Source of Breakup in Bassman Clone?

[The New Steve H]

I stored pool acid in my garage--a very stupid idea--and it caused some corrosion in the area where it was sitting. Sadly, one object in that area was my old 5F6A Bassman clone.

Now the amp breaks up on loud notes, and not in a good way. It sounds like there is a weak connection in there somewhere.

I shot De-Oxid into the pots and turned them. I cleaned the contact surfaces on the jacks.

Still getting some breakup.

Any idea where I should look next?

I didn't know capped pool acid makes things rust. But it does.

[Colossal]

Did corrosion extend to the laminations on your power or output transformers?

Capped pool acid is not capped as you found out the hard way. It is industrial grade hydrochloric acid, usually with some sulfuric acid as an impurity. It will volatilize and find its way to ruining things around it. I always double contain acids and bases for safety, so a five gallon bucket with a closable/removable lid like a Gamma Seal is useful. Or in the lab, acids and bases go in their proper acid/base cabinet with ventiliation.

Do not mix bleach or hydrochloric acid with ammonia or you may find yourself nominated for a Darwin Award.

[The New Steve H]

There is a bit of crud on the PT, but not much.

Mainly, things that used to be shiny are not.

It acts like an input jack is not making good contact. Using an overdrive pedal makes it worse.

I wonder if there is a ground issue at the inputs.

[The New Steve H]

I used to get the same problem when I used a crappy cable to connect a cab to an amp. The cable had brass plugs, and when they turned brown, it caused breakup.

[strelok]

Is it possible the acid corroded the solder joints?

[Reeltarded]

reflow every ground to the chassis

[Stevem]

Have you done a simple test and just tryed out the amp thru a different speaker?

[The New Steve H]

I have tried other speakers.

[The New Steve H]

Today I plopped the amp on its side and removed and scraped everything that looked suspicious. I can't find the breakup issue now. I assume there was something weird going on with a ground or a crusty input jack.

Thanks for the help.

[pdf64]

It may have been some surface oxide preventing a good 0V mechanical connection to the chassis.

[The New Steve H]

I also found an electrolytic cap that had gotten smooshed down so the leads may have been close enough to make contact. Probably not great for the sound.

I took the opportunity to correct one of my more eccentric design features, which was little Sharpie arrows indicating the EQ pot directions. Incorrectly.

I used to have the pots in backward, but I fixed them and never changed the labels. So if you played the amp, you'd be like, "I have the treble all the way up and it still sounds muffled!"