Agilent Technologies E3630A service manual Step Action Response Probable Cause

Page 19

Table A-7. +6V Supply Troubleshooting

SYMPTOM

 

STEP - ACTION

 

RESPONSE

 

PROBABLE CAUSE

 

 

 

 

 

 

 

The +20V supply must operate properly before troubleshooting the -20V supply.

 

 

 

 

 

 

 

High output voltage

1.

Attempt to turn off Q1 by

a.

Output voltage remains high.

a.

Q1 shorted.

(higher than rating)

 

shorting emitter-to-base

b.

Output voltage becomes near zero

b.

Remove short and proceed to

 

 

of Q1.

 

volt.

 

step 2.

 

2.

Measure voltage at

a.

Measured voltage is more than

a.

Check for defective Q4.

 

 

base of Q4.

 

-0.6V.

 

 

 

 

 

b.

Measured voltage is less than

b.

Check for open CR6, R11 and

 

 

 

 

-0.6V.

 

check for defective U2A.

 

 

 

 

 

 

 

Low output voltage

1.

Measure voltage at the

a.

Measured voltage is less than

a.

Check for open Q1, Q6, R25, or

(lower than rating)

 

base of Q4.

 

-0.6V.

 

CR5.

 

 

 

b.

Measured voltage is more than

b.

Proceed to step (2).

 

 

 

 

-0.6V.

 

 

 

2.

Eliminate current limit

a.

Output voltage increases.

a.

Check for U2B defective.

 

 

circuit as a source of

b.

Output voltage remains low.

b.

Reconnect lead and proceed to

 

 

trouble by disconnecting

 

 

 

step (3).

 

 

anode of CR7.

 

 

 

 

 

3.

Measure voltage at

a.

Measured voltage is near

a.

Check for defective U2A.

 

 

pin 3 of U2.

 

-0.7V.

 

 

 

 

 

b.

Measured voltage is zero volt.

b.

Check for CR9 and CR10 shorted.

 

 

 

c.

Measured voltage is near

c.

Check for open R29, shorted R11,

 

 

 

 

+0.7V.

 

or leaky or shorted C5.

 

 

 

 

 

 

 

Table A-8. +20V Preregulator/Control Circuit Troubleshooting

STEP

ACTION

 

RESPONSE

 

PROBABLE CAUSE

 

 

 

 

 

 

 

Set output voltage at 12V+0.5V.

 

 

 

 

 

 

 

 

 

1

Measure pin 1 of U14.

a.

Measured voltage is -12V.

a. Proceed to step (2).

 

 

b. Measured voltage is near

b.

Check for defective U14A.

 

 

 

+4.3V.

 

 

 

 

 

 

 

2

Measure pin 1 of U13.

a.

Measured voltage is near +1V

a. Check for defective U13 or

 

 

 

 

 

CR12.

 

 

b. Measured voltage is near 0V.

b. Check for open Q11 or R81.

 

 

 

 

 

3

Measure pin 1 of U11.

a.

Measured voltage is near +1V

a. Check for defective U11.

 

 

b.

Measured voltage is near 0V.

b.

Check for open Q11 or R82.

 

 

 

 

 

 

Table A-9. -20V Preregulator/Control Circuit Troubleshooting

STEP

ACTION

 

RESPONSE

 

PROBABLE CAUSE

 

 

 

 

 

 

 

Set output voltage at -12V-0.5V.

 

 

 

 

 

 

 

 

 

1

Measure pin 7 of U14.

a.

Measured voltage is -12V.

a. Proceed to step (2).

 

 

b. Measured voltage is near

b.

Check for defective U14B.

 

 

 

+4.3V.

 

 

 

 

 

 

 

2

Measure pin 1 of U12.

a.

Measured voltage is near +1V

a. Check for defective U12 or

 

 

 

 

 

CR31.

 

 

b. Measured voltage is near

b.

Check for open Q10 or R56

 

 

 

+4.3V.

 

 

 

 

 

 

 

3

Measure pin 1 of U10.

a.

Measured voltage is near +1V

a. Check for defective U10 or

 

 

 

 

 

CR27.

 

 

b.

Measured voltage is near 0V.

b.

Check for open Q10 or R55.

 

 

 

 

 

 

A-10

Image 19
Contents April Dual Output Power SupplyGround the Instrument Safety SummaryBefore Applying Power Safety Symbols Do not Service or Adjust AloneTable of Contents General Information Line Fuse SpecificationsOperating Instructions InstallationInstallation Data Input Power RequirementsOverload Protection Circuits Turn -ON Checkout ProcedureOperation Tracking Ratio ControlOutput Capacitance Load ConsiderationsPulse Loading Reverse Current LoadingReverse Current Loading Solution Principles of Operation Service InformationType Required Characteristics USE Recommended Model MaintenanceTest Equipment Required Performance Tests Figure A-4. Current Sampling Resistor Connections Rated Output, Tracking, Meter Accuracy, and Cur- rent LimitLoad Regulation Load Effect Load Transient Response Time Common Mode Current CMISymptom Check Probable Cause TroubleshootingInitial Troubleshooting Procedure Open Fuse TroubleshootingStep Action Response Next Action Symptom Step Action Response Probable CauseRemove short and proceed to Step Action Response Probable Cause Current Limit Adjustment Adjustment and CalibrationMeter Calibration Ordering Information Replaceable PartsCode Manufacturer Address 6CDNG#4GRNCEGCDNG2CTVU.KUV 6CDNG#4GRNCEGCDNG2CTVU.KUV%QPVF 45+5614-96% 100%6142156622+052%%106 Certification Quality Manager Seoul 153-023 Korea