[Elecraft] KPA100 problem

[Steven Pituch]

Hi all,
In my previous email I had described that I had my kpa100 working in the K2
enclosure but that it had died when I tried to install it in the EC2 case.
I was getting "info 080" and Lyle Johnson had suggested a problem with the
aux bus line.
I have refined search down to the 5 V line that supplies the max 1406.  When
I remove U1 on the kpa100 board I get a dead short at pin 1 of U1.  This
could mean that the 5 V regulator is bad but there are other components
connected to this line and any one of these components could be defective
(U3, U4, C23, C89, U6, etc).

I am now faced with developing a procedure to isolate the bad part.  I have
already inspected the board for shorts and do not see any.  The fact that
the kpa100 worked before leads me to believe that a component may have
shorted itself out.

I could destructively remove each component until the short disappeared but
then I would need to replace possibly a lot of parts.  The other option
would be to isolate each part one at a time by cutting traces.  Once the
part was deemed OK, I would have to patch the trace and go on to the next
part.  I would end up with a lot of patched traces.

Any suggestions?

Thanks,
Steve, W2MY

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