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Marantz Circuit Board Coating

J

Jawknee

New Member
New to the forum. Hope someone will be kind enough to help answer my question.

Had to perform some repairs on my Marantz 2265B.

The boards seem to have some kind of coating on the track side. There does not appear to be any coating on the component side.

I don’t think it is a conformal coat. It washes off with isopropyl alcohol. As far as I can tell, none of the conformal coats wash off with isopropyl. At least none that are around today.

I’d like to recoat the reworked board with as close to the original material as I can.

Any idea what the coating may be?

My guess is that it may be a coating of flux. Maybe a type R flux that is not activated. Or could it be something like violin rosin mixed with alcohol as a carrier?

Thanks Much to anyone that can help!
 
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yes, yes yes.
And Ok, sure.
Probably and you could try.
Good luck.
I'm happy to help.

Welcome to AK. :)
 
I have a stupid question Dingman. Why would you want to put the flux back on? I was under the impression you removed the flux (if you choose to) after you're done with you work. Is that wrong?

Thanks, Chris
 
Jawknee said:
Thanks Avionic. That is a suitable coating but I don't think that is what is on there. I don't think acrylic will wash off with alcohol.
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Probably not. Personally...I don't bother with such coatings..I strip off the ugly soiled coating and just leave a clean shiny board.Conformal coatings are for harsh enviorments.. Like marine or aircraft , or military and /or industrial applications.
 
cemerson said:
I have a stupid question Dingman. Why would you want to put the flux back on? I was under the impression you removed the flux (if you choose to) after you're done with you work. Is that wrong?

Thanks, Chris
Click to expand...
By NASA high reliability soldering standards.. all flux is removed from the board. Yes ..Uncle Sam sent me to the NASA FTD high reliability course.
 
Chris, I admire your attention to detail.
Ya, that's old flux that just wasn't cleaned off after production.
I do see some people depopulate boards to give them a bath and they come out so nice and shiny. I haven't done that myself.
 
Do be careful with the "washing" to get rid of the old flux. I've seen where people get too enthusiastic and either break things or get that crud washed into parts it should not be in. I normally do not clean off old flux unless it's really egregious or I'm working on the spot. When I do I use a cut down acid brush and wooden handled qTips. Same tools i used at Hughes years and years ago :) I went to the same course @aviconic.. for Space and Comm and Ground Systems ( RADAR). Fun times. The only thing I do differently now is much of the time when cleaning stuff like this I'll wear some throw away gloves.
 
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