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

John Ackermann N8UR jra at febo.com
Fri Mar 23 18:46:07 UTC 2012


Great advice.  I have the manual, but it doesn't include schematics.  I 
think someone on the list has a PDF of the schematics, so I'll be 
digging around for that before I start digging into the box.

John

On 3/23/2012 2:36 PM, J. Forster wrote:
> Not w/ that instrument, but try the following. I assume you have the book
> w/ schematics.
>
> Power the unit and with a DMM or VOM check the PS rails to see which is sick.
>
>  From the book, locate all bypass caps on that rail.
>
> Put your DMM across each in turn. The one with the lowest drop is likely
> the culprit. If there is more than one w/ low voltage, it's likely the one
> closest to the power supply.
>
> You might try touching all the bypass caps to see if any are runni9ng hot.
> This does not always work, because zero voltage or zero current dissipates
> nothing.
>
> -John
>
> ==============
>
>
>
>
>> My SRS SR-620 counter died last weekend.  After superficial
>> troubleshooting, it looks like there's probably a short on one of the
>> power supply rails.  Symptom is that nothing lights up when power is
>> turned on, but one or more of the three terminal regulators gets very,
>> very hot (can't tell which one since they're all bolted to the side rail
>> as heat sink).  The unit had been running continuously for several weeks
>> when the failure occurred.
>>
>> I just learned from SRS that they charge a flat rate 25% of the current
>> list price for repairs!  (To be fair, if you're the original purchaser,
>> it's only 20%.)  The SR620 currently lists for about $5K, so we're
>> talking about a mighty expensive shorted cap (if that's what it is)!
>>
>> Anyway, has anyone here troubleshot an SR-620 with a problem like this,
>> or have any general insights about working on one of these beasts?
>>
>> Thanks,
>>
>> John
>>
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>
>
>
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