Agilent Technologies E4350B, E4351B service manual 6. OV Will Not Fire Troubleshooting

OV Will Not Fire Troubleshooting

"OV Will Not Fire"

Start

Turn off supply and remove top cover. Turn on and check secondary bias and reference voltages. (Test Points 9 through 17, Table 6-3)

		Troubleshoot the appropriate
Voltages OK	No
		defective circuit.
?

Yes

Program voltage and current to full scale and OV to 1/2 full scale. Check voltage at A5 J722- 22 (TP40), A1U405 and A1U602 with respect to common (TP9).

J722-22 approx. 2.7V

?

Yes

A1U405-7 approx. 0V

?

Yes

A12U602-6 approx.

5V

?

Yes

Check voltage across A1R516

Yes

A1U602-6 approx. 5V

?

Yes

Check A1Q701 and CR700.

No		Replace A5 DSP board
							Check voltage at A1U405-5 with
							respect to common (TP9)
					No
									Yes
				Check A1R644, R747 and C417.
				Voltage at A1U603-7 should be		No		A1U405-5 Negative
				approx. 2V.			?
			Check A5 J721-12. If not 5V,						Yes
	No		replace A5 DSP board. If 5V
			check A1U602 and DSP cable.					Check A1U405.

	Check A1U410, Q701
No
	(B-E short?)

Figure 3-6. OV Will Not Fire Troubleshooting

Service Addendum 15