I'm removing the tar off the relay board. I'm finding areas which look like a soldering iron touched and melted the plastic. I don't know if this was used to tack down some of the traces or something else. One area looks like someone laid down a soldering tip.

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Click to view attachment

Click to view attachment

Was this normal or something else?

Thanks,

DaveB

Normal

It is heat staking used to hold the traces in place during assembly.

Both boards I’ve cleaned had same heat staking in places on the board.

If you look carefully you’ll see they melted top down toward the trace. If the trace had overheated they would be melted at the base where the trace sits.

Yes they are all that way.

Great - Thanks for the help.

After I check out and repair the board, I was going to use a clear epoxy instead of the tar to seal the traces. My other option is to use an RTV with a vacuum. Anyone have issues using an epoxy for the environmental seal?

Thanks,

DaveB

I posted this question about three different types of relay boards.

http://www.914world.com/bbs2/index.php?sho...=355156&hl=

George

George,

Thanks for the link. I didn't expect to see so much variability in these relay boards.

DaveB

I took my relay board off to clean it and discovered the underside was cracked like the Nevada salt flats.
So, I ordered some of this stuff to give it a good reseal:
https://www.amazon.com/MG-Chemicals-Black-R...d/dp/B07B3Z8CLY

I took the easy route and bought a refurbed board from BDStone, pretty sure he uses black Flexseal and it's really nice.

I considered that, but mine cleaned up really nice and I like the idea of using modern flame retardant circuit board epoxy (potting compound). This stuff will probably outlive me given the service temp is -40F to 347F. The engine bay heat won't even come close to pushing it's performance envelope.