HP 6448B Operating And Service Manual Download Page 3

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Summary of Contents for 6448B

Page 1: ... that Hewlett Packard s former test and measurement life sciences and chemical analysis businesses are now part of Agilent Technologies The HP XXXX referred to in this document is now the Agilent XXXX For example model number HP8648A is now model number Agilent 8648A We have made no changes to this manual copy Support for Your Product Agilent no longer sells or supports this product You will find ...

Page 2: ...82 0241 1 For Serials above 610241 Check for inclusion of For 9erials B elciw 610182 I J change page I I d I I I I l Refer to Appendix A I I I I I 100 Locust Avenue Berkeley Heights I I NeW Jersey 07922 I 1 I 1 __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ i _ _ ________ __ _ _ HP Part No 06 448 0001 I 1 Printed April 1968 I J 1 ...

Page 3: ... Output Capacitance Rever d Voltage Loading 3 3 3 3 3 4 3 5 3 5 3 5 3 5 3 5 Section Page JI I II OPERATING INSTRUCTIONS Cont d 3 48 Revers Current Loading 3 6 i IV PRINCIPLES OF OPERATION 4 1 l ii I 4 1 Overall Description 4 1 4 12 Detailed Circuit Analysis 4 3 4 13 AC Input 4 3 4 15 DC ouiput i 4 3 4 1 1 Feedback Loop 4 3 4 22 Voltage Gomparlson Amplifier 4 3 4 25 Current Comparison Amplifier 4 4...

Page 4: ...ng Remote Voltage Programming Constant Voltage Remote Resistance Programming Constant Current Re mote Sensing Normal Parallel Connections Auto Parallel Two and Three Units Auto Tracking Two and Three Units OveraUiJlock Diagram Operdtlllg locus of a CV CC Power Supply SCR Regulator Control Timing Diagram I I I I I 3 2 3 2 3 3 3 3 3 4 3 4 3 4 3 5 4 1 4 2 4 4 I IV Test Setup 5 2 5 2 Front Panel Termi...

Page 5: ...ds tho limits established by these controls 1 3 Output voltage and current can be continu ously monitored on the two front panel mete s The power supply as both front an_d rear output terminals Either the positive ornegative output terminal may be ground ed or the pc wer supply can I I be oper11ted Ilo11ting at up to amaximum of 300 Volts off ground 1 4 OPERATING CAPABILITIES 1 5 Terminals at the ...

Page 6: ...l I l f I I I I I I I 1 I J I 1 f I I I l 1 I I 1 1 I Table lJ l Specification C ntlnued 1 I 1 I r r _ IUPPLE AND NOISE Less than 600mVrms 2Vp p de to 20MHz I 1 LOAD TRANSIENT RECOVERY Less than 200nisec ls requlr d for output voltage r covery to within 30oomy of the nominal output voltage following a loe l change from fu Uoad lo half load or half loa d to foll load xcludln9 he lnltlarnarrow spike...

Page 7: ...oper Instrument operation I i1 ii ommen ds that the lnst lment panel nd cabinet be grounded This lnstru111ent ls equipped with a three conductor power cable The third cond ctor ls the ground co_ndu tor a d when the cable Is plugged Into an appropriate receptacle the Instrument ls grounded The offset pln on the p ower cable 2 7 INSTALI AT ON DAT 2 8 The lnstru en Is shipped ready for bench operatio...

Page 8: ... I 1 I I f ll I 1 1 I i 1 I I I I 1 I l I I I I II I l I I I I I 1 i i I I l 1 1 1_j 1 r 1 i I f I I I I I 1 I I I ...

Page 9: ...ng conr actions between particular terminals 3 1 on the terminal strip at the rear of the power sup ply The terminal designations are stenciled In white n the powar supply above their respective terminals Although the strapping patterns illustra ted In this section show the positive terminal grounded the operator can ground either buss or operate the power supply up to 600Vdc of round floating The...

Page 10: ...advantage of the low output Impedance of the power supply Each pair of connecting wires should be as shortas possible and twisted or shielded to re duce l lois e piCkup f shield 15 used connect ope I 3 2 end to power supply ground terminal and leave the other end uncpnnect7d I 3 13 If load consideration s require that the output power distribution terminals be remotely located from the power suppl...

Page 11: ...Ampere The programming oefflclent Is adjusted r i r r H il J iitt ir J r F tf f J 0 t 1 a r rt 1 Wi VJ Si t t Ll t l tf fi r1 t 1 p _ J 1 1S t8 i t f i j j_ 1 _ _ CZ t i_ _1_ 1 I _ J _ 1 t J Figure 3 5 t emote Resistance Programming Constant Current jf I l for an ac curacy of 6 at the factory If greater programming accuracy Is required It may be a chieved by ahanglng resistor R41 as outlined In Pa...

Page 12: ...put current Is the sum of the output cur rents of the Individual power supplies The output CURRENT controls of each power supply can be separately set fhe output voltage controls of one power supply should be set to the desired out put voltage the other power supply should be set for a slightly larger output voltage The supply set to the lower output voltage will act as a con stant voltage source ...

Page 13: ... resistors 3 40 SPECIAL OPERATING CONSIDERATIONS 3 41 PULSE LOADING 3 42 Tl ie power supply will automatically cross over from constant voltage to constant current op eration or the reverse ln response to an increase over the preset limit in the output current or volt age spectlvely Although the preset limit may be set higher than the average output current or voltage high peak currents or voltage...

Page 14: ...e power suppl may actually deliver a reverse current to the power I I I 1 3 6 supply during a portion of its operating cycle An external source cannot be allowed to pump current into the supply without loss of regulation and pos siblP damage to the output capacitor To avoid these effects it is necessary to preload the sup ply with a dummy load resistor so that the power I supply delivers current t...

Page 15: ...he and terminals for low ac output Im pedance and to help supply large puls1 currents SCR regulators control the ac Input to provide good one Input circuit is used at a time I 4 4 The voltage and current comparison circuits operate In a similar manner Each clrc ilt has an amplifier that amplifies an error voltage that Is proportl naI to the difference between the actuaI output and the programmed o...

Page 16: ...d attached RL loUT 0 and E QUT E s the front panel voltage control settlng When a loail re sistance is applied to the output terminals of the power supply the output current Increases while the output voltage remains constant point D thus represents a typical constant voltage operating point Further decreases in load resistpnce are ac ompanled by further increases in louT with no change iri the ou...

Page 17: ...he VOLTAGE control 4 3 programming resistor R2 has been adjusted so that the supply Is yielding the desired output voltage Further assume that the output voltage Instantane ously rises goes posltllre due to a variation In the external load circuit 4 19 Note that the change may be in the form of a slow rise in th output voltage or a posltive golng ac signal An ac signal ls coupled to QI through cap...

Page 18: ...ws to the collector of Q4 to tum It on Base current ls controlled by the vo ttage or current cir cults via CR7 or CRB respectively For example during constant voltage operation the collector voltage of QI voltage lnput forward b lases CR7 CRB reverse biased by QB the current through CR7 will vary as QI collector voltage varies and thus vary Q4 base current therefore the collector current of Q4 ls ...

Page 19: ...ormer n the voltage Is lnsuffl clent to forward bias the rectlflers ln the bridge In order to maintain definltlon between the end of one cvcle of the rectified output 11 1d tt a beginning of the next cyc le diode CR41 provfdes anproxl mately o 7 Volts at the rectlfled outpui The cur rent for CR41 Is supplll d through CR46 As the voltage across the secondary winding moves away from the zero cross o...

Page 20: ...4 The 33Vdc ls the voltage across C21 The I I 4 6 1 l j 1 33V across C20 provides the unregulated Input to the regulator I 4 47 For the 30Vdc Jranslstor Ql0 ls the erro r detector amplifier Zener diode V l and diode CR6 provide ll ref 1rence voltage at the emitter of 010 Voltage dlv der R35 R36 supplies an error voltage to the base of Ql0 which amplifies and applies lt to the base of series regula...

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Page 22: ...edures described In this section Table 5 1 Test Equl ment Requ lred REQUIRED RECOMMENDED TYPE CHARACTERISTICS USE MODEL Dlfferential Sensitivity lmV full scale Measure DC Voltages 3420 See Note Voltmeter min Input Impedance callbratlon procedures 1 10 megohms min Variable Range 2 00 260Vac 90 l30Vac Vary AC input Voltage Equipped with voltmeter Transformer accurate within 1 Volt AC Voltmeter Accur...

Page 23: ...detector In which one Input terminal ls grounded to avoid ground loops and circulating currents 5 5 PERFORMANCE TEST 5 6 The following test can be used as an lncom I Ing lns ectlon check and appropriate portions of the test can be repeated either to check the oper ation of the Instrument after repairs or for perlodlc maintenance tests The tests are performed using a nominal 115Vac 1 60Hz single ph...

Page 24: ...Uory 5 3 To check the Constant Voltage load regula proceed as follows a Connect test setup as shown In Figure b Tum CURRENT controls fully clockwise c Tum on supply and adjust VOLTAGE con trols until front panel voltmeter Indicates exactly the maximum rated output voltage J Figure 5 3 Coi istant Voltage Test S tup ferentlal voltmeter e Disconnect load resistors f Reading on differential voltmeter ...

Page 25: ...itude of this resulting noise signal can easily be much greater than the true ripple developed be tween tlio plus and minus output terminals of the power supply and can completot y invalidate the meusurement 5 20 Tho same ground current and pickup problems can exist If an RMS voltmeter is substituted in place of the os7illoscopo lri rtgure 5 4 However the oscl loscope display unlike tho true RMS m...

Page 26: ...jection Ls attained 5 25 To check the rlpple and nolsa output pro ceed as follows a Connect the oscilloscope or RMS volt meter as shown Ln Figures 5 4B or 5 4C b Adjust VOLTAGE control untll front panel meter Lndicate s maximuni rated output voltage c The observed rlpple and noise should be less than 600mVrms and 2V p p 5 26 Noise Spike Mensuremont When a hlgh re quency spike measurement Ls being ...

Page 27: ...Tum CURRENT controls fully clockwise C Tum on supply and adjust voltage con trols until front panel ammeter Indicates exactly l 5 Amperes d Close the fine switch on the repetitive load switch setup e set the oscllloscope for Internal sync and lock on either the positive or negative load transient spike f Set the vertical Input of the oscilloscope for ac coupling so that small de level changes in t...

Page 28: ...blllze for a sufflclent period of time at ealih temperature of measllremen Flgure 5 B Output Impedance Test Setup 5 37 The temperature coefficient specified ls the maximum temperature dependent output voltage chan ge whlc h will result overany 10 c Interval The differential voltmeter or digital voltmeter used to measure the output voltage change of the sup ply should be placed outside the oven and...

Page 29: ... output current measurements the current sampling resistor must be treated as a four terml nal device In the manner of a meter shunt the load current ls fed to the extremes of the wire leading to the resistor while the sampling termi nals are located as close as possible to the reslst an e portion Itself see Figure S 9 Generally 5 8 any current sampling resistor should be of the low noise low temp...

Page 30: ...opera tion are understood refer to the overall trouble shooting procedures In Paragraph 5 55 to locate the symptc m and probable caus 5 53 The schematic diagram at the rear of the manual Figure 7 3 contains normal voltage read ings taken at various points within the circuits These voltages are positioned adjacent to the ap plicable test points Identified by encircled num bers Component and test po...

Page 31: ... b Check reference voltages Table 5 2 c Check the regulatlon characteristics of zener diode VRl as follows 1 Connect dlfferentlal voltmeter across VRl 2 Connect appropriate load reslstor RL given ln Figure 5 3 across and H output terminals 3 Perform steps b through f of Paragraph 5 13 4 If the d fferentlal wltmeter reading varies by more than l0mV replace VRl d Ensure that upply Is not current lim...

Page 32: ...wer levels 5 59 REPAIR AND REPLACEMENT 5 60 Before servicing a printed wiring board re fer to Figure 5 11 Sactlon VI of this manual con tains a llstof replaceable parts 5 61 ADJUSTMENT AND CALIBRATION 5 62 Adjustment and caUbratlon may be required after performance testing troubleshooting or rq palr and replacement Perform only those adjust ments that affect the operation of the faulty cir cult an...

Page 33: ...a l lVac tween ACC and 45 b b Proceed to Step 3 3 Check the operation of a Output remains high a SCR Regulator Control tl e SCR Regulator Cori Circuit Q7 or associated trot Circuit by shorting components defective Q4 emitter to_ collector R4fcr to waveforms on Figure 7 2 b Output decreases b Proceed to Step 4 4 Check the conduction a Output remalns hlgh a Q4 or associated compo capability ofQ4 by ...

Page 34: ... ige to the etched circuit board will result I l I J 1 Apply heat sparingly to lead of component to be replaced If lead ofeom110nentpasses through n eyelet In the circuit board apply heat on com ponent side c o ponent does not passihrough an eyelet apply lteat to conductor side of boa rd 3 Bend clean tinned lead on new part and carefully Insert through eyelets or holes ln board p 11 IIiIIi QlZO r ...

Page 35: ...grammlng current proceed as follows a Tum off supply and short the output io H b Turn the VOLTAGE and CURRENT controls fully clockwise c Remove R41 and connect a decade resis tor set to 90K ohms In Its place d Turn on the supply and adjust the decade resistance until the front panel meter Indicates l BAmps 5 73 TRANS f NT BCOVERY TIME 5 74 To minimize the transient resulting from a load change pro...

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Page 37: ... r addresses Specify the following lnformaito11 f r each part Model complete s rlal r umber anr I any Optlon or specla I odiflcatlon J number s of qie Instrument Hewlett Packard part number circuit reference des ignator and description To ord r a part not listed In Table 6 4 give a cumplete des rlpt on of tpe part its funct On and t ts lociltion A B C CB CR OS Table 6 1 Reference De igd tors asse ...

Page 38: ... TransistO Electronics Corp Minneapolis Minn CODE NO 0 7138 07263 07387 07397 07716 07910 07933 08484 08530 08717 08730 c08806 08863 08919 09021 09182 09213 09214 09353 09922 llll5 ll236 11237 11502 11711 12136 12615 12617 12697 13103 14493 14655 14936 15801 16299 MANUFACTURER ADDRESS Westinghouse Electric Corp Electronic Tube Div Elmira N Y Fairchild Camera and Instrument Corp Semiconductor Div M...

Page 39: ..._Omcr City Pa Thomas and Betts Co Philadelphia Pa Union Carbide Corp New York N Y Ward Leonard Electric Co Mt Vernon N Y Use Code 71785 assigned to Clncli Mfg Co Chicago Ill I 6 3 CODE ADDRESS NO MANUFACTURER 70563 70901 70903 71218 71279 71400 71450 71468 Amperlte Co nc Union City N r Beemer Engrg ICo Fort Washington Pa BeIden Corp Chicago Ul Bud Radio nc Willoughby Ohio Cambridge Thermionic Corp...

Page 40: ...J 8329 Bendix Corp Electric Power Div 83330 83385 83501 Eato9to wn N J Herman H Smith Inc Brooklyn N Y Central Screw Co Chicago Ill Gavitt Wire and Cab e Div of A marace Esna Corp Br opkficld Mass I 6 4 CODE Nd 83508 83594 83835 83877 86838 87034 87216 87585 87929 88lj0 0 0245 1 90634 90763 91345 I MANUFACTURER ADDRESS 1 Grant Pulley and Hardware Co West Nyack N Y Burroughs Corp Electronic Compone...

Page 41: ...NPN sl NOT ASSIGNED SS NPN sl SS PNP sl SS NPN st i Rl J R2 fxd nlet film 182Kn 1 W 1 var ww 200Kn l0Tum TQ l 4 l l 4 l l 4 2 l 2 l l 10 13 2 2 2 2 l l l 4 2 l l 2 l 6448B 6 5 MFR PART NO 160Pl54910 150Dl05X9035A2 192P22292 150D474X9035A2 160P47396 161P47406 l 60Pl0494 36Dl02F400CE2A D70996 1 150Dl05X9035A2 30D206G050DC4 150D105X9035A2 l92P82392 l92P2249R8 I AM33 Curve 4 obd 1N4828 I 1N4828 1N485B...

Page 42: ... 2 l l l l 3 l 1 l 1 1 1 1 1 2 2 I l l l I 6448B 6 6 I MFR PART NO MFR RS CODE PART NO Type CEA T O obd 07716 0757 0465 l Type CEC T obd 07716 0757 0311 EB 1045 01121 0686 1045 l Type C42S ohd 16299 0698 3667 2 obd 09182 2100 1847 l Type C42S obd 16299 0698 3667 TYr e CEA T O obd 07716 0757 0449 l Type CEA T O obd 07716 0757 0460 l Type EB obd 01121 l EB 3035 01121 0686 3035 l EB 1055 01121 0686 1...

Page 43: ...mper Rear Panel 4 Knob CURRENT Control l l Knob VOLTAGE Control Universal Cpupllng Voltage Control 2 l Motor Fan Casting Fan Blade Fa i Bushing Front Panel Control Insulator Heat Sink Standoff Insulator For Cl2 and R21 l l 2 4 l 6448B 6 7 MFR PART NO MFR RS CODE PART NO obd 09182 0440 0042 l 1N2163A 06751 1902 0763 l obd 09182 5060 6114 obd 09182 06448 60001 obd 09182 0 6448 60002 obd 09182 06448 ...

Page 44: ...ION 17 and or 18 CR17 18 SCR 35A 400prv R21 fxd comp 22 5 lW R58 fxd m_et ox 75K _ 5 2W Tl Transformer Power T2 Transformer Blas I I I TQ l 4 2 l l 6 4 l 1 4 2 i l l l I 5448B 6 8 MFR PART NO obd obd obd 9323 A 194 0 obd 1661 3066 H4021 T4 4 obd 2658 38539 GB 2205 T Pe C42S obd obd obd I MFR RS CODE PART NO 09182 0380 70091 l 09182 0380 0718 l 09182 0380 0723 l 06540 0380 0396 l 05277 2190 0898 l ...

Page 45: ... _ I 1 _ l 11 I I l 1 1 1 I I I 1 I ...

Page 46: ... the schematic are marked directly on the main printed il lng board Voltages are given on the schematic adjacent to the app lcable test polnts identified by ench c led numbers on both the schematic and printed wiring boa rd Included on the schematic apron are the av11forms asso clated with the SCR control circuit portion of the unit i 1 i 7 1 I I I i 1 ...

Page 47: ...ANGE 1 Ql 3 8 10 to 2N3906 Motorola 04713 iq Part No 1853 0036 These tra nslstors should be replaced by 1853 0065 as shown In Table 6 4 under Ql 3 8 10 I CHANGE 2 R24 to 33K H l 8W lq Part No 0698 5089 This mslstor should be replaced by 0698 4484 as shown In Table 6 4 under R24 CHP GE 3 R25 to lOK Type 110 i Part No 2100 0396 This potentiometer shou ld be replaced by 2100 18 4 as shown In Table 6 ...

Page 48: ... i I Clt 7 15 47 C 5 Q 7V c 1 1JMl C7 I 04 1 c a ooil ca I _ aoy T5t R53 01 I AC It I ZJ C lt 9 tit I fl u Vaw II IZ tlO 1001 300IC 47 C tO L11 CZ ZOOl t 15Y lt7 I 00 QJ l rr woo NDT I lfll KE J ro H MF V1 5 Wlc OTHE VWl F NOT lll L AND l1W R OR M l tlN rourANCE Cl l EGUUTO r ci wr CIKCU T J lt EM TERMINAi A IC l IIOWN IN tvORMAL TRAPPINf1 FD ti OF Fl Ol IT P IN t CONf fOI 0Etyor J vOl rAGC C tJIJ...

Page 49: ... 0 1 I I I I I I I 1 I I I I i I ...

Page 50: ...e to u specification table 1 1 and Paragraph 2 14 The minimum ac power lir e protection capacity required for SCk firing surges ts 20 amperes when operated from a US volt t tne and 10 amperes when opernted from il 230 v Jtt llne On the schematic change the reference designator md value of the current samplln g reS 1stcr from RSj R23 ln SW Iu th pl certble parts t lble udd Lcc kwasher Internal toot...

Page 51: ...e to l2k 1 HP Part No 069B 50B8 R21 Change to 390n 2W H Part No 0696 3633 RS6 Delete R56 Tl Change to HP Part No 644B B0092 T2 Change to HP Part No 9100 2195 i T3 Change to HP Part No 5060 7176 I Chapter 2 delete paragraph 2 1 6 an substitute the following 2 16 CONNECTIONS FOR 20B 230 VOLT OPCR ATION Opilon 27 and 2B respectively Tl ls rewired as follows Connection between termlnals 1 and 3 is rem...

Page 52: ...ith a I 0 mlcr henry induct nee I 5060 6114 l ERRATA 1 I In the th lrd sent nce of paragraph 3 4 change the word posltlve to negative Add the following notice to paragraph l 18 tf ectlve December 1 1975 extra manuals may be obtained by ordering Option 9l 0 when ordering your instrument The nun bet of extrn manuals depends 9n the number of tlon 91 Os ordered In the parts list change the HP art No o...

Page 53: ...ation Delete th replace CR17 CRIB R55 CR51 and t7 with tdac l two types of posts listed on page 6 7 and add CR52 HP Part No 1884 0218 change C12 to C 3 HP Part No 0160 4323 change R21 to R61 390a 0 511 HP black bln11ng post HP rart Nb 1510 0107 qty I Part No 0686 3915 change TS1 to HP Part No 0440 ard red binding post Hr Part NT 151 0 0091 qty 2 0079 chang T3 to HP Part No 5080 1914 Replace the se...

Page 54: ...s Installed on the shaft of potentiometer R2 CHANGEi15 Replace Fan Motor Caning and Blade with Fan tube axlal HP Part No 316u 0056 1 CHANGE 16 ln the 1tePlaceable parts list Fage 6 S add the following parts C34 22µF 250V HP P N 0160 4259 CR53 HP P N 1901 0050 page 6 6 add R62 l 6k w HP P N 0686 1625 page 6 7 add VR2 400Jl1W 23 7 V HP P N 1902 3256 oO the r chematic_C34 is to be placed on the inboa...

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HP 6448B, Operating And Service Manual

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