Burning Odor

[Valvehead]

I have a Fender here that killed a screen res and burned the pcb. I cleaned it up with contact cleaner and alcohol.

So.......what can I use to try and get rid of the Burnt board smell ??

[The Dude]

Cat pee? It masks everything.

Seriously though, I've usually found that when you get rid of all the "burn residue", the smell goes with it. A couple of times I've used a little blast of Ozium and that seems to do the trick.

[nosaj]

Cat pee? It masks everything.

Seriously though, I've usually found that when you get rid of all the "burn residue", the smell goes with it. A couple of times I've used a little blast of Ozium and that seems to do the trick.

I was thinking Whiskey and Cigarrette smoke would do it.

[Valvehead]

the spot on the pcb is pretty bad , but the size of a dime.......i might dremel that out

[The Dude]

I was thinking Whiskey and Cigarrette smoke would do it.

I refer to that as "the vintage smell". It also adds mojo.

[The Dude]

the spot on the pcb is pretty bad , but the size of a dime.......i might dremel that out

I usually grind out anything that's not "circuit board color". If not, it can be conductive.

[Valvehead]

I usually grind out anything that's not "circuit board color". If not, it can be conductive.

yep...and theres only 3 or 4 traces to cut..will be an easy repair

[TimmyP1955]

I usually grind out anything that's not "circuit board color". If not, it can be conductive.

If it's a JCM2000, the "circuit board color" part can be conductive too

[Tone Meister]

Liquid Electrical Tape - discovered it many years ago wiring boats, and for me it is indispensable for insulating those hard to reach places and odd electrical connections. I'd bet it will work like a charm to seal that burned spot.

[Tom Phillips]

I suppose that there are useful applications of liquid electrical tape. I have some in the shop but hardly every find a situation where I would trust it and I wouldn't want people to find it in an amp I had worked on and associate it with my workmanship. Maybe a dab of it is useful to seal a joint against corrosion or to discourage tampering. Having said that, and stating up front that I'm not getting on Tone Meister's case, the advertising photos showing liquid electrical tape in use are totally ridiculous.

[Tone Meister]

I suppose that there are useful applications of liquid electrical tape. I have some in the shop but hardly every find a situation where I would trust it and I wouldn't want people to find it in an amp I had worked on and associate it with my workmanship. Maybe a dab of it is useful to seal a joint against corrosion or to discourage tampering. Having said that, and stating up front that I'm not getting on Tone Meister's case, the advertising photos showing liquid electrical tape in use are totally ridiculous.

Wow, with me being the complete jackleg novice here, I could not disagree more. In a marine environment, it seals against corrosion as well as insulates, and I've made many connections that have lasted 20 years or more on boats that see daily use. A butt connector might last a season, maybe.

I use it often when dealing with large multi-pin audio connectors rather than heat shrink each individual pin connection, and I'll insulate certain hard to reach connections on other connector types so I don't have to futz with a small piece of heat shrink and risk heat damage with the heat gun. If you've ever hand-built VGA cables with the DE-15 D-sub connector, you well know what a pain it is to stuff 15 individually heat-shrunk wires inside the connector body. In my novice exuberance, I don't understand why a neatly applied coat wouldn't seal a burned spot on a PCB as well as anything else. Especially given that grinding it away isn't an option.

Tom, what is it that you don't trust and why do you consider it an unprofessional insulating solution? And what would you suggest to seal the spot in discussion?

[Tom Phillips]

Tone Meister,
OK. When I said "I suppose that there are useful applications of liquid electrical tape...." you gave a good answer.

...Tom, what is it that you don't trust and why do you consider it an unprofessional insulating solution?...

My comments were directed at things like amp repairs of the electronics inside the chassis. For splices I use heat shrink and for everything else I use soldered connections to a terminal strip, PCB or other hard connection. I find that there are very few instances where wire splicing is required in electronics repair. My personal feeling when I find liquid tape, electricians tape or wire nuts in an amp it screams armature job. BTW, I put ground connections attached to the power transformer mounting bolts in the same bad design / bad workmanship category. The transformer bolts always seem to loosen over time. That might be caused by the repetitive heating & cooling cycles and the constant low level vibration. In the case of the earth safety ground, it is a violation of the code.

I do like to use liquid tape to weatherproof (or at least lengthen the life) of connections in some types of outdoor equipment.

... And what would you suggest to seal the spot in discussion?

My approach would be to leave the spot unsealed if it were just discolored a little because I don't believe that "sealing" would provide any benefit and may hide subsequent damage. However, if the spot looked carbonized, was a deep black color and/or if the fiber of the board was showing through then I would grind out all the damaged material and add jumpers to reconnect any resulting missing traces.

Cheers,
Tom

[Tone Meister]

Tone Meister, ...

Cheers,
Tom

Understood and agreed on all points. All I can say is you guys would have had great fun at my expense had I been the one needing to deal with that odored spot on that PCB, because I am awfully sure I would have found a way to seal it rather than having thought of the approach you describe.

Thanks Tom, as usual I learn better ways to accomplish things every time I visit this forum.

[Enzo]

I suspect the marine environment is 12vDC? Don't know the voltage rating of your stuff. I worry about 500v and such products. But I also admit total ingorance of the product performance. In electronics we have something called corona dope. it is a high voltage insulating paint. We used to use it around third anode voltages in TV sets.


I agree with Tom about sealing a burnt spot. ANything carbonized must be ground away or otherwise removed. Covering it up doesn;t change its character, an arc can strike under the covering if the board material is still carbonized.

[Telesis]

FWIW, another alternative is to treat the area with a Conformal Coating type product. These products have high surface insulation resistance as well and are usually clear. They are readily available. This product is normally used to coat PCBs that will be exposed to corrosive and/or potentially conductive environments. The poor man's alternative is a little clear nail polish!