Removing burn marks from circuit boards

[michel.o...@gmail.com]

Hi group,

I have googled but I did not find a response to my question... Here
goes:

I am going to repair a Gottlieb Sys80 Driver board that has 3 big burn
marks on the solder side, below the 3 big metal transistors. The board
color is no longer green, but brown and black (and it smells burnt as
well).

Is there any way to remove these burn marks ? Thanks.

-Michel

[seymour...@excite.com]

It's usually the circuit board material itself that's scorched - you
can't remove these marks you could only mask them (and for what purpose
I don't know) it would be the equivalent of painting it. As long as
the traces and pads are in good shape, you don't need to worry about
it.

[michel.o...@gmail.com]

I don't know yet if the traces and pads are in good shape, but I am
confident I can fix that easily.

Well, if the circuit board material is scorched, so be it. If I can get
the board to work correctly, it's okay. I was just wondering.

-Michel

[Mark Clayton]

Michel:

Burned is burned. You can take a razor blade and scratch away the
black stuff, but there's no way to remove that "lightly toasted" look.
But you could always paint over it with green enamel.

-Mark
--
http://pinballpal.com/

"michel.o...@REMOVETHISgmail.com" <michel.o...@gmail.com> wrote in message
news:1141313771.6...@e56g2000cwe.googlegroups.com...

[Ken Layton]

It depends on how bad it is. If it's mostly smoke then 99% rubbing
alcohol or solder flux remover will clean it right up. However if the
circuit board material itself is actually burnt you're out of luck. If
there's a hole/pit in the board it can be filled in with epoxy glue and
sanded down. Then you could paint that area.

[beaver]

I have done that. See here for the before and after:
http://www.edcheung.com/album/album05/pinball/cpu.htm#use
(you may have to hit reload afterwards to jump to the right spot).

I did it by using a combination of Novus2 and alcohol with a tiny
(1/4") cup brush in my Dremel tool. The spinning tool and solvent were
used to scrub the carbon off.

Edward Cheung

[johnny electron]

no, you cant, i do this everyday, and see alot worse, trust me.
as long as the solder runs arent damaged in the burned area, it should
be ok, but i would have to see it, to tell you for sure.

[over...@spam.ftc.gov]

On 2 Mar 2006 07:36:11 -0800, "michel.o...@REMOVETHISgmail.com"
<michel.o...@gmail.com> wrote:

It might also be a good idea to mount a socket for the TO3s and a
separate heat sink for each one. Prevents the board from getting
scorched again. Mount the socket on standoff screws above the board.

Jim

[michel.o...@gmail.com]

Great website about pinball restoration! And amazing work on the
Williams testbench!

I checked your before and after photos but I can't help to notice that
the end result looks greasy... Is that caused by solder flux?

Your website looked familiar, but then I found out why... I used the
same technique you used to make a playfield rotisserie! Thanks for the
idea!

-Michel

[beaver]

Interesting remark about the greasy look. No one else has said that
before. What you are seeing is the copper next to the hot spot
wrinkling a little due to the heat of the failure. Then my polishing
the area with Novus caused the surface to shine like that. There
actually is no grease on the surface. This is true especially because
I washed the area with alcohol, so it is completely degreased.

On your last note, that rotisserie I made ($40) has served me well. I
am glad to hear someone else using the idea.

Edward Cheung

[michel.o...@gmail.com]

I modified your design a bit to make it look like the original metal
playfield rotisserie which could easily be taken apart and stored. The
only difference is that I made it out of wood.

My problem was that my desk was not long enough to attach the wooden
bars to it. So, I bought a large rectangular piece of wood, mounted 2
wooden bars under it over its entire length (for strength), and that
whole piece is put on my desk. It's heavy and rigid.

On top of that, I build 2 upside down T structures out of wood on which
I attached the plumbing parts, like you did. Those T structures are
fixed to the big rectangular piece of wood using wing bolts. The
playfield then goes between these 2 T structures. Looks wonderful! :-)

-Michel