Lesson learn about Agilent E3615A repairing

[BD1QMP]

Here I will sharing my lesson learn of E3615A repairing.
Finally, I found the issue are caused by contacts issue of S1-S5, at least 3 switches have this issue.
and when followed the table A-5 for trouble shooting, the higher out put of out+ plus grounding issue of S1-S5 cause the A/D chip (TC14433) in display board fail.

Warning:
when you are following table A-2 to check the power supply, if you found the voltages of TP6-Point3 and TP6-Point5 are abnormal, but the voltage output of the voltage regulator are fine. you need check the S1-S5 immediately. the ground connection in S1/S5 may cause higher voltage in A/D chip and then burn it.

The A/D chip TC14433 is very difficult to find. My play is redesign the display board with MAX1447 (I have 4 chips in hand).


service manual is here:  https://wiki.physics.wisc.edu/yavuz/images/2/24/E3614a.pdf