Re: DM501A problem


 

On one hand, I have a DM501A with problems as well although not the
same problems. On the other hand, the service manual I have has split
schematics which are also not very good scans. On the gripping hand
(obscure?), I will be spending some time today fixing up the schematic
scans (including the LD120 and LD121 scans) and then make them
available at which point I may be able to make some more constructive
suggestions.

Mine almost works after cleaning all of the mechanical switches. They
may need even more cleaning.

My DM501A has those terrible Texas Instruments edge wipe sockets. Have
you tried reseating all of the ICs? Pay particular attention to any
which feel loose.

I may end up preemptively replacing the sockets and aluminum
electrolytic capacitors in mine and then cleaning the boards in my
ultrasonic cleaner.

On 30 Sep 2016 04:07:57 -0700, you wrote:

Hi,

Thanks. I did check them, they are OK. The power supply seems to be OK. So I'll continue looking at the AD and associated circuitry.

Szabolcs

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