Re: DC503A S1810 repair/replacement ?

Andy Warner


- Locating a new switch was going to be a fools errand
- Repairing the switch also seemed impractical
- I got lucky because the missing signals were simply grounding control
signals F & G depending on the selected function
- Was able to design a small PCB to fit where U1601 was located, and
synthesize the F & G control signals using open-drain 74HC parts


Posted here as encouragement for others who might find themselves in a
similar situation.
Screwed up the rework board in two areas highlighted as A & B in

DC503A is working like a champ now, including period B & width B modes,
which were borked previously.

On Fri, Jul 31, 2020 at 10:48 PM Andy Warner <andyw@...> wrote:

Bought a DC503A a while back (as-is) and finally got around to debugging
its strange behavior.
Turns out the function switch (S1810) is missing a set of wipers.


In the photo, you can see the two plastic stumps where the wiper is
supposed to be.
It was nowhere to be found, I guess someone must have disassembled the
switch before me to remove the wreckage.

Any suggestions on repair/replacement strategies ?
Anyone got a dead DC503A they would be willing to sell me all or part of
(if so, please contact me off list at: andyw at pobox dot com)


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