HP_6289A.p31-40

and turn on supply.POWER SUPPLY CASEd.Adjust CURRENT control until front panelmeter reads exactly the maximum rated output cur-CC-SNDrent.e.Read and record voltage indicated ondifferential voltmeter.f.Short out load resistor (Ry)by closingswitch S1.g.Reading on differential voltmeter shouldnot vary from reading recorded in step e by moreA.INCORRECT METHOD GROUND CURRENT IS PRODUCES 60CYCLE DROP IN NEGATIVEEAD WHICH ADDS TO THE POWERthan the following:SUPPLY RIPPLE DISPLAYED ON SCOPE.Model No,6253A,62B4A6255A,6289AVariation (mVdc)±0.183±0.265POWER SUPPLY CASEOSCILLOSCOPE CASE62B1A6294AAC-Model No.ACC-Variation (mVdc)±0.5±0.355-36 Line Requlation.To check the line regulationGNDPATHproceed as follows:a.Utilize test setup shown in Figure 5-4TWISTED PAIRleaving switch Sl open throughout test.LENGTH OF LEAD BETWEEN R AND OUTPUTb.Connect variable auto transformer be-TERMINAL OF POWER SUPPLY MUST BE HELD TO ABSOLUTEtween input power source and power supply powerMINIMUM.B.A CORRECTMETHDDUSING A SINGLE ENDED SCOPE.REAK GROUND CURRENT LOOP,TWISTEDinput.DUTPUT FLOATEDc.Adjust auto transformer for 105Vac input.PAIR REDUCES STRAY PICKUP DN SCOPE LEADS.d.Turn VOLTAGE control(s)fully clockwise.e.Set METER switch to highest current rangePOWER SUPPLY CASEOSCILLOSCOPE CASEand turn on supply.f.Adjust CURRENT controls until front panelmeter reads exactly the maximum rated output cur-rent,g.Read and record voltage indicated on dif-ferential voltmeter.h.Adjust variable auto transformer for 125LENGTH OF LEAD BETWEEN RT AND GROUNDED OUTPUTVac input.1.Reading on differential voltmeter shouldTERMINAL OF POWER SUPPLY MUST BE HELD TO ABSOLUTEMINIMUM.not vary from reading recorded in step g by moreC.A CORRECT METHOD USING A DIFFERENTIAL SCOPE WITHFLOATING INPUT.GRDUND CLRENT PATH IS BROKEN:than the following:COMMON MODE REJECTION OFModel No,6253A,6284A6255A,6289AJGNORES DIFFERENCE IN GROUBSUPPLY SCOPE,SHIELDEDWO-WIRE FURTHER REDUCESVariation (mVdc)±0.183±0.265STRAY PICKUP ON SCOPE LEAD.Model No.62B1A6294AVariation(mvdc】±0.15±0.35M0DEL】6253A6255A6281A6284A6289A6294A5-37 Ripple and Noise.Most of the instructionsRI (OHMS}0.330.660,200.330.661.0pertaining to the ground loop and pickup problemsRL(oHMs】6261.062659associated with constant voltage ripple and noisemeasurement also apply to the measurement of con-stant current ripple and noise.Figure 5-12 illus-Figure 5-12.CC Ripple and Noise Test Setuptrates the most important precautions to be observedwhen measuring the ripple and noise of a constantcurrent supply.The presence of a 120 cycle wave-b.Rotate the VOLTAGE control fully cw.form on the oscilloscope is normally indicative of aC.Set METER switch to highest current rangecorrect measurement method.A waveshape havingand turn on supply.60 Hz as its fundamental component is typically as-d.Adjust CURRENT control until front panelsociated with an incorrect measurement setup.meter reads exactly the maximum rated output currente.The ripple and noise indication should be5-38 Ripple and