor R20 in conjunction with R21 and C3 helps stabilize the feedback loop Diode CRS lim its voltage excursions on the base of Q2A Resis tor R19 shunting the
105. xd met film 6 2Ko 2190 1 8w 8 Type CEA T O I REG 07716 0698 5087 2 R3 fxd met film 15Ka 1 1 8w 2 Type CEA T O LC 07716 0757 0446 1 R4 64 65 fxd met film 20K4 1 8w 6 Type CEA T O ERG 07716 0757 0449 2 R5 26 29 76 77 fxd met film 1 5Ka 1 1 8w 10 Type CEA T O LRC 07716 0757 0427 2 R6 25 fxd comp 360Ka 595 w 4 EB 3645 A B 01121 0686 3645 1 R7 fxd met film 61 9Ka 1 l 8w 2 Type CEA T O LR C 07716 0757 0460 l R8 28 fxd comp 560K 3 576 lw 4 EB 5645 A B 01121 0686 5645 H R9 11 17 27 32 37 48 55 78 NOT ASSIGNED R10 var ww DUAL 10K 1004 2 HLAB 09182 2100 0997 i R12 fxd ww 1 3Ka 596 3w 2 242E1325 Sprague 56289 0811 1803 1 R13 19 fxd comp SLECTED 5 4 Type EB ALB 01121 l R14 fxd comp 3 34 5 Za 2 EB 0335 A B 01121 0686 0335 l R15 fxd comp 330K 5 iw 2 EB 3345 A B 01121 0686 3345 R16 var ww DUAL 9004 104 2 HLAB 09182 2100 0994 1 6255A 6 5 Reference Designator Description R18 fxd ww 5Ka 5 3w 2 24255025 Sprague 56289 0811 2138 P R20 fxd met film 1K 1 lw 2 Type CEB T O UR C 07716 0757 0338 1 R21 fxd comp 39a 5 w 2 EB 3905 A B 01121 0686 3905 1 R24 fxd met film 4 75Ka 196 1 8w 2 Type CEA T O LRC 07716 0757 0437 i R30 var ww 5Ka Modify 2 Type 110 F4 Cr Tun 11236 2100 1824 1 R31 fxd comp lKa 5 w 2 EB 1025 A B 01121 0686 1025 1 R33 38 fxd comp 10Ka 5 lw 4 EB 1035 A B 01121 0686 1035 i R34 fxd comp 1604 x596 lw 2 EB 1615 A B 01121 0686 16

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