Question on old electronic repair

rizbone · Post by **rizbone** » Mon Aug 18, 2014 8:23 am

I have an older switch that has been mummified in some manner and then stopped working. My question is, once you dig out the tar, asphalt, or whatever it was "protecting" the electronics, and manage to repair the thing, what is a good modern substitute to put back in the device?

Curt A · Post by **Curt A** » Mon Aug 18, 2014 10:32 am

Put up a pic of what you are attempting to repair and maybe someone can help...

VintageTechnologies · Mon Aug 18, 2014 11:25 am

I once had to rebuild the power supply of an Atwater Kent 44 radio. I kept all the tar that I carefully scraped out of the power module. After replacing the paper-foil capacitors, I melted the tar and poured it back in to conceal the repairs. I don't know what to recommend for a new potting compound.

Curt A · Post by **Curt A** » Mon Aug 18, 2014 12:06 pm

As far as a modern substitute to refill the switch, most modern ones are epoxy filled...

rizbone · Post by **rizbone** » Mon Aug 18, 2014 1:59 pm

Thanks. The repair was the easy part, now I just need to fill in the "tar" I didn't keep any, but I can probably locate something else around the place with enough to melt back into the new one. I don't want to use epoxy as I think it would be nearly impossible to open it again should anything else break.

Curt A · Post by **Curt A** » Mon Aug 18, 2014 2:38 pm

Why not use candle wax?

HisMastersVoice · Post by **HisMastersVoice** » Mon Aug 18, 2014 3:35 pm

Curt A wrote:Why not use candle wax?

I think the low melting point combined with the high operating temperature of early electronics would likely be disastrous.

Curt A · Post by **Curt A** » Mon Aug 18, 2014 4:19 pm

Never thought about the heat part... I guess it could cause some type of surprise. Typically, any switches that I have messed with don't give off heat, unless defective, but what do I know...

HisMastersVoice · Post by **HisMastersVoice** » Mon Aug 18, 2014 4:40 pm

Curt A wrote:Never thought about the heat part... I guess it could cause some type of surprise. Typically, any switches that I have messed with don't give off heat, unless defective, but what do I know...

I wasn't referring to the switch giving off heat necessarily. I suppose I based my comment on the assumption that said switch was attached to something containing one or more of these, which do give off heat:

: radiotron.jpg (161.06 KiB) Viewed 1987 times

Curt A · Post by **Curt A** » Mon Aug 18, 2014 4:43 pm

Those are out of my experience level... if something doesn't wind up, I try to avoid it...

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