HP ScanJet ADF

From: Carlos Murillo <carlos_murillo_at_epm.net.co>
Date: Fri May 31 22:01:54 2002

At 11:36 PM 5/31/02 +0100, you wrote:
>> I guess I will just proceed with repairing the board. The 24v input seems
>> to be shorted to ground -- that shouldn't be to difficult to find.
>
>Probably a shorted decoupling capacitor (if it's a 'dead short' or close
>to one). I have been known to carefully cut power traces to find out
>which section is shorted, and then home in on the problem. Or you can
>desolder components to test them.
>
>Don't use the trick I once saw recomended of applying a high current
>(10's of amps) PSU to attempt to burn out the short. Something will burn
>out, it's true, but it will just be the weakest connection, not
>necessarily the shorted component.
>-tony

This is the kind of situation in which an HP547A current probe is
most handy. You can easily follow the high current path with it.
Of course, you need to monitor (and limit) the current supplied to
the board under test.

carlos.

--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo_at_nospammers.ieee.org
Received on Fri May 31 2002 - 22:01:54 BST