that orange stuff....

[ilyaa]

this is just a question:

i just got a furman spring reverb rack thing and it wasnt working right and i opened it up and there is that amber-looking gunk all over the PCB solder joints.

an amp i fixed recently had the same stuff that was causing intermittent noise and when i cleaned it, it got all better.

now what IS that gunk? and why sometimes when i re-flow solder on an older board does it seem to appear?

is it rosin? but if it is, is it bad? it certainly seemed to be in the case of the amp....is it nicotine (i think roly maybe mentioned that) or other noxious residue? or just oxidation?

just curious.....

[Enzo]

equipment that lives in the bars does get a coating of nicotine, but it is not selective.  The entire surface will be covered, not spots.   Besides, you will know the stuff is nicotine because any such equipment will stink of cigarette smoke.


Solder has rosin flux in it, and it bubbles out when soldering, leaving a brown blob of it.   The stuff itself is not really much of a danger, but it might be indicative of solder work that was never done well in the first place though.   Flux also has some potential for adsorbing moisture from the air, which is more of a bother to tube amps because of their high voltages.

Alcohol will clean the stuff off.

[joshdfrazier]

Alot of my older amps (pre 1970's) have orange/brown gunk on the boards. Always figured it was flux.

[J M Fahey]

Alcohol as suggested by Enzo, scrubbed with an old toothbrush and wiped/absorbed off with clean paper towels works wonders.

[ilyaa]

i guess my real question is:

is that stuff always bad? should it be cleaned off if its all over the solder joints?

[DrGonz78]

It can't hurt to clean it and depending on how bad it looks will be the big indicator. I have used some solder where I can actually smell a pine tree sap like smell and I hate that solder.

Here read this page...
http://store.curiousinventor.com/guides/how_to_solder/kind_of_solder/

[nashvillebill]

Note that some circuit boards in industrial devices will be covered with a "conformal coating" which looks like heavy varnish, it's intended to protect the circuitry from moisture and corrosive fumes.  I have not seen any guitar amps with conformal coating, though I have vague recollections of a pedal which had it...wait a minute, all of my recollections are vague though.

In the case of the OP, though, it's almost certainly the solder flux as already mentioned.  Conformal coating is much more uniform and covers everything. I just wanted to touch all the bases here, but again, in the OP's amp, it's solder flux he's seeing and not conformal coating.

[J M Fahey]

In general lines it´s not *bad* by itself and in fact I spray my homemade PCBs with a light varnish which is exactly that: pine sap dissolved in alcohol, go figure.
It both protects copper from oxidation and helps future soldering.
But the difference with what you see is that commercial solder has extra additives , mainly to "eat"  any slight copper corrosion they might find, it´s often some mercuric salt, (in very small amounts but it is there), and salts of any kind tend to attract moisture (bad) in differing amounts, so those "improved" fluxes often carry the label "wash residue after soldering" .
Homemade flux is definitely milder, if not as effective (fine with me).

[AsaLuman]

equipment that lives in the bars does get a coating of nicotine, but it is not selective.  The entire surface will be covered, not spots.   Besides, you will know the stuff is nicotine because any such equipment will stink of e cigarettes smoke.


Solder has rosin flux in it, and it bubbles out when soldering, leaving a brown blob of it.   The stuff itself is not really much of a danger, but it might be indicative of solder work that was never done well in the first place though.   Flux also has some potential for adsorbing moisture from the air, which is more of a bother to tube amps because of their high voltages.

Alcohol will clean the stuff off.

Thanks for wonderful suggestion..I have not used alcohol before so will try to use it for cleaning purpose and hope it works..