Agilent Technologies E3630A service manual Step Action Response Next Action

Table A-3. Initial Trobleshooting Procedure

STEP	ACTION		RESPONSE		NEXT ACTION
1	Check output voltage of +20V	a.	Normal	a.	Proceed to step (2).
	supply.	b.	Zero volts	b.	Check ac line fuse (F1). If blown, proceed to "Open Fuse
					Troubleshooting" paragraph. If not blown, check bias
					and reference voltages (Table A-4).
		c.	Output voltage lower or	c.	Check bias and reference voltages (Table A-4).
			higher than rating
2	Check output voltage of -20V	a.	Normal	a.	If +20V and -20V outputs are both normal with no load, a
	supply in fixed tracking ratio				supply might be current limiting under load. To check this
	mode.				adjustment see steps (l) thru (p) on page A-4.
		b.	High, low, or zero out-	b.	Proceed to -20V supply troubleshooting.
			put voltage.
3	Check output of +6V supply.	a.	Normal	a.	If the output of this supply is normal unloaded but its volt-
					age falls when loaded, check the current limit adjust-
					ment, steps (q) thru (t) on page A-4.
		b.	High, low, or zero out-	b.	Proceed to Table A-7.
			put voltage.

Table A-4. Bias and Reference Voltage Check

STEP	ACTION		RESPONSE		NEXT ACTION
1	Check +12V bias.	a.	Normal (+12V ± 5%)	a.	Proceed to step (3).
		b.	Voltage high	b.	Check U3 for short.
		c.	Output voltage lower or	c.	Check U3 for open.
			higher than rating
				Note: A short within U2, U6, U8, U9 or U14 can cause low
					+12V or -12V bias voltages.
2	Check -5V reference.	a.	Normal (-5V ± 2%)	a.	Proceed to step (3).
		b.	Voltage high	b.	Check U5 for open.
		c.	Voltage low	c.	Check U5 and Q2 for short.
3	Check -12V bias.	a.	Normal (-12V ± 5%)	a.	Proceed to +20V supply troubleshooting, Table A-5.
				b.	Check U1 for short.
		b.	High voltage
				c.	Check U1 for open.
		c.	Low voltage

Table A-5. +20V Supply Troubleshooting

SYMPTOM		STEP - ACTION	RESPONSE		PROBABLE CAUSE
High output voltage	1.	Attempt to turn off Q9 by	a. Output voltage remains high.	a.	Q9 shorted.
(higher than rating)		shorting emitter-to-base	b. Output voltage becomes near zero	b. Remove short and proceed to step
		of Q9.	volt.		(2).
	2.	Measure voltage at	a. Measured voltage is less than 0	a. Check for open CR13 or R36 and
		base of Q5.	volt.		check for defective U6A.
			b. Measured voltage is more than 0	b.	Check for defective Q5.
			volt.

A-8