HP ScanJet ADF

From: Matthew Sell <msell_at_ontimesupport.com>
Date: Fri May 31 13:03:57 2002

Another problem to keep an eye out for are tantalums that were inserted
onto the board *backwards*, with the polarities wrong.

I saw this on a few different production boards from different
manufacturers. It seems the power supplies work perfectly fine for a while,
and short out later on in life.

Replacing the capacitor fixed the problems.

         - Matt


At 06:32 PM 5/31/2002 +0100, you wrote:

>Tom Uban 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.
>
>Just a suggestion: I fixed an HP 1980B oscilloscope that had a shorted
>power supply by replacing a shorted tantalum capacitor. Tantalums
>tend to go short-circuit for no good reason, and result in the
>short-to-ground symptom that you mention.
>
>--
>John Honniball
>coredump_at_gifford.co.uk



Matthew Sell
Programmer
On Time Support, Inc.
www.ontimesupport.com
(281) 296-6066

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