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HP 6186C User's Manual

1. Cl fxd mylar luF 200V 192P10492 56289 0160 0168 l CZ fxd cer 05 F 400V 33C17A3 CDH 56289 0150 0052 1 C4 fxd mica 18pF 300V 28480 0160 0356 1 CS fxd mylar 068p F 200V 292P68392 PTS 56289 0160 0166 1 C7 fxd mylar luF 200V 192P10492 56289 0160 0168 CGI fxd mylar Olp F 200V 192P10392 56289 0160 0161 1 C10 fxd mica 33pF 300V 28480 0160 2150 1 CE fxd mylar 0689 F 200V 292P68392 PTS 56289 0160 0166 C14 fxd mica 100pF 500V ROMISELOLT 00853 0140 0041 H GI5 fxd elect 22W F 35Vde 150D226X0035R2 56289 0180 0160 1 Ci fxd elect 4 7u F 35Vde 150D475X9035B2 56289 0180 0100 1 C17 18 ixd elect 22uF 35Vde 150D226X0035R2 56289 0180 0160 C20 fxd ceramic lu F 25V 5C13C CML 56289 0160 0127 1 C21 fxd elect luF 35Vdc 150D105X9035A2 56289 0180 0291 l C22 ixd elect 4 7u F 35Vde 150D475X9035B2 56289 0180 0100 C23 fxd ceramic 0 47uF 25V 28480 0160 0174 I C26 fxd ceramic 01 100V obd 91418 0150 0093 e C28 fxd ceramic 0 474 F 25V 28480 0160 0174 C33 fxd mica 20pF 500V 28480 0160 0370 CRI 2 Diode Si 200mA 180V SG3396 03877 1901 0033 8 GR3 5 Diode Si S0m 75V DA2050 03508 1901 0642 5 GR6 Diode Si 200mA 180V 8G3396 03877 1901 0033 GR7 8 Diode Si 50mA 75V DA2050 03508 1901 0642 CR9 10 Diode Si 200mA 180V SG3396 03877 1901 0033 GRIL 12 Diode Si 150mA 15V STB523 03508 1901 0460 1 CR13 16 Diode Si 200m 180V 5G3396 03877 1901 0033 6 5 GRI7 CR18 19 CR20 21 GR22 CR23 IR 24 25 CR26
2. 1854 0631 1854 0690 64494 See Note On Page 6 11 Power NPN Si TO 3 Power NPN Si TO 3 115 230V Line Switch Recessed DPDT Slide 3101 1234 CHASSIS ASSEMBLY ELECTRICAL RII5A R115B fxd ww 20k 5 40W Center Tapped fxd ww 400 5 40W 0811 3236 0818 0011 91637 12697 Type HLT 35 Type V8ZT R117 11819 TI Transformer Power includes Standoffs 28480 106186 80091 A2 BOARD MECHANICAL Jumper Rear Barrier Blocks 422 13 11 013 71785 0360 1143 Socket integrated Circuit Zl and 72 133 98 92 061 71785 1200 0763 l Standoff Q24 25 1 4 Hex 2300 83330 0380 0716 4 Heat Dissipator TO 5 Q37 Q39 TXBE 032 031B 98978 1205 0030 Insulator Transistor TO 5 28480 0340 0166 FRONT PANEL MECHANICAL Meter Trim Bezel Meter 3 1 2 Meter Combining Pin Front Panel Basic Front Panel Control Section Insert Front Panel Output Section Insert Insulated Strip Nylon Terminals EL 2 3 Corporate Logo Knob Assembly RIS Knob Assembly 82 and R75 Shoulder Washer and GND Binding Posts Lampholder Clear D I Lampholder Base DSI Fastener DS2 312 Dia Stand Tilt Foot Assembly Hinge Foot Assembly REAR PANEL MECHANICAL Panel Rear Heat Sink Rear Panel Q26 27 28 35 36 Cover Rear Barrier Strips Insulating Strip Mylar Copper Clad Q26 27 28 Shoulder Wa
3. minals 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 strips at the rear of the power sup ply The terminal designations are stenciled in black on the power supply above or below their respective terminals The operator can ground either output terminal or with added precautions to protect the user operate the power supply up to 300Vde above ground The load may be con nected to either the front or the rear terminals without any degradation of performance 3 5 The following paragraphs describe the pro cedures for utilizing the various operational capa bilities of the power supply A more theoretical description of the operational features of this sup ply is contained in Application Note 90A DC Pow er Supply Handbook available at no charge from your local Hewlett Packard sales office 3 6 NORMAL OPERATING MODE 3 7 The power supply is normally shipped with its rear terminal strapping connections arranged for constant current voltage limit local program This strap ping pattern is illustrated in Figure 3 2 The operator merely selects a constant current output using the front panel controls as described in Para graph 3 9 AO Ai A2 A Figure 3 2 Normal Strapping Pattem 3 8 CONSTANT CURRENT 3 9 To select a constant current output proceed as follows a With output terminals
4. varies from approxi mately 0 7 to 12V 2 Re install Z2 and remove l0ka pot Voltage indicated on Z2 or QS defective connected in Step 1 Check opera external voltmeter i i tion of Z2 as follows does not change a If voltage on external voltmeter is Voltage goes from Check for defective negative short Q7A collector to od negative value Q5 Q7 open RIS or 3 REA EE l towards zero missing strap be S voltage on external voitmeter is tween terminals Al approximately zero short Q7B and A2 collector to emitter Voltage goes from Check for defective zero towards negative Q5 Q7 or shorted value RIS Table 5 7 Voltage Limit Light Circuit Troubleshooting ACTION RESPONSE PROBABLE CAUSE NOTE The procedures in this table are based on the assumption that the voltage limit cir cuit and the programming guard supply are operating correctly Check out proce dures for these circuits are given in Steps 5 through 7 of Table 5 3 Check 29V and 15Vreference volt ages light bulb and VRIS Proceed to Step 2 Attempt to turn on light by shorting a Light does not go on Q17 collector to emitter Light goes Check Q17 and O19 for open b Proceed to Step 3 Attempt to turn on lamp driver Q17 by Light does shorting Q20 collector to emitter Light goes a Check Q20for open Q21 for short b Check CR22
5. 2 19 A recessed two position slide switch locat ed on the rear panel permits operation from either a 115 or 230 volt power source Before connect ing the instrument to the power source check that the white number visible on the switch slide matches the nominal line voltage of the source required slide the switch to the other position using a thin bladed screwdriver if 2 20 When the instrument leaves the factory the proper fuse is installed for 115 volt operation An envelope containing a fuse for 230 volt operation is attached to the power cord Markings on the rear panel adjacent to the fuse holder indicate the correct fuse rating for operation from either a 115 2 2 volt or a 230 volt power source Make sure that the correct fuse is installed if the position of the slide switch is changed 2 21 POWER CABLE 2 22 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 is plugged into an appropriate receptacle the instru ment is grounded The offset pin on the power cable s three prong connector is the ground con nection 2 23 To preserve the protection feature when op erating the instrument from a two contact outlet use a three prong to two prong adapter and con nect the green lead on the a
6. b Adjust potentiometer R11 see Figure 7 3 to obtain reading of 0 200uVdoc on differential voltmeter 5 65 This adjustment can also be used to set the zero current programming accuracy when the supply is remote resistance programmed However the adjustment should not be made if the total minimum resistance of the remote programming device po tentiometer switched resistor setup etc and its connecting wires exceeds approximately 10 ohms Using the constant current comparator zero adjust ment to set the output current to zero under this condition may result in the supply not meeting its temperature coefficient specification Proceed as follows to perform this adjustment a Connect test setup shown in Figure 7 3 b Set both range switches to highest current range turn VOLTAGE control fully clockwise and connect lead of differential voltmeter to Rg c Connect remote resistance programming setup see Figure 3 3 and adjust remote resist ance to zero minimum d Turn on supply and adjust potentiometer Ril see Figure 7 3 for reading of exactly zero on differential voltmeter 9 66 CONSTANT CURRENT PROGRAMMING CURRENT 5 67 This procedure adjusts the constant current programming current within the supply The pro gramming current is factory set to within 0 25 of imA and should not need adjustment thereafter un less 100mA range current sampling resistor R1 or reference supply zener diode VR4 is replaced The progr
7. 0698 6275 2100 0896 0757 0283 0811 1978 0698 3265 0686 3025 0698 3382 0686 3005 0686 1515 0686 2025 0686 5105 0686 2035 0686 5125 0757 0427 0686 1825 0757 0420 0686 2005 0813 0010 0686 2725 0683 7515 0686 1025 0811 1861 0686 1035 0686 3025 0686 1235 0686 3025 0686 7515 0686 1325 0686 5115 0686 3025 0686 1055 0686 5145 0686 2035 0686 3615 0757 0283 0698 3430 0764 0046 0686 1025 0764 0031 0811 1918 0686 2015 0686 5625 10686 1035 0698 3382 0757 0283 0761 0083 0686 2015 0686 0515 0764 0028 MFR HP TQ I MFR PART NO CODE PART NO pune Fa pak ml kel pi pd hue panne pab mal peat REF DESIG RIS R96 R97 R98 R99 RL00 101 R105 R106 R107 R108 R103 R110 TBI TB2 VRI VR2 VR3 VR4 VRS VR6 VR7 8 VR9 10 VRI I VR12 13 VRI4 VRIS VRIS VRI9 FA ees CR54 R74 VR101 103 105 VRI02 104 106 fxd comp 470n 5 1 2W Diode zener 2 37V 400mW 1 5210939 2 04713 1902 3002 1 Diode zener 7 DN 400mW 3 8210939 146 04713 1902 0064 3 Diode zener 7 5V LW 2 8211213 104 04713 1902 0799 Diode zener 6 2V 400mW 20ppm 1 I N825 28480 1902 1221 1 Diode zener 7 DV 1W SZ 1213 104 04713 1902 0799 Diode zener 12 4V 400mW 1 1902 3185 1 Diode zener 7 5V 400mW SZ10939 146 04713 1902 0064 Diode zener 150V 1 watt 2 8211213 440 04713 1902 0586 2 Diode zener 16 2V 400mW 2 28480 1902 0184 2 Diode zener 5 62V 400mW 3 28480 1902 3104 3 Diode
8. PRECISION CONSTANT CURRENT SOURCE MODEL 6186C OPERATING AND SERVICE MANUAL FOR SERIALS 1443A 00101 AND ABOVE For Serials Above 1443A 00101 a change page may be included HP Part No 06186 90005 Printed January 1975 SAFETY SUMMARY The following general safety precautions must be observed during all phases of operation service and repair of this instru ment Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design manufacture and intended use of the instrument Hewlett Packard Company assumes no liability for the customer s failure to comply with these requirements BEFORE APPLYING POWER Verify that the product is set to match the available line voltage and the correct fuse is installed GROUND THE INSTRUMENT This product is a Safety Class 1 instrument provided with a protective earth terminal To minimize shock hazard the in strument chassis and cabinet must be connected to an elec trical ground The instrument must be connected to the ac power supply mains through a three conductor power cable with the third wire firmly connected to an electrical ground safety ground at the power outlet For instruments designed to be hard wired to the ac power lines supply mains connect the protective earth terminal to a protective conductor before any other connection is made Any interruption of the protec tive grounding conductor or disconne
9. at which point it is clamped by the regulating action of the voltage limit circuit 4 28 When CR22 and CR21 are conducting the programming guard supply provides a current through Ry and CR21 of such magnitude that the voltage drop across Ry exactly equals the forward voltage drop across CR22 This insures the con tinuing fullfillment of the primary condition requir ed by the main current regulating feedback loop zero potential between the positive output terminal and the guard conductor The voltage drop across resistor Ry is also used to trigger the voltage limit light circuit since the voltage drop is present only when the voltage limit circuit is activated Note that even during voltage limiting action the output of the programming guard supply EG is maintained at a value equal te the potential at the positive output terminal Both guarding action and the normal control action of the main current regu later continue minimizing any output current tran sients which might tend to occur during transfer from voltage limit mode to normal output current mode Output voltage transients are also OT minimized since the voltage limit circuit goes in to operation in as little time as it takes to turn on the two isolation diodes 4 29 DETAILED CIRCUIT ANALYSIS See Figure 7 4 4 30 REFERENCE SUPPLY 4 31 The reference supply is an independent reg ulated voltage supply that provides stable bias and reference voltages used th
10. perly grounded receptacle to minimize electric shock hazard Operation at line voltages or frequencies in excess of those stated on the data plate may cause leakage currents in excess of 5 0 mA peak SAFETY SYMBOLS Instruction manual symbol the product will be marked with this symbol when it is necessary for the user to refer to the instruction manual refer to Table of Contents Indicates hazardous voltages or indicate earth ground terminal G M The WARNING sign denotes a hazard It calls attention to a procedure practice or the like which if not correctly per formed or adhered to could result in personal injury Do not proceed beyond a WARNING sign until the indicated conditions are fully understood and met WARNING The CAUTION sign denotes a hazard It calls attention to an operating pro cedure or the like which if not correct ly performed or adhered to could result in damage to or destruction of part or all of the product Do not proceed beyond a CAUTION sign until the indicated con ditions are fully understood and met I CAUTION I DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT Because of the danger of introducing additional hazards do not instali substitute parts or perform any unauthorized modification to the instrument Return the instrument to a Hewlett Packard Sales and Service Office for service and repair to ensure that safety features are maintained Instruments which
11. 5 44 To locate the cause of trouble follow Steps 1 2 and 3 in sequence 1 Check for obvious troubles such as open fuse defective power cord input power failure 115 230V switch in wrong position incorrect strap ping pattern refer to Figure 3 2 or defective meter check output current with external ammeter Next remove top and bottom covers 2 retaining screws each and inspect for open connections charred components etc If the trouble source cannot be detected by visual inspection proceed to Step 2 2 Disconnect load and connect short cir cuit across output terminals of supply Shorting the output terminals is an extremely important step failure to short the output terminals may result in the destruction of the shunt regulator transistors 3 Examine Table 5 2 for your symptom and its probable cause The symptoms listed in Table 5 2 are of two kinds the first of which is symp toms due to easily corrected trouble sources such as a single defective component or an incorrect internal adjustment For these symptoms direct troubleshooting procedures are given in the table The second sind of symptom includes primarily those resulting from failure of a feedback loop For these symptoms the table refers the reader to one or more of Tables 5 3 through 5 7 5 45 Table 5 3 presents a sequenced isolation and initial troubleshooting procedure for the series reg ulator programming guard supply and constant cur
12. CR27 CR29 OR30 31 R34 39 40 CR41 43 GR44 R45 OR48 49 GR50 ORS CR52 53 GRS5 56 Ll 2 3 QI Q2 5 Q7 Q8 Q3 11 12 14 O15 16 Q17 Q13 22 Q24 25 Q29 O30 31 332 933 34 O37 Q38 Q39 Ri RZ R3 R4 RS R7 8 RJ RIO Rli R12 R13 R14 R16 R19 R20 RZI MFR HP OERO CRON TQ SAO AR o GODE PART Se Diode Si Diode Si Rect Si Diode Si Diode Si Diode Si Rect Diode Si Diode Si Rect Si Diode Si Rect Si Diode Si Diode Si Diode Si Diode Si Diode Si Rect Si Diode Si 200mA 10V 200maA 180V 1A 800V 200mA 180V i50mA 15V 200mA 180V Si 1A 800V 200mA 180V 200mA 180V 1A 800V 200mA 180V 1A 800V 200mA 180V 1A 800V 50mA 75V 200mA 180V i50mA 15V 1A 200V 200mA 80V Ferrite Bead O17 20 21 emitter Gi la A U UJ GO Lo UG ta U UJ UG U WA wm Lo Go G2 Ua Go LO fxd fxd ixd fxd fxd fxd fxd fxd var fxd fxd fxd fxd fxd fxd fxd SS NPN dual Si 35 NPN Si SS NPN dual Si PNP Si NPN Si PNP i T0 5 NPN Si PNP Si NPN Si NPN Si NPN Si PNP Si NPN Si NPN St PNP 5L NPN Si T0 66 ww 100n 0 5 10W 5ppm ww 900 0 5 1 2W Sppm ww Jka 0 5 1 2W 5ppm comp 4 3kn 25 1 2W met film 196 1 1 8W met film 23kn 1 1 3W met film 3 57ko 1 1 8W met film 390ka 1 1 8W ww Zka 5 CC Comp Zero met film 3k 1 1 8W met film 249ka 21 1 8W met film 68 Ika 1 1 8W met
13. Yardeny Laboratories Inc Plainfield N Morristown N New York N Arco Electronics Inc Great Neck N TRW Capacitor Div Ogallala Ne RCA Corp Electronic Components Harrison 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 Bridgeport Conn Cutler Hammer Inc Power Distribution and Control Div Lincoln Plant Lincoln Ill Litton Precision Products Inc USECO Div Litton Industries Van Nuys Calif Gulton Industries Inc Metuchen N F United Car Inc Chicago Ill Miller Dial and Nameplate Co El Monte Calif Chicago Il Aitleboro Mass Dale Electronics Inc Columbus Neb Elco Corp Willow Grove Pa Honeywell Inc Div Micro Switch Freeport Ill Whitso Inc Schiller Pk HL Sylvania Electric Prod Inc Semi conductor Prod Div Woburn Mass Essex Wire Corp Stemco Controls Div Mansfield Ohio Raytheon Co Components Div Ind Components Oper Quincy Mass Wagner Electric Corp Tung Sol Div Radio Materials Co Augat Inc Livingston N J Southco Ine Lester Pa Leecraft Mfg Co Inc LCa NY 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
14. diodes CR32 and CR33 and capacitors 030 and C31 The circuit operates as follows during the negative half cycle of the input voltage C31 is charged through CR33 to one half the peak to peak voltage appearing across the secondary of trans former Tl During the positive half cycle of the input voltage capacitor C30 is charged through CR32 to the same level Thus the output voltage appearing across the series combination of C30 and C3 is double the value it would be for a full wave bridge circuit SECTION V MAINTENANCE 5 1 INTRODUCTION 5 2 Upon receipt of the power supply the per formance check Paragraph 5 5 should be made This check is suitable for incoming inspection If a fault is detected in the power supply while making the performance check or during normal operation proceed to the troubleshooting proce dures Paragraph 5 38 After repair and replace ment Paragraph 5 47 perform any necessary ad justments and calibrations Paragraph 5 51 Be fore 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 performing any main tenance checks turn on the power supply and al low one hour warm up 5 3 TEST EQUIPMENT REQUIRED 5 4 Table 5 1 lists the test equipment required to perform the various procedures described in this section Differential Voltmeter Variable Voltage Transformer AC
15. source negative terminal grounded one end of the shield can be connected to the guard terminal des ignated METER on the front and terminal AO on the rear and the other end left unconnected This ef fectively projects the internal guard voltage along the shield affording absolute protection against leakage If the supply is used as a negative source the above method cannot be utilized How ever the use of a shielded cable will be sufficient to prevent shunt leakage in most applications CAUTION Never connect the guard METER on the front panel and terminal AO on the rear panel to either the positive or the negative output terminal Mak ing this connection will result in loss of current control and will damage differential amplifiers Ql and Q7 3 12 OPERATION AS A CONSTANT VOLTAGE SOURCE 3 13 The instrument may be operated as a moderately well regulated constant voltage source by operating it in the voltage limit mode VOLTAGE LIMIT light on When operating as a voltage source the output volt age range is from 0 5 to 300Vdc Inthis situation the output voltage will be held approximately constant at the limitlevel andthe output current will change to meet varying load conditions For further information please consultan HP sales engineer 3 14 OPERATION BEYOND RATED OUTPUT 3 15 The maximum output voltage and current of the supply is internally limited to 315Vdc and 110 115mA in order to protect internal c
16. 08730 08806 08863 08919 09021 09182 09213 09214 09353 09922 11115 11236 11237 11502 11711 12136 12615 12617 12597 13103 14493 14655 14936 15801 16299 CTS of Berne Inc I Hamlin Inc MANUFACTURER ADDRESS Westinghouse Electric Corp Electronic Tube Div Elmira N Y Fairchild Camera and Instrument Corp Semiconductor Div Mountain View Calif Los Angeles Calif Sylvania Slectric Prod Inc Sylvania Electronic Systems Birtcher Corp The Western Div Mountain View Calif IRC Div of TRW Inc Burlington Plant Burlington Iowa Continental Device Corp Hawthorne Calif Raytheon Co Components Div Semiconductor Operation Mountain View Calif Breeze Corporations Inc Union NI Rellance Mica Corp Brooklyn N Y Sloan Company The Sun Valley Calif Vemaline Products Co Inc Wyckoff N J General Elect Co Minia ture Lamp Dept Cleveiand Ohio Nylomatic Corp Norrisville Pa RCH Supply Co Vernon Calif Airco Speer Electronic Components Bradford Pa Hewlett Packard Co New jersey Div Rockaway N F 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 Coro Tung Sol Div Bloomfield N Berne Ind Chicago Telephone of Cal Inc So Pasadena Calif IRC Div of TRW Inc Boone Plant Boone N C General Instrument C
17. CHARACTERISTICS Values See Figure 5 3 0 5ppm 4 Terminal 10W I 1 2W Rg1 2 3 inductive Range 0 100K Accuracy 0 1 plus 1 ohm Make before break contacts 5 Must be non Current Sampling Resistors Decade Resistance Box NOTE A satisfactory substitute for a differ ential voltmeter is a reference voltage source and null detector arranged as shown in Figure 5 1 The reference voltage source is adjusted so that the voltage difference between the supply being measured and the reference volt age will have the required resolution for the measurement being made The voltage difference will be a function of the null detector that is used Exam ples of satisfactory null detectors are HP 419A null detector a de coupled oscilloscope utilizing differential in put or a 50mV meter movement with a 100 division scale For the latter a 2mV change in voltage will result ina meter deflection of four divisions CAUTIOIN Care must be exercised to avoid ground loops and circulating currents when using an electronic null detector in which one input terminal is ground ed 5 5 PERFORMANCE TEST 5 6 The following test can be used as an incom ing inspection check and appropriate portions of the test can be repeated either to check the oper ation of the instrument after repairs or for periodic maintenance tests The tests are performed using a 115Vac 60Hz single phase input power source If the
18. Q15 and Q16 cause the current through the two transistors to be shared equally R40 is a bleed resistor that allows tum on of the reference supply by providing a current path into the output of the regulator Diode CR14 is one of many turn on turn off didoes used throughout this instrument In general the func tion of these diodes is to eliminate output current and voitage transients when the unit is first turn ed on or when input power is suddenly removed Specifically CR14 blocks series regulator bias and bleed current flow through VR3 VR5 and C15 to circuit common and thus to the output of the unit at turn off 4 34 Zener diode VR7 biased from the 12 4V out put through CR16 and R68 provides a regulated 7 5V output VR3 and VR5 provide a regulated 15V output An additional unregulated 29V output used in the voltage limit lamp circuit and the bleed circuit is drawn from the positive end of C35 4 35 PROGRAMMING GUARD SUPPLY 4 36 The programming guard supply is an inde pendent regulated variable voltage supply As described in Paragraph 4 4 it provides the pro gramming voltage for the constant current compa rator and also provides a guard potential that eliminates leakage currents flowing between the instrument s output terminals Paragraph 4 16 describes the operation of the programming guard supply in operational amplifier terms the follow ing paragraphs describe the supply s operation on a stage by stage
19. Set both range switches to the highest current range connect side of ac voltmeter to Rgj and turn on supply d Adjust CURRENT control until front panel meter indicates exactly 100 e AC voltmeter should read less than Z2mV If it does not refer to Paragraph 5 59 f Repeat Steps d and e with both range switches set to middle current range and ac volt meter connected to Rg2 g Repeat Steps d and e with both range switches set to lowest current range and ac volt meter connected to Rs3 rms 5 19 High Frequency Noise Measurement When measuring high frequency noise an oscilloscope of sufficient bandwidth 20MHz or more must be used Figure 5 4A shows the correct method of measuring the output ripp e of a constant current supply using a single ended scope Ground loop paths are broken by floating the oscilloscope case with a 3 to 2 adapter 5 20 Either 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 verti cal input terminals of the scope When using shielded two wire it is essential for the shield to be connected to ground at one end only to prevent ground current from flowing through this shield and inducing a noise signal in the shielded leads 5 21 To verify that the oscilloscope is not dis playing ripple induced in the leads or picked up from the grounds the scope lead should be shorted to the scope lead at the
20. cess to various control points within the unit to expand the operating capabilities of the instru ment A brief description of these capabilities is given below a Remote Programming Both the output current and voltage limit can be programmed con trolled from a remote location by means of an ex ternal voltage source or resistance The output current can be rapidly programmed up and down using this facility current programming speed is less than 1Omsec from zero to 99 of maximum rated output with an accuracy of 1 b External Voltage Monitoring The output voltage of the supply can be externally monitored with an accurate differential or digital voltmeter connected to either front or rear meter terminals Connecting the meter to the active guard in the supply prevents output performance degradation c AC Modulation of Output An external ac component can be superimposed on the de out put current of the supply This feature allows dynamic measurements such as zener impedance and small signal h parameters to be made with a minimum of difficulty 1 9 SPECIFICATIONS 1 10 Detailed specifications for the power sup ply are given in Table 1 1 1 11 OPTIONS 1 12 Options are customer requested factory modifications of a standard instrument The following option is available for the instrument covered by this manual Where necessary de tailed coverage of the option is included through out the manual Option No Description
21. correct result is not obtained fora particular check do not adjust any internal controls pro ceed to troubleshooting Paragraph 5 38 5 7 CONSTANT CURRENT TESTS 5 8 For all output current measurements the quipment Required Continued RECOMMENDED MODEL Measure output current cal ibrate ammeter RI R2 and R3 parts table Adjust programming accuracy POWER SUPPLY REFERENCE UNDER TEST Differential Voltmeter Substitute Test Setup Figure 5 1 current sampling resistor must be treated as a four terminal device In the manner of a meter shunt the load current is fed to the extremes of the wire leading to the resistor while the sampling termi nals are located as close as possible to the resist ance portion itself see Pigure 5 2 In addition the resistors should be of the precision low noise low temperature coefficient less than Sppm C type and should be used at no more than 10 of their rated power so that their temper ature rise will be minimized CURRENT SAMPLING TERMINALS TO TO POSITIVE POWER SUPPLY TERMINAL NEGATIVE POWER SUPPLY TERMINAL SAMPLING RESISTOR LOAD TERMINALS Current Sampling Resistor Connections Figure 5 2 NOTE If difficulty is experienced in obtain ing adequate sampling resistors it is recommended that duplicates of the sampling resistors R1 R2 and R3 used in the unit be obtained from the factory 5 9 The monitoring device should be c
22. en tire output range of the supply 1 4 Special attention has been given to circuit details in this power supply to allow well regu lated performance to be maintained down to very low output currents of the order of lpA The use of a three position RANGE switch and a 10 turn output CURRENT control result in resolution down to 0 SpA 1 5 Separate meters are used to measure output voltage and current Output current can be mea sured in any of three ranges in accordance with the RANGE switch setting on the front panel Out put voltage is measured in one range 1 6 The power 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 at up to a maximum of 300 volts above ground Adequate safety pre cautions must be taken to protect the operator when the supply is used in this mode 1 7 The supply incorporates an active guard that prevents leakage currents from degrading the out put current regulation Because the voltage at the positive output terminal is held equal to the guard voltage the latter is also used to drive the front panel meter or an external high accuracy volt meter This effectively isolates the voltmeter from the main supply and eliminates the usual output regulation degradation associated with connecting a voltmeter directly across the output of a constant current source 1 8 Terminals at the rear of the unit allow ac
23. gree Farenheit fixed germanium Henry Hertz integrated circuit inside diameter incandescent kilo 103 milli 1073 mega 106 micro 1076 metal Reference Designators Continued vacuum tube neon bulb photocell etc zener diode socket integrated cir cuit or network Description Abbreviations manufacturer modular or modified mounting nano 1079 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 00629 00656 00853 01121 01255 01281 01295 01686 01930 02107 02114 02606 02660 02735 03508 03797 03877 03838 04009 04072 04213 04404 04713 05277 05347 05820 06001 06004 06486 06540 06666 06751 EBY Sales Co Inc Table 6 3 Code List of Manufacturers MANUFACTURER ADDRESS Jamaica N Y Asrovox Corp New Bedford Mass Sangamo Electric Co S Carolina Div Allen Bradley Co Litton Industries Inc Beverly Hills Calif TRW Semiconductors Inc Lawndale Calif Pickens S C Milwaukee Wis Texas Instruments Inc Semiconductor Comp
24. in Paragraphs 4 24 through 4 28 In summary the voltage limit circuit is an independent regulated variable voltage supply that establishes a preset voltage limit across the shunt regulator When the output voltage is less than the limit voltage isolation diode CR22 has zero volts across it and CR21 is reverse biased When the output voltage slightly exceeds the pre set limit voltage CR22 and CR21 conduct allow ing a portion of the output current to be diverted away from the load and through the shunt regulator 4 59 The voltage limit circult consists of a differ ential amplifier Q33 Q34 an error amplifier Q32 and a shunt regulator Q35 Q36 One input of the differential amplifier Q34 base senses a fraction of the voltage limit circuit output voltage via the variable voltage divider formed by R84 R87 and R85 R86 in series with VOLTAGE control R75 The other input Q33 base is connected to zener diode VR12 This diode connected in series with VR13 and biased through R115A R115B establishes a 5 6V reference against which the fraction of the limit voltage appearing at the other input is com pared The combination of VR12 and VR13 also es tablish a 11 2V bias voltage source for Q32 Q33 and Q34 in the voltage limit circuit as well as Q38 in the bleed circuit Diodes CR27 and CR29 form a limiting network which protects against break down from overvoltage Selected resistor R87 ad justs the value of the current supplied b
25. loops formed by th interconnection of the three circuits 4 15 PROGRAMMING GUARD SUPPLY 4 16 The programming guard supp y is an OLTAGE f CONTROL PROG RAMMING GUARD CURRENT SUPPLY CONTROL Rg RR R31 32 MAIN CURRENT REGULATOR SERIES REGULATOR CURRENT COMP 0102 03 ZI Rg R79 DIODE VRI2 4 3 INPUT COMP amp ERROR AMPL PROGRAMMING VOLTAGE INPUT COMP D Ro ERROR AMPLA Eg Er z OUTPUT REG R 97 Z2 08 09 CURRENT t SAMPLING METER RESISTOR O zk I i SRO CONDUCTOR VOLTAGE LIMIT LEVEL EL CR21 CR22 ISOLATION DIODES Q32 33 34 ae 3 SHUNT REGULATOR 035 36 VOLTAGE LIMIT CIRCUIT Simplified Schematic independent regulated variable voltage supply The operation of this supply is most easily under stood when it is drawn in the standard operational amplifier configuration shown in the top third of Figure 4 2 An input voltage Er derived from the reference supply and reference diode is applied to summing point S via resistor Rp The output voltage Eg is fed back to this same summing point through resistor Rg the front panel CURRENT con trol Because the input impedance of the amplifier is high the input current to the amplifier can be considered negligibly small and all of the input current flows through both resistors Rr and Rg The feedback and th
26. open or shorted see NOTE adjust CURRENT and RANGE controls for desired output current b With output terminals open adjust VOLT AGE control for maximum output voltage allowable voltage limit as determined by load conditions If a load change causes the voltage limit to be ex ceeded the power supply will automatically cross over to voltage limited output at the preset volt age limit and the current supplied to the load will drop proportionately When this occurs the VOLT AGE LIMIT lamp on the front panel will light In for high peak voltages corresponding to suddenly increased load resistance which can cause 3 2 unwanted crossover Refer to Paragraph 3 38 NOTE Regardless of the supply s mode of operation constant current or voltage limit the front panel ammeter always indicates the programmed output cur rent This enables the operator to set the output current using the front panel CURRENT and RANGE controls without shorting the output terminals 3 10 CONNECTING LOAD 3 11 Loads for a constant current source must be connected in series not in parallel if the desired output current is to be supplied to each load Extreme care must be taken to avoid shunt paths external to the power supply The presence of shunt paths will tend to degrade the performance of the supply If the load is remotely located from the supply shunt paths can be avoided by using shielded cable If the supply is used as a positive
27. sink whose conduction is controlled by driver Q38 The base of Q38 senses a portion of the output voltage at the guard conductor through voltage divider R98 R99 As the output voltage decreases Q38 increases its conduction thus increasing Q37 s conduction This increase in current approximately balances the decrease in the current flowing through R100 and R101 thus the total current drawn through the series regulator by the bleed circuit is maintained at a relatively constant level 4 56 Driver stage Q38 is biased from the lower end of R115B in the voltage limit circuit This point maintained at approximately 11 2V by VR12 and VR13 serves as a bias voltage source for Q32 Q33 and Q34 in the voltage limit circuit as well as Q38 in the bleed circuit Sink transistor Q39 is biased by R100 and R101 R94 is a power sharing resistor that reduces the power dissipa tion in Q37 and Q39 Diodes CR39 and CR40 are base emitter junction protection diodes Diode CR25 prevents reverse current flow from the 11 2V bias voltage source into the guard conductor Diodes CR30 and CR44 are turn on turn off diodes CR30 normally off and CR44 normally on allow current to flow from the 11 2V bias voltage supply point through R100 and R1O1 at turn off thus keeping transistors Q37 and Q39 biased on as the 29V reference supply voltage is falling 4 57 VOLTAGE LIMIT CIRCUIT 4 58 The operation of the voltage limit circuit is explained functionally
28. the supply its relatively low resistance would degrade the load regulation and diminish the load current Instead the voltmeter is connected between the guard conductor and the negative out put terminal remember that the guard is maintained at the same potential as the positive output termi nal The meter drive current is thus supplied by the programming guard supply and not by the main regulated current supply The ammeter is connect ed between circuit common and the guard conduc ter allowing it to indicate the output voltage of the programming guard supply As described in Paragraph 4 3 the IR drop across the current sam pling resistance is held equal to the output voltage of the programming guard supply thus measuring this voltage produces an indication of the output current flowing through the current sampling resis tor 4 7 The turn on turn off control consists of a pair of long time constant networks that allow the supply to achieve a gradual turn on and turn off characteristic thus minimizing any current tran sients appearing in the output when the instrument is first turned on or when power is suddenly re moved At turn on the control circuit withholds drive current from the series regulator until all other circuits in the supply have stabilized At turn off the control circuit immediately interrupts the drive current thus preventing the series regu lator from remaining on while its bias and control voltages are fa
29. varies its conduction in order to keep the output current at a constant level The range of the output current is selected by the current RANGE switch the position of the switch determines the value of current sampling resistance that is placed in series with the posi tive output terminal Overall Block Diagram 4 3 The series regulator is part of a feedback loop whose other components include the constant current comparator and the current sampling resis tor s The purpose of this feedback loop is to maintain the current flowing through the series regulator at a constant well regulated value During normal constant current operation the con stant current comparator continuously compares the voltage drop across the current sampling resistor with the reference voltage from the programming guard supply If a difference between these two voltages exists thatis if the IR drop across the current sampling resistor does not equal the pro gramming guard supply voltage the constant current comparator sends an amplified error signal to the series regulator The error signal alters the conduction of the series regulator until the voltage drop across the current sampling resistor once again equals the programming guard supply volt age Thus the actual output current is held con stant at level proportional to the programming guard supply voltage 4 4 The programming guard supply is an indepen dent regulated variable voltage su
30. voltage limit pro gramming current to within 15 of 1mA It allows the supply to provide 105 of the maximum rated output voltage despite the 15 total tolerance of the VOLTAGE control R75 and the differential amplifier reference zener diode VR12 This adjustment is necessary if either of these compo nents are replaced it can also be performed as an accuracy check before remote resistance program ming the voltage limit 5 71 To adjust the voltage limit programming cur rent proceed as follows a Set RANGE switch to 100mA position and turn VOLTAGE control fully clockwise b Set CURRENT control for front panel am meter reading of 100mA no load c Connect high impedance differential volt meter across output terminals of supply NOTE Do not let voltage on differential volt meter exceed 317 volts Voltages in excess of this level will damage the shunt regulator transistors in the volt age limit circuit d Connect decade resistance box set for 50kn in place of R87 mounted on standoffs on main circuit board see Figure 7 3 e Turn on supply and adjust decade resist ance until differential voltmeter reads 315 2Vdc f Turn off supply and replace decade re sistance box with appropriate value 5 1 2W resistor in R87 position 5 72 VOLTAGE LIMIT ZERO 5 73 To adjust the voltage limit zero voltage pro gramming accuracy proceed as follows a Set RANGE switch to 100mA position ad just CURRENT control f
31. zener diode string discussed in Para graph 4 61 also provides protection for the sefies regulator If the output voltage of the supply ex ceeds approximately 345 volts as would happen when the strap between A5 and A6 was removed under no load conditions diode CR41 conducts This action diverts most of the series regulator drive current supplied from Q22 through the zener string and thus limits the voltage applied to the series regulator to less than 345 volts Under this condition zener diode VR15 holds the voltage limit approximately 16 volts higher than the voltage on the series regulator 4 63 Zener diodes VR16 and VRI7 provide a bias voltage that allows the output of the supply to be set completely to zero Without these diodes the 4 9 minimum output voltage appearing between the out put terminals would be the sum of the forward drops of CR21 and CR22 the minimum Vog col lector emitter voltage of Q35 and Q36 and the drop across emitter resistors R116 and R93 minus the forward drop of CR26 With these diodes con nected between the shunt regulator transistors and the negative output terminal the effect of these voltage drops is neutralized and the minimum out put voltage appearing between the output terminals becomes zero Resistor R114 connected across the diodes limits the maximum resistance of the circuit Diode CR46 connected from the junction of the voltage doubler filter capacitors to the junction of R115
32. 0686 5125 0686 1235 0686 5105 ee kb buet coe bach bei besi hd REF DESIG R22 R23 R24 R25 R27 28 R23 R30 R31 R32 R33 R34 R35 R36 R37 R40 RAL 42 R43 R44 R45 46 R47 R48 R50 R51 R52 R53 R54 R55 R56 R57 R58 R59 R60 R61 R62 63 R64 R65 R66 R67 R68 R69 R790 R71 73 R76 R77 78 R79 R80 R81 82 R83 R34 R85 R86 87 R88 R90 R93 R94 fxd xd fxd fxd fxd DESCRIPTION comp 150n 5 1 2W comp Blo 5 1 2W comp 510n 5 1 2W comp 10ka 5 1 2W met film 64ka 1 1 8W 25ppm var fxd fxd ww ixd ww fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd Exd fxd fxd fxd ixd fxd fxd ixd ixd ixd fxd ixd fxd fxd fxd fxd fxd fxd fxd fxd ixd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd fxd ww 15 met film Zka 1 1 8W 5 9ko 1 1 4W Selected 5 3W met film 118k 1 1 8W comp 3ka t5 1 2W met film 5 49ka 1 1 8W comp 30a 5 1 2W comp 150n 5 1 2W comp 2kn 5 1 2W comp 5la 5 1 2W comp 20kn 5 1 2W comp 5 Ika 5 1 2W met film 1 5ka 1 1 8W comp 1 8kn 5 1 2W met film 750a 1 1 8W comp 20a 5 1 2W met ox 8200 5 3W comp 2 7ka 5 1 2W comp 750a 25 1 4W comp ika t5 1 2W met ox 750 5 SW comp 10k 5 1 2W comp 3kn 5 1 2W comp 12kn 45 1 2W comp 3kn 5 1 2W comp 750n 45 1 2W comp l ka 5 1 2W comp 510n 5 1 2W c
33. 5 4 Reference and Bias Voltages Continyed METER NORMAL RIPPLE NORMAL POSITIVE VDC P P MEET MK saa NE In spo fom em KNC Je fee om 8 METER COMMON CHECK IF PROPER INDICATION IS NOT OBTAINED CR35 36 37 38 QII VR3 5 NOTE If the 15V reference voltage is much more negative than normal VR3 and or VR5 open also check Q1 Q7 Z and Z2 for possible damage due to over voltage Table 5 5 Voltage Limit Circuit Troubleshooting NOTE The procedures in this table are designed to be performed after Steps 1 through 5 of Table 5 3 have been performed If it is necessary to independently perform the procedures given in this table first connect short circuit across the output terminals of the supply and then perform Step 5 of Table 5 3 STEP ACTION RESPONSE PROBABLE CAUSE PART VOLTAGE LIMIT LOCKED UP LIMIT LIGHT OFF Attempt to turn on shunt regulator Voltage at test point a Check O35 and O36 for transistors Q35 Q36 by shorting 21 measured from open also check CR31 Q32 collector to emitter TPL1 does not change for open Voltage at test point Proceed to Step 2 21 decreases Attempt to turn on error amplifier Voltage at test point Check O32 for open Q32 by shorting Q34 collector to 21 does not change emitter Voltage at test point Check O34 for open O33 21 decreases for short R75 for open Q30 Q31 for open or missing stra
34. 5V IW 3 A4 HEAT SINK BOARD 0686 1015 0686 1005 EB 1015 EB 1005 fxd comp 1004 5 1 2W 1 fxd comp 10 25 1 2W I FRONT PANEL ASSEMBLY ELECTRICAL 2140 0047 Line Indicator Lamp Neon l ALC Voltage Limit Indicator Lamp incand Amber l 1450 0305 MCL A3 1730 Tip Jack Panel Mount White Meter 1251 2440 105 601 6 8 MER HP CODE PART NO RS 28480 1510 0094 28480 1510 0522 REF DESIG DESCRIPTION MFR PART NO 5 Way Binding Post Red 1 5 Way Binding Post Black 1120 1151 1120 1157 28480 28480 Voltmeter 3 1 2 0 360V Ammeter 3 1 2 0 120mA 1251 2441 Tip plug white Meter 105 301 74970 var ww 10k 5 10 Turn 2W Current Control mold car 250ka 10 Voltage Control fxd comp 47kn 5 1 2W 28480 2100 1866 2100 2909 0686 4735 28480 01121 EB 4735 3101 1605 3100 1935 09353 28480 Line switch SPDT Toggle 7101PYZI Current Range witch Rotary REAR PANEL ASSEMBLY ELECTRICAL 5 Way Binding Post N P Brass Ground 137 1510 0044 Fuse Cartridge 1A 125V Slow Blow Fuse Cartridge 0 5A 250V Slow Blow Type 3AG 313 0015 2110 0007 Type 3AG 313 5005 2110 0202 1251 2357 Receptable Input Power 8120 1348 Power Cord
35. A R115B is another turn on turn off diode it allows C32 to charge up rapidly when the supply ls first turned on thus allowing the voltage limit circuit to take effect before the series regulator is activated 4 64 VOLTAGE LIMIT PROGRAMMING CURRENT SOURCE 4 65 The voltage limit programming current source provides the programming current that flows through VOLTAGE control R75 and resistors R85 R86 and R84 R87 This current produces a voltage drop across R84 R87 exactly equal to the voltage drop across VR12 The output of the programming cur rent source is always greater than the current value required to satisfy the above condition any addi tional current flows through VR8 and CR20 into the shunt regulator Note that this excess current is actually necessary to maintain the voltage limit circuit s regulation since the current through the shunt regulator must be variable in order to allow the feedback loop to reach a stable regulating con dition During rapid down programming diode CR20 becomes back biased because the voltage at the top of R75 is falling faster than C25 can dis charge through the shunt regulator allowing the excess current to flow through the programming potentiometer and R84 R87 The programming cur rent source thus limits the maximum current that can flow through R75 R85 R86 and R84 R87 If CR20 were not present in the circuit C25 would discharge through these components possibly damaging R75 4 66 T
36. Attempt to turn on light by shorting Light does not go on Q21 base to emitter Light goes on Table 5 8 Adjustments Necessary After Replacement of Semiconductor Devices ADJUSTMENT REFERENCE CIRCUIT ADJUST PARAGRAPH CR20 Voltage limit programming current source R86 R87 5 5 69 5 72 5 5 69 5 72 Constant current comparator Rll Constant current comparator zero adjust Q7 Programming guard supply R29 Guard zero adjust VR4 Reference supply 6 2V reference R32 Adjustment of R11 and R29 must be checked before R32 is adjusted VR8 Voltage limit programming current source R86 R87 5 72 5 47 REPAIR AND REPLACEMENT 5 49 It is recommended that a low power soldering iron 50 watts maximum be used on this instrument 5 48 Section VI of this manual contains a list of The use of a solder sucker greatly simplifies replaceable parts If the part to be replaced does component replacement especially where multi not have a standard manufacturer s part number it lead parts are concerned In addition only high is a special part and must be obtained directly quality rosin core solder should be used when re from Hewlett Packard After replacing a semicon pairing the printed circuit boards ductor device refer to Table 5 8 for necessary checks and adjustments 5 50 To facilitate repair the main A2 printed circuit board in this instrument can be placed ver tically on edge to allow ea
37. C2 C4 05 C33 and R4 provide gain and phase compensation for the stage At turn on diodes CR50 and CR51 clamp the output of amplifier Z until the series regulator is turned on and the cur rent feedback loop stabilizes This prevents C2 from charging up to 12 4 volts and delaying the start of regulation until it discharges The amplifier acts as a variable current sink for the drive current supplied tothe series regulator through transistor 022 in the turn on tum off control see Paragraph 4 47 For example if the sampling resistor voltage drop is momentarily higher than the output voltage of the programming guard supply amplifier Z1 increases its conduction and diverts more drive current away from the series regulator causing a corresponding decrease in the regulated output current This de crease causes the sampling resistor voltage to drop returning the differential amplifier to a balanced condition Diode CR17 connected in the error am plifier s output line prevents the amplifier output from reversing and driving current into the series regulator such current would generate an unwanted turn on signal 4 46 TURN ON TURN OFF CONTROL 4 47 The turn on turn off control consists of a pair of long time constant networks that allow the supply to achieve a gradual turn on and turn off characteristic by controlling the drive current to the series regulator The source of the drive cur rent is the 12 4V reference voltage
38. DC COUPLED SWITCH n3253 2 MERCURY RELAY CLARE TYPE HGP 1002 OR WE 276B CAN SE USED TO PROGRAM THE SUPPLY TRANSISTOR SWITCHING NETWORK CAN ALSO BE USED PARTICULARLY IF 60Hz LEAKAGE MAKES WAVEFORM DIFFICULT TO OBSERVE IL SVAC 60Hz REPETITIVE LOAD S SWITCH NOTE i Figure 5 7 Programming Speed Test Setup 100 2 3 4 5 6 TIME MS Figure 5 8 Up Programming Speed Waveform d Allow one hour warm up adjust CURRENT control to obtain front panel ammeter reading of ex actly 100 and then record differential voltmeter reading e Over 8 hours differential voltmeter reading should not vary by more than 1 25mV f Repeat Steps d and e with both range switches set to middle current position and differ ential voltmeter connected to R32 g Repeat Steps d and e with both range switches set to lowest current position and differ ential voltmeter connected to Rg3 5 34 Temperature Coefficient Definition The change in output cur rent per degree Centigrade change in the ambient temperature under condi tions of constant input ac line volt age output current setting and load resistance 5 35 The temperature coefficient of the supply is measured by placing the supply in an oven and varying it over any temperature span within the operating range of O to 55 C The external test setup current sampling resistors ot Bai and Rg3 should not be placed in the oven but instead must be
39. Decadial Current Control 3 Digit Decadial 07716 1140 0020 NOTE There is no direct commercial replacement for transistors Q35 and Q36 For these transistors the 6186C uses RCA 2N5240 s that are selected for BVCEO ICER and Ig p second breakdown The specifications and test conditions for these characteristics are tabulated below BVCEO 375V min ic 100mA pulse loading imA max Vcg 375V Rygg 200a case temp 125 Vor 300V T I sec case temp 0 C to 125 C ICER Ig b 25maA min A4 Heatsink Board Figure 7 1 SECTION Vil CIRCUIT DIAGRAMS This section contains component location dia grams and a schematic diagram of the power supply The component location diagrams show the physi cal locations and reference designators of parts mounted on the printed circuit boards and chassis The schematic diagram illustrates the circuitry of the entire power supply Voltages are given in italics adjacent to test points which are iden tifled by circled numbers both on the schematic and on the component location diagrams Component Location Diagrams 7 1 AER ve ASA BOR SA Ky vi Figure 7 2 Chassis Component Location Diagr m FSE
40. INE DIAGRAM 2 12 Figure 2 1 illustrates the outline shape and dimensions of the 6186C supply ba E 15 758cm EK 30 87cmi iB 48cm Figure 2 1 Outline Diagram 2 13 RACK MOUNTING 2 14 This instrument may be rack mounted in standard 19 inch rack panel either alongside a similar unit or by itself Figure 2 2 shows how both types of installations are accomplished CLAMP RETAINING SCREWS E R MODULE INSTRUMENT OR FILLER PANEL STOCK NOG 50808760 DIVIDER AND END CLAMPS 7 ADAPTOR FRAME STOCK NO 5060 8762 Figure 2 2 Rack Mounting One and Two Units 2 15 To mount one unit alone or two units side by side proceed as follows a Place adaptor frame on bench b Remove feet and tilt stand from 2 1 instrument s Place instrument s in frame c Place divider clamp between instruments If mounting one instrument alone place blank panel in position that would be occupied by second instrument d Place divider clamps in position on each end and push the instrument or instrument blank panel combination into frame e Insert screws on either side of frame and tighten 2 16 INPUT POWER REQUIREMENTS 2 17 This power supply may be operated continu ously from either a nominal 115 volt or 230 volt 48 63Hz power source The input power required when operating from a 115 volt 60Hz power source at full load is 90 watts 0 9 amperes 2 18 115 230 VOLT OPERATION
41. NOMINAL OUTPUT CURRENT NOMINAL e OUTPUT CURRENT mm i im SEG ai TIME fe UNLOADING TRANSIENT LOADING TRANSIENT Figure 5 6 Load Transient Recovery Time Waveforms 5 29 Programming Speed Definition The time usecs required for the output current to change from zero amps to within X milliamps of the maximum rated output or from maximum rated output to within X millamps of zero X is generally of the same order as the load regula tion specification 5 30 To check the constant current remote pro gramming speed proceed as follows a Connect test setup shown in Figure 5 7 b Turn VOLTAGE control fully clockwise c Set RANGE switch to 100mA position and turn on supply d Adjust CURRENT control until front panel meter indicates exactly 100mA e Close line switch on mercury wetted relay and observe waveform on oscilloscope Rise time indicates up programming speed and fall time indicates down programming speed f Programming speed should be within tol erances of Figure 5 8 Output should rise from zero to 297 volts within 10 milliseconds Fall time down programming should be almost identical to rise time shown in Figure 5 8 except for inversion 5 31 Drift Stability Ge JET Definition The change in er curs rent for the first 8 hours following a one hour warm up period During the interval of measurement all parameters such as load resistance output set ting ambient temperature and inp
42. RE 5 3 AND TABLE 5 1 FOR HIGH FREQUENCY MEASUREMENTS LOW INDUCTANCE RESISTORS SHOULD BE USED Figure 5 4 High Frequency Ripple and Noise Test Setup 5 24 Load Transient Recovery Time Definition The time X for output current recovery to within Y milliamps of the nominal output cur rent following a Z amp step change in load voltage where Y is generally of the same order as the load regulation specification the nominal output current is defined as the dc level halfway between the Static output current before and after the imposed load change and Z is the specified load voltage change normally equal to the full load volt age rating of the supply 5 25 Transient recovery time may be measured at any input line voltage combined with any output voltage and load current within rating 5 26 Reasonable care must be taken in switching the load resistance on and off A hand operated switch in series with the load is not adequate since the resulting one shot displays are difficult to observe on most oscilloscopes and the arc energy occurring during the switching action com pletely masks the display with a noise burst Transistor load switching devices are expensive if reasonably rapid load current changes are to be achieved POWER SUPPLY i UNDER TEST OSCILLOSCOPE 6 O00 CONTACT PROTECTION NETWORK 4302 5W OO0 L F S00V wirEWOUND tk THIS DRAWING SHOWS A SUGGESTED METHOO OF B
43. Sealectro Corp Mamaroneck N Y ETC Inc Cleveland Ohio International Electronic Research Corp Burbank Calif Boston Mass Franklin Ind Chicago NL Table 6 4 Replaceable Parts REF MFR DESIG DESCRIPTION TQ MFR PART NO CODE ike NO Al INPUT BOARD G25 fxd elect 10 F 450Vdc 1 28480 0180 2365 1 C29 fxd ceramic 1 OuF 220Vac 1 28480 0160 3679 1 30 31 fxd elect 300uF 250Vdc 2 28480 0180 1886 l C32 txd elect 80u F 300Vdc i 28480 0180 1851 1 C34 fxd ceramic OlpF 500V l 28480 0150 0081 l C35 fxd elect 490uF 85Vdc 1 28480 0180 1888 1 C36 fxd elect 68uF 15Vdc 1 150D686X0015R2 56289 0180 1835 1 C37 fxd film luF 500Vdc I 28480 0160 0269 l 03508 03508 03508 1901 0330 1901 0327 1901 0330 A14N A14B A14N CR32 33 CR35 38 OR46 700mA 800prv Rect Si IA 200prv Rect Si 700mA 800prv GER fxd met ox 150ks 5 2W Type C 428 16299 0764 0049 R112 113 fxd comp 10n 5 1 2W EB 1005 01121 0686 1005 R114 fxd comp 2700 5 1 2W EB 2715 91121 0686 2715 R117 fxd comp 1004 5 3W 242E1015 56289 0813 0050 R119 var ww 100a 20 Ripple Adj Type 110 F4 11236 2100 0281 SZ10939 74 04713 1902 3070 VR16 17 Diode zener 4 22V 400mW A2 MAIN BOARD
44. UILDING amp LOAD SWITCH HOWE VER OTHER METHODS COULD BE USED SUCH AS A TRANSISTOR SWITCHING NETWORK MAXIMUM LOAD RATINGS OF LOAD SWITCH ARE SAMPS 500V 250W NOT 2500W USE MERCURY RELAY CLARE TYPE HGF 1002 OR WE TYPE 2768 USVAC 60Hz REPETITIVE LOAD SWITCH NOTE I Load Transient Recovery Time Test Setup Figure 5 5 5 27 A mercury wetted relay connected in the load switching circuit of Figure 5 5 should be used for loading and unloading the supply When this load switch is connected to a 60Hz ac input the mercury wetted relay will open and close 60 times per second Adjustment of the 25K control permits adjustment of the duty cycle of the load current switching and reduction in jitter of the os cilloscope display 5 28 To check the load transient recovery time of the supply proceed as follows a Connect test setup shown in Figure 5 5 b Turn VOLTAGE control fully clockwise c Set front panel RANGE switch to 100mA position and turn on supply d Adjust CURRENT control until front panel ammeter indicates exactly 100mA e Close line switch on repetitive load switch setup f Adjust 25K potentiometer until stable display is obtained on oscilloscope Recovery waveform should be within tolerances shown in Figure 5 6 Output should return to within 100mV of nominal value in less than 1 millisecond UNLOADING we TRANSIENT NOMINAL OUTPUT CURRENT LOADING 7 TRANSIENT im SEC
45. Voltmeter Oscilloscope DC Volt Ammeter Repetitive Load Switch Resistive Loads Table 5 1 REQUIRED CHARACTERISTICS Sensitivity lmV full scale min Input impedance 10 Resolution megohms min I ppm of range Range 90 130 volts Output current 2 amperes min Equipped with voltmeter ac curate within 1 volt True rms Sensitivity 0 lmV full scale deflection min Accuracy 2 Differential input Sensitivity and bandwidth L00uV em and S00kHz for general measure ments 5mV sensitivity and 50MHz bandwidth for noise spike measurement or to check for high frequency oscillation Voltage sensitivity ImV full scale min Current sensi tivity lmA full scale min Accuracy 2 Switching Rate 60 400Hz Rise time 2usec Values See Figure 5 3 30W 3 0 3W RLI 2 3 must be noninductive She Test Equipment Required Measure dc voltages cali bration procedures Vary ac input Measure ac voltages and rms ripple Measure ripple display transient response wave forms measure noise spikes Measure de voltages and currents Measure transient response and programming speed Power supply load resis tors RECOMMENDED MODEL HP 3420A B See Note HP 3400A i HP 180A with 1821A time base and 1806A vertical plug in 1801A plug in for measure ments requiring a wide bandwidth HP 412A See Figures 5 5 and 5 7 Table 5 1 Test E REQUIRED
46. amming current and thus the programming co efficient can also be checked and adjusted if necessary before remote resistance programming the supply NOTE To obtain an accurate adjustment al ways zero the constant current compa rator and guard amplifier Paragraphs 5 61 and 5 63 before making this ad justment 5768 To adjust the constant current programming current proceed as follows a Connect test setup shown in Figure 5 3 b Set both range switches to highest cur rent range connect lead of differential voltmeter to Rg and turn VOLTAGE control fully clockwise c Remove strap between terminals Al and A2 and connect precision programming resistor 10ka 0 1 between terminals AO and Al d Connect decade resistance box in place of R32 mounted on standoffs on main circuit board see Figure 7 3 e Turn on supply and adjust decade resist ance box for reading of 10 0 025Vdc on differential voltmeter f Turn off supply and replace decade resist ance box with appropriate value 5 3W wire wound resistor in R32 position NOTE Due to the limited range of 3 watt re sistor values available it may be nec essary to select a resistor value that gives an output voltage of slightly less than 9 975Vdcand thentrim the voltage towithin 10 0 025Vde by adding a 1 8 watt 100ppm metal film resistor in parallel with the 3 watt resistor 5 69 VOLTAGE LIMIT PROGRAMMING CURRENT 9 70 This procedure adjusts the
47. anel RANGE switch and external test setup range switch 51 to highest current position 100mA and HI respectively connect terminal of differential voltmeter to Rg and turn on supply d Adjust current control until front panel ammeter reads exactly 100 e Read and record voltage indicated on differential voltmeter f Short out load resistor RL by closing switch 52 g Reading on differential voltmeter should not vary from reading recorded in Step e by more than 300uVdc h Repeat Steps d through g with both range switches set to middle current range lOmA and MED and differential voltmeter connected to Rg2 i Repeat Steps d through g with both range switches set to lowest current range imA and LO and differential voltmeter connected to Rg3 5 15 Source Effect Line Regulation Definition The change lot in the static value of dc output cur rent resulting from a change in ac input voltage over the specified range from low line 104 or 208 volts to high line 127 or 254 volts or from high line to low line 5 16 To check the constant current line regulation on all three current ranges proceed as follows a Connect test setup shown in Figure 5 3 In addition connect variable autotransformer be tween input power source and power supply power input b Tum VOLTAGE control fully clockwise c Set both range switches to highest cur rent position connect differential voltmeter to Hai an
48. appear damaged or defective should be made inoperative and secured against unintended operation until they can be repaired by qualified service personnel SECTION I GENERAL INFORMATION 1 1 DESCRIPTION 1 2 This power supply is designed for applica tions requiring a constant current source possess ing a high degree of regulation and stability and very low ripple characteristics Typical applica tions for this power supply include semiconductor device measurements such as transistor reverse breakdown voltage and current transfer ratio four terminal resistance measurements testing compo nents such as diodes and electrolytic capacitors and various other applications in electrochemistry electromagnetics and other fields For detailed applications information refer to Application Note 128 Applications of a DC Constant Current Source available at no charge from your local Hewlett Packard sales office 1 3 The supply is completely transistorized all silicon and is suitable for either bench or rack operation It is of the constant current voltage limit type that will furnish full rated output cur rant at the maximum rated output voltage or can be adjusted throughout the output range The front panel CURRENT control is used to establish the output current level the front panel VOLTAGE con trol is used to establish the output voltage limit ceiling Both the CURRENT and VOLTAGE con trols are continuously variable throughout the
49. aul Minn 59730 IThomas and Betts Co Philadelphia Pa 76385 Minor Rubber Co Inc Bloomfield N J 61637 Union Carbide Corp New York N Y 76487 James Millen Mfg Co Inc 83743 Ward Leonard Electric Co Malden Mass Mt Vernon N Y 76493 IT W Miler Co Compton Calif Use Code 71785 assigned to Cinch Mfg Co Chicago fll 6 3 76530 76854 77068 77122 77147 77221 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 83298 83385 83501 Table 6 3 MANUFACTURER ADDRESS Cinch Oak Mfg Co Div of Oak Electro Netics Corp Crystal Lake 111 Bendix Corp Electrodynamics Div No Hollywood Calif Palnut Co Mountainside N J Patton MacGuyer Co Providence R L 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 Electronic Components Div Camden N J Resistance Products Co Harrisburg Pa Illinois Tool Works Inc Shakeproof Div Elgin IL Everlock Chicago Inc Chicago Ill Stackpole Carbon Co St Marys Pa Stanwyck Winding Div San Fernando Electric Mfg Co Inc Newburgh N Tinnerman Products Inc Cleveland Ohi Stewart Stamping Corp Yonkers Waldes Kohinoor Inc LC Whitehead Metals I
50. basis 4 37 The programming guard supply consists of a differential amplifier and associated constant cur rent source Q7A Q7B and Q5 an error amplifier 22 and an output regulator Q8 and Q9 The differential amplifier consists of two matched sil icon transistors housed in a single package this configuration minimizes thermal differential drift since both transistors operate at the same temper ature Transistor Q5 connected as a constant l current source biases the emitters of both transis tors in the package Q5 is biased with the com bination of VR1 and R34 these components are shared with Q4 in the constant current comparator One input of the differential amplifier Q7A base is connected to the circuit common point through resistor R30 The other input Q7B base is con nected to a summing point terminal Al at the junction of programming resistor R15 and current pullout resistors R31 andR32 Diodes CR7 CR8 and CR49 forma limiting network that protects the input from overvoltage Potentiometer R29 GUARD ZERO ADJUST allows the differential amplifier base to base voltage to be balanced by varying the ratio of the differential amplifier s collector currents 4 38 Instantaneous changes in the eutput of the programming guard supply terminal A0 result in an increase or decrease in the summing point po tential this unbalances the differential amplifier and produces an error signal The error signal is amplified and
51. ceed as instructed in the following paragraphs 2 3 MECHANICAL CHECK 2 4 If external damage to the shipping carton is evident ask the carrier s agent to be present when the instrument is unpacked Check the in strument for external damage such as broken con trols or connectors and dents or scratches on the panel surfaces If the instrument is damaged file a claim with the carrier s agent and notify your local Hewlett Packard Sales and Service Office as soon as possible see list at rear of this manual for addresses 2 5 ELECTRICAL CHECK 2 6 Check the electrical performance of the in strument as soon as possible after receipt Sec tion V of this manual contains performance check procedures which will verify instrument operation within the specifications as stated in Table 1 1 This check is also suitable for incoming quality control inspection Refer to the inside front cover of the manual for the Certification and Warranty statements 2 7 INSTALLATION DATA 2 8 The instrument is shipped ready for bench operation It is necessary only to connect the in strument to a source of power and it is ready for operation 2 9 LOCATION 2 10 This instrument is cooled by natural convec tion Sufficient space should be allotted 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 tem perature remains between 0 C and 5500 2 11 OUTL
52. ction of the protective earth terminal will cause a potential shock hazard that could result in personal injury If the instrument is to be energized via an external autotransformer for voltage reduction be certain that the autotransformer common terminal is connected to the neutral earthed pole of the ac power lines supply mains INPUT POWER MUST BE SWITCH CONNECTED For instruments without a built in line switch the input power lines must contain a switch or another adequate means for disconnecting the instrument from the ac power lines supply mains DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE Do not operate the instrument in the presence of flammable gases or fumes KEEP AWAY FROM LIVE CIRCUITS Operating personnel must not remove instrument covers Component replacement and internal adjustments must be made by qualified service personnel Do not replace com ponents with power cable connected Under certain condi tions dangerous voltages may exist even with the power cable removed To avoid injuries always disconnect power discharge circuits and remove external voltage sources before touching components DO NOT SERVICE OR ADJUST ALONE Do not attempt internal service or adjustment unless another person capable of rendering first aid and resuscitation is present DO NOT EXCEED INPUT RATINGS This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a pro
53. cuit can be completely isolated by lifting the cathode of CR21 Isolate programming guard supply by lifting one end each of jumper Jl and diode CR43 Check operation of programming guard supply by connecting external volt meter between terminal AO and terminal A3 Vary front panel CURRENT control a One or more reference volt ages zero or much higher than correct value One or more reference volt ages slightly low All reference voltages cor rect within given toler ances Voltage at test point 21 does not change Voltage at test point 21 varies from zero to approximately 315Vdc Voltage indi cated on exter nal voltmeter does not change Voltage indi cated on exter nal voltmeter varies from approximately 0 7 to 10 5V de Front panel ammeter should follow external volt meter ACTION RESPONSE REACTION Troubleshoot reference circuit as directed in Table 5 4 under particular reference voltage After establishing proper refer ence voltages proceed to Step 5 Slightly low voltages are usually caused by loading due to a defect in a circuit other than the reference supply Proceed to Step 5 Proceed to Step 5 Voltage limit circuit is de fective Perform trouble shooting procedures given in Table 5 5 After estab lishing proper operation Response b proceed to Step 6 Voltage limit circuit is op erative Pr
54. d differential voltmeter connected to Rg3 5 12 Voltage To check the output voltage pro ceed as follows a Connect test setup shown in Figure 5 3 except connect differential voltmeter between METER and output terminals or between AO and output terminals see Figure 3 7 Leave switch S2 open throughout test b Set front panel RANGE switch to 100mA position and set external test setup range switch Si to high position c Turn VOLTAGE control fully clockwise 5 3 LOAD POWER SUPPLY RESISTORS UNDER TEST CURRENT SAMPLING RESISTORS SI RANGE MAKE BEFORE BREAK CONTACTS DIFFERENTIAL VOLTMETER aa H MEDIUM RANGE ODEL NO SCH or 39 sk Ik 61860 gt tor lasok Pigure 5 3 Output Current Test Setup and turn on supply d Adjust CURRENT control until front panel voltmeter indicates exactly 300Vdc e Differential voltmeter should read 300 7 2Vde If it does not refer to voltmeter calibra tion procedure in Paragraph 5 57 5 13 Load Effect Load Regulation Definition The change Alour in the static value of the de output current resulting from a change in load resistance from short circuit to a value which yields maximum rated output voltage 5 14 To check the constant current load regulation on all three output current ranges proceed as fol lows a Connect test setup shown in Figure 5 3 b Turn VOLTAGE control fully clockwise c Set both range switches front p
55. d negative output ter minals AO Al A2 A od POWER SUPPLY Figure 3 7 External Voltage Monitoring NOTE The external voltmeter must not draw more than lmA from the programming guard supply the AO or METER ter minal A current drain in excess of lmA will seriously impair the opera tion of the power supply 3 33 EXTERNAL AC MODULATION 3 34 Figure 3 8 shows a method of superimposing an ac component on top of the adjustable de output current of the supply The de current level is con trolled in the normal fashion from the front panel while the ac component of the output current is determined by the modulation percentage The percentage of modulation is determined by the am plitude of the external voltage input and the value of the series resistance according to the following formula Modulation 100 Esource p p Rx in Ke The programming voltage appearing across terminals Al and A3 should be limited to 10V p p and must not exceed 12 volts if damage to the instrument is to be avoided Using the above formula the user would require an external resistance of 2Ka and a 4 volts peak to peak in put signal from the external source to modulate a de current level of 50mA by 100 In this case the output current would swing between 100mA and zero amperes The output current should never be allowed to swing beyond the rating of the supply 100mA or clipping of the output and possible in ternal dama
56. d turn on supply d Adjust autotransformer for a low line in put e Adjust CURRENT control until front panel ammeter reads exactly 100 f Read and record voltage indicated on dif ferential voltmeter g Adjust autotransformer for a high line in put h Reading on differential voltmeter should not vary from reading recorded in Step f by more than 300uVdc i Repeat Steps d through h with both range switches set to middle current range and differential voltmeter connected to Rg2 j Repeat Steps d through h with both range switches set to lowest current range and differential voltmeter connected to Rg3 5 17 PARD Ripple and Noise Definition The residual ac current which is superimposed on the dc output current of a regulated supply Ripple and noise is specified and measured in terms of both its rms and peak to peak value 5 18 RMS Measurement To check the rms ripple and noise on all three current ranges proceed as follows a Connect test setup shown in Figure 5 3 substituting true rms ac voltmeter for differential voltmeter neither terminal grounded and connect ing positive terminal of supply to ground NOTE To prevent extraneous 60Hz pickup the external range switch 1 and load resistors Ry and Rg should be en closed in a shielded box In addition the leads connecting the sampling re sistor to the ac voltmeter should be twisted or shielded b Turn VOLTAGE control fully clockwise c
57. dapter to ground 2 24 REPACKAGING FOR SHIPMENT 2 25 To insure safe shipment of the instrument it is recommended that the package designed for the instrument be used The original packaging mate rial is reusable If it is not available contact 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 specifying the owner model num ber full serial number and service required ora brief description of the trouble SECTION Ill OPERATING INSTRUCTIONS Figure 3 1 3 1 TURN ON CHECKOUT PROCEDURE 3 2 The following checkout procedure describes the use of the front panel controls and indicators and ensures that the meter and programming cir cuits are operable Actual output current should be checked with an external ammeter connected between the positive and negative output terminals before connecting delicate loads a Set LINE switch QD to ON and observe that LINE light goes on b Set RANGE switch to desired current range c Adjust CURRENT control 4 until front panel ammeter indicates desired output current no load connected Operating Controls and Indicators d Adjust VOLTAGE control 6 until front panel voltmeter indicates desired voltage limit a VOLTAGE LIMIT lamp 8 should be on with no load connected f Connect load to front or rear output ter
58. diodes VRI 01 through VRL06 protect each of these three series stages from excessive voltage due to the unequal voltage division that might occur during a transient caused by shorting the out put Note that the use of Darlington pairs in this circuit reduces the power dissipation in the bias network since the drive current of Q26 and 927 flows through Q24 and Q25 instead of R73 and R72 4 52 Diode CR18 limits the reverse bias on the base emitter junction of Q29 CR19 provides a path for the series regulator bleed current at turn on through the 29V unregulated reference supply voltage to circuit common C20 and R70 shape the frequency response of the series regulator 4 53 BLEED CIRCUIT 4 54 The bleed circuit maintains a continuous current flow through the series regulator keeping it on and in its active region at all times The circuit has two internal current paths an active path and a passive path Resistors R100 and R101 connected from 29V to the negative output bus and thus effectively from circuit common to the negative output bus form the passive path These resistors draw a current through the series regulator whose magnitude is proportional to the supply output voltage 4 55 In order to maintain the bleed current ata relatively constant value over the complete range from no load to full load another current path active is provided by transistors Q37 and Q39 These transistors form a variable current
59. e determined by the voltage programming coefficient given in Table 1 1 The entire voltage span for the programming source is approximately 0 10 volts The programming voltage should never be allowed to exceed 12 volts Voltages in excess of this will result in excessive power dissipation in the instrument and possible damage 3 23 The lmA programming current flowing into terminal Al from the reference supply see sche matic imposes two restrictions in the voltage programming mode The first restriction is that the voltage source must be capable of sinking absorb ing this lmA current the second restriction is that if the programming terminals are opened the lmA programming current will cause the output cur rent to rise to an excessive level refer to CAUTION note of Paragraph 3 20 A protection resistor previously mentioned in the CAUTION note can be employed to limit the output current to a safe value under any conditions AO AI AS A VOLTAGE SOURCE Remote Voltage Programming Constant Current Figure 3 4 3 24 If the user s voltage source cannot sink the imA programming current the programming cur rent path to terminal Al can be opened by removing resistor R32 mounted on standoffs from the main printed circuit board This does not detract from the voltage programming performance in any way but does eliminate the need for sinking the pro gramming current Opening R32 also eliminates the need for an open
60. e output span OUTPUT TERMINALS Positive and negative output meter positive and ground terminals are provided on the front panel Two rear barrier strips include output guard and other terminals necessary for remote programming ac modulation and other control functions Either the positive or the negative output terminal may be grounded or the supply may be floated at up to 300 volts above ground PROGRAMMING SPEED Less than lOmsec is required to program from zero to 99 of the maximum rated output current of each range or from the maximum rated output current of eachrange to less than 1 of that current REMOTE PROGRAMMING CONSTANT CURRENT Programming Source Resistance Accuracy 1 of output 0 04 of range Voltage Accuracy 0 5 of output 0 04 of range REMOTE PROGRAMMING VOLTAGE LIMIT Remote programming of the voltage limit at l volt per volt accuracy 20 or 820 ohms per volt with an accuracy of 15 or 3V whichever is greater is available at the rear terminals COOLING Convection cooling is employed the supply has no moving parts SIZE 6 17 32 15 76 cm H x 12 3 8 30 87 cm Dx 7 3 4 19 7 cm W WEIGHT 13 lbs 5 9 Kg net 17 lbs 7 7Kg shipping SECTION II INSTALLATION 2 1 INITIAL INSPECTION 2 2 Before shipment this instrument was in spected and found to be free of mechanical and electrical defects As soon as the instrument is received pro
61. e very high gain of the amplifi er holds the two inputs to the amplifier equal therefore since one input is connected to circuit common summing point S is held at zero potential virtual ground From the above state ments the standard gain expression for an opera tional amplifier is easily derived as EG Er RQ Rp This equation indicates that the output voltage EG of the programming guard supply is linearly depen dent upon the setting of the current control RQ doubling the value of RQ doubles the output volt age Thus linear control of the regulated output current is assured 4 17 MAIN CURRENT REGULATOR 4 18 As discussed in Paragraph 4 3 the output of the programming guard supply provides the pro gramming voltage Eg for the main current regula tor This dc voltage negative with respect to cir cuit common is applied to one of the inputs of the constant current comparator The other input is connected to the current sampling resistor Ry The constant current comparator continuously com pares the voltage drop across the current monitor ing resistor IouTRM with the programming volt age Eg If these voltages are momentarily un equal due to a load disturbance or change in the output current control setting the error voltage is amplified and applied to the series regulator tran sistors altering the current conducted through them and forcing the voltage drop IouTRM to once again equal EG 4 19 The o
62. ed at the end of Table 6 4 under Me chanical and or Miscellaneous The former consists of parts belonging to and grouped 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 part not listed in Table 6 4 give a complete description of the part iis function and its location Table 6 1 Reference Designators assembly miscellaneous blower fan electronic part capacitor fuse circuit breaker jack jumper diode relay inductor meter device signal ing lamp Table 6 1 plug transistor resistor switch transformer terminal block thermal switch Table 6 2 ampere alternating current assembly bd board bracket oC cd coef comp ORT GT de DPDT DPST elect encap F OF fxd Ge H Hz degree entigrade card coefficient composition cathode ray tube center tapped direct current double pole double throw double pole single throw electrolytic encapsulated farad de
63. ed to Rs3 5 38 TROUBLESHOOTING 5 39 Before attempting to troubleshoot this instru ment insure that the fault is with the instrument and not with an associated circuit The perform ance test Paragraph 5 5 enables this to be deter 5 8 mined without removing the instrument s covers 5 40 A good understanding of the principles of operation is essential for effective troubleshooting it is recommended that the reader study at least Paragraphs 4 1 through 4 28 of Section IV if not the entire section Once the principles of operation are understood refer to the overall troubleshooting procedures in Paragraph 5 43 to locate the symp tom and its probable cause 5 41 The schematic diagram at the rear of the manual Figure 7 4 contains normal voltage read ings taken at various points within the instrument Note 12 on the Schematic gives the measurement conditions These voltages in italics are posi tioned adjacent to the applicable test points iden tified by encircled numbers The component loca tion diagrams Figure 7 1 through 7 3 at the rear of the manual should be consulted to determine the location of components and test points 9 42 If a defective component is located replace it and re conduct the performance test When a component is replaced refer to the Repair and Re placement Paragraph 5 47 and Adjustment and Calibration Paragraph 5 51 sections of this man ual 5 43 OVERALL TROUBLESHOOTING PROCEDURE
64. en terminals A0 and Ai Set the CURRENT control for 100mA and open circuit the output terminals Vary the VOLTAGE control if the DVM reading varies the programming guard amplifier is eliminated as a possible source of trouble f Internal or external current leakage path between positive and negative output terminals Poor line regulation a Improper measurement technique Refer to Para graph 5 15 b Defectinreference supply Referto Table 5 4 High ripple a Improper measurement technique Refer to Para graph 5 17 b Ground loops in operating setup c Ripple Adjust control R119 set incorrectly Refer to Paragraph 5 59 1 d Differential amplifier Q1 defective e Leaky filter capacitors C30 and or C31 Table 5 2 Overall Troubleshooting Continued SYMPTOM Oscillation Instability PROBABLE CAUSE a Operational amplifiers Z1 or Z2 defective a Differential amplifiers Q1 or Q7 defective Table 5 3 Series Regulator Programming Guard Supply and Constant Current Comparator Isolation and Initial Troubleshooting STEP ACTION RESPONSE REACTION Isolate series regulator as follows a Set RANGE switch to 100mA and VOLTAGE control fully clockwise b Connect ammeter or short circuit Bras with clip on probe or 1004 10W resistor and voltmeter across output terminals c Remove Z1 from socket d Connect a 5Ka pot across CRI8 as shown in sketch at right Set the po
65. esired the voltage limit should be set for the peak requirement and not the aver age 3 40 REVERSE VOLTAGE LOADING 3 41 Diodes VR6 and CR43 are connected in 3 6 series internally across the supply Under normal operating conditions the series combination of these diodes is reverse biased fanode connected to the negative output terminal Ifa reverse volt age is applied to the output terminals positive voltage applied to the negative output terminal the diode combination will conduct shunting cur rent through it These diodes protect the series regulator transistors SECTION IV PRINCIPLES OF OPERATION 29V UNREGULATED LIZ AV 7 5V ECK W REFERENCE SUPPLY TURN ON TURN OFF CONTROL TRANSFORMER RECTIFIER AND FILTER SERIES REGULATOR PROGRAM MING GUARD SUPPLY CURRENT CONTROL g CONSTANT CURRENT COMPARATOR amp ERROR lt RANGE DOMA SWITCH o d Nan CURRENT Wi SAMPLING RESISTOR CIRCUIT COMMON VOLTAGE LEMIT LAMP GIRCUIT CURRENT BLEED CIRCUIT METER CIRCUIT VOLTAGE LIMIT CONTROL VOLTAGE LIMIT aa DENOTES FEEDBACK PATH Figure 4 1 4 1 OVERALL BLOCK DIAGRAM DISCUSSION 4 2 The major circuits of the power supply are shown in Figure 4 1 The input ac line voltage passes through the power transformer and is con verted by the rectifier and filter to raw or un regulated dc This raw dc is applied to the series regulator which
66. fed to the programming guard sup ply s output regulator which alters its conduction sufficiently to return the output voltage to its former level selected by the setting of CURRENT control R15 and thus balance the differential am plifier Because the summing point is held at a virtual ground by the high gain of the supply s feedback loop a constant current flows from the 0 2V reference through R31 and R32 this produces a constant current through the programming poten tiometer which insures linear programming Re sistor R33 connected in parallel with R31 and R32 4 6 provides an extra current that allows for the toler ance of R15 this insures full range programming 4 39 Amplifier Z2 is a high gain bipolar output IC operational amplifier Components C7 C9 C10 Cil R25 and R36 provide gain and phase compensation for the stage CR9 and CR10 form a limiting network that protects the input from overvoltage 4 40 The programming guard supply output regu lator is a push pull emitter follower Its function is to maintain the programming guard voltage vari able between 0 and minus 10 volts with respect to circuit common at the level set by the CURRENT control If a change in the CURRENT control set ting requires the voltage to decrease become less negative the positive error signal produced by Z2 drives Q9 into greater conduction and decreases the conduction of Q8 pulling the output voltage to wards 12 4V If the v
67. film 196n 1 1 8W comp 5 Iko 25 1 2W comp 12kn 5 1 2W comp 5la 5 1 2W 6 6 I 9 2 2 10 EA EGEN bel pi pot pra GA ND SG9309 SG3396 A14N 3G3396 STB523 SG3396 ALAN 5G3396 SG3396 AL4N SG3396 Al4N SG3396 AI4N DA2050 5G3396 STB523 A14B FDH6308 2N5416 121200 2N5416 12173 121200 38640 40346 T2173 2N4240 2NIZIIA 40327 KA TZ1200 40327 TZ173 40327 Type Tid Type E30 Type E30 EB 4325 Type CEA T O Type CEA T O Type CEA T O Type CEA T O CT 100 4 Type CEA T O Type CEA T O Type CEA T O Type CEA T O EB 5125 EB 1235 EB 5105 03877 03877 03508 03877 03508 03877 93508 03877 03877 03508 03877 03508 03877 03508 03508 03877 03508 03508 07263 28480 56289 56289 56289 02735 02735 56289 56289 56289 56289 01686 01686 01686 01121 07716 07716 07716 07716 84048 07716 07716 07716 07716 01121 01121 Olizi 1901 0461 1901 0033 1901 0330 1901 0033 1301 0460 1301 0033 1901 0330 1301 0033 1901 0033 1901 0330 1901 0033 1901 0330 1901 0033 1901 0330 1901 0642 1901 0033 1901 0460 1901 0327 1901 0050 9170 0894 1854 0221 1854 0071 1854 0221 1853 0099 1854 0071 1853 0041 1854 0095 1853 0099 1854 0311 1854 0244 1854 0232 1853 0099 1854 007 I 1854 0232 1853 0099 1854 0232 9811 2859 0811 2112 0811 2858 0686 4325 0698 3440 0698 3269 0698 3496 1698 5093 2100 1774 0757 1093 0757 0270 0757 0461 0698 3440
68. functioning pro perly Verify proper oper ation of supply Isolate trouble in constant current comparator to either driver amplifiers Q2 Q3 or input comparator Q1 as follows a If output current is locked up short QlA collector to emitter b If output current is locked down short Q1B collector to emitter Output current does not change Check for defective Q2 3 or 4 After replace ment supply should function normally Ver ify proper operation of supply b Output current decreases if locked up or increases if locked down b Defect in Q1 or Q4 stage After replacement supply should function normally Verify proper operation of supply Table 5 4 Reference and Bias Voltages Refer to Schematic and Figure 7 3 for test point locations NOTE The measurements in this table are designed to be performed after Steps 1 through 3 of Table 5 3 verification of operation of the series regulator have been perform ed If the instrument is operating correctly the correct results will be achieved for these measurements regardless of the performance or non performance of these three steps However if the instrument is not functioning correctly correct measure ment results cannot be guaranteed unless these three steps are performed since a defective seriesregulator will usually affect one or more of the reference voltages Table
69. g 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 33173 G E Co Tube Dept Owensboro Ky 73506 Bradley Semiconductor Corp 35434 Lectrohm Inc Chicago Hil New Haven Conn 37942 P R Mallory 6 Co Inc 73559 Carling Electric Inc Hartford Conn Indianapolis Ind 73734 Federal Screw Products Inc 42190 Muter Co Chicago IIL Chicago Ill 43334 New Departure Hyatt Bearings Div 74193 I Heinemann Electric Co Trenton NT general Motors Corp Sandusky Ohio 74545 Hubbell Harvey Inc Bridgeport Conn 44655 Ohmite Manufacturing Co Skokie IlL 74868 Amphenol Corp Amphenol RF Div 46384 Penn Engr and Mfg Coro Danbury Conn Doylestown Pa 74970 E F Johnson Co Waseca Minn 47904 Polaroid Corp Cambridge Mass 75042 I IRC Div of TRW Inc Philadelphia Pa 49956 IRaytheon Co Lexington Mass 75183 Howard B Jones Div of Cinch 55026 ISimpson Electric Co Div of American Mig Corp New York N Y Gage and Machine Co Chicago Hl 75376 Kurz and Kasch Inc Dayton Ohio 56289 Sprague Electric Co North Adams Mass 75382 Kilka Electric Corp Mt Vernon N Y 58474 Superior Electric Co Bristol Conn 75915 Littlefuse Inc Des Plaines Ill 58849 ISyntron Div of FMC Corp 75381 Minnesota Mining and Mfg Co Homer City Pa St P
70. ge will result A4 AS AG Figure 3 8 External AC Modulation 3 35 The coupling capacitor Co should be chosen so that its reactance is at least ten times smaller than Ry at the frequency of interest For input frequencies up to 50Hz the output of the supply can be modulated 100 Above 50Hz the modulation capability decreases linearly to ap proximately 10 at 500Hz 3 36 It is possible to simultaneously remote re sistance program and externally modulate the dc current output simply by combining the strapping patterns of Figures 3 3 and 3 8 as follows a Connect external modulation source coupling capacitor and series resistor between terminals Al and A3 as shown in Figure 3 8 b Do not connect strap between terminals Al and A c Connect remote programming resistance between terminals AO and Al as shown in Figure 3 3 If it is desired to simultaneously remote voltage program and externally modulate the de current output please consult an HP sales engineer 3 37 SPECIAL OPERATING CONSIDERATIONS 3 38 PULSE LOADING 3 39 The power supply will automatically cross over from constant current operation to voltage limited operation if the output voltage reaches the preset limit due to an increase in load resistance Although the preset limit may be set higher than the average output voltage high peak voltages due to pulse loading may reach the preset limit and cause crossover to occur If this crossover limiting is not d
71. guard supply the differential am plifier consists of two matched silicon transistors in a single package The emitters of the differen tial amplifier are biased by constant current source Q4 as mentioned in Paragraph 4 37 the biasing components for Q4 VR1 and R34 are shared with Q5 in the programming guard supply One input of the differential amplifier Q1B base is connected to the output of the programming guard supply ter minal A0 through jumper J1 used in the trouble shooting procedure the other input Q1A base is connected to the outboard side of the appropriate current sampling resistor Rl R2 and or R3 through R16 and current RANGE switch 2 Diodes CR3 CR4 and CR48 form a limiting network that protects the input from overvoltage R16 limits the peak current that output transients can inject into the programming guard supply through CR3 and also acts as a fuse Potentiometer R11 CONSTANT CURRENT COMPARATOR ZERO ADTUST allows the differential amplifier base to base voltage to be balanced by varying the collector voltage on QIA 4 44 Differential driver amplifier Q2 Q3 is an emitter follower its primary function is to match the relatively high output impedance of differential amplifier QIA Q1B to the relatively low input im pedance of amplifier ZL CRI and CR2 forma limiting network similar in purpose to CR3 and CR4 4 45 Output amplifier Z1 is a high gain bipolar output IC operational amplifier Components
72. he current source is comprised of two series stages Q30 and Q31 Functionally these two transistors and R78 can be considered as one transistor two series transistors are re quired only because of the high voltages involved Base bias for Q30 and Q31 is provided by R77 R78 and CR23 note that the voltage across these com ponents varies from approximately 100 volts to over 400 volts as the voltage limit setting is var gt ied Thus the total output current of the program ming current source is variable and depends on the voltage limit setting the difference between the current flowing through R84 R87 and the total cur rent is the excess current mentioned in Para graph 4 65 Zener diode VR8 adds an extra bias voltage to the output of the voltage limit circuit By allowing the voltage limit circuit output to be depressed below the reference voltage at the sum ming point 5 6V the voltage limit can be set to approximately zero 4 67 VOLTAGE LIMIT LIGHT CIRCUIT 4 68 The voltage limit lamp circuit energizes the front panel LIMIT lamp whenever the voltage limit circuit is activated As mentioned in Paragraph 4 28 a voltage drop equal tothe forward drop across CR22 is developed across R60 Ry whenever the voltage limit circuit is triggered this voltage appearing on the base of Q20 is the turn on signal for the limit light circuit 4 69 Transistors Q20 and Q21 form the voltage limit sensing switch When the limit l
73. held at a constant temperature while this measurement is made 5 36 The differential voltmeter used to measure the output current change of the supply should be placed outside the oven and should have a long term stability adequate to insure that its drift will not affect the overall measurement accuracy 5 37 To check the temperature coefficient on all three current ranges proceed as follows a Connect test setup shown in Figure 5 3 Strip chart recorder can be substituted for differen tial voltmeter to obtain permanent record b Turn VOLTAGE control fully clockwise c Set front panel RANGE switch and exter nal test setup range switch S1 to highest current position connect lead of differential volimeter to Raj and turn on supply d Adjust CURRENT control to obtain front panel ammeter reading of exactly 100 e Insert supply into temperature controlled oven voltmeter and load resistors remain outside oven Set temperature to 30 C and allow one hour warm up f Record differential voltmeter indication g Raise oven temperature to 400C and allow one hour warm up h Reading on differential voltmeter should not vary from reading recorded in Step i by more than Go i Repeat Steps d through h with both range switches set to middle current position and differential voltmeter connected to R92 j Repeat Steps di through th with both range switches set to lowest current position and differential voltmeter connect
74. ight is not on Q21 is on and Q20 is off Emitter current for Q20 is supplied by constant current source Q19 Components R57 R58 R59 and CR13 provide base bias f r Q21 and allows the switch io func tion properly in the presence of a varying common mode voltage the 0 to 10V output of the program ming guard supply appears between the guard and circuit common When the circuit is activated Q20 turns on and Q21 tums off driving Q17 into conduction Current thus flows from 29V through R55 LIMIT light DS2 and Q17 to 1SV VRIS keeps a constant 5 6V across the light preventing lamp burnout from overvoltage 4 70 METER CIRCUIT 4 71 The ammeter M2 connected between cir cuit common and the guard measures the output voltage of the programming guard supply As ex plained in Paragraphs 4 3 and 4 11 the constant current comparator holds the drop across the cur rent sampling resistor equal to this output refer ence voltage the ammeter thus indicates the pro grammed output current Potentiometer R106 al lows calibration of the ammeter The voltmeter M1 is connected between the guard and the neg ative output terminal As explained in Paragraph 4 22 the guard conductor is maintained at the same potential as the positive output terminal the voltmeter thus indicates the output voltage of the supply Potentiometer R110 allows calibration of the voltmeter 4 72 VOLTAGE DOUBLER 4 73 The voltage doubler circuit is comprised of
75. impedances of internal leakage paths have been made as high as possible by careful mechanical design For example the series regu lator transistors are electrostatically isolated from the chassis by a copper clad mylar shield connect ed to circuit common the transistors are insulated from the shield with a layer of boron nitride which has an extremely high insulation resistance 4 21 Further reduction in leakage both internal and external is achieved through active guarding The operation of the active guard depends on the fact that the unwanted leakage currents are flowing through some impedance to get into or out of the sensitive circuit By carefully surrounding the sensitive circuit with a conducting surface or guard each of the impedances between the sensi tive circuit and the outside world can be split into two parts one between the guard and the sensitive circuit and one between the guard and the rest of the world When the voltage between the guard and the sensitive circuit is kept at zero the guard ac complishes its purpose of eliminating unwanted currents flowing into or out of the sensitive circuit The guard is not connected directly to the sensitive circuit if it were then no improvement would re sult 4 22 As discussed in Paragraph 4 4 and shown in Figure 4 2 by a dotted line the positive output terminal the current sampling resistor and the non inverting input to the constant current compa rator are all surrou
76. is cannot be de pended on if the instrument is in need of re pair If the front panel milliammeter responds appropriately when the current control is ad justed the programming guard supply is func tioning Use an external milliammeter in series with the output to monitor the output current directly while troubleshooting to avoid mis interpreting trouble symptoms CAUTION The RANGE switch must be kept on the 100mA position at all times while trou bleshooting this instrument Switching to a lower range may cause the de struction of current sampling resistors R2 or R3 Overall Troubleshooting PROBABLE CAUSE CAUTION Do not operate the supply without a short across the output terminals If a shorted series regulator is the trouble source op erating the supply without a short across the output terminals will resuit in the de struction of transistors 035 and or O36 Shorted series regulator Check Q24 25 26 27 28 29 and VR2 Shorted series regulator and shorted voltage limit transistors See a above and check Q35 and Q36 Also check VR19 and isolation diode CR22 Short on printed circuit board Check for loose pieces of wire etc External current path between common A3 and negative output terminal Check strapping pat tern and instrumentation connections Defective rectifier diodes in main supply and or reference supply Check CR32 33 35 38 Serie
77. lling 4 8 The bleed circuit maintains a continuous small current flow through the series regulator This current provides a path for leakage currents and keeps the series regulator on and in its active region at all times even when little or no output current is being drawn from the supply Maintain ing this on condition insures that the supply will maintain its regulation at very low output currents 4 9 able limit on the output voltage of the supply the output voltage exceeds the preset limit set with the front panel VOLTAGE control a shunt regulator gate diode is driven into conduction The shunt regulator draws current away from the load causing the output voltage of the supply to be clamped to the preset limit level The voltage limit circuit provides an adjust If 4 10 The voltage limit lamp circuit drives the front panel LIMIT lamp this circuit is activated by the shunt current that flows through the voltage limit circuit when the supply output voltage rises to the preset limit level When lit the lamp informs the supply operator that the full programmed output cur rent is no longer being supplied to the load and that the output voltage has reached the preselected limit 4 11 The combination of the programming scheme and the voltage limit circuit used in the 6186C al low the output current to be set without shorting the output terminals As noted in Paragraph 4 6 the front panhel ammeter indicates the programmed
78. must be realigned in accordance with the manufacturer s instructions until proper com mon mode rejection is attained H in 5 23 To check the high frequency noise output on all three ranges proceed as follows a Connect test setup shown in Figure 5 4A or 5 4B b Set both range switches to highest cur rent range turn VOLTAGE control fully clockwise and turn on supply c Adjust CURRENT control until front panel ammeter indicates exactly 100 d Noise reading on oscilloscope should be less than 50mV p p e Repeat Steps b and c with switches set to middle current range ing should be less than 50mV p p f Repeat Steps b and c with both range switches set to lowest current range Noise read ing should be less than 40mV p p both range Noise read 5 5 RANGE SWITCH POWER SUPPLY CASE OSCOPE SE TWISTED USE 3 70 2 ADAPTER TO A BREAK GROUND PATH A MEASUREMENT METHOD USING A SINGLE ENDED SCOPE 3 TO 2 ADAPTER BREAKS GROUND CURRENT LOOP TWISTED PAIR REDUCES STRAY PICKUP ON SCOPE LEADS RANGE SWITCH Lo RL3 Om omen L CH Rey POWER SUPPLY CASE Rs3 Om AA SHIELDED TWO WIRE B BETTER METHOD USING DIFFERENTIAL SCOPE WITH FLOATING INPUT GROUND CURRENT PATH IS BROKEN COMMON MODE REJECTION OF DIFFERENTIAL INPUT SCOPE IGNORES LIKE POLARITY INPUTS SHIELDED WIRE FURTHER REDUCES STRAY PICKUP ON SCOPE LEADS NOTES i FOR VALUES OF LOAD RESISTORS R AND Rs SEE FIGU
79. nc 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 F 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 Du Bois Pa Sylvania Electric Products Inc Electronic Tube Div Receiving Tube Operations Emporium Pa Switchcraft Inc Chicago IIL 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 N J Bendix Corp Electric Power Div Eatontown N J Herman H Smith Inc Brooklyn N Y Central Screw Co Chicago Ill Gavitt Wire and Cable Div of Amerace Esna Corp Brookfield Mass City of Industry Calif 88245 90634 90763 91345 91418 91506 91637 91662 91929 92825 93332 93410 94144 94154 94222 95263 95354 95712 95987 96791 97702 98291 98410 98978 99934 Renbrandt Inc Code List of Manufacturers Continued MANUFACTURER ADDRESS Grant Pulley and Hardware Co West Nyack Burroughs Corp Electronic Components Div U S Radium Corp
80. nded by a guard conductor con nected to the output of the programming guard sup ply The constant current comparator keeps the positive output terminal and the guard conductor within one millivolt of each other for any load or output setting Any leakage impedance connected to the positive output terminal thus has nearly zero volts across it and leakage currents are forced to flow through the guard instead of the positive out put terminal 4 23 VOLTAGE LIMIT CIRCUIT 4 24 The basic function of the voltage limit circuit is to provide an adjustable limit on the power sup ply output voltage This limit is necessary to pre vent the output voltage from rising to the raw supply voltage of more than 400 volts when the load is removed such prevention is necessary for the protection of both load and operator 4 25 The voltage limit circuit is an independent regulated variable voltage supply with output voltage EL The voltage divider formed by the volt age limit control Rp and resistor Rp allows a frac tion of this output voltage to be applied to one in put of a comparator A zener diode connected to the other input of the comparator establishes a ref erence voltage Ifa difference exists between the reference voltage and the fraction of the output voltage an error signal is produced by the compa rator and applied to the shunt regulator which varies its conduction until the output voltage Ey is at the level required by the setti
81. ng load effect in the 61860 TEMPERATURE COEFFICIENT Output change per degree Centigrade is less SOURCE EFFECT LINE REGULATION than 75ppm of output plus 5 ppm of range switch The output current changes less than 25ppm of setting In constant voltage operation the minimum output voltage is 0 5V 1 2 Model 6186C Specifications Continued DRIFT STABILITY Total output current drift is less than 100ppm of output plus 25ppm of range switch setting Stability is measured for 8 hours at constant ambient constant line voltage and constant load after an initial warm up of one hour INTERNAL IMPEDANCE AS A CONSTANT CURRENT SOURCE Output Impedance Typical R in parallel with C Output Range 900pF 10 000 Meg C R R 1 000 Meg C 700pF R 100 Meg 1500pF The formula Z RXg W R F w can be used for calculations up to 1MHz LOAD TRANSIENT RECOVERY TIME Less than Imsec for output current recovery to within 1 of the nominal output current on the 100mA range following a full load change in output voltage less than 1 6msec on the 10mA range and less than 4msec on the lm range RESOLUTION 0 02 of the range switch setting METER RANGES 1 2 12 120mA 360V Accuracy scale 2 of full OUTPUT CONTROLS Range switch selects desired output current range and selects meter range Ten turn current and single turn voltage controls permit continu ous adjustment over entir
82. ng of the voltage limit control 4 26 When voltage limiting action is not occuring the setting of the voltage limit control establishes across the shunt regulator as described in Para graph 4 25 a preset voltage limit Ez which is higher than the positive output voltage and its twin the guard voltage Since there is zero volts across the series combination of isolation diode CR22 and resistor Ry no current flows through them Potential Eq is thus present at their junc tion back biasing isolation diode CR21 Any small reverse leakage current flowing through CR21 flows through Ry and into circuit common via the programming guard supply but does not flow into CR22 or the positive output terminal The shunt regulator conducts a standby current through bias resistor Rp this current insures that the shunt voltage regulator is operating in its linear region ready to react quickly when voltage limiting action is required thus minimizing crossover transients 4 27 If the output voltage exceeds the preset volt age limit value CR22 and CR21 conduct momen tarily placing a potential higher than E on the col lector of the shunt reguiator This unbalances the voltage limit comparator which causes the shunt regulator to increase its conduction diverting a portion of the current that would otherwise flow to the load Since the load receives less current the output voltage of the supply drops until it reaches the preset voltage limit Ep
83. nion Inc Centraiab Div Milwaukee Wis Mineral Wells Texas 71700 General Cable Corp Cornish 21520 Fansteel Metallurgical Corp Wire Co Div Williamstown Mass No Chicago HL 71707 Goto Coil Co Inc Providence RL 22229 Union Carbide Corp Electronics Div 71744 Chicago Miniature Lamp Works 22753 23936 Mountain View Calif UID Electronics Corp Hollywood Fla Pamotor Inc Pampa Texas 71785 Chicago fll Cinch Mfg Co and Howard B Tones Div Chicago IL 24446 General Electric Co Schenectady N Y 71984 Dow Corning Corp Midland Mich 24455 General Electric Co Lamp Div of Con 72136 I Electro Motive Mfg Co Inc 31514 31827 sumer Prod Group Willimantic Conn Nela Park Cleveland Ohio 72619 I Dialight Corp Brooklyn N Y General Radio Co West Concord Mass 72599 I General Instrument Corp Newark N J LTV Electrosystems Inc Memcor Com 72765 I Drake Mfg Co Harwood Heights Ill ponents Operations Huntington Ind 72962 Elastic Stop Nut Div of 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 IMG Magnetics Corp New Hampshire Div Rochester N D SAE Advance Packaging Inc Santa Ana Calif Budwig Mig Co Ramona Calif 72982 73096 73138 73168 73293 73445 Amerace Esna Corp Union N J Erie Technological Products Inc Erie Pa Hart Mf
84. nual is shipped with each instrument 1 15 INSTRUMENT IDENTIFICATION 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 HP Part Number shown on the title page 1 16 Hewlett Packard power supplies are identi fied by a three part serial number The first part is the power supply model number The second Table 1 1 Model 6186C Specifications INPUT initial value plus 5ppm of range switch setting 115 230Vac 10 single phase 48 63Hz for any line voltage change within the input rating 0 9 amp 90 watts nominal 115Vac 104 to 127Vac or 208to 254Vac and at any out put current and voltage within rating OUTPUT 0 100mA 0 300Vde PARD RIPPLE AND NOISE OUTPUT CURRENT RANGES Ripple and Noise rms p p O lmA 0 10mA 0 100mA mA da tohtHkz ati H Bee ia D LOAD EFFECT LOAD REGULATION The output current changes less than 25ppm of initial value plus 5ppm of current range switch 10 setting for a load change which causes the output voltage to vary from zero to maximum when meas ured with the negative output terminal grounded if the positive output is grounded the load effect is less than t100nA output current change for the TEMPERATURE RATING same full load change in output voltage The re Operating 0 to 55 C Storage 40 to 75 C lative humidity must be less than 50 when meas uri
85. oceed to Step 6 Programming guard supply is defective Perform trou bleshooting procedures given in Table 5 6 After establishing proper opera tion Response b proceed to Step 8 Programming guard supply is operative Proceed to Step 8 Table 5 3 Series Regulator Programming Guard Supply and Constant Current Comparator Isolation and Initial Troubleshooting Continued ACTION RESPONSE REACTION 21 is defective Install 8 Plug Z1 originally in constant current a Voltage indi comparator into Z2 socket and re cated on exter new Z1 in constant current perform Step 7 nal voltmeter comparator and re install does not 22 in programming guard change supply Proceed to Step 9 b Voltage indi 421 is operative Return Z1 cated on exter to its original socket in nal voltmeter constant current compara varies from tor and re install Z2 in approximately programming guard supply 0 7 to 10 5V Proceed to Step 9 de Test constant current comparator as a Output current Defect in constant current follows as indicated comparator circuit Pro a Reconnect jumper Jl and diode on external ceed to Step 10 CR43 ammeter does b Remove the 5K pot connected across not change CR18 b Output current b Constant current compara as indicated on external am meter varies over full range c Attempt to control output current with front panel CURRENT control tor is operative supply should be
86. oltage is required to in crease become more negative the negative error signal produced by Z2 drives Q8 into greater con duction and decreases the conduction of Q9 push ing the output voltage towards 15V This push pull action results in much faster programming than if a single ended stage were used Zener diode VR6 connected across load resistor R19 and output filter capacitor Cl prevents the programming guard sup ply output voltage from going positive at turn off or from exceeding 12 4V The combination of VR6 and CR43 connected in series from the minus output terminal to circuit common also provides reverse voltage protection for the entire instrument 4 41 CONSTANT CURRENT COMPARATOR 4 42 The constant current comparator is a differ ential amplifier whose function is to compare the voltage drop across the current sampling resistor with the output voltage of the programming guard supply and to produce an error signal proportional to the difference As discussed in Paragrapn 4 18 the error signal is applied to the series regulator which alters its conduction until the IR drop across the sampling resistor equals the programming guard supply voltage thus keeping the output current constant at the desired level 4 43 The constant current comparator consists of a differential amplifier and associated constant current source Q1A Q1B and Q4 a differential Griver amplifier Q2 Q3 and an output amplifier 21 As in the
87. omp 3kn 5 1 2W comp 1Meg 5 1 2W comp 510kn 5 1 2W comp 20kn 25 1 2W comp 360n 5 1 2W film 2ka 1 1 8W film 21 5a 1 1 8W met ox 33kn 5 2W comp Ikn 5 1 2W met ox 47ka 25 2W ww 30kn 5 LOW comp 200n 5 1 2W comp 5 6kn 25 1 2W comp I Oka 5 1 2W met film 5 49ka 1 1 8W met film k 1 1 8W comp Selected 5 1 2W met ox 68K 5 1W comp 200n 5 1 2W comp 5 ln t5 1 2W met ox 100ke 5 2W kn 5 Guard Zero Adj 6 7 gt w Non Fei ot fe CO ok NV BO rz BO LA no DO EB 1515 01121 EB 5105 01121 EB 5115 91121 EB 1035 01121 Type CEA T O 07716 Type CT 100 4 07716 Type CEA T O 07716 28480 obd 28480 Type CEA T O 07716 EB 3025 01121 Type CEA T O 97716 EB 3005 91121 EB 1515 01121 EB 2025 01121 EB 5105 01121 EB 2035 01121 EB 5125 01121 Type CEA T O 07716 EB 1825 01121 Type CEA T O 07716 EB 2005 01121 242E8215 56289 EB 2725 01121 CB 7515 01121 EB 1023 or121 243E7515 56289 EB 1035 01121 EB 3025 01121 EB 1235 01121 EB 3025 01121 EB 7515 o1121 EB 1325 01121 EB 5115 01121 EB 3025 01121 EB 1055 01121 EB 5145 01121 EB 2035 01121 EB 3615 01121 Type CEA T O 07716 Type MF4C1 19701 Type C 425 16299 EB 1025 01121 Type C 428 16299 247E3035 63743 EB 2015 01121 EB 5625 01121 EB 1035 91121 Type CEA T O 07716 Type CEA T O 07716 Type EB obd 91121 RG 32 11502 EB 2015 91121 EB 51G5 01121 Type FP42 27167 0686 1515 0686 5105 0686 5115 0686 1035
88. omponents While the supply may be operated in the region be tween the rated output 300Vdc 100mA and the maximum output 315Vdc 110 115mA without being damaged it cannot be guaranteed to meet all of its performance specifications 3 16 OPTIONAL OPERATING MODES 3 17 REMOTE PROGRAMMING CONSTANT CURRENT 3 18 Either a resistance or a voltage source can be used to control the constant current output of the supply The CURRENT control on the front panel is automatically disabled when the supply is used in the remote programming mode It is rec ommended that shielded cable with the shield connected to terminal A3 be used to connect the programming resistance or voltage source to the supply 3 19 Resistance Programming Figure 3 3 In this mode the output current varies at a linear rate determined by the remote resistance program ming coefficient This coefficient is different for each output current range as shown in Table 1 1 of this manual The programming coefficient is de termined by the constant current programming cur rent which is adjusted to lmA 0 25 at the facto ry If greater programming accuracy is required it can be achieved by adjusting resistor R32 as outlined in Paragraph 5 66 AO AI AZ A 3 PROGRAMMING RESISTOR RL Figure 3 3 Remote Resistance Programming Constant Current 3 20 Use stable low noise low temperature co efficient programming resistors to maintain the power suppl
89. onents Div Dallas Texas Manchester N D Rockford IH Dover Ohio Saugerties N Y RCL Electronics Inc Amerock Corp Sparta Mfg Co Ferroxcube Corp Fenwal Laboratories Morton Grove IL Amphenol Corp Broadview Ill Radio Corp of America Solid State and Receiving Tube Div Somerville N J G E Semiconductor Products Dept Syracuse N Y Eldema Corp Compton Calif Transitron Electronic Corp Wakefield Mass Pyrofilm Resistor Co Inc Arrow Hart and Hegeman E ar Knolls NJ zctric 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 6 Battery Dept Irmo 5 0 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 NM H General Devices Co Inc Indi napolis 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 07138 07263 07387 07397 07716 07910 07933 08484 08530 08717
90. onnected across the current sampling resistors as shown in Figure 5 3 As indicated in this illustration neither output terminal of the power supply is grounded and the measuring device case is con nected to the junction of the load and sampling resistors This arrangement prevents ground loop paths and minimizes shunt current paths The external range switch must have a high insulation resistance 100000Ma or greater to avoid signi ficant leakage that would degrade the performance of the supply 5 10 RATED OUTPUT AND METER ACCURACY 5 11 Current To check the output current on all three ranges proceed as follows a Connect test setup shown in Figure 5 3 leaving switch S2 open throughout test b Turn VOLTAGE control fully clockwise c Set front panel RANGE switch to 100mA position set external test setup range switch S1 to high position connect terminal of differential voltmeter to Rg and turn on supply d Adjust CURRENT control until front panel ammeter indicates exactly 100 e Differential voltmeter should read 10 0 24Vdc If it does not refer to ammeter calibra tion procedure in Paragraph 5 55 f Repeat Steps d and e with front panel RANGE switch set to 10mA position external test setup range switch S1 set to medium position and differential voltmeter connected to Rag 9 Repeat Steps d and e with front panel RANGE switch set to imA position external test setup range switch S1 set to low position an
91. or front panel ammeter read ing of 100mA no load and turn VOLTAGE control fully counterclockwise b Connect high impedance differential volt met r across output terminals of supply c Connect decade resistance box set for 10kn in place of R86 mounted on standoffs on main circuit board see Figure 7 3 d Turn on supply and adjust decade resist ance box until differential voltmeter reads 0 50mVde e Turn off supply and replace decade re sistance box with appropriate value 5 1 2W resistor in R86 position SECTION VI REPLACEABLE PARTS 6 1 INTRODUCTION 6 2 This saction 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 i 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 list
92. orp ztifier Div Philadelphia Handle Co Inc Camden N J U S Terminals Inc Cincinnati Ohio Lake Mills Wisconsin Clarostat Mfg Co Inc Dover N H Thermalloy Co Dallas Texas Hewlett Packard Co Loveland Div Loveland Colo Cornell Dubilier Electronics Div Federal Pacific Electric Co Newark N J General Instrument Corp Semicon ductor Prod Group Hicksville N Y Fenwal Elect Framingham Mass Corning Glass Works Electronic Components Div Raleigh N C Newark N J Use Code 28480 assigned to Hewlett Packard Co Palo Alto California 18324 19315 19701 Table 6 3 Code List of Manufacturers Continued ADDRESS MANUFACTURER 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 J Signetics Corp Sunnyvale Calif Bendix Corp The Navigation and Control Div Teterboro N J Electra Midland Corp CODE NO 70563 70901 70903 71218 71279 71400 71450 71468 71590 MANUFACTURER ADDRESS Union City Nv Fort Washington Pa Belden Corp Chicago Ill Bud Radio Inc 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 Amperite Co Inc Beemer Engrg Co Globe U
93. out put current If the supply is operating in the nor mal constant current mode all the programmed out put current is delivered to the load if the supply is operating in the voltage limit mode part of the programmed output current or all of it if no load is connected is flowing through the shunt regula tor Thus the series regulator and the current sam pling resistor are always conducting the program med output current and the ammeter actually in dicating the output voltage of the programming guard supply indicates the programmed output cur rent regardless of the load connected to the supply 4 12 The reference supply provides reference and R48 REFERENCE fore pi D POWER TRANS FORMER AC IN RECTIFIER AND FILTER V Rp LIMIT Pigure 4 2 bias voltages for the constant current section of the instrument The supply has four regulated outputs 12 4V 7 5V 6 2V and 15V An ad ditional unregulated output 29V is provided for use in the bleed circuit and the voltage limit lamp circuit 4 13 SIMPLIFIED SCHEMATIC DISCUSSION 4 14 The simplified schematic of Figure 4 2 il lustrates the three main circuits in the power sup ply These circuits the programming guard sup ply the main current regulator and the voltage limit circuit are delineated by separate shaded areas in the figure The following paragraphs discuss the functional details of each circult and the feedback
94. p between terminais A5 and AG 5 14 Table 5 5 Voltage Limit Circuit Troubleshooting Continued ACTION RESPONSE PROBABLE CAUSE PART B VOLTAGE LIMIT LOCKED DOWN LIMIT LIGHT ON Attempt to turn off shunt regulator Q35 Q36 by shorting Q32 base to emitter a Voltage at test point a Check 035 and Q36 for 21 measured from short and VR9 10 11 14 TP does not change 15 for short Voltage at test point Proceed to Step 2 21 increases Attempt to turn off error amplifier Q32 by shorting Q34 base to emitter Voltage at test point 21 does not change Check Q32 for short b Check Q34 for short Q33 for open R75 for short Voltage at test point 21 increases Table 5 6 Programming Guard Supply Troubleshooting STEP ACTION RESPONSE PROBABLE CAUSE CAUTION The procedures in this table should only be performed after at least Steps Gh H and 6 of Table 5 3 have been performed 1 Check output regulator transistors Q8 a Voltage indicated on a Q8 or Q9 defective and Q9 as follows external voltmeter a Connect external voltmeter be does not change b Bad Rica AO A AS b Voltage indicated on b Q8 and Q9 operative Remove d HOR SKJER external voltmeter Proceed to Step 2 c Connect one end of a 10ka pot to test point 10 15V the other end to terminal A3 and the wiper to pin 6 of 22 socket d Vary pot over full range
95. part is the serial number prefix consisting of a number letter combination denoting the date of a 014 Three Digit Graduated Decadial significant design change and the country of man Current Control A dial that re ufacture The first two digits indicate the year places the 10 turn current control 10 1970 11 1971 etc the second two dig knob and allows accurate resetting its indicate the week 01 through 52 and the let of the output current to within ter A QG J or U designates the U S A 0 1 West Germany Japan or the United Kingdom re spectively as the country of manufacture The 1 13 ACCESSORIES third part is the power supply serial number a different 5 digit sequential number is assigned to 1 14 The accessories listed in the following each power supply starting with 00101 chart may be ordered with the instrument or separately from your local Hewlett Packard field sales office refer to list at rear of manual for 1 17 If the serial number prefix on your unit does not agree with the prefix on the title page addresses l of this manual change sheets supplied with the HP Part No Description manual define the differences between your in strument and the instrument described by this 5060 8762 Rack Kit for mounting one or manual two units Refer to Section II for details 5060 8760 Filler panel to block unused 1 18 ORDERING ADDITIONAL MANUALS half rack when mounting only one unit 1 19 One ma
96. power supply terminals The ripple value obtained when the leads are shorted should be subtracted from the actual ripple measurement 5 22 In most cases the single ended scope method of Figure 5 4A will eliminate non real com ponents of ripple and noise well enough to allow a satisfactory measurement to be obtained How ever in more stubborn cases or in measurement situations where it is essential that both the power supply case and the oscilloscope case be connect ed to ground e g if both are rack mounted it may be necessary to use a differential scope with floating input as shown in Figure 5 4B Two single conductor shielded cables may be substi tuted in place of the shielded two wire cable with equal 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 effects of any common mode signal produced by the difference the ac potential between the power supply case and scope case Before using a differential input scope in this manner however it is imperative that the common mode rejection capability of the scope be verified by shorting together its two in put leads at the power supply and observing the trace on the CRT If this trace is a straight line then 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
97. pply that si multaneously performs two distinct functions In its primary or programming function its output voltage serves as a reference against which the drop across the sampling resistor is compared in order to maintain the output current at a constant level In its guard function its output is con nected to a copper guard conductor surrounding the positive output terminal Since the constant cur rent comparator maintains the positive output ter minal at the same potential as the output of the programming guard supply no leakage current flows from the positive output terminal Instead leakage current that would normally flow from the positive output terminal flows from the guard con ductor via the low impedance programming guard supply 4 5 As mentioned above and shown in Figure 4 1 the circuit common point for the supply is the inboard side of the current sampling resistor This is a significant point because it insures that only the output current flows through the current sampling resistor In this way any leakage cur rent flowing directly between the supply s two out put terminals is eliminated and precise load reg ulation is obtained Note that the circuit common point is at a different potential than both the neg ative output terminal and the chassis ground 4 6 The guard conductor also serves asa con venient connection point for the meter circuit Tf the voltmeter were to be placed directly across the output of
98. programming terminals during the switching interval Opening the programming ter minals A4 and A6 causes the output voltage to rise to an excessive level that may damage the load AQ A AS A3 PROGRAMMING RESISTOR Figure 3 5 Remote Resistance Programming Voltage Limit 3 30 Voltage Programming Figure 3 6 In this mode the voltage limit will vary in a 1 to 1 ratio with the programming voltage voltage source The voltage source used must be capable of sink ing the lmA programming current flowing into ter minal A6 and it must be floating with respect to the output terminals and earth ground VOLTAGE SOURCE Remote Voltage Programming Voltage Limit Figure 3 6 3 31 EXTERNAL VOLTAGE MONITORING 3 32 If an accurate measurement of the output voltage is required it can be obtained by connect ing an external voltmeter between the front panel METER and terminals or between the rear A0 and terminals as shown in Figure 3 7 When connected in this manner the external voltmeter will indicate the actual output voltage with an accuracy of millivolt Notice that the meter is connected between the guard and the negative ter minal rather than the positive and the negative ter minal Connecting the meter to the guard supply effectively isolates the meter from the main power supply preventing the performance degradation that would occur if the meter were connected dir ectly across the positive an
99. re 4 2 the circuit consists of a common emitter stage in series with a common base stage This configuration called cascode in technical literature effectively combines the advantages and eliminates the disadvantages of each of the two types of circuits A common base stage has high output impedance very desirable in a constant cur rent source but is difficult to drive because all the drive current must go through the collector bias source A common e itter stage while easy to drive has a relatively low output impedance Combining these two circuits in a cascode config uration results in an amplifier that is both easy to drive and has a high output impedance 4 51 Referring to the schematic diagram Figure 7 4 it can be seen that transistor Q29 is the com mon emitter stage emitter connected to circuit common through R50 and that Q24 through Q28 when taken as a unit form the com mon base stage base connected to circuit common through the reference supply Transistors Q24 and Q26 form a Darlington pair as do transistors Q25 and Q27 leakage resistors R62 and R63 can be con sidered as having negligible effect upon the Dar lington action Viewing each pair as a single transistor it can be seen that 024 026 Q25 027 and Q28 form a string of three equally biased common base stages R73 R72 R71 VR2 and R51 form the bias network Three series stages are required due to the high power dissipation involved Zener
100. rent comparator This table is referenc d in Table 5 2 At various points in Table 5 3 instruc tions direct the reader to one of Tables 5 4 5 5 or 5 6 depending upon the results of tests in Table 5 3 After completing the procedures in Tables 5 4 5 5 or 5 6 the reader is directed to re enter Table 5 3 at the former exit point This is suggested because following the procedures in Table 5 3 through to the end of the table Step 10 even after locating and replacing a defective com ponent provides a rapid and effective method of testing all the circuits in the instrument 5 46 In some special circumstances it may be de sirable to go directly to Tables 5 4 5 5 or 5 6 without first going through at least a portion of Table 5 3 Instructions at the beginning of each of the three tables provide for this possibility Table 5 7 voltage LIMIT light troubleshooting is refer enced in Table 5 2 only however instructions are provided at the beginning of Table 5 7 relating it to Table 5 3 Table 5 2 SYMPTOM Blows fuses Output current locked up or not controllable throughout entire range D NOTE While troubleshooting this instrument keep in mind that the front panel milliammeter does not indicate output current directly but in stead provides a reading proportional to the output voltage of the programming guard sup ply Ordinarily this voltage is proportional to the output current but th
101. roughout the instrument All the references voltages are derived from raw dc obtained from full wave rectifier CR35 CR38 and filter capacitor C35 all the voltages are measured with respect to the circuit common point Be jA 4 32 The regulating circuit consists of differential amplifier Q11 Q12 driver Q14 and series regula tor Q15 Q16 Temperature compensated zener diode VR4 connected to the base of Q12 and bias ed by resistor R48 provides a stable reference voltage 46 2 volts with respect to circuit common for one input of the differential amplifier The voltage divider formed by resistors R45 and R46 ap plies half of the 12 4V regulated output 6 2V to the other input Q11 base The feedback loop functions to maintain the difference between these two inputs at zero For example if the 12 4V output momentarily increases Q11 increases its conduction which decreases the conduction of Q14 and therefore lowers the base current flowing out of series regulator Q15 Q16 The 12 4V out put thus decreases from its higher than normal value back to 12 4V 4 33 Triple junction diode CR12 sets the operating level for O14 Note that the output of the differen tial amplifier is taken from both collectors this has the effect of doubling the voltage gain of the Stage when compared with the customary single collector output differential amplifier configura tion Resistors R41 and R42 in the emitters of series regulating transistors
102. s regulator programming guard supply or constant current comparator defective Refer to Table 5 3 Table 5 2 Overall Troubleshooting Continued SYMPTOM PROBABLE CAUSE a Voltage limit circuit defective Refer to Table 505 Measured output current zero LIMIT light on continuousiy Measured output current zero LIMIT light not a Series regulator programming guard supply or on constant current comparator defective Refer to Table 5 3 b Voltage limit circuit defective and limit light cir cuit defective Refer to Tables 5 3 and 5 7 Voltage limit fails to operate VOLTAGE control a Voltage limit circuit defective Refer to Table has no effect LIMIT light not on 5 5 Voltage limit wili not go to zero a Zener diodes VR16 VR17 or VR8 shorted LIMIT light not functioning at all though volt a Voltage limit light circuit defective Refer to age limit operation and supply output current Table 5 7 are normal LIMIT light will not operate at low output cur a Isolation diode CR22 shorted rent levels a Improper measurement technique Refer to Para graph 5 13 b Differential amplifiers Q1 or Q7 defective Poor load regulation c Defect in reference supply Refer to Table d Dirt on printed circuit board e Internal or external current leakage path between terminal Al and negative output terminal To verify that this is the trouble connect a DVM betwe
103. sher Double Heat Sink and TI Bracket Serial Plate Insulator Transistor 026 27 28 35 36 Fuseholder Fl Hex Nut Fuseholder Lockwahser Fuseholder Flat Neoprene Washer Fuseholder Insulator Boron Nitride Q26 27 28 35 36 CHASSIS ASSEMBLY MECHANICAL Chassis Internal Bracket Transformer Tl Cover Side Cover Top Cover Bottom Fastener Top and Bottom Covers Side Frame Assembly Foot Assembly Spacer Side Frame Assembly Shoulder Washer Double Tl Mounting Cable Clamp C 17373 102 24D 342014 903 12 901 129 H 4001 C 8020 632 24B REF MER HP DESIG DESCRIPTION TQ MFR PART NO CODE PART NO RS 5020 8061 4040 0483 1480 0181 06186 20006 06186 00011 06186 00012 5020 5754 7120 1254 0370 1091 0370 1099 2190 0494 5040 0234 5040 0305 0510 0123 1490 0032 5040 0700 06186 00010 06186 20005 06186 00007 06186 20023 0340 0172 7120 1111 0340 0795 1400 0084 2950 0038 2190 0054 1400 0090 0340 0411 06186 00001 06186 00003 5000 8565 5060 8585 5000 9444 0590 0052 5060 0703 5060 0728 5020 0701 0340 0492 1400 0116 MFR HP DESCRIPTION TQ MFR PART NO CODE PART NO RS CHASSIS ASSEMBLY MECHANICAL Standoff 6 32 x 1 2W A2 Board 1951E 00866 0380 0093 Guide Printed Circuit Boards 28480 0403 0150 MISCELLANEOUS Manual 06186 90005 Carton Packing 9211 1347 Floater Pad Packing 9220 1545 Fuse Envelope Fi 230V 9320 0234 OPTION 14 3 Digit
104. shown in Figure 5 3 external range switch and medium and low range load resistors can be eliminated if desired b Turn VOLTAGE control fully clockwise set front panel RANGE switch to 100mA position and connect differential voltmeter to Hat c Turn on supply and adjust CURRENT con trol for reading of 10 0Vdc on differential voltmeter d Adjust potentiometer R106 see Figure 7 3 until front panel ammeter indicates exactly 100mA 5 57 VOLTMETER CALIBRATION 5 58 To calibrate the voltmeter proceed as follows a Connect test setup shown in Figure 5 3 except connect differential voltmeter between METER and output terminal or between AO and output terminal see Figure3 7 External range switch and medium and low range load resistors can be eliminated if desired b Set front panel RANGE switch to 100mA position turn on supply and adjust CURRENT con trol until front panel ammeter reads exactly 100mA c Adjust VOLTAGE control until differential voltmeter reads exactly 300Vdc d Adjust potentiometer R110 see Figure 7 3 until front panel voltmeter reads exactly 300Vdc 5 59 RIPPLE MINIMIZATION 5 60 To adjust the supply for minimum output cur rent ripple proceed as follows a Connect test setup shown in Figure 5 4B External range switch and high and medium range load resistors can be eliminated if desired b Turn VOLTAGE control fully clockwise set front panel RANGE switch to lmA position turn CURRENT con
105. sy access to both sides To accomplish this remove the two hold down screws and slide the board towards the front of the unit and out of its plastic guide channels Sufficient lead length is provided to allow the board to be placed vertically 5 51 ADJUSTMENT AND CALIBRATION 5 52 Adjustment and calibration may be required after performance testing troubleshooting or re pair and replacement If more than one adjustment must be performed the sequence of adjustments presented in the following paragraphs should be followed 5 53 VOLTMETER AND AMMETER ZERO 5 54 The meter pointers must rest on the zero calibration mark on the meter scale when the instru ment is at normal operating temperature resting in its normal operating position and turned off To zero set the meters proceed as follows a Turn on instrument and allow it to come up to normal operating temperature about one hour b Turn instrument off Wait one minute for power supply capacitors to discharge completely c Insert sharp pointed object pen point or awl into small indentation near top of round black plastic disc located directly below meter face d Rotate plastic disc clockwise until meter reads zero then rotate counterclockwise slightly in order to free adjustment screw from meter sus pension Pointer should not move during latter part of adjustment 5 55 AMMETER CALIBRATION 5 56 To calibrate the ammeter proceed as follows a Connect test setup
106. t for minimum resistance e Short O22 collector to emitter 2 Increase the resistance of the Ska pot gradually while observing the external ammeter If the meter does not respond turn the pot back to zero resistance Output current as indicated on external ammeter does not change CAUTION Output current as indicated on external ammeter var ies from zero to approxi mately 100maA Do not allow the output current to exceed 100mA 3 Set the resistance of the 5Ka pot fora reading on the external ammeter of about 50mA then remove short across Q22 Output current as indicated on external ammeter drops to zero Output current essentially unchanged CONNECT ACROSS CRIS Series regulator is defect ive Check 026 27 28 VR2 024 25 O29 After establishing proper opera tion of series regulator Response b proceed to Step 3 Series regulator is opera tive Proceed to Step 3 O22 defective Replace Q22 and proceed to Step 4 O22 operative Proceed to Step 4 Table 5 3 Series Regulator Programming Guard Supply and Constant Current Comparator Isolation and Initial Troubleshooting Continued Check all reference voltages listed in Table 5 4 To check voltage limit circuit leave supply connected as in previous step and connect external voltmeter be tween test point 21 and negative out put terminal Vary VOLTAGE control if desired the voltage limit cir
107. terminal protection resistor Opening the programming terminals when no pro gramming current is flowing results in zero output current rather than an excessive output current 3 25 The programming voltage source must always be floating ungrounded If the negative output terminal is grounded shunt leakage paths from the floating programming source to the negative termi nal must be avoided To accomplish this the case of the voltage source can be connected to the circuit common terminal A3 thus affording pro tection against leakage If this method is used ensure that the case is not grounded by any means such as the power line 3 26 REMOTE PROGRAMMING VOLTAGE LIMIT 3 27 The voltage limit of the supply can be pro grammed with a remote resistance or voltage source if required Note that the front panel VOLTAGE con trol is automatically disabled in the following pro cedures 3 28 Resistance Programming Figure 3 5 The voltage limit of the supply is determined by the programming coefficient of 820 ohms per volt The voltage programming current is lmA and is factory adjusted to within 15 Adjustment of the pro gramming accuracy can be achieved by adjusting resistors R86 and R87 as described in Paragraphs 5 69 and 5 72 3 29 A switch can be used in conjunction with various resistance values in order to obtain dis crete voltages The switch should have 3 4 make before break contacts to avoid momentarily opening the
108. the path the current follows during normal operation is through CRIS into the emitter of O22 saturated during nor h D k mal operation out the collector through R69 and CR45 and into Q29 and Z1 At turn on capacitor C18 initially couples 15V to the base of Q29 keeping it in cutoff The series regulator drive current is thus diverted through CR34 into C18 As C18 charges CR34 becomes back biased and CR45 becomes forward biased switching the drive current into the series regulator Capacitor C18 then continues charging through R65 insuring that CR34 remains back biased Diode CR6 provides a discharge path for C18 at turn off resetting the circuit for another turn on cycle 4 48 At turn off the voltage on capacitor C21 discharging through R66 falls slowly compared to the 12 4V reference This reverse biases the base emitter junction of Q22 immediately turning it off and interrupting the series regulator drive current The series regulator is thus prevent ed from remaining on while its bias voltages are falling such a condition could result in uncon trolled output current transients 4 49 SERIES REGULATOR 4 50 The series regulator is the heart of the con stant current supply it regulates the output cur rent by altering its conduction in accordance with the feedback signal from the constant current com parator and the main error amplifier Reduced to its basic form see Main Current Regulator block in Figu
109. trol fully counterclockwise and turn on supply c Adjust R119 see Figure 7 3 for minimum 60Hz ripple displayed on oscilloscope Note that both 60Hz and 120Hz ripple as well as spikes and harmonics are displayed on scope R119 is to be adjusted until combined amplitude of spikes har monics and 60Hz ripple is minimum 5 61 GUARD AMPLIFIER ZERO 5 62 This adjustment minimizes the offset between the bases of the guard input amplifier Q7 The offset should be checked and adjusted if neces sary whenever Q7 is replaced Proceed as follows to perform this adjustment a Place short across output terminals of supply and allow supply to warm up for a half hour b Connect differential voltmeter across diode CR8 on main circuit board see Figure 7 3 c Set RANGE switch to 100mA position turn VOLTAGE control fully clockwise and turnonsupply d Adjust CURRENT control until front panel ammeter indicates exactly 100mA e Adjust potentiometer R29 see Figure 7 3 to obtain reading of 0 200uVde on differential voltmeter 5 63 CONSTANT CURRENT COMPARATOR ZERO 5 64 This adjustment minimizes the offset be tween the bases of the constant current comparator input amplifier Q1 The offset should be checked and adjusted if necessary whenever Q1 is re placed Proceed as follows to perform this adjust ment a Perform Steps a through d in Paragraph 5 62 above except connect differential voltmeter across diode CR4 see Figure 7 3
110. ut line voltage are held constant 5 32 The stability of the supply in constant cur rent operation must be measured while holding the temperature of the power supply and the external current sampling resistor Rg as constant as pos sible A thermometer should be placed near the supply to verify that the ambient temperature re mains constant during the measurement period The supply should be put in a location immune from stray air currents if possible the supply should be placed in an oven which is held ata constant temperature Care must be taken that the measuring instrument has a stability over the eight h hour interval which is at leastan order are magnitude be tter than the stability specific ification of the power supply being measured The supply will drift T Considerably less over the eight hour measurement interval than during the hour warm up 5 33 To check the output stability on all three ranges proceed as follows a Connect test setup shown in Figure 5 3 Strip chart recorder can be substituted for differ ential voltmeter to obtain permanent record b Turn VOLTAGE control fully clockwise c Set front panel RANGE switch and ex ternal test setup range switch S1 to highest cur rent position connect lead of differential volt meter to Ra and turn on supply OSCILLOSCOPE POWER SUPPLY YNDER TEST CONTACT PROTECTION NETWORK OOF R 400V Gen 1 2W LINE i OSCILLOSCOPE SHOULD BE zs i
111. utput current is thus related to the pro gramming voltage and the reference voltage by the relationship lout EG Ry EpRQ RRRy As this equation suggests current sampling resis tor Ry is a critical component and is selected to have low noise low temperature coefficient and low inductance Its ohmic value is large enough to give an adequate current monitoring voltage yet small enough to minimize its temperature rise and the resulting resistance change caused by its own power dissipation Note that the same pro gramming voltage is used on all three output cur rent ranges and that the range is changed by switching the value of the current sampling resis tors see Figure 4 1 4 20 The high output impedance of the power sup ply is a result of several factors both electrical and mechanical First the series regulator tran sistors are in a cascode configuration see Para graph 4 50 which has an inherently high output impedance Second the high open loop gain of the constant current comparator and error amplifier provides greatly increased closed loop output im pedance when feedback is introduced Third there is no physical output capacitor placed across the output terminals Although the output imped ance falls off with frequency due to the necessary gain and phase compensation in the amplifier cir cuits it is much higher than it would be if a ca pacitor were connected across the output terminals Am 4 Finally the
112. y s temperature coefficient and stabil ity specifications A switch may be us d to set discrete values of output current 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 CAUTION If the programming terminals A0 and Ali should open at any time during the remote resistance programming mode the output current will rise to a value that may damage the power supply and or the load If in the particular programming configuration in use there is a chance that the terminals might become open it is suggested that a 10K protection resistor be per manently connected across the pro gramming terminals Like the pro gramming resistor this resistor should be a low noise low tempera ture coefficient type Note how aver that when this resistor is used the resistance value actually pro gramming the supply is the parallel combination of the remote program ming resistance and the protection resistor across the programming ter minals 3 21 If the negative output terminal of the supply is grounded care must be taken to avoid leakage current paths from the programming source to the negative output terminal ground Shunt paths such as this will seriously degrade the perform ance of the supply 3 22 Voltage Programming Figure 3 4 In this mode the output current varies at a linear rat
113. y the voltage limit programming current source see Paragraph 4 64 required to flow through R84 R87 to produce a voltage drop exactly equal to that pro duced by VR12 Since this current is also flowing through programming potentiometer R75 adjusting the current adjusts the voltage limit programming coefficient Selected resistor R86 compensates for tolerance variations in VR8 By making the sum of the voltage drops across VR12 R85 R86 and the end resistance of R75 equal to the sum of the volt age drops across VR8 and CR20 the voltage limit can be adjusted to approximately zero when pro grammed to zero 4 60 The feedback loop functions to maintain the difference between the two inputs to the differen tial amplifier at zero For example if the voltage limit level appearing at the collector of Q35 sud denly increases Q34 increases its conduction driving error amplifier Q32 and shunt regulator Q35 Q36 into greater conduction The voltage limit level thus decreases from its higher than desired level back to the level at which the differ ential amplifier is balanced The function of 032 is thus to amplify the error signal produced by the differential amplifier to a level sufficient to drive the shunt regulator Diode CR31 protects Q32 in the event of a collector base short in either Q35 or Q36 zener diode VR19 limits the maximum cur rent flow through Q35 and Q36 4 61 The shunt regulator must dissipate power over a relativel
114. y wide range of voltages and currents Over most of this range Q35 functions as a driver for Q36 while Q36 shunts the necessary current and shares the power dissipation with collector load resistors R117 R118 and R119 If the shunt regulator must shunta relatively high current whilea relatively low voltage limit is programmed however the ability of Q36 to conduct sufficient current is limited by these collector resistors Under these circumstances Q36 goes into saturation and 035 shunts the additional current required to maintain the programmed voltage limit This additional cur rent flows through the base emitter junction of Q36 Capacitor C25 catches the initial voltage limit transient that occurs each time the circuit goes into voltage limit resistor R91 discharges C25 at turn off Bias resistor R79 allows the shunt re gulator to conduct a standby current and allows C25 to be charged to the desired level this insures that the regulator is always operating in its linear region ready to react quickly when voltage limit ing action is required Diodes VR9 VR10 VRII VR14 VR15 and CR42 connected in series from the negative output bus to the collector of the shunt regulator transistors protect the transistors by preventing the voltage across them from exceeding approximately 360 volts such protection becomes necessary if the supply is inadvertently operated without the strap connecting rear terminals A5 and A6 4 62 The
115. zener 28 7V 1 watt 1 8Z11213 272 04713 1902 0572 I Diode zener 16 2V 400mW 23480 1902 0184 Diode zener 5 62V 400mW 28480 1902 3104 MER HP DESCRIPTION TQ MFR PART NO GOD PART NO EB 4715 01121 0686 4715 fxd comp 390n 5 1 2W EB 3915 01121 0686 3915 fxd comp 470n 5 1 2W EB 4715 01121 0686 4715 fxd comp 5lOka 5 1 2W EB 5145 01121 0686 5145 fxd comp 24kn 5 1 2W 1 EB 2435 01121 0686 2435 l fxd ww 10k 25 10W 2 247E1035 56289 0311 2702 1 fxd met film 9 09kn 1 1 8W I Type CEA T O 07716 0757 0288 1 var ww 5kn 20 Ammeter Adj 2 Type 110 F4 11236 2100 1824 1 fxd met film lika 1 1 8W i Type CEA T O 07716 0757 0443 1 fxd met ox 150ka 5 2W H Type 0 428 16299 0764 0049 1 fxd met film 6 ka 1 1 8W l Type CEA T O 07716 0698 5087 1 var ww 5ka 20 Voltmeter Adj Type 110 F4 11236 2100 1824 0360 1550 0360 1551 28480 28480 Rear Barrier Block 5 Terminals I Rear Barrier Block 4 Terminals 1 Diode zener 4 99V IW I 8Z11213 54 04713 1902 0533 Integrated Circuit Operational Amplifier 2 27014 1820 0223 LM301AH A3 HEAT SINK BOARD 1901 0330 0686 5115 Al4N EB 5115 Rect Si LA 800V I fxd comp 510 5 1 2W i 1902 0586 Diode zener 150V 1W 2 SZ 1213 440 5211213 392 1902 0661 Diode zener 7

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