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| Fingernail Polish to protect exposed copper? |
Posted by: Garrett on 2020-11-04 18:39:36
A week ago I received the analog board for my 1991 Macintosh Classic back from having it re-capped. It works pretty well, but the guy who recapped it suggested that I add some fingernail polish over exposed copper traces (the nasty electrolyte ate away the silkscreen) to protect them from the elements/humidity. I just wanted to double-check: will fingernail polish work fine? I bought LA Colors "Rapid Dry Top Coat" clear nail polish at Walmart for less than $1. (It says it's flammable and to keep away from heat/flame.) I'm assuming I just spread it over the exposed copper?
Hopefully this isn't a dumb question - but how do you remove the plastic shield on the back of the analog board? It appears to be held in place by multiple little plastic rivets(?) that hold it in place. Do those just pop out and pop back in?
Also hoping this isn't another dumb question - but do I need to remove the logic board to discharge the CRT? Last time I did it I removed the logic board to be safe since I was grounding to the metal chassis of the computer. Is it safer/better to ground to the ground screw on the CRT?
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Posted by: karrots on 2020-11-04 19:08:59
You can pop the rivet out from the back side by pushing on the center. or from the front by getting a screwdriver in between the top of the rivet and the next layer.
You should probably discharge the CRT before doing anything else inside the chassis to avoid shock.
I can't speak for the nail polish. I personally purchased some UV solder mask and use that on any exposed copper. You can get a tube for about $5.
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Posted by: 360alaska on 2020-11-04 21:35:14
4 Options I use:
1. Tin the bare copper
2. Nail polish works good
3. Insulating varnish:
https://www.amazon.com/MG-Chemicals-GLPT-Insulating-Varnish/dp/B00S4H8V1Q
4. Green conformal coating pen:
https://www.all-spec.com/Product/419D-P-GR-33018
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Posted by: Garrett on 2020-11-04 22:09:13
So the nail polish should be good? I don't have a soldering iron, and I don't have any of the other chemicals or conformal coating. I'll try to apply it tomorrow.
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Posted by: 360alaska on 2020-11-04 22:17:20
It's basically just a lacquer, not a problem. IF that's what you want to use go for it.
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Posted by: Garrett on 2020-11-04 22:20:21
Does it come off easy if needed? I just want something that will protect those traces so it doesn't cause any issues later down the road. Is it worth paying extra $$$ and buying the proper conformal coating?
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Posted by: LaPorta on 2020-11-05 02:41:00
Another option I use: liquid electrical tape. Gooey and sticky, but easily applied with a toothpick.
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Posted by: Challenger 1983 on 2020-11-05 08:53:12
You can use some superglue, I use this to cover traces as it can be easily dissolved by acetone if you ever need to get to the trace, plus it dries fairly quickly
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Posted by: karrots on 2020-11-07 06:09:33
Down side to superglue is it breaks down at around 100c. So don't expect to be soldering around in it.
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