On Friday, November 15, 2019 at 5:30:14 AM UTC-8, John-Del wrote:
On Thursday, November 14, 2019 at 11:14:21 PM UTC-5, Ralph Mowery wrote:
In article ,
says...
eport if the normal operation is restored when heated.

If so, the first thing to get checked is the electros. I pull every one and test them for value, ESR, and dielectric absorption. Testing ESR in circuit on many modern circuit boards is a waste of time.




Once pulled, you might as well not test them, just replace them.

You may want to test the new ones before you put them in.


If you know the board *will* be fixed and put back in service, then yes, by all means replace them. But if I pull an electro during testing and it's good, I put it back and continue working on the board. No sense changing good caps on a board that may have to be replaced, like OP is dealing with..

Lots of these industrial boards use custom ICs, ICs and semis that have been intentionally defaced, and processor ICs for which there is just no data. Sometimes you just have to replace a board.

'lytic caps go bad eventually. After removing the caps for testing you've already run the risk of damaging the board. Why put the old ones back? In broadcast gear small value caps are the most common failures. I've replaced thousands of 100uF 25 V caps. Unit price 32 cents, 1000 for $83. Buy in bulk and replace in bulk. It costs less than testing and re-installing.

G²