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914World.com _ 914World Garage _ What's Hiding Under Relay Board

Posted by: 914Sixer Oct 6 2020, 04:43 PM

Cleaning up another round of relay boards. This one looked clean but this is what I found. Some of that nasty green stuff that goes after copper.

Attached image(s)

Posted by: seanpaulmc Oct 6 2020, 07:13 PM

What do you clean them up with before resealing?

Posted by: 914Sixer Oct 7 2020, 06:53 AM

Putty knife, small screw driver and 1 hr of picking, then a bath of lemon juice. Stiff bristle bush to go over the copper tracks with the lemon juice. You may have to go over them several times to clean corrosion.

Posted by: VaccaRabite Oct 8 2020, 10:25 AM

Are you re-potting or pouring in epoxy resin?

Zach

Posted by: 76-914 Oct 8 2020, 10:33 AM

Any acid used, even Lemon juice, needs to be neutralized and thouroughly cleaned or the green will return with a vengeance. I wonder what those boards look like from the east coast area?

Posted by: bob164 Oct 8 2020, 10:52 AM

Whats the best way to neutralize the acid?

Posted by: 73-914 Oct 8 2020, 11:01 AM

baking soda

Posted by: bob164 Oct 8 2020, 11:09 AM

Thanks

Posted by: trojanhorsepower Nov 11 2020, 07:25 PM

So I am working on this now. I have read about people solder the joints before repotting. When I tried I had trouble not melting the plastic around the joint. Also I am having trouble getting the solder to stick. I am pretty familiar with solder in more normal electrical work, but this has me baffled. I have used all the flux I have and nothing seems to help.

Any tips?

Thanks

Peter

Posted by: 914Sixer Nov 11 2020, 07:45 PM

Not needed in my opinion. I have done close to 100 boards at this point. I have never found a problem with the joint. -6 boards are slightly different in that they did soldier the bottom in 4 places.

Posted by: trojanhorsepower Nov 12 2020, 05:00 PM

Great,
Ill just repot it.

Thanks,

Peter

Posted by: trojanhorsepower Nov 12 2020, 06:05 PM

So how bad an idea would it be to bead blast both sides of the board?