Electronics > Repair
Keithley 2002 repair help
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nikonoid:
In a form of a short update, I finally had a bit of time to take the new (burned) K2002 apart.

I removed capacitors and diode bridge around burned spots. One capacitor blew a hole in its side while another leaked from the bottom. Basically a poster project on why you need to change capacitors in this.

As a result, there is one surface trace that was eaten - no big deal, one via that looks burned - no problem. And then a large burn through the board. It is basically ok on the bottom and a large extended black hole on the top.

In attempt to understand the damage I "x-rayed" the board with a flashlight. Then I superimposed top and bottom view in photoshop and traced all the relevant conductors in 4 colors.

Red, Green, Blue and Yellow for all 4 layers of the PCB, with Red being component layer and blue and green two internal layers.



It appears that burned area did not have other top or bottom conductors. What got taken out is 3 internal conductors and 3 vias getting from layer 2 to 3.

Unfortunately as you can see all 3 traces start and end outside of area that I have reverse engineered. They probably are not even a part of power supply.

I will have to do more tracing work just to understand what these traces are.

More photos are coming. Wish me luck.



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TiN:
I don't miss this :). Keithley 2001/2 are great for learning how to decipher cryptic layout. Often I had situation when trace goes under 1206 resistor/cap, and going out from the other side. You think, easy, same trace between the pads, right? Mhm, not quite ,there are two vias hidden under the thing.  ;)

Luck will not help here, but dedication and xxx amount of hours and late nights will do ;) Looking forward for your fixes.  :popcorn:
My take would be to cut whole charred area and air-wire all connections with copper thin wire. You don't want leakage (burnt PCB is conductive carbon) to give you horrors.
Zucca:
nikonoid I hope you will fix it. It´s so inspiring what you are doing...
WastelandTek:
I agree that you are going to have to dremel out all the burnt fiberglass...what a task you have set yourself
nikonoid:
I am actually considering very small drill first and then needle file by hand, as there are many good traces nearby.


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