Agilent Technologies E3630A service manual Step Action Response Probable Cause

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.

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