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Modular SCR Power Control Service Manual

1. Figure 3 Q01 Board Layout 39 1710 LL LA SH Ir L 6H HSIH H3ONVYO LEA Z Send El ang sI GHYV2 J1OHINOO F HB t 35n4 EL gyp4 tt 2 F om N mn SOL FE EX ome og ase Bory ORB De ENN SET 220 UI Ora B 3 I IANTO gt D I TS Me Power Base Operation The Q01 uses one pair of SCRs connected in inverse parallel to control a resistive or inductive load The main board contains the power supply output drivers and connections for the transformer and the control card The Q01 accepts all control cards The standard Q01 power base takes any transformer from 120VAC to 480VAC 600VAC requires a special base The Q01 main board provides power and FWZ full wave zero cross to detect zero crossover to the control board The control board then outputs a pulse for each half cycle to turn ON the instrument SCRs which in turn fire the power SCRs Two windings of the power transformer provide power for the instrument SCRs See schematic 02 0655 on Page 33 Load Circuit Figure 4 Q01 Block Diagram ZQ Li and Typical Load Lt Circuit Control Card jis VAC T1 Heater DAS NAV L2 Operation Theory Chapter 3 WATLOW QPAC Service Manual Q32 Figure 5 Q32 Board Layout Figure 6 Q32 Block Diagram and Typical Load Circuit Three Phase Two Leg Q32 qan gan woo A35 Wo3 WDI S A Zao A Os3 JINVW
2. 5V R29 eae 74HC02 A 5V 19 5110 O 100K 01 R44 10 9104 42 1150 390K R15 V 10 9394 1K 5V A EN UMS 9 5077 40K 18 1053 R45 i 100K i MCN WEM PHASE LOCK LOOP g CR2 1N914 4 c29 RZ 18 1053 R46 a 74HC04 330K 10 9334 18 1053 10 CR7 1N914 ER 8 O O 10 9221 74HC B8 74HCO4 74HCO4 R51 V R 5 19 5077 19 5074 19 5074 220 PHASE ROTATION UBC AA 5 6 18 3007 wr SPARE 74HCO4 2 77MS DELAY 74HC04 R10 1M USA 74HC04 74HC04 74HC04 c9 A61 C10 10M 2 R11 100K C11 1 TANT 5V NY R14 LED3 1 4 220 PLL USB 3 4 1 1 2 e 3 3 4 4 5 5 6 6 P 7 8 8 9 9 1 al 1 h w u e adawe OVUVU MAIN BOARD 08 5337 POWEH DRIVER SECTION REF 08 5338 Cod 39 DOT BL uuu Z4HCO8 _ 58 19 9077 LM358N 19 5048 ea aa ei ea ei ei A m m l o e M e e o e a 18 1045 itia a R1 4 7 SW 1 P 10 5069 2 p E R4 3D LE 4 480v 40K 25W 1K 10W J1A R3 cre ESES 1 BM 7 30 SN 1 AS TA LK PPPoE 7 A 1 2 39K y P 10 9393 Mr qe ma 2 H11C 1 as 7 18 1045 pr og R7 4 7 5W AS uni sk dow 1 mor on PEB NOT ON PCB 350V 10 5054 J2A R9 CRS e 10K 25N LJ 240V R11 27 22 39K 10 9393 TG 2 H14C 1 NA 18 1045 10 5069 BB T R43 a7 1p SW s R14 2b ome NOT ON PCB 3p 4K 10W i La 40K 25W L 3 480V 10 5084 J3A R15 CR8 D l S 10K 25W 18 0016 I I SN 3 240V 12 1019 i 50
3. Operating erratic and inconsistent Half output One or more LEDs not lit on the Q33 base E DE ee Overview Chapter 1 WATLOW QPAC Service Manual Specifications QPAC Specifications Operation Modular control base with plug in card and transformer e Plug in control cards e Solid state contactor AC or DC input Burst firing zero cross control fixed or variable time base e Phase angle control with soft start and current limiting or digital input e Plug in transformers 50 60Hz e 120 VAC operation e 208 240 VAC operation e 380 VAC operation e 415 VAC operation 480 VAC operation 600 VAC operation consult factory Power bases Single phase Q01 1 pair of SCRs Three phase Q32 2 leg control 2 pair SCRs Resistive load only balanced or unbalanced burst firing zero cross only e Three phase Q33 3 pair hybrid SCRs diodes Recommended for phase angle only with balanced load Control Cards QCA Solid state contactor AC Input 08 5285 e 120 VAC O 30mA minimum AC signal input sources ie Triacs or mechanical relay outputs with noise suppression require customer supplied resistors across the power control AC command signal input terminals to prevent false firing e 24 VAC input 2002 10 watts typical e 120 VAC input 1KQ 25 watts typical e 240VAC input two 1KQ 25 watts in series typical QCD Solid state contactor DC Input 08 5286 ON 4 to 10VDC OFF OVDC Built in noise reduction network QBF
4. QPAC 33 a p p Ui 6 2K FWZ TO CARD Je 3 gt R2 zen HS pm c27 R1 DEMO Main Board n7 15 said AMET 24K P4 5V R3 C26 Q U6B 50K c28 001 6 an ower 12K 7 oie R56 CX R2 25 5 n 510K 14 SIN P2 43 Section E LESER usB ne R57 AS 6 VCOUT P1 he 270 5V hen PU T 400K key oo en 4K LED 4 10K 5V 4046 m 74HCO2 O CA1 POWER ON R13 x 001 UPA 1N914 R12 IP 1 R54 m s beoe 2 U A 4 A52 220 10K 74HCo2 SERA BRN WH j4 3 a heri c12 s 510K 4 TANT esi IP 9 gt VR1 C4 c3 BRA Sos T N B 44 BRN ya 2 21 ac OUT PA VI g VO J8 4 gt BLU WH d AC SOUT D c2 E 18 4005 1 TANT P1 R6 TP COM fp P2 BLU J1 1 470K 001 lt TOMKJ2 7 J2 8 sv L P3 V2 O P4 T BM R62 ee ce 40K PULSE FROM CARD G USD P7 N 4 TANT C30 R59 USF ues D y J2 1 CR3 10K 513 RED WH 13 oie KV TO CARD KJ2 2 TPS TE qee 001 P2 4N4005 R15 gep ea R19 R20 J4 1 10K LOOK map iK 44 510 RED R17 d 001 R22 OR j 74HC04 iib deep Et UZA C14 c13 J4 6 CR4 2 R21 ORG WH 2 2M 1N4005 PIn18 4o 7 rer PHASE LOSS OK 100 EA 4 6 U7B 5 R38 Lv lt 7 74HC08 10 2222 2 77MSDELAY R34 2 2K ew Hi1AA 1 10 0047 S 4 7 14 28 R40 18 1035 CR5 33K 1 2W 4N4005 0333 iia ee ie via hi 19 5073 R43 100K 2W 10 2104 100K 1 2W 10 0104 R42 68K 1 28W 10 0683 Cee 02 1KV 12 1125 Schematics Appendix R36 1MEG 10 9105 J5 2 HS T STAT J5 1 HS T STAT R39 A preme JL TI
5. Modular SCH Power Control Service Manual LOW Watlow Controls 1241 Bundy Blvd P O Box 5580 Winona MN 55987 5580 Phone 507 454 5300 Fax 507 452 4507 QPAC SA10 9403 10 00 April 1994 Made in the U S A CS Printed on Recycled Paper Use The Manual Chapter 1 Page 4 Chapter 2 Page 8 Chapter 3 Page 9 Chapter 4 Page 15 Chapter 5 Page 17 Appendix Page 31 y 43 NOTE Details of a Note appear here in the narrow box on the outside of each page AN CAUTION Details of a Caution appear here in the narrow box on the outside of each page d WARNING Details of a Warning appear here in the narrow box on the outside of each page 2 WATLOW QPAC Service Manual How to Use the Manual General Description e Indication of Malfunction e Specifications e Cleaning Fans Fins Filter Tightening Connections e Periodic Test Runs e Base amp Firing Cards e Operation Theory e Test Procedures e SCHs e Troubleshooting e Bench Testing e Waveforms and Schematics Notes The user s manual contains informational notes to alert you to important details When you see a note icon look for an explanation in the margin y J Safety Information This user s manual also has boldface safety information notes to protect both you and your equipment Please be attentive to them Here are explanations A The Caution symbol exclamation point in the wide text column alert
6. on the control card The SCR Switch Will Not Turn ON With the command signal full ON check the VAC voltage across the L1 and T1 ter minals They should read approximately 1 5VAC If you are reading the line volt age potential the SCR is not gating on The mother board or control card may be bad Try another control card or contact the factory The Interlock Connection on the QPAC Control Card is Open Measure voltage from Terminal 5 to Terminal 1 or 2 on the control card Voltage must be present at both Terminal 1 and 2 If not place a jumper between these terminals If you are using the interlock feature check the interrupt switch or the interlock The Unit is in Emergency Shut Down ESD For Fan Cooled Units ONLY If the heat sink temperature exceeded 187 F 86 C the on board thermostat will close and the QPAC will enter Emergency Shut Down More than likely a clogged or non operational fan is the cause Check the fan and clean if necessary If the problem still exists check for a shorted heat sink thermostat Measure from the thermostat unclog the fan check for fan power or replace the fan The Control Card is Bad First try to re seat the control card Make sure there is a good connection between the control card and the mother board If there is still a problem replace the control card with another card Also check the troubleshooting section on Page 29 or 30 See Page 5 for ordering a replacement card WATLOW QPA
7. 10 OHM y I 10 9100 y L 1 l gt 261 crm 4 O 1 I2 S vr o EDGE CONN CTOR 21 0046 WATLOW QPAC Service Manual OHM 10 5121 R3 SK GAIN 11 0058 5V A C TP 1 19 5077 6 C1 001utf 74HCO8 S u TP 3 12 1149 woes 100V 74HCO8 ER Y 10K R23 10 9103 1 ere 04 R10 22K cs 9 U1C 19 5055 85 458 8 R20 10 10K LF444N 10 9103 19 5055 R9 10K 10 9103 S5V R16 R17 SSK 18K 11 0058 BIAS V R18 47K 10 9473 5V NS A R19 100K LF444N 4 10 9104 UiA 19 5055 1 4 5 1 na a C3 12 1151 p u an 1uf sov SV 12 1144 vo D vi 19 5061 REG SV TANT 35v D SV R21 10K 10 9103 JP 3 qoem m m mimm nm m cmm em tit in tet tnt TP 4 R24 100 10 9101 O 3 O Lo we we a a e o gt e oe ee e d e e e es ee ow oe ae oe e om ee c e e e a oe ON MOTHER BOARD LF444N 19 5055 a A ew ew ew ew ew ew ew ew ew ew aw ew aw ew aw ee ee aw ew ow a Lo e e e c co ce ee ee ee p OMD co ov co ov o e oe or en ow Schematics Appendix Appendix Schematic 02 0729 QPAC Variable Time Base Burst Fired CRe U2D U2C 9 11 8 O O T P 4 Ces 74HC00 74HC00 FWZ gt 3 LG v gt E T SV gt 6 2N3904 T oup COM gt 7 KEY COM gt E 10 LED gt 11 LED 12 5V UeB 4 I o R22 4HC O C4 400K 001 R23 i T P 3 4 10K g
8. Verify that the signal from the temperature control is correct i e 4 20mA 1 5VDC etc Refer to the control card section or the control user s manual A Partially Open Heater s Check all the connections from the circuit breaker to the heater Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control Check the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater 20 WATLOW QPAC Service Manual Troubleshooting Chapter 5 Problem No Heat Blown Fuse This can be done one of two ways Measure voltage across the fuse If there is voltage present the fuse is bad You can also check the fuse for continuity using an ohmmeter Replace the fuse if necessary Open Heater Check all the connections from the circuit breaker to the heaters Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control Check the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater Bad Connection Check all the connections from the circuit breaker to the heaters Measure the cur rent and output voltage from the heater If voltage is present and no curr
9. ds mde n I LEV gt e V OG I i R9 4K i kml WATLOW QPAC Service Manual 33 Appendix Schematic 02 0682 QPAC 32 Mother Board NOTES 1 All resistors are 1 4 W unless otherwise specified 2 All capacitors are valued in uf unless specified 3 Ref PCB Bare see 35 0205 Rev C 4 Ref Assy of PCB see 08 5320 L1 IO See R9 12 3001 T28 1K 1 2w 10 0102 SN 2 sn l 12 3001 R7 c3 1K 1 CR1 10 0102 12 1087 18 1035 SCR 1 CR2 L T2C R10 N LA DA EO 1K 1 2W 10 0102 um o 12 1069 RB 30K 10 0100 ea 1wf e 70 9303 10 2820 e B82 2w T10 SEC 12V 108 0153 R8 lt COM Rd 30K 10W 172W NG CF Brat 10 5118 004 pee Ld 21 0071 J2 1 E 18 1035 CR CES TU 19 5038 SEC 12V 18 4005 1N4005 2 lt y AC OUT Ms 3 C FWZ Ti 4 Ac ouv Key T1 T2 BR1 c7 l 5 C ESC T3 SEC 12V 2200MFD 6 CE Y 12 1152 10 0102 E 7 ES COM J2 3 Ew 8 lt COM 1K 1 i C KEY 7 y I lt COMU lt gt LED 1 1 Mom q MG C TIED J 1 I 1 21 0046 LEQSI HLLOCL SEE 02 0681 WIRING DIAG XFMR NOTE LAST USED R 14 C B U2 CR4 34 WATLOW QPAC Service Manual Schematics Appendix Appendix Schematic 02 0798 O C ZERO CROSS PLA NOTE CALIBRATE ZERO CROSS NOTCH WITH JUMPER IN PHASE ANGLE POSITION Cp gt Fn PHASE ANGLE H8
10. Het eee to a Tito gt a amp BF Burst Fired with a Four Second Time Base 08 5289 The BF card is designed for time proportioning with a 4 second time base It can be field changed to a 1 second time base by removing R17 A 4 20mA input is standard and can easily be changed to accept a voltage input by removing R8 and read justing the bias and gain pots for any voltage input from O 3VDC to 0 15VDC The output of the card is disabled if the emergency shut down goes low Figure 11 QBF Board Layout Operation Theory Chapter 3 WATLOW QPAC Service Manual 13 R11R18 R9 ag BURST FIRING VARIABLE TIME BASE U2cg lt tr 2 a H ul N DO Figure 12 QBV Board Layout ATE CONTACTOR 48 5265 TB1 Figure 13 QCA Board Layout 08 8286 Figure 14 QCD Board Layout 14 WATLOW QPAC Service Manual BV Burst fired with a Variable Time Base 08 5342 The BV card is time proportioning with a vari able very fast time base At 50 power one full cycle is ON and one full cycle is OFF At 25 power it is ON one cycle and OFF for three At 90 it is ON nine cycles and OFF for one As the command signal gets farther from 5096 power the time base gets longer The maximum cycle time is 1 of 360 cycles The BV card is standard setup for 4 20mA into 250Q It can be changed to 1 5 VDC by removing the resistor on the plug located on the back of the card adding a small circui
11. Last changes see ECN 2188 10 05 88 Schematics Appendix SIGNAL AC INPUT H6 10 0103 10K 1 2W H7 10 0103 10K 1 2W 10 9103 5V 19 5078 eee a o M o o ee H11A1 H10 2 2MEG 10 9223 22K 10 9224 Q1 GA 19 0027 1N390 4 204 12 1149 5V N R4 10K i d 10 9103 ESD gt gt ml ULA 2 74HCOBN 19 5077 10 9102 UB 7 4HCO N 19 5077 R9 10K 10 9103 10 9101 1uf 35V 12 1144 TANT WATLOW QPAC Service Manual ir igi H 21 g AS 100 OHM i TO OPTOS ON MOTHER BD p Utua H 1C1 l 12 1 37 Appendix Schematic 02 0657 QPAC 01 TPR Board Zero Cross NOTES 1 All resistors are 1 4 W 5 unless otherwise speci fied 2 All capacitors are valued in microfarads unless noted Last used R 26 C 8 Q 3 4 Ref AssY PCB 08 5289 PCB Bare 3135 0180 go 38 R7 10 OHM 10 9100 5V A R8 10 9152 1 5K E 21 0048 Po i l 781 3 uz qs 10 9223 FWZ gt 1 Adm 19 0025 sv 8103 1N3643 I l D 1 l l i EspZsrar gt l ENE NE IN RS 10K R11 10K je 1 10 9103 R6 c2 10 9223 4 10K 1uf 10 9103 5 12 1144 A 5V T A R1 Y T i R12 100 4 7K 10 9104 i JUMPER 10 9472 1N3906 INSTALL EXTERNALLY Q2 19 0028 1 1 R13 19 0016 y 4 7K 10 9472 2N6027 C7 l Q3 I 10uf NG 12 1142 TAY y I8 2 21 0983
12. if necessary If the problem still exists check for a shorted heat sink thermostat unclog the fan check for fan power or replace the fan The Control Card is Bad First try to re seat the control card Make sure there is a good connection between the control card and the mother board If there is still a problem replace the control card with another card Also check the troubleshooting section on Page 29 or 30 See Page 5 for ordering a replacement card The Phase Angle Card is Installed The QPAC 32 is interlocked and cannot operate with a phase control card Troubleshooting Chapter 5 WATLOW QPAC Service Manual 21 The QPAC Transformer or Resistor Fuse R10 is Bad Check for AC voltage present at the transformer T1 see Page 34 for transformer wiring Be extremely careful High voltage is present on the transformer connec tions If no voltage is present verify that the resistor fuse is good by measuring across R10 You should be able to visually determine whether or not the fuse is bad The resistor will usually be black or dark brown if open It should read a mini mal voltage of 1V If it reads open circuit line voltage R10 is bad See Page 5 for ordering a replacement transformer The QPAC Mother Board is Bad Check the DC voltages at the J1 connector Place the voltmeter common on pin 7 or 8 They should read as follows J1 Connector Without Card With BF Card Test Point Installed T STAT Not Used 3 to 5V V 11 to
13. input signal for proper calibration i e 4 20mA at 4mA The output should be full OFF At 20mA the output should be full ON 22 WATLOW QPAC Service Manual Troubleshooting Chapter 5 The QPAC Mother Board is Bad Refer to the mother board troubleshooting procedure on Page 28 The T1 Load Connection is Open If T1 is open at the heater the leads will occasionally couple AC back and turn on L3 and T3 SCRs Check the load with an ohmmeter at Q32 Problem Partial Heat Incorrect Phase Rotation The phase rotation must be A B C Measure voltage T1 to T2 T2 to T3 and T3 to T1 If itis not within 2 to 5 reverse any two L leads and try again One of Two SCRs Won t Turn ON Half Waving This is most likely a problem with the mother board A gate signal may be missing Refer to the mother board troubleshooting procedure on Page 28 The Gain Adjustment is Too Low Recalibrate the bias and gain adjustments by following the procedure on Page 16 There is an Insufficient Control Signal Verify that the signal from the temperature control is correct i e 4 20mA 1 5VDC etc Refer to the control card section or the control user s manual A Partially Open Heater s Check all the connections from the circuit breaker to the heater Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control C
14. 0 R17 SCH3 D3 27 l 2 4 7 7 A TO L2 39K R23 j E 10 9393 ee DE H11C 4 P ee ae ne me oe oe TO L4 U3 R24 19 5054 4 7 To L3 A e e A ooo WATLOW QPAC Service Manual Appendix Schematic 02 0672 DC Input QPAC Series NOTES 1 All resistors are 1 4 W 5 unless otherwise speci fied 2 All capacitors are valued in microfarads unless noted 3 Last Used R 8 C 3 CR Sy 1 U 1 Sy 4 Remove Pin 5 from J1 Re connector before solder SK x ae ing in place 10 9152 dni 10 9112 R3 22K p MA 10 9223 i PABT OF 184 E553 i R1 10K 5a we E 1 ENZ gt e 4N3904 400v 004 aie SUE EY AAA 19 0027 12 1149 Ps HH C7 By PART T SEE NOTE 4 i U18 AAT_QF_ TB1 UA44 44 l 2 R5 100 U4 U2 6 l 4 s i r L TO OPTO S ON MOTHER BD I R8 10K 1 10 9101 H11CI 10 9403 7A4HC B e 4HCO8 19 5077 l CR1 18 1053 1N914 l l i RS 10K l p 10 9103 I l l l R7 I 10K c3 I l Auf Sov I l l 1 l EE e a S 21 0046 PAE I M COMMON BUS Le ma rer os am i GE 36 WATLOW QPAC Service Manual Schematics Appendix Appendix Schematic 02 0673 AC Input QPAC Series NOTES i All resistors are 1 4 W unless otherwise speci fied All capacitors are valued in microfarads unless noted Ref PC Board Bare 35 0177 Last used R 10 C 3 U 2
15. 0 E o 12 1144 AER LEH uo et 59 CI CE ZX180 FSV gt TT gn L 87 12 1144 SE N CB ZAA s 2A T luf mo TB1 7 a La Y 110 la 0 2 all 5V feo TD 3 ZX180 5 TP 2 Zzx180 gt RS 4 5K U6B S B 2 lt cum d D D 10 92 23 l 74HCOOQ 74HCOO C1 C6 49 5066 49 5066 1N3904 001uf 19 0027 42 1149 U7B 5 B5 p 19 5110 id CTB 4 MEK ANNE OK LED YELLOW 19 5066 ZX180 5V Re 18 3007 gade nci adv 9 uuum cae mue Men MAL Gen ke eae dis Wie aes uc as oaa ugs ME Wa a 10 9104 R9 R10 48 1053 10 9392 iin rike a USC 10 9181 CR4 R12 10 j TS VCOUT p1 s 1N91 4 3 9K Ms C4 74HCOON SIN Pe i i 1uf 49 5066 12 1149 R3 aria ato a TANT a I 10 C2 R4 l 15 dh 1ut 100K 10 9104 12 1151 101 C3 3 E 1uf TANT 4 TER NZ eee ee Schematics Appendix Watlow QPAC Service Manual Watlow Controls 1241 Bundy Blvd P O Box 5580 Winona MN 55987 5580 Phone 507 454 5300 Fax 507 452 4507
16. 0VAC 600VAC consult factory Power Dissipation Watts e 1 5 watts amps per controlled leg Line Voltage Compensation 10 A in line 296A in load in the 3096 to 70 power region QAF QAL amp QBV Isolation e Command signal to load 1250VAC minimum Linearity 296 3096 to 7096 power region All units except QAD QCA amp QCD Off State Leakage Current e 20mA O 480VAC SCR Protection l2t fuses provided dv dt 200V usec minimum l2t are fast acting fuses designed to protect SCRs and capable of opening blowing inside 1 2 cycle 2 3 msec They are not designed for protection of other parts of the heater system and should not be used in place of circuit breakers or fusible disconnects Q33 units equipped with MOV and snubber Q01 amp Q32 units snubber only Q32 3rd leg fuse kit may be used but not required with 3 phase 2 leg models Cooling e Fans provided in 75A to 100A units must be supplied with 120VAC or 240VAC 20 watts fan power each All fans wired by the customer Q01 75A through 300A units 1 fan Q32 30A through 100A units 1 fan 150A 200A 300A units 2 fans Q33 30A through 100A units 2 fans 150A 200A 300A units 3 fans Natural convection only Q01 30A and 50A units Heat Sink Thermostat SCRs that incorporate a fan for forced air cooling can reach unsafe temperatures if the fan fails All Loyola SCRs with fan cooling incorporate a heat sink thermostat to remove power from the SCR in case of fan failure filter b
17. 11 Overview 30 3 leg 30 to 300A Phase angle control with digital input QAD 08 5314 For 10 amp 30 3 wire controls only not for 3 2 leg controls Q01 is a single phase power control that operates with any type of firing method such as burst fired phase angle variable time base and AC It uses a pair of back to back SCRs package or individual depending on amperage ratio Q32 is a 3 phase 2 leg power control that can operate on most types of firing methods except phase angle and controls two of the three legs The QPAC 32 was designed for zero cross applications only It uses two pairs of SCRs individ ual or SCR package depending on amperage ratio Q33 in a 3 phase 3 wire hybrid SCR and diode power control that operates with any type of firing method It features a series of jumpers for fast AC input changes after changing transformers and a jumper for changing from burst fired to phase angle fir ing It also has LEDs to indicate Power On Phase Lock Loop Phase Rotation and Phase Loss For fast malfunction diagnostics and for bench troubleshooting complete data is on the board at a series of test points Integrated circuits are easy to change by simply plugging and unplugging for replacement or testing Indications of Malfunction No output under any circumstances Full ON output at all times and the load is uncontrollable Output is not proportional to the command signal unbalanced output
18. 14VDC 15 to 22VDC FWZ 11 to 14VDC 11 to 14VDC V 15 to 18VDC 15 to 18VDC Q32 connected to Pin 1 Q01 or Q33 Not Used Not Used 5V 5V 0 1V 5V 0 1V COM COM meter common KEY COM LED Not Used Pulses possible COM See scope pictures on Page 31 Problem Full or Partial Uncontrollable Heat The SCR Switch is Shorted Remove the control card and power up the QPAC The output should be OFF If the unit is still full ON remove power and disconnect the load wires and measure across L1 and T1 and L3 and T3 with an ohmmeter If resistance is low 5Q or less the SCR is shorted and must be replaced See Page 5 for ordering a replacement SCR A Heater is Partially Shorted Disconnect the control card the output should be OFF If not disconnect the power and heater and measure the heater resistance It should match the heater KW rating The Control Card has the Wrong Bias Adjustment The bias adjustment is set too low and needs to be readjusted See the Bias and Gain Adjustment procedure with the appropriate control card on Page18 The Control Card is Bad First try to re seat the control card Make sure there is a good connection between the control card and the mother board Power down the control and remove the control card Power up without the control card installed If there is no heat the control card is bad Replace the control card See Page 5 for ordering An Excessive Input Signal from the Temperature Control Check the
19. Burst firing zero cross control Fixed Time Base 08 5289 Process input factory set O 4 20mA Input impedance 2504 clip resistor for 5KQ voltage input Time Base 4 seconds clip resistor for 1 sec QBV Burst firing zero cross control Variable Time Base 08 5342 Process input factory set O 4 20mA Input impedance 2504 clip resistor for 5KQ voltage input Bias and Gain card optional QAF Phase angle control 08 5288 Process input factory set O 4 20mA Input impedance 2504 clip resistor for 5KQ voltage input e Soft start 10 sec approximately QAL Phase angle control with current limit 08 541 1 Some heater elements change resistance during their operation i e silicon carbide In order to control at a slow ramp it is often advantageous to limit the current Sensing the current is via a current transformer This is NOT a means of protecting the SCR Process input factory set O 4 20mA e Input impedance 250Q move jumper for 5K voltage input e Soft start 10 sec approximately Current transformer included Current Limiting QAD Phase angle control with digital input 08 5314 e Remote digital phase control Interface Centronics parallel 8 lines Power steps 256 6 WATLOW QPAC Service Manual Overview Chapter 1 Output e 120VAC through 480VAC 600VAC consult factory 1 2 or 3 pole e 30 through 300 amps per pole Power Frequency 50 60 Hz Voltage 10 120 208 240 277 380 415 48
20. C Service Manual Troubleshooting Chapter 5 The QPAC Transformer or Resistor Fuse R10 is Bad Check for AC voltage present at the transformer T1 see Page 35 for trans former wiring Be extremely careful High voltage is present on the transformer connections If no voltage is present verify that the resistor fuse is good by mea suring across H10 You should be able to visually determine whether or not the fuse is bad It should read a minimal voltage of 1V If it reads open circuit line voltage R10 is bad See Page 5 for ordering a replacement transformer The QPAC Mother Board is Bad Check the DC voltages at the J1 connector Place the voltmeter common on pin 7 or 8 They should read as follows Test Point Card Installed T STAT Not Used 3 to 5V V 11 to 14VDC 15 to 22VDC FWZ 5VDC Pulses 5VDC Pulses V 15 to 18VDC 15 to 18VDC Q32 connected to Pin 1 Q01 or Q33 Not Used Not Used 45V 5V 0 1V 5V 0 1V COM COM meter common KEY COM LED Pulses possible COM See scope picture on Page 15 The Phase Loss LED is Not ON Any one or a combination of phases are low 20 or greater Measure the incoming voltage on L1 and L2 L2 and L3 and L3 and L1 Incorrect Phase Rotation Phase Rotation LED is Not ON The phase rotation must be L1 L2 L3 Reverse any two L leads and try again The Phase Lock Loop PLL is not synchronized with the AC Line PLL LED is Not ON There is probably noise on the AC line
21. Check the incoming power with a scope and try a different power source The Zero Cross or Phase Angle Jumper is in the Wrong Location Move the jumper See the Zero Cross Calibration procedure on Page 15 The Unit is Calibrated for the Wrong Frequency The Zero Cross Calibration procedure must be performed at the operating fre quency 50 or 60Hz See this procedure on Page 15 Troubleshooting Chapter 5 WATLOW QPAC Service Manual 25 Problem Full or Partial Uncontrollable Heat The SCR Switch is Shorted Remove the control card and power up the QPAC The output should be OFF If the unit is still full ON remove power and disconnect the load wires and measure across L1 and T1 with an ohmmeter If resistance is low 5Q or less the SCR is shorted and must be replaced See Page 5 for ordering a replacement SCR A Heater is Partially Shorted Disconnect the control card the output should be OFF If not disconnect the power and heater and measure the heater resistance It should match the heater KW rating Card has the Wrong Bias Adjustment The bias adjustment is set too low and needs to be readjusted See the Bias and Gain Adjustment procedure with the appropriate control card on Paget6 The Control Card is Bad First try to re seat the control card Make sure there is a good connection between the control card and the mother board Power down the control and remove the control card Power up without the control card installed
22. EG du C413 2N3906 4uf TANT 5V 5V A U4C R23 2 2K 74HCOBN 2N6027 19 0016 8 R36 100K R35 82 NU TB1 11 pe EEE R37 I 330 l l gt l N4B 1N914 40K CURRENT LIMITING Sd LED I w LED 1 R I X haras Jf 19 2 En 2 18 3007 VW TB1 12 SPARES 74HC08 U4B R25 2 2K 74HCOBN c11 i 5v 4uf TANT 35v l l i 74HC14 i U3E U3C pa as R29 2 2K i A 5 ZAR Lu usi 4N914 1N914 74HC04 TP 5 WATLOW QPAC Service Manual ON MOTHER BD 41 Appendix Schematic 02 0671 QPAC Parallel Computer Interface NOTES 1 All resistors are 1 4 W unless 5V otherwise specified 2 All capacitors are valued in microfarads unless noted SIP PACK 1 ANI 16 10 7001 R15 COM BUS J1 10K 10 9103 1 U7D UPDATE 12 i i 5V 18 i 11 cg 01 R13 74HCO2 10K 49 5110 g STROBE 12 1150 i 12 1150 C10 m bM MM 01 l U7C 8 l 74HC02 19 5110 214 M 180 i 10 9181 ETT SN 49 5051 42 WATLOW QPAC Service Manual U2 PROM U4 da US 19 5051 IE D ET 4 gja0 48 BE A1 P1 ZA3 15 71 p3 pex Slag E 39 A f U7A ici Hg 48 16 12 Ps i Rit 100 i AB T 15 P6 cozzo bt po TO OPTO S gt A7 p7 40 9101 E 5V MCK 1 bek 7 4HCO2N A it 75 SPE 49 511
23. ELOW Tin E ac O 2 2 TE Onm 4 4o2n P H 8 E MADE IN U S A ere us R3B R28 C18 A SN Tn ca C7 R53 W 8a pid I B T H 1 A R61 R14 RBZ R18 Re1 SABE Fuel A24 TL F T kia MODULAR L OPAL 3 POWER CONTROL El O x AR OL QB 3 POWER BASE W ESD E Er cre x41 m s f I E TRANSFORMER FWZ b Ld Asa ga V j Me CAS CR7 ci r H L 5 dia ER I R25 R27 COM P O La G VOLTAGE PLUG COM H Y E MOVE JUMPERS 5 E uus in Pr o d CONTROL L 480 380 AND 415 E COM 12 T A A 6 CONNECTOR E FROM DRIVE CONNECTOR GATE T WIRE 120 VAC TO FANS GATE DRIVE COMPONENT SIDE Power Base Operation Figure 7 Q33 Board Layout The Q33 uses three SCR diode pairs and Power Board hybrid in inverse parallel to control a resistive or inductive ungrounded load The Q33 has two boards The main board contains the power supply phase locked loop PLL phase counters zero cross fil ter detector phase loss and phase rota tion circuitry The output board contains the SCR protection artificial neutral and output drivers The Q33 accepts 208 to 480 volt transformers as standard 600VAC must be special ordered The Q33 is intended for use on phase control although it can be used on zero cross with some loss of output by moving one jumper to shift the zero cross notch The Q33 is much more complicated than the Q32 sinc
24. HIBILNI O3JINV IVANA dI EL Zl1 11 39VLI10A OVOl aHnsvaM NO HaMDd HLIM r o 1 7 TL Hn N Zz m Uu 1 i SET 2 za S N N N 23 H zn ab HD 2D QHYV2 J0HlNO2 zr uH n u EIH BeZ Z18 NYJ OL JV SL10A BZ 3HIM ZE uper v 10401 MOTLYM 37 EN s Power Base Operation The Q32 uses two pair of SCRs connected in inverse parallel to control two lines of a three phase ungrounded resistive load The main board contains the power supply the output drivers connections for the transformer and any of the zero cross control cards It is interlocked so that it will not allow any output if a phase angle card is installed Q32 s will accept 208 to 480 volt transformers as standard 600 volt units need to be special ordered The master portion of the Q32 operates the same as the Q01 Once SCR 2 fires transformer T2 receives load voltage and T2B then turns on SCR 4 approximately 60 degrees before zero crossing on L3 phase As soon as L3 goes negative SCH 4 is ON The next half cycle SCR 1 is fired and T2C turns on SCR 3 See schematic 02 0682 on Page 34 Power FWZ Supply dii Control Card L1 L3 VAC Load Circuit 30 Heater Slave Transformer 10 WATLOW QPAC Service Manual Operation Theory Chapter 3 Q33 Three Phase Three Leg Q33 Zero cross jumper 4 R4 R3 RZ RI 9 9 6 0 amp ert c4 L et TORA ARE B
25. If there is no heat the control card is bad Replace the control card See Page 5 for ordering An Excessive Input Signal Check the input signal for proper calibration i e 4 20mA at 4mA The output should be full OFF At 20mA the output should be full ON The QPAC Mother Board is Bad Refer the the mother board troubleshooting procedure Problem Partial Heat One of Three SCRs Won t Turn ON Half Waving This is most likely a problem with the mother board A gate signal may be missing Refer to the mother board troubleshooting procedure on Page 28 29 The Gain Adjustment is Too Low Recalibrate the bias and gain adjustments by following the procedure on Page 16 There is an Insufficient Control Signal Verify that the signal from the temperature control is correct i e 4 20mA 1 5VDC etc Refer to the control card section or the control user s manual A Partially Open Heater s Check all the connections from the circuit breaker to the heater Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control Check the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater The Zero Cross or Phase Angle Jumper is in the Wrong Location Move the jumper See the Zero Cross Calibration procedure on Page 15 WATLOW QPAC Service Manual T
26. LL CHANGE AS FOLLOWS I RAD TECH VERSION IS 3 6K 1 4W SX 1 P N 10 9362 I QPAC AND VPAC VERSION IS 1 261 OHM 1 4 W 5 TS1 4 AA d pP nM 3 187 gt i 1 1 I I I I l IP e i 1 l 1 I l l l R26 i t 2 2K I I i 1 r ce i 5V elo 1uf TANT I l 12 1144 1 I 35v l i R15 1 I 470 1 74HC1 4 1 10 9471 I 1 CRI 4 R18 81 1 1 1 19 5061 Ls a a a 2 2K i 1 8 1 035 1 8 001 a 74HCO4N be we we am om 7 4HG124 m a T STAT RIG UP 5 45V 1 5K v SV 40 WATLOW QPAC Service Manual Schematics Appendix Appendix R10 47K Schematic 02 0701 Bi ud QPAC Phase Fired with Current Limit R31 Tr 2 2K NOTES e A 1 All resistors are 1 4 W 5 R32 unless otherwise speci ce one fied TBA 3 002 74HC14 R30 Qs C410 2 All capacitors are valued En R lo 3904 001uf in microfarads unless noted 7 TB1 1 5V O U4D N2B wee 42 R38 CURRENT 4 10 LIMIT IN 100K L gt LF444 R16 N2A 20K 10K pw EE T eg I AS 10K INTERLOCK R8 5 6K 1 ULA N1D 2 4 4 10K 3 c3 n LF444 A 4 A TANT E N1 100MFD inis SIGNAL i 35V 5V l T R7 n9 47K 8 2K COMMON 47K P1 L 5K 1 2W NA BIAS R15 220K a LIES 10 9224 i S7 R14 470 R13 1 5K 5V SV 6 Schematics Appendix c12 01 G1 1N3904 R28 10K D2 1N914 74HC14 R34 1 M
27. Lz La O55 PS Load Circuil nm 55 Heater Output Board Main Boarc 12 WATLOW QPAC Service Manual Operation Theory Chapter 3 R m ZR TLOW LOYOLA Sa E AF Phase Angle Fired 08 5288 The AF card provides a delayed SCR turn ON pro viding an infinitely variable voltage and current from full OFF to full ON The AF card can be used on resistive inductive or Tungsten lamp loads It includes a 10 second soft start and a missing half cycle detector to put it into emergency shut down ESD and retrigger the soft start A low signal on the ESD terminals puts the QPAC in ESD The input is factory set for 4 20mA into 25090 It can be converted to a voltage input by removing R3 and readjusting the bias and gain potentiometers for any voltage fan 0 3VDC to 0 15VDC R n d q gt CCCI di A A O ro 20 tar TBI 12 Figure 9 QAF Board Layout AL Phase Angle Fired with Current Limit 08 5411 8 h HEP ae EN The AL card incorporates all of the features p N Ne Na Of gt of the AF card with the addition of a two mode controller to hold the output current at a pre set maximum level The load current is monitored by a CT current transformer and the maximum output can be set by a poten u3 tiometer on the card U2 cE a 15 Ee ud y e JETA Figure 10 QAL Board Layout 3 S2BSMADE IN USA BF Zero Cross Control Cards work on all bases I MIR
28. R10 S 11 PCLK 4 7K 5V lt T P 5 SS Gen Q4 C 74HC74 2 Reo 2N6027 6 8K 5V Rie H5 A G2 2N3904 4 7K 100K 3 R18 R19 R11 4 7K 4 7 onm 2 7K FWZ R24 C7 22K 1 a P4 REF SG WAVE 1K aal 5 Nul X NZ NZ COUNT CLEAR DELAY OUTPUT PULSES 50 POWER NOTE Control Type Adjustable Bias and Gain l BIAS Potentiometer Input or Fixed Input Use R20 W3 Bias Gain Range Card 50 POWER Do not use P1 STAIRCASE GENERATOR RANGE CARD Fixed Input Connector AL I NUT Do not use R20 W3 4 SENS GARE BIAS AND GAIN Schematics Appendix WATLOW QPAC Service Manual 39 Appendix 5V Schematic 02 0656 E ONE QPAC Phase Fired ae U3A R37 22K NOTES 1 All resistors are 1 4 W 596 TB1 3 R1 10K n a 74HC14 unless otherwise speci Ewz 3904 OO01uf fied 12 1149 2 All capacitors are valued Y in microfarads unless a noted 3 Last used R 42 C 10 CR 5 Q 4 U 3 P 2 cs c7 01 HE 4 2 1uf TANT 12 1144 5V pois 74HCOSM I I 1 1 R36 19 0016 LF444 NZ 82 i 2N6027 4 1 RS 1 l ik R10 5 6K R21 100K p v TR 3 7 1 10 SV TB1 11 i LED R7 10K i R12 47K i ps QN MOIHMER BD i 1 LF444 1 c3 it I R8 1 1 oi 10K I 12 1144 I l I 1 we i i SV 1 T ne R23 10K 1 gt 10K ag i 1 4 I 10K 1 ras t I 47k d 1 1 P1 gy TE SS 1 LF444 SK 1 2w U1D 1 R42 TB1 12 8 2K LED 1 1 REE NA 1 NOTE 1 I R3 VALUE WI
29. VE EV ica din 5 Replacement Paris uendra 5 Indication of Malfunction occcoccnoccnnconcnccccncccnnoconcnnnnnnconononannnnos 5 OPAC SDECIICANONS suse 6 Preventative Maintenance Cleaning Cooling Fans Fins and Filter 8 Tightening Connections sese 8 Penodic Test RUNAS t E 8 Operation Theory of Base and Firing Cards Single Phase Model QU iudico Dee ates d itia eni 9 Power Base Operation cccccccccccnnccncccccoonccononononaconononononanonnnnnnnanos 9 Taree Phasa TWO beg Q32 sr 10 Power Base Operation occcccccconncccncococonnconnnonononnnnnnnononanncnnnnnnnnos 10 Three Phase Three Led OI san 11 Power Base Operation nonea a 11 Zero Gross Control GardS as 13 Test Procedures Orid 92 cive ti Tie paced Los ue esa rar v oen abd ues eod zi E 15 Q33 Zero Cross Adjustment rrrrrnnnoovvvrvvonrrnrnrrrrrrrnnnnnnnnnnnnnnenn 15 Bias and or Gain Adjustments ccccccccconccnnncccccnonnnnnccnnnancnnncnnnnnos 16 Current Limit Adjustments occccccconnnccnccccnonnncnnnnnnnnnnonnnnnononanenos 16 Troubleshooting Indications of Malfunction aaa 17 Troubleshooting Guidelines esses 17 OT T LDIESNOONNI ise race a 18 032 TrOUbleSHOOlllig sip natn oeste nisi ia 21 299 T Ubleshootmg sore bann exin do dotes senex css 24 BENCENO rn Er ETE 27 Testing SCRs in the Unit eese 28 Installing an SCR Package sitial ain
30. W DC 4 thermal joint compound or equivalent to the base of the heat sink or bottom of SCR pack age Put in screws and tighten See Chapter 1 page 5 for replacement parts and torque settings Troubleshooting the Base and Control Cards QPAC 01 The QPAC 01 main board provides power and FWZ to detect zero crossover to the control board The control board then outputs a pulse for each half cycle to turn ON the instrument SCRs which in turn fire the power SCRs Two windings of the power transformer provide power for the instrument SCHs See schematic 02 0655 on Page 33 QPAC 32 The master portion of the QPAC 32 operates the same as the QPAC 01 Once SCR 2 fires transformer T2 receives load voltage and T2B then turns on SCR 4 approximately 60 before zero crossing on the L3 phase As soon as L3 goes neg ative SCR 4 is ON The next half cycle SCR 1 is fired and T2C turns on SCR 3 Pin 5 on the Q32 base is connected to Pin 1 All phase angle cards have Pin 5 grounded therefore if a phase angle card is used on a Q32 base it will stay in permanent emergency shut down See schematic 02 0682 on Page 34 QPAC 33 The QPAC 33 is a lot more complicated since it controls all three legs and can be used for zero cross or phase control U6 U3A and USB make up a noise filter and the zero cross detector FWZ This produces a negative going pulse at each zero crossing for phase angle and slightly after zero for zero cross firing U1 and U2
31. al 5 to Terminal 1 then from Terminal 5 to 2 on the control card Voltage must be present at both Terminal 1 and 2 If not place a jumper between these terminals If you are using the interlock feature check the interrupt switch or the interlock The Unit is in Emergency Shut Down ESD For Fan Cooled Units ONLY If the heat sink temperature exceeded 187 F 86 C the on board thermostat will close and the QPAC will enter Emergency Shut Down More than likely a clogged or non operational fan is the cause Check the fan and clean if necessary If the problem still exists check for a shorted heat sink thermostat unclog the fan check for fan power or replace the fan The Control Card is Bad First try to re seat the control card Make sure there is a good connection between the control card and the mother board If there is still a problem replace the control card with another card Also check the troubleshooting section on Page 29 or 30 See Page 5 for ordering a replacement card The QPAC Transformer or Resistor Fuse R10 is Bad Check for AC voltage present at the transformer T1 see Page 33 for transformer wiring Be extremely careful High voltage is present on the transformer connec tions If no voltage is present verify that the resistor fuse is good by measuring across R10 You should be able to visually determine whether or not the fuse is WATLOW QPAC Service Manual Troubleshooting Chapter 5 bad The resistor will
32. amplifier providing both proportional and integral feedback for limiting the current into U2B U2A is a comparator to turn on the LED when in limit See scope picture 12 TP1 top inverted FWZ TP2 ramp TP3 comparator output and the load current waveform measured by a CT scope picture 13 TP4 top ESD TP5 soft start dump and TP6 bottom soft start ramp See schematic 02 0701 on Page 41 QAD Card 08 5314 U4 and U5 make up a phase locked loop PLL which is synchronized to the 50 or 60 Hz line It produces an output 256 times the full wave frequency 120 X 256 30 72KHz for the U5 and 100 x 256 25 6KHz at 50 Hz The input lines DO to D7 are used to set the power level desired When the input lines are programmed to give an output level the address line is low Pin 1 and the strobe line is pulsed low the octal D latch U1 will be updated The output of the latch goes through the prom U2 for inversion and to linearize the output curve the output of the prom is then used to program U3 which counts down from zero cross to whatever power level is set in See Scope Picture 14 TP1 FWZ TP2 ZX180 and TP3 ZX180 Scope 15 TP2 TP3 and TP5 output Picture 3 TP4 MCK high frequen cy clock See schematic 02 0671 on Page 42 WATLOW QPAC Service Manual Troubleshooting Chapter 5 Appendix Figure 16 Scope Picture 1 M Figure 20 2ms div FWZ CA or CD Card U1 3 QBF Card TP1 Figure 17 15ms div 1 top Ramp QBF TP2 2 Comp
33. arator Out QBF TP3 Figure 22 Scope Picture 7 Scope Picture 3 200ms div aars 2 Gating Output TP4 5us div MCK TP 9 QPAC 33 Base QAD Card TP 4 Scope Picture 8 Figure 19 Scope Picture 4 QBV 5ms div 1 FWZ TP1 and TP2 2 Ref Sine Wave TP 2 Scope Picture 9 TO 1 top FWZ TP6 4 T On C U5 8 6 Load On T2 2 T On A U8 12 5 Load On T1 7 Load On T3 3 T On B U8 8 5ms div 1 FWZ TP1 2 Count Clear Delay TP3 Waveforms Appendix WATLOW QPAC Service Manual 31 Appendix Figure 25 Scope Picture 10 f Figure 28 Scope Picture 13 QBV 5ms div 1 FWZ TP1 2 Output Pulses TP4 Scope Picture 11 nnd bad ne E QAF and QAL 2 Second div 1 ESD TP4 2 Soft Start Dump TP5 3 Ramp TP6 Sequence at 50 Output TP1 TP2 TP4 and TP5 Figure 27 Scope Picture 12 2 ZX180 TP2 3 ZX180 TP3 Scope Picture 15 o QAF and QAL 2ms div 1 FWZ TP1 3 Comparator Output TP3 2 Ramp TP2 4 Load Current QAF and QA 2ms div 1 2X180 TP2 3 Output Pulse 2 ZX180 TP3 4 Load Current TP5 32 WATLOW QPAC Service Manual Waveforms Appendix Appendix Schematic 02 0655 QPAC 01 Mother Board NOTES 1 oc 0 All resistors are 1 4 W 5 unless otherwise speci fied All capacitors are valued in microfarads unless noted Last Used R 10 C 6 U 2 Ref PCB Bare 35 0179 Ref Assy PCB 08 5287 Fuse 2 F2 used on sin g
34. caution must be used as high voltage is present when power is applied On power bases of 100 amps or less the heat sinks should be at ground potential Units above 100 amps are electrically hot Before troubleshooting make sure you have isolated the problem to the QPAC Make sure all connectors and load terminations are tight and the control card is seated properly Next verify that there is AC power present at L1 and L2 For three phase units check at L3 by measuring phase to phase Phase to ground is meaningless on ungrounded three phase loads Verify that there is a good com mand signal i e 4 20mA from the temperature control and that the temperature control is operating properly Troubleshooting the QPAC can be narrowed down to three distinct problems Unit has no heat Unit has partial heat Full or partial uncontrollable heat Once you have determined the category that best describes your situation read through the appropriate section on the following pages Follow the procedure which applies to you Troubleshooting Chapter 5 WATLOW QPAC Service Manual 17 Problem No Heat Blown Fuse This can be done one of two ways Measure voltage across the fuse If there is voltage present the fuse is bad You can also check the fuse for continuity using an ohmmeter Replace the fuse if necessary Prior to changing fuses check the heaters and wiring for a possible short or loose connections Open Heater Check all the connection
35. e it controls all three leg s and can be used for zero cross or phase control U6 U3A and U3B make up a noise filter and the zero cross detector FWZ This produces a negative pulse at each zero crossing for phase angle and slightly after zero for zero cross firing U1 and U2 make up a phase locked loop PLL which runs at 256 times the full wave frequency 30 72KH at 60 Hz or 25 6KH at 50Hz This divides each half cycle Operation Theory Chapter 3 WATLOW QPAC Service Manual 11 Q33 Block into 256 parts When the control card sends out a pulse U7A picks the correct half cycle and sends the pulse to U3D which starts counter 41 U9 and counts to 1 for a short delay When U1 counts down it sends a pulse to the output board to fire SCR 1 and resets U3C and sets U4A See schematic 02 0798 on Page 35 This starts counter 2 U10 which counts to 85 to give a 2 77ms delay It sends an output pulse to fire SCR 2 resets U4B sets U4D and starts counter 3 Counter 3 U11 counts to 85 sends an output pulse to fire SCR 3 U11 counts to 85 sends an output pulse to fire SCR 3 and resets U4C to finish the cycle U12 is used to detect the loss of L2 phase phase loss and U13 is used to detect the proper phase rotation U7B U7C and U7D combine phase loss phase rota tion PLL and the thermostat for emergency shut down ESD Figure 8 Q33 Block Diagram and Typical Load Circuit Phase AC Li
36. e scope common to test point COM on the mother board next to the control card plug 7 Connect the Channel A probe to Test Point 1 TP1 located on the upper right corner of the mother board The card is unplugged 8 Connect the Channel B probe to Test Point 6 TP6 FWZ 9 Turn power ON 10 Adjust potentiometer P1 until the FWZ notch Channel B is centered on the sine wave Channel A Refer to the scope picture below em 2V Div Figure 15 Q33 Scope Output A AS A A om on on on mo3 Ros FOROR 3 5 c 9 5 Roo roro mon so ro ot mos n os o on won s os qs rou oo on mon om on oron on on oho od o4 9 a 9 on o3 39 A 4 9 9 4 NBo x a amp NA X 34 9 4 4 v 4 o3 o aoa 5V Div TOR Roa os Ro 8 38 9 82 8 i E s moa mos on son ius os son on o 4 a 9 o noa on oas ho o omo o9 OA OP c ox amp a X 4 P X 9 VW amp 4 9 5 v OXOB 4 VF Yo PON o4 E o3 n 2ms Div Test Procedures Chapter 4 WATLOW QPAC Service Manual 15 These adjustments are necessary for the following control cards QBF Bias and Gain adjustments QBV Gain adjustment QAL Bias Gain and Current Limit adjustments M NOTE QAF Bias and Gain adjustments Any adjustments or troubleshooting of this unitshould b Bias and or Gain Adjustments done by a qualified technician The bias and gain are factory set for a command signal of 4 20mA However if minor or major adjustments are req
37. ent is flow ing there is a bad connection or heater Repair or replace Open Limit or Safety Contactor Within the Thermal System The overtemperature limit contactor may have tripped Check the limit or safety contactor Locate the cause for the limit tripping correct and reset Command Signal Polarity is Backwards Verify that the mA or VDC control signal from the temperature control is wired cor rectly Make sure Terminal 5 is and Terminal 4 is on the control card The SCR Switch Will Not Turn ON With the command signal full ON check the VAC voltage across the L1 and T1 ter minals and the L3 and T3 terminals They should read approximately 1 5VAC If you are reading the line voltage potential the SCR is not gating on The mother board or control card may be bad Try another control card or contact the factory The Interlock Connection on the QPAC Control Card is Open Measure voltage from Terminal 5 to Terminal 1 then from Terminal 5 to 2 on the control card Voltage must be present at both Terminal 1 and 2 If not place a jumper between these terminals If you are using the interlock feature check the interrupt switch or the interlock The Unit is in Emergency Shut Down ESD For Fan Cooled Units ONLY If the heat sink temperature exceeded 187 F 86 C the on board thermostat will close and the QPAC will enter Emergency Shut Down More than likely a clogged or non operational fan is the cause Check the fan and clean
38. gnal from the temperature control is abruptly increased a short overcurrent through the load may occur as the QAL card circuitry detects the higher current 1 Attach a clamp on ammeter to the load line 2 Adjust the QAL card current limit potentiometer fully counterclockwise for mini P D o mum current flow Turn the temperature control ON and adjust the input signal to the control card for 096 power Turn the power to the QPAC ON Gradually increase the input signal Adjust the current limit potentiometer clockwise until current to the load is mea surable Gradually increase the input signal to 10096 power then adjust the current limit potentiometer to obtain the desired maximum current to the load 16 WATLOW QPAC Service Manual Test Procedures Chapter 4 Procedures Chapter 5 Troubleshooting Indications of Malfunction No output under any circumstances Full ON output at all times and the load is uncontrollable Output is not proportional to the command signal unbalanced output Operating erratic and inconsistent Half output One or more LEDs not lit on the Q33 base pru ss ae Troubleshooting Guidelines Troubleshooting the QPAC should be limited to changing fuses transformers SCRs and printed circuit boards Any other troubleshooting should be done on a test bench and by a qualified electronic technician capable of working on high voltage j WARNING When working on a power control
39. he output drivers and power resis tors to form the artificial neutral See schematic 02 0798 on Page 35 QCD and CA Cards 08 5286 and 08 5285 FWZ at Pin 3 is shaped by Q1 to form a window around the zero cross point See ocope Picture 5 This is summed with the command signal by U1A and with the ESD line by U1B to provide a high output at Pin 11 if the input signal is high the ESD signal is high and it is at zero cross The CA card accepts an AC signal and U2 gives a high for each half cycle See schematic 02 0672 QCD and 02 0673 QCA on Page 36 37 QBF Card 08 5289 Q1 and U2B make up the zero cross notch providing that the ESD signal is high Q2 and Q3 make up a linear ramp with a 4 second time base and approximately 2 volts high U1C is the input amplifier with the Bias and Gain amplifiers and U1D is used as a comparator to give a high output any time the ramp exceeds the input signal U2A adds the output of the comparator and the FWZ signal to give output pulses only during the zero cross notch See scope picture 5 TP1 FWZ scope picture 6 TP2 amp 3 ramp top and comparator output bottom scope picture 7 TP2 amp 4 ramp top and output pulses bottom See schematic 02 0657 on Page 38 QBV Card 08 5342 U2A is used to make up the FWZ signal U1A is a flip flop clocked by the FWZ to provide a square wave of one full cycle duration U2B provides a delayed pulse slightly after the end of each full cycle The input signal g
40. heck the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater Troubleshooting Chapter 5 WATLOW QPAC Service Manual 23 Problem No Heat Blown Fuse This can be done one of two ways Measure voltage across the fuse If there is voltage present the fuse is bad You can also check the fuse for continuity using an ohmmeter Replace the fuse if necessary Open Heater Check all the connections from the circuit breaker to the heaters Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control Check the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater Bad Connection Check all the connections from the circuit breaker to the heaters Measure the cur rent and output voltage from the heater If voltage is present and no current is flow ing there is a bad connection or heater Repair or replace Open Limit or Safety Contactor Within the Thermal System The overtemperature limit contactor may have tripped Check the limit or safety contactor Locate the cause for the limit tripping correct and reset Command Signal Polarity is Backwards Verify that the 4 20mA control signal from the temperature control is wired correct ly Make sure Terminal 5 is and Terminal 4 is
41. ia 28 Troubleshooting the Base and Control Cards 28 Waveforms and Schematics oooocccncccnccnnncnnncnononnnonnnononenennnnnnos 31 WATLOW QPAC Service Manual 3 Overview Figure 1 The QPAC 01 SCR Power Control Chapter 1 QPAC Modular SCR Power Control Hr r ar wu ow 1 g E E A a l 4 F Vm a M FE il e ie iP eH T B F PERA ui drer piihi fetes l General Description The QPAC Power Controls are a family of solid state controls used for electric heating applications A solid state power control provides output power that is pro portional to the input command signal from a temperature control This proportion al output power helps to produce a closely controlled heater temperature which saves energy and prolongs heater life by holding heater elements at a nearly con stant temperature The QPAC has a modular construction with plug in features for flexibility The three modules of the QPAC are the power base transformer and control card See Figure 2 Power bases are available in 30 to 300 ratings in single phase three phase two leg and three phase three leg configurations A transformer plugged into the power base allows the QPAC to operate on any voltage from 120 to 480VAC The plug in control card sets the QPACs firing mode Control cards are available in solid
42. le phase 30 amp 50 amp units Fuse mounted by cus tomer on single phase 75 and 100 amp units Schematics Appendix por Bi J La y l l Le UY T1 Q l T Y A E E J 4 2W 10 0047 Ui OPTO I I 19 5054 2 I I 1 U2 OPTO 19 5054 I I PART OF J1 oc m ooo ooo SCR 1 J4 2 gt 12v SECONDARY J4 1 J4 6 12V SECONDARY Je 1 12V SECONDARY J2 2 J2 2 12V SECONDARY LU J2 3 ENUBBER i 10 9102 pa CK i 1 Qo T STAT ZAN a gt SNL APR MFO 46 0200 120V 12 12 12 12V GENERAL ANALOG lo y 46 0204 240V 12 142712 12V GENERAL ANALOG 16 0200 277 V 12 12712 12V GENERAL ANALOG 46 0203 480 12 12 1i2 12V GENERAL ANALOG 32 FWZ l i O ii i I i su 5 I COM i D7 i COM Es KEY i 1 COM C3 1uf 100V D10 I W 5 Ri 10 1 2 42 4069 n3 39k 10 0100 LED R2 82 2W 5 l 1M i gt LED peace Ui OPTO JE am 19 4094 10 9112 e I RITO C f 100V RS 10 1 2w C4 1u em 10 0100 10 9393 pum R6 82 2W i i rg a U2 OPTO R8 s 19 5054 EU jm j 2 N OF Ji 2 rEELi Ai 31 19 5038 EI Oo VI g VO O gt C l N 2 1 D1 A Zu A E TI T l l 12 1144 l NY e Q gt l l
43. lockage or excess heat in the enclosure Agency Approval UL recognition to 300 Amps UL873 File E43684 Listed under UL508 File E73741 Mounting Orientation Heat sink fins must be vertical Operating Environment e 32 F to 122 F 0 C to 50 C e 0 to 90 RH non condensing Weight lbs kg Phase 30 2 leg Q32 30 3 wire Q33 8 3 6 Options e Manual Control Kit 1KQ potentiometer 408 5362 e 240VAC fans in place of 120VAC fans 600VAC operation consult factory Specifications Overview Chapter 1 WATLOW QPAC Service Manual 7 Procedures Chapter 2 Preventive Maintenance Cleaning Cooling Fans Fins and Filter Cooling a power control is critical to its reliable operation Your unit should be inspected and cleaned every six months more frequently in dirty environments To achieve this follow this simple procedure 1 Remove power from the control There may be more than one disconnect since the fan power is separate from the main power 2 Inspect and clean the cooling fans and heat sink fins In most cases an air hose is sufficient to remove lint or dirt which may block air flow 3 Once again inspect and clean any fans and or filters which may bring air into or out of the enclosure If the filters are not cleanable replace them Tightening Connections Loose arcing connections can and will destroy SCRs Stranded wire has a ten dency to cold flow when clamped in a screw down co
44. make up a phase locked loop PLL which runs at 256 times the full wave fre quency 30 72KH at 60 Hz or 25 6KH at 50 Hz This divides each half cycle into 256 parts When the control card sends out a pulse U7A picks the correct half cycle and sends the pulse to U3D which starts counter 1 U9 and counts to one for a short delay When U1 counts down it sends a pulse to the output board to fire SCR 1 and resets USC and sets U4A This starts counter 72 U10 which counts to 85 to give a 2 77 millisecond delay and sends an output pulse to fire SCR 2 resets U4B sets U4D and starts counter Z3 Counter 3 U11 counts to 85 sends an output pulse to fire SCR 8 and resets U4C to finish the cycle 28 WATLOW QPAC Service Manual Troubleshooting Chapter 5 U12 is used to detect the loss of L2 phase phase loss and U13 is used to detect the proper phase rotation U7B U7C and U7D combined phase loss phase rota tion PLL and the thermostat for ESD Scope picture 2 shows the AC input L1 to L3 at TP1 and TP6 FWZ after zero cross calibration Scope picture 3 is the high frequency clock TP9 MCK Scope picture 4 shows the sequence of operation at approximately 5096 power From top to bottom FWZ zero cross reference Timing output A phase U8 Pin 12 Timing output B phase U8 Pin 8 Timing output C phase U5 Pin 8 Load Current T1 Load current T2 Load current T3 DI Vr GIN The output board contains the SCR protection t
45. mpression connector After installation and every six months 1 Remove power from the control 2 Inspect and tighten all connections from the circuit breaker to the heaters Periodic Test Runs If the system has been idle for a period of time it is necessary to perform regular maintenance and periodically test the equipment If the system has been idle for a period of time follow this procedure before further use 1 Make sure the power is turned OFF 2 Check for moisture dirt or foreign materials in the enclosure 3 Check all connections making sure they are tight Certain heater types take on moisture when not in use 1 Disconnect the heaters from the power control 2 Test the heaters for resistance to ground using a high pot tester or a megger Check with the heater manufacturer for the resistance or proper high pot tester It may be necessary to dry the heater out before running it with the QPAC To test the system 1 When calling for full heat measure the output voltage and current for each phase 2 Make sure the system removes all current from the load when the temperature control is not calling for heat Voltage may still be measured from phase to ground 3 Check any safety or limit controls in the system 8 WATLOW QPAC Service Manual Maintenance Chapter 2 Chapter 3 Operation Theory of Base and Firing Cards Single Phase Model Q01 LEM ODM HDI WoD WOO N9ISUO NOLSNJI 037 037
46. oes into Q2 emitter fol lower which produces a collector current proportional to the voltage across the emitter resistor Q1 is used as a zener to linearize the output Q3 is an emitter fol lower used to discharge C5 every other half cycle Q5 prevents C5 from being dis charged when ON Once C5 voltage reaches the program point of Q4 R14 R16 it charges C5 through R19 and sets U1B Since C5 can only reach its peak when Q5 is OFF TP2 low U1B will always stay on for one full cycle With U1B output high U2D will allow two output pulses insuring one full cycle output minimum If ESD is low U2D is inhibited from allowing FWZ pulses See Scope Picture 8 for TP1 amp TP2 FWZ top and TP2 bottom Scope Picture 9 for TP1 FWZ top and count clear bottom Scope Picture 10 for TP1 amp TP4 FWZ top and output on the bottom Scope Picture 11 for TP1 2 4 5 showing FWZ SQ wave output and the stair case waveform on C5 See schematic 02 0729 on Page 39 Troubleshooting Chapter 5 WATLOW QPAC Service Manual 29 QAF Card 08 5288 Q1 makes up the FWZ signal which is inverted by U3A to give a high signal for all of the half cycle but the zero cross notch USB CR1 R19 and C5 detect missing half cycles which then pulls C7 low with CR2 When C7 is low the AF card is in ESD Q4 and Q3 make a linear ramp which is reset at the end of each half cycle by the output of UBA U1C accepts the input signal and performs the bias and gain function U1B adds the
47. roubleshooting Chapter 5 Bench Testing Bench Testing Hookups Equipment Required Dummy Load min 1A 0 15VDC Command signal QPAC 01 Single Phase Command Signa 4 20mA or 0 5VDC Control Card lt QPAC 32 Es 3 Phase Load Command Signa 4 20mA or AC 0 5VDC Control Card ZN QPAC 33 3 Phase Load Command Signa 4 20mA or 0 5VDC AC Control Card Troubleshooting Chapter 5 X NOTE Dummy loads can be made up using 100 watt light bulbs Bulbs can be put in series to obtain the proper voltage rat ing Aeach 100 watt 120V bulbs per phase for 480V An SCR will not latch without a load WATLOW QPAC Service Manual 27 Testing SCRs in the Unit A shorted SCR will show full uncontrollable line voltage at the T terminals To test turn main power OFF remove the L and T wires On a QPAC 01 measure resis tance from L1 to T1 On a QPAC 32 measure resistance between L1 to T1 and L3 to T3 On a QPAC 33 measure resistance between L1 to T1 L2 to T2 and L3 to T3 A reading of 5 ohms resistance or less indicates that the SCR is shorted A high resistance reading indicates that the SCR is good On a Q33 unit a low reading will occur in one direction and a high reading in the other direction This is normal Installing an SCR Package After removing the old SCR package thoroughly clean the heat sink and the base of the new SCR package to be installed Add a thin coat of DO
48. s from the circuit breaker to the heaters Measure the heater current Next measure the voltage across the heater If voltage is present and no current is flowing there is a bad connection or heater Disconnect the heater from the power control Check the resistance of each element The resis tance should correspond with the heater KW rating If not replace the heater Bad Connection Check all the connections from the circuit breaker to the heaters Measure the cur rent and output voltage from the heater If voltage is present and no current is flow ing there is a bad connection or heater Repair or replace Open Limit or Safety Contactor Within the Thermal System The overtemperature limit contactor may have tripped Check the limit or safety contactor Locate the cause for the limit tripping correct and reset Command Signal Polarity is Backwards Verify that the mA or VDC signal from the temperature control is wired correctly Make sure Terminal 5 is and Terminal 4 is on the control card The SCR Switch Will Not Turn ON With the command signal full ON 20mA for a 4 20mA signal check the VAC volt age drop across the L1 and T1 terminals They should read approximately 1 5VAC If you are reading the line voltage potential the SCR is not turning on The mother board or control card may be bad Try another control card or contact the factory The Interlock Connection on the QPAC Control Card is Open Measure voltage from Termin
49. s you to a CAUTION a safety or functional hazard which could affect your equipment or its performance A full explanation is in the narrow column on the outside of the page The Warning symbol lightning bolt in the wide text column alerts you to a WARNING a safety hazard which could affect you and the equipment A full explanation is in the narrow column on the outside of the page Technical Assistance If you encounter a problem with your Watlow control review all of your configuration infor mation to verify that your selections are consistent with your application Inputs Outputs Alarms Limits etc If the problem persists after checking the above you can get technical assistance by dialing 1 507 454 5300 An Applications Engineer will discuss your problem with you Please have the following information available when calling Complete model number e Bar Code Number All configuration information User s Manual Your Feedback Your comments or suggestions on this manual are welcome please send them to Technical Writer Watlow Controls 1241 Bundy Blvd Box 5580 Winona MN 55987 5580 Phone 507 454 5300 Fax 507 452 4507 The QPAC Service Manual is copyrighted by Watlow Winona Inc 1994 with all rights reserved blr 0693 Contents Table of Contents Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Appendix Contents QPAC Modular SCR Power Control Page General Des cnplion sai 4 O
50. soft start from C9 R40 and U1D adds the line voltage compensation The output of U1D is then compared to the ramp by U1A to output a square wave from U2B providing ESD is high and it is during the high output period of U3A See Scope picture 12 TP1 top inverted FWZ TP2 ramp TP3 comparator output and the load current waveform measured by a CT scope pic ture 13 TP4 top ESD TP5 soft start dump and Tp6 bottom soft start ramp See schematic 02 0656 on Page 40 QAL Card 08 5411 Q4 makes up the FWZ signal which is inverted by U3A to give a high signal for all of the half cycle but the zero cross notch U3B CR5 R33 and C12 detect miss ing half cycles which then pulls C13 low with CR2 When C13 is low the AF card is in ESD Q4 and Q3 make a linear ramp which is reset at the end of each half cycle by the output of USA U1A accepts the input signal and performs the bias and gain function U1B adds the soft start from C4 R15 and U2B adds the signal from the current limit circuit U2C adds the line voltage compensation the output of U2C is then compared to the ramp by U2D to output a square wave from UAC providing ESD is high and it is during the high output period of U3A A current transformer is used to monitor the output of the power control and provides an AC signal to TB3 Its input is then converted to a DC signal by U5 which provides a DC output equivalent to the true RMS value at the CT U1D provides a gain of 4 and U2C is a two mode
51. state contactor burst firing zero cross or phase angle modes with a wide variety of input options This modular approach using a stan dard power base with plug in transformers and control cards allows power control users distributors and OEMs to maintain minimum inventories while still providing rapid service 4 WATLOW QPAC Service Manual Overview Chapter 1 Overview SCHs Part Numbers Plug in transformers 50 60 Hz Unit QPAC 01 amp Part Number Rating Q PAC 32 Q PAC 33 120VAC 16 0200 30A 18 4013 1 18 5179 1 208 240VAC 16 0201 50A 18 4013 1 18 5179 1 gt 277 16 0202 e 75A 18 4013 1 18 5179 1 380VAC 16 0208 e 100A 18 4015 1 18 5179 1 e 415VAC 16 0207 e 150A 18 5052 2 NOTE 3 e 480VAC 16 0203 200A 18 5052 2 NOTE 3 M 600VAC 16 0209 e 300A 18 5052 2 NOTE 3 PU Y consult factory 1 SCR Type Module Torque 40 LB 2 SCR Type 3 4 Stud Torque 280 300 LB 3 SCR 18 5052 Diode 18 1044 Power Bases Control Cards Part Number with Motherboards e Solid state contactor AC input QCA 08 5285 e QPAC 01 Solid state contactor DC input QCD 08 5286 14 30 to 300A Burst firing zero cross fixed time base QBF 08 5289 QPAC 32 Burst firing zero cross variable time base QBV 08 5342 Figure 2 f 3 2 leg 30 to 300A Phase angle control QAF 08 5288 ORRE Modularity e QPAC 33 e Phase angle control with current limiting QAL 08 54
52. t board 08 7210 containing bias and gain pots allow the card to be adjusted for any voltage from 0 3VDC to 0 15VDC or current between 0 and 25mA The card output is removed if the emergency shut down signal is low CA Contactor with an AC Input Signal 08 5285 The CA control card operates the same as the CD card except it requires a 120VAC input command signal The CA can be special ordered for 24VAC or 240VAC if required The QPAC can be kept OFF if the emergency shut down signal is held low CD Contactor with a DC Input Signal 08 5286 The CD control card operates the QPAC power control as a zero cross solid state contactor A 3 30VDC input signal is required to switch ON the QPAC and a 0 1VDC is required to switch it OFF The QPAC can be kept OFF if the emergency shut down signal is held low Operation Theory Chapter 3 Procedures Chapter 4 Test Procedures Q01 and Q32 No power base adjustments are required on the Q01 and Q32 models See the bias and gain control card procedures Q33 Zero Cross Adjustment Follow this step by step procedure to test the Q33 zero cross adjustment Equipment Needed Dual trace oscilloscope Procedure 1 Set Channel A on the scope to 5 volts per division 2 Set Channel B to 2 volts per division 3 Center both channels vertically 4 Place the zero cross jumper in the phase angle position See Page 11 for the board layout Unplug the control card 6 Connect th
53. try to re seat the control card Make sure there is a good connection between the control card and the mother board Power down the control and remove the control card Power up without the control card installed If there is no heat the control card is bad Replace the control card See Page 5 for ordering An Excessive Input Signal from the Temperature Control Check the input signal for proper calibration i e 4 20mA at 4mA The output should be full OFF At 20mA the output should be full ON The QPAC Mother Board is Bad Refer to the mother board troubleshooting procedure on Page 28 Troubleshooting Chapter 5 WATLOW QPAC Service Manual 19 Problem Partial Heat This problem can be broken down into two categories Uncontrollable Heat One of Two SCRs has Shorted Half Waving is Continuous This condition exists when one of two SCRs is shorted allowing half of the AC sinewave to pass through the heater uncontrolled See Page 19 to test for shorted or open SCRs The Bias Adjustment is Too High Recalibrate the bias and gain adjustments by following the procedure on Page 16 Insufficient Heat One of Two SCRs Won t Turn ON Half Waving This is most likely a problem with the mother board A gate signal may be missing Refer to the mother board troubleshooting procedure on Page 28 The Gain Adjustment is Too Low Hecalibrate the bias and gain adjustments by following the procedure on Page 16 There is an Insufficient Control Signal
54. uired follow this adjustment procedure 1 Set the temperature control for zero output 4mA or OVDC by adjusting the set point below the ambient temperature or put the control in manual mode at 0 power a If there is an output turn the bias potentiometer clockwise until the output just disappears b If there is no output turn the bias potentiometer counterclockwise until the output is noted then turn it back to until it is just OFF Set the temperature control for full output 20mA or 5VDO by turning the set point above the ambient temperature or put the control in manual mode at 10096 power a If the output of the SCR is full ON turn the gain potentiometer counter clockwise until a drop in the output is noted Next turn the pot back to until the output is just full ON b If there is no SCR output or the output is not full ON turn the gain potentiometer pot clockwise until the output is just full ON 3 Repeat Steps 1 and 2 until no further adjustments are necessary Current Limit Adjustments The QAL control card is a phase angle control with the capability to limit the maxi mum current to the load A potentiometer on the QAL card adjusts the current limit setting Use the following procedure to adjust the current limit on initial setup The purpose of the procedure is to bring the load power up slowly so the maximum cur rent to the load is not exceeded before the current limit is adjusted 3 Note If the input si
55. usually be black or dark brown if open It should read a mini mal voltage of 1V If it reads line voltage R10 is bad See Page 5 for ordering a replacement transformer The QPAC Mother Board is Bad Check the DC voltages at the J1 connector Place the voltmeter common on pin 7 or 8 They should read as follows Test Point Card Installed T STAT 3 to 5V V 15 to 22VDC FWZ 11 to 14VDC 11 to 14VDC V 15 to 18VDC 15 to 18VDC Q32 connected to Pin 1 Q01 or Q33 Not Used Not Used 5V 5V 0 1V 5V 0 1V COM COM meter common KEY COM LED Not Used Pulses possible COM See scope pictures on Page 31 Problem Full or Partial Uncontrollable Heat The SCR Switch is Shorted Remove the control card and power up the QPAC The output should be OFF If the unit is still full ON remove power and disconnect the load wires and measure across L1 and T1 with an ohmmeter If resistance is low 5Q or less the SCR is shorted and must be replaced See Page 5 for ordering a replacement SCR A Heater is Partially Shorted or Shorted to Earth Ground Disconnect the control card the output should be OFF If not disconnect the power and heater and measure the heater resistance It should match the heater KW rating The Control Card has the Wrong Bias Adjustment The bias adjustment is set too high and needs to be readjusted See the Bias and Gain Adjustment procedure with the appropriate control card on Page16 The Control Card is Bad First

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