[time-nuts] Anyone familiar with SR-620 repair?

J. Forster jfor at quikus.com
Fri Mar 23 22:21:19 UTC 2012


Most instrument PCBs have scores of bypass caps...  all in parallel.

-John

=========


> Shouldn't be too bad, a 10uF cap would have 15 Ohms impedance at 1KHz,
> 150
> Ohms at 100Hz, and one could inject at different places on the trace...
> away  from the big bypass caps.
>
> Doing the same with DC and a simple multimeter should work too.
>
> bye,
> Said
>
>
> In a message dated 3/23/2012 14:31:42 Pacific Daylight Time,
> jfor at quikus.com writes:
>
>>  Here is a trick or two that may work:
>>
>> feed a very small AC  voltage with say 1KHz and 10mV into the bad power
>> rail. It won't hurt  anything.
>>
>> Then use an old cassette players' magnetic pickup  and amplifier to
> follow
>> the signal to the short. No need for  expensive hall effect meters.
>
> Good bypass caps are near AC shorts. I've  not tried it, but am not
> optomistic. It would work on stuck signals lines,  but not well on  power,
> IMO.
>
>
>






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