[time-nuts] KS-24361 Power Module Repair

[Bob Stewart]

OK, that explains your comment.  This is most likely a silicone based potting compound.  It's a bit softer than an eraser when cold.  Very little of it was actually stuck to the board or components.  If it had been a hard, epoxy-based covering, I wouldn't have bothered with it.

Bob

      From: Chuck Harris <cfharris at erols.com>
 To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
 Sent: Monday, April 13, 2015 2:18 PM
 Subject: Re: [time-nuts] KS-24361 Power Module Repair
   
No, I meant exactly what I said.

When you are removing epoxy potting compound, put it in an oven
set to 140C, and let it cook until up to temperature.  The potting
epoxy will become about as soft as pencil eraser rubber.  You can
then pick at it, and get pretty big chunks to come off.  When the
epoxy starts to feel hard again, pop it back in the oven.

-Chuck Harris

OBTW, we are not talking about crystal ovens here, but rather unpotting
power supply modules.

Al Wolfe wrote:
>    This seems a bit toasty and is equivalent to 284F. Maybe meant 140F not C?
>
>> An oven set to 140C is your friend when doing jobs like
>> this.
>
>    FWIW, the GE Progress Line two-way radios oscillator crystal holders had an octal
> base, held two crystals, and the heating element could be used on 6 volts or 12 volts
> depending on which way the holder was plugged in.  I have no idea of how well they
> held the temperature. Always planned to use one with an external proportional
> controller but never got around to it.
>
> Al, k9si
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