HP 6236A, Operating And Service Manual

Page 1: ...HP Archive This vintage Hewlett Packard document was preserved and distributed by www hparchive com Please visit us on the web Scanned by on line curator Tony Gerbic For FREE Distribution Only ...

Page 2: ...ODELS 6236A AND 6237A OPERATING AND SERVICE MANUAL FOR MODEL 6236A SERIALS 1507A 00141 AND ABOVE MODEL 6237A SERIALS 1507A 00101 AND ABOVE For Serials above 1507A 00141 or 1507A 00101 a change page may be included Hewlett Packard Printed February 1975 ...

Page 3: ...ng power to the supply make cer tain that its line voltage selector switch S3 is set for the line voltage to be used See CA UTION notice in Paragraph 3 2 for additional information on S3 1 5 All controls meters and output terminals are loca ted on the front panel Two single turn potentiometers con trol the 6V or 18V and 20V outputs A three position meter switch selects one of the supplies for disp...

Page 4: ...NPUT POWER Standard Option 104 127Vac 120Vac nominal 47 63Hz single phase 112W 140VA Other line voltage options are listed in Paragraph 1 11 DC OUTPUT AND OVERLOAD PROTECTION oto 20V Outputs Maximum rated output current is 0 5A Short circuit output current is 0 55A 5 and a fixed current limit circuit limits the output of each sup ply to this maximum at any output voltage setting Unbal anced loads ...

Page 5: ... for the user s information only and are not warranteed specifi cations RESOLUTION Minimum output voltage change obtainable using front panel voltage control oto 20V Outputs 70m V Model 6236A oto 6V Output 20mV Model 6237A oto 18V Output 70mV 1 3 TEMPERATURE RANGES Operating 0 to 40 C ambient At higher temperatures output current is derated linearly to 50 at 55 C Storage 40 C to 75 C METER RANGES ...

Page 6: ...ecked against its elec trical specifications Section V includes an in cabinet per formance check to verify proper instrument operation 2 7 INSTALLATION DATA 2 8 The instrument is shipped ready for bench opera tion Before applying power to the instrument see the CAUTION notice in Paragraph 3 2 2 9 Location 2 11 Outline Diagram 2 12 Figure 2 1 illustrates the outline shape and dimen sions of this su...

Page 7: ...ption other than the one marked on its identifying label without being relabeled in some way check the setting of the line voltage selector switch and the fuse rating before applying power See CAUTION in Paragraph 3 2 2 23 To insure safe 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 availab...

Page 8: ... ed when the instrument is received and before it is connect ed to any load equipment Proceed to the more detailed procedures beginning in Paragraph 5 6 if any difficulties are encountered CAUTION e Set the 20V VOLTAGE control for a 20 volt meter indication and short the 20V output terminal to the com mon terminal with an insulated test lead The ammeter should indicate a short circuit output curre...

Page 9: ...rent limit is factory adjusted to operate at 2 75A 5 when the 3 2 output is 6 volts At lower output voltages the circuit reduces the maximum obtainable output current linearly until 1A 15 flows vvhen the output is shorted The short circuit current cannot be adjusted but R46 can be set to limit the maximum current at 6V to 2 75A 5 See Para graph 5 47 for current limit calibration instructions 3 11 ...

Page 10: ...age source while the supply set to the higher output will act as a current limited source dropping its out put voltage until it equals that of the other supply The constant voltage source will deliver only that fraction of its total rated output current which is necessary to fulfill the total current demand 3 19 Special Operating Considerations high current output pulse may damage load components ...

Page 11: ...a heavy line in Figure 3 3 If the operating point reaches the diagonal current limit line a decrease in load resistance moves the operating point 4 1 down the line reducing the output voltage and current Current foldback is controlled by a second operational amplifier in the regulator which monitors the dc output current This current comparison amplifier takes control of the output away from the v...

Page 12: ...ding 0 55 amps When the overload is removed the output of the current comparison amplifier goes negative reverse biasing CR5 and returning control to the voltage 4 2 comparison amplifier 4 20 Turn On Turn Off Control When the power supply is turned on or off Q15 in the turn on control circuit with holds turn on bias from Q1 while the regulator bias voltages are too low This prevents an output volt...

Page 13: ...ch 672mV Once E R48 reaches this value the current com parison amplifier controls the series regulator transistor so as to prevent ER48 and thus the supply s output current from increasing further At 0 25 ohms R48 develops 672mV at 2 69 amps Since 0 22 amps of the current through R48 is bias current for Q7 the nominal current limit corresponding to a 5 volt output is 2 69 amps minus 0 22 amps or a...

Page 14: ...ator transistors 01 03 and 07 and holds 4 4 the 6 2V reference at a low value This prevents an out put voltage transient by ensuring that the operational am plifiers are energized and other essential bias voltages are present before the series regulator transistors are turned on The circuit also prevents an output transient when the sup ply is turned off by removing the turn on bias from the se ri...

Page 15: ...he instrument after repairs If the correct result is not obtained for a particular check proceed to the troubleshooting procedures of Para graph 5 32 CAUTION Before applying power to the supply make certain that its line voltage selector switch S3 is set for the line voltage to be used See CA UTION notice in Paragraph 3 2 for addi tional information on S3 Table 5 1 Test Equipment Required REQUIRED...

Page 16: ...t current measurements a current sampling resistor should be inserted between the load resistor and the output of the supply An accurate voltmeter is then placed across the sampling resistor and the output current calculated by 5 2 dividing the voltage across the sampling resistor by its ohmic value The total resistance of the series combination should be equal to the full load resistance as deter...

Page 17: ...ing each supply the other two must be fully loaded Current Limit k Disconnect all loads from the supply I Connect the test setup shown in Figure 5 3 to the 20 volt output Substitute a short for RL and leave the load circuit switch open m Set the voltage of the t20V supplies to 20 volts n Close the load switch and determine the current flow through the current sampling resistor meter shunt by measu...

Page 18: ...ASE OSCILLOSCOPE CASE AC AC ACC ACC GND GND VERTICAL G G INPUT B A CORRECT METHOD USING A SINGLE ENDED SCOPE OUTPUT FLOATED TO BREAK GROUND CURRENT LOOP TWISTED PAIR REDUCES STRAY PICKUP ON SCOPE LEADS 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 SUPP...

Page 19: ... of the oscilloscope to ensure that the supply output is safely grounded When using shielded two wire it is essential for the shield to be connected to ground at one end only to prevent ground current flowing through this shield from inducing a signal in the shielded leads 5 27 In most cases the single ended scope method of Figure 5 4B will be adequate to eliminate non real compon ents of ripple s...

Page 20: ...g the covers from the instrument by using the appropriate portions of the performance test of Paragraph 5 6 5 34 A good understanding of the principles of opera tion is a helpful aid in troubleshooting and the reader is advised to review Section IV of the manual before begin ning detailed troubleshooting Once the principles of oper ation are understood proceed to the initial troubleshoot ing proce...

Page 21: ...ncy ranges c Oscillation only in the current limiting mode can be caused by an open C3 C13 or C23 Transient voltage overshoot a Overshoot only in the 20V supply can be caused by a at turn on or turn off shorted 013 b Overshoot in all three supply outputs can be caused by an open 014 or a shorted 015 Table 5 3 Initial Troubleshooting Procedure STEP ACTION RESPONSE NEXT ACTION 1 Check output voltage...

Page 22: ...al a Proceed to step 2 common 7 5V 5 b Voltage high b Check VR3 for open c Voltage low c Check VR3 for short Note A short within U1 U2 U3 or U4 can cause low 7 5V or 12 4V bias voltages 2 Check 6 2V reference a Normal a Proceed to step 3 TP2 to common 6 2V 5 b Voltage high b Check V R1 for open c Voltage low c Check VR1 and Q14 for short VR2 and Q15 for open A short within U4 could reduce this vol...

Page 23: ...t TP8 is positive check Z1 for open between pins 5 and 13 check R8 for open and check for defective R6 or U1 b If TP8 is approx 0 7V proceed to step 3 a If TP7 is approx 0 7V check CR6 for short b If TP7 is approx 1 4V proceed to step 4 a If TP13 is approx 0 7V replace U1 b If TP13 is zero volts check for open R10 and shorted CR2 or CR3 c If TP13 is approx 0 7V check for open R2 shorted R1 or leak...

Page 24: ...p 4 4 Measure voltage at TP14 a If TP14 is approx 0 7V replace U2 b If TP14 is zero volts check for shorted CR22 or CR23 c If TP14 is approx 0 7V check 1 for open between pins 6 and 12 or short between pins 7 and 12 and check for leaky or shorted C12 Table 5 7 6V or 18V Supply Troubleshooting SYMPTOM STEP ACTION RESPONSE PROBABLE CAUSE High output voltage 1 Attempt to turn down loop a If output vo...

Page 25: ...t if these are available If neither of these are immediately available and a part is needed without delay for operation or troubleshooting verification the parts listed in the Alternate column can be tried with a high probability of success 5 45 Notice that both the commercial and alternate re placements listed in Table 5 8 apply only to the HP power supplies covered by this manual and their use i...

Page 26: ...oth 20 volt ranges their accuracy will be the same Adjust R58 so that the percentage error in the 6V range or 18V range is equal to the error in the 20 volt ranges Turn R58 clockwise to increase the indications or counter clockwise to decrease them If R58 cannot calibrate all voltmeter ranges to within the 4 specification check the values of the resistors in the voltmeter circuit 5 53 Panel Ammete...

Page 27: ...ble throw pot potentiometer DPST double pole POp peak to peak single throw ppm parts per million elect electrolytic pvr peak reverse encap encapsulated voltage F farad rect rectifier OF degree Farenheit rms root mean square f d fixed Si silicon Ge germanium SPDT single pole H Henry double throw Hz Hertz SPST single pole IC integrated circuit single throw ID inside diameter SS small signal incnd in...

Page 28: ...Components h c Phoenix Arizona Robinson N ugent Inc New Albany N Y Torrington Mfg Co Van Nuys Calif 07137 07138 07263 07387 07397 07716 07910 07933 08484 08530 08717 08730 08806 08863 08919 09021 09182 09213 09214 09353 09922 11115 11236 11237 11502 11711 12136 12615 12617 12697 13103 14493 14655 14936 15801 16299 Transistor Electronics Corp Minneapolis Minn Westinghouse Electric Corp Elmira N Y F...

Page 29: ...1637 63743 73506 73559 73734 74193 74545 74868 71700 74970 71707 71744 71590 Delco Radio Div of General Motors Corp Kokomo Ind Atlantic Semiconductors Inc Asbury Park N J Fairchild Camera and Instrument Corp Mountain View Calif Daven Div Thomas A Edison Industries McGraw Edison Co Orange N J Signetics Corp Sunnyvale Calif Bendix Corp The Navigation and Control Div Teterboro N J Electra Midland Cor...

Page 30: ...Chicago III 82647 Metals and Controls Inc Attleboro Mass Use Code 71785 assigned to Cinch Mfg Co Chicago III 6 4 CODE MANUFACTURER ADDRESS 82866 Research Products Corp Madison Wisc 82877 Rotron Inc Woodstock N Y 82893 Vector Electronic Co Glendale Calif 83058 Carr Fastener Co Cambridge Mass 83186 Victory Engineering Springfield N J 83298 Bendi x Corp Eatontown N J 83330 Herman H Smith Inc Brooklyn...

Page 31: ...237A fxd elect 3000pF 40V 1 32D5278 DOB 56289 0180 1899 1 C28 29 6236A fxd cer 05pF 400V 33C17A3 CDH 56289 01 50 0052 6237A Not used C30 6236A Not used 6237A fxd cer O lpF 500V 1 41 C92B5 CDH 56289 0160 0269 1 C31 6236A fxd tant 0 47pF 35V 1 150D474X9035A2 56289 0180 0376 1 6237A fxd elect 0 15pF 35V 1 Tll0A154K035AS 61637 0180 0218 1 C32 fxd mica 330pF 500V 1 obd 72136 0160 2012 1 C33 fxd elect 4...

Page 32: ... 4099 1 R13 fxd camp 15k 5 1 2W 1 EB1535 01121 0686 1535 1 R14 fxd camp 510 5 1W 1 GB5115 01121 0689 5115 1 R15 fxd camp 10k 5 1 2W 2 EB1035 01121 0686 1035 1 R23 fxd ww 0 25 10 3W 1 K46593 14841 0811 1829 1 R24 fxd camp 18 5 1 2W EB1805 01121 0686 1805 R26 var ww 3k Type 110 F4 71450 2100 1823 R28 fxd ww 1 25 1 2 5W 28480 0811 3384 R32 fxd film 1391 1 8W Type CEA T O 07716 0698 4099 R33 fxd film ...

Page 33: ...ype MF4C T O 19701 0757 0443 R65 fxd film 16 2k 1 1 8W 1 Type MF4C T O 19701 0757 0447 1 R66 fxd film 470 1 1 4W 1 Type MF52C T O 19701 0698 3506 1 R67 6236A fxd ww 135 5 3W 1 Type 242E 56289 0812 0112 1 6237A fxd ww 220 5 2W 1 Type BWH 75042 0811 1763 1 R68 6236A fxd ww 250 5 3W 1 Type 242E 56289 0811 1219 1 6237A fxd ww490 5 3W 1 Type 242E 56289 0811 1801 1 R69 6236A fxd ww 100 5 10W 1 Type 247E...

Page 34: ...33 Heat Sink 011 1 28480 5000 6025 Spacer for 011 heat sink 2 28480 0380 0716 Rubber bumper 4 28480 0403 0086 Front Panel Mechanical Binding Post red 4 28480 1510 0091 Binding Post black 1 28480 1510 0107 Hex nut nylon 3 8 32 5 28480 2950 0144 Meter bezel 2 28480 4040 0571 Spring compression meter mount 8 28480 1460 0720 Retainer push on for OSI 1 28480 0510 0509 Knob R1 R41 S2 3 28480 0370 1099 M...

Page 35: ...RK ARE SHOWN BELOW SCHEMATIC NOTES I ALL COMPONENTS ARE LOCATED ON P C BOARD UNLESS OTHERWISE INDICATED 2 t DENOTES CHASSIS MOl tITED COMPONENTS 3 DENOTES CONSTANT VOLTAGE FEEDBACK PATH 4 DENOTES CURRENT LIMIT FEEDBACK PATH 5 ALL RESISTORS IN OHMS I BW 1 UNLESS OTHERWISE INDICATED 6 THE SQUARE PLATED PADS ON THE P C BOARD INDICATE ONE OF THE FOLLOWING A PIN 1 OF AN I C OR TRANSFORMER B POSITIVE EN...

Page 36: ...2 o flJ o TO R58 VOLTMETER Zl H 3 250 WAOJUST 12 26K l ew R71 R56 __ 8 471 270 20V 1 1 6 6V OR 18V S3 LINE VOLTAGE SELECTOR SWITCH 240V r 220V r 120V r IOOV L o 5 V D S _ 2AR2 METER CIRCUIT V MI t R73 SEE TABLE 7 5V I r Zl E 5 3 4 12 4V 1 I ew ZI B OT025A 612 OR IA S2B 5 1 8W 0 TO 1 _ 7 16 r O 5A 32 V S2BRI CR60 i 96 f 12 4V I J3 flJ CW R59 AMMETER 250 UAOJUST CRII RI5 10K 5 112W RI4 510 5 4 IW 6 ...

Page 37: ...1 ERRATA On the title page change the appl icable serial numbers to Model 6236A Serials 1436A 0010l and above Model 6237A Serials 1511 A OOl 01 and above CHANGE 1 To the parts Iist and the schematic add ferrite bead inductor L3 HP Part Number 9170 0894 L3 is installed on either lead of diode CR49 CHANGE 2 This change to the Model 6236A replaces the printed circuit board mounted pots used previousl...

Page 38: ...925 North Hollywood California San Diego 92123 5500 Howard Street 1041 Kingsmill Parkway Rockville 4 Choke Cherry Rd Tel 714 279 3200 Skokie 60076 Columbus 43229 Maryland Skokie Illinois TWX 910 335 2000 Tel 312 677 0400 Tel 614 436 1041 Their complete addresses TWX 910 223 3613 are listed above St Joseph Service Only Tel 217 469 2133 CANADA ALBERTA BRITISH COLUMBIA MANITOBA NOV4 SCOTIA ONTARIO QU...