Re: TDS694C 50 Ohm Overload


They were about $5 apiece when I bought them IIRC, and there are 4 per board I think.  It has been a while. It's a slightly finicky job, the joints are not very easy to reach and the boards are very fragile being ceramic.

As far as Ebay sellers checking things,  you will probably not have much luck there unless the seller is somewhat knowledgeable about the scope. You might be able to guide one through running SPC and checking the error log.


On Jan 4, 2020 9:14 PM, "Reginald Beardsley via Groups.Io" <> wrote:

On Sat, Jan  4, 2020 at 05:30 PM, EricJ wrote:

A lot of SPC fails on TDS scopes seem to be related to contact
resistance in
the switching relays on the hybrid acquisition boards. I have a TDS754D
had that problem. Changing the relays solved it.


On Jan 4, 2020 4:00 PM, "Reginald Beardsley via Groups.Io"
<> wrote:

If it works on the higher setting, the problem is in the input section
ahead of the ADC.  I'd look for a burned 50 ohm resistor. Or perhaps a
cracked solder joint.

I saw several of these on ebay with the SPC fail, but had been unable
find any information about what might be wrong with such a unit.  How
you get the input damage information?


How hard is it to get replacement relays and what do they cost?

Is there a blog post about reviving these things?

And what do you ask an ebay seller to do to find out the status of  an



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