Should I attempt to clean this up off the motherboard? Any idea what will clean it safely?
Power Supply Seepage
Power Supply Seepage
I was looking inside my PCjr this morning and I noticed some strange coloring on the motherboard over near where the power supply was (I recently replaced it with the ATX power supply mod). I pulled out my old power supply card and noticed the Siemens B82723-G5-A12 part is leaking. I presume this is a transformer?
Should I attempt to clean this up off the motherboard? Any idea what will clean it safely?
Should I attempt to clean this up off the motherboard? Any idea what will clean it safely?
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DoctorOctal
- Posts: 94
- Joined: Mon Mar 02, 2020 12:41 pm
Re: Power Supply Seepage
This is a common problem with the long board power supply but isn’t too serious apart from the messiness.
The blue component is a choke (an inductor) that’s meant to prevent electrical noise from passing between the mains and the computer. The green stuff is potting compound that has a tendency to leak out.
The green goo is not conductive and presumably not corrosive, so it should be safe to just leave on the motherboard. Sometimes it leaks into connectors and prevents good contact or easy insertion; in such cases, you’ll want to clean it up.
I’ve found that it’s slightly soluble in alcohol. Start by gently scraping up the bulk of it with a spudger, small flat-head screwdriver, your fingernail through a paper towel, or some such tool. Be careful not to scratch the PCB or traces. Then clean up the remaining film with isopropyl alcohol and a brush.
As for the choke, I don’t think you need to do anything about it. Chuckphd53 desoldered and re-potted his, but I haven’t yet noticed any problems leaving it as-is. I wouldn’t expect the loss of potting to make a big difference in its electrical properties. It might be less robust structurally—more susceptible to damage in shipping. Perhaps there would be less electrical isolation between the two sides (it’s actually two coils in one package), but it’s operating at a low voltage where that shouldn’t be a concern. I’d be interested in hearing thoughts from someone with more expertise.
A side note about the green goo: thinking that heating it might make it runny and thus easier to clean up, I applied heat using a hot-air rework station. I increased the heat gradually up to 200 C and found that the goo never liquefied. It softened up and was a bit easier to wipe off, but the heat didn’t help much overall. I guess the potting just oozes slowly when it gets warm.
The blue component is a choke (an inductor) that’s meant to prevent electrical noise from passing between the mains and the computer. The green stuff is potting compound that has a tendency to leak out.
The green goo is not conductive and presumably not corrosive, so it should be safe to just leave on the motherboard. Sometimes it leaks into connectors and prevents good contact or easy insertion; in such cases, you’ll want to clean it up.
I’ve found that it’s slightly soluble in alcohol. Start by gently scraping up the bulk of it with a spudger, small flat-head screwdriver, your fingernail through a paper towel, or some such tool. Be careful not to scratch the PCB or traces. Then clean up the remaining film with isopropyl alcohol and a brush.
As for the choke, I don’t think you need to do anything about it. Chuckphd53 desoldered and re-potted his, but I haven’t yet noticed any problems leaving it as-is. I wouldn’t expect the loss of potting to make a big difference in its electrical properties. It might be less robust structurally—more susceptible to damage in shipping. Perhaps there would be less electrical isolation between the two sides (it’s actually two coils in one package), but it’s operating at a low voltage where that shouldn’t be a concern. I’d be interested in hearing thoughts from someone with more expertise.
A side note about the green goo: thinking that heating it might make it runny and thus easier to clean up, I applied heat using a hot-air rework station. I increased the heat gradually up to 200 C and found that the goo never liquefied. It softened up and was a bit easier to wipe off, but the heat didn’t help much overall. I guess the potting just oozes slowly when it gets warm.