Cleaning degraded foam off a circuit board

[apa]

I've got an old Moog Opus 3 that I opened up to clean pots. The
protective foam seems to be reverting to the petroleum from whence it
came. I pulled off the big pieces that were still intact and scrapped
off as much as I could but there's still sticky, gooey black gunk all
over the pots and on the circuit board. Is there a good way to clean
this stuff off? Is there any truth to idea that the foam becomes
conductive as it degrades and ends up causing problems wit the
circuitry? What solvents would be safe to use on the board?

Thanks, Andy

[Scott Dorsey]

apa > wrote:
>I've got an old Moog Opus 3 that I opened up to clean pots. The
>protective foam seems to be reverting to the petroleum from whence it
>came. I pulled off the big pieces that were still intact and scrapped
>off as much as I could but there's still sticky, gooey black gunk all
>over the pots and on the circuit board. Is there a good way to clean
>this stuff off? Is there any truth to idea that the foam becomes
>conductive as it degrades and ends up causing problems wit the
>circuitry? What solvents would be safe to use on the board?

The urethane, when it breaks down, absorbs moisture from the air. The
end result is a tiny little bit conductive. Not very conductive, but
conductive enough to totally screw up high-Z condenser microphone circuits.

Try cleaning it off with Goo-Gone or Ronsonol, then using some alcohol to
get the solvent off. Flux remover will take it off too, but it's harder
to work with.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."