Carol Ann Amps

[pdf64]

The ‘black goop’ I’m used to has been an epoxy resin. I think similar stuff was used to pot Fender’s PTs, in the 80s maybe. A dremel grinder / cutting disc is needed to get through it. Maybe suitable heat treatment would soften it, but still, I get the feeling that removing it totally without wrecking the board would be next to impossible.
I’m surprised he’s behaving like this, Alan Philips seemed a good guy and a competent EE and businessman. We had a bit of interaction on TGP, and he then asked if I’d be interested in undertaking UK repairs. Which is more in Mick’s league, I wish I’d passed it on to him at the time, then we might have had a way forward on this.

[stokes]

The ‘black goop’ I’m used to has been an epoxy resin. I think similar stuff was used to pot Fender’s PTs, in the 80s maybe. A dremel grinder / cutting disc is needed to get through it. Maybe suitable heat treatment would soften it, but still, I get the feeling that removing it totally without wrecking the board would be next to impossible.
I’m surprised he’s behaving like this, Alan Philips seemed a good guy and a competent EE and businessman. We had a bit of interaction on TGP, and he then asked if I’d be interested in undertaking UK repairs. Which is more in Mick’s league, I wish I’d passed it on to him at the time, then we might have had a way forward on this.

Thats what it is like, the potting material in transformers.Very hard, not pliable like a silicon type rubbery mix.I'm sure trying to cut thru it would be a disaster.Cutting traces and board and even if I get thru it without damaging the board when I try to pull it off the components will come off the board.Thinking the only way to do any kind of repair would be to just replace the entire board.

[DrGonz78]

Can you post a photo of the guts of this amp? I am sure we are dying to see what you are seeing. I googled Carol Ann amps and could not find an example of the black resin coated mess.

[dmeek]

Try a heat gun. Usually works for me. Be careful not to melt anything else with too much heat

another vote for photos, including the foil side of the pcb

[Leo_Gnardo]

Thats what it is like, the potting material in transformers.Very hard, not pliable like a silicon type rubbery mix.I'm sure trying to cut thru it would be a disaster.Cutting traces and board and even if I get thru it without damaging the board when I try to pull it off the components will come off the board.Thinking the only way to do any kind of repair would be to just replace the entire board.

There are several materials commonly found in transformers to "glue" the windings together and keep out moisture. Epoxy, for sure. Resins of other types as well. Old Ampeg transformers like the ones in B15's, the can is filled with what's termed a "wax" but it behaves and smells like tar. However, it does melt at @150-200F. If you could pinch a couple slivers of this amp's goop and subject them to tests, it might reveal what you're dealing with. Heat up a sliver and if it melts & smells like tar then you know something & maybe can deal with it. No dice with that? Try a few solvents like acetone and xylene, see if the stuff melts or dissolves. Beats making assumptions and going in whole hog with the wrong approach.

[J M Fahey]

FWIW: old Fender transformers used some kind of Polyester resin (1/3 to 1/4 the cost of Epoxy) to pot transformers.
They fully assembled them and then poured catalyzed and accelerated rosin through a hole in one of the bells.

Rosin looks opaque (it´s naturally transparent) because it´s loaded with "mineral dust", typically finely ground talcum or chalk, which are dirt cheap (literally )
If they want black they add some carbon black (chimney soot) which is very black and very cheap.

PCBs are most often (not always) gooped in Epoxy, which can also have minerals and colorants added.

It is softened with a heat gun and crumbled away in little pieces with a sharp needle without damaging components, the pedal guys do it all the time.

It is regular 2 component Epoxy, NOT the very very hard type used to make transistor and IC packages.

This is a successfully degooped "miracle" pedal

Enough to read and replace components, not too nice to look at though.

[stokes]

No pics, I dont have the amp.He bought it to me for the second time about a week or so ago, even after I told him I wouldnt/couldnt work on it.What he described on the phone sounded like a tube.I would have told him to change the tubes himself, but if it turned out not to be the problem he wouldnt be able to put the old tubes back since the builder broke off the guide pins so I did it for him,I was able to check the bias and it was all good.As for that pic JM posted of the successfully degooped "miracle" pedal I'd be damned if I called that successful.Maybe ok for a 100 dollar pedal but a $2000 amp, not so much.

[g1]

If the option is the $2000 amp going in the dumpster, sometimes you have to deal with what you got. It might not be pretty.
Afterward, you could tack on some kind of insulating 'curtain' or something so no one would have to look at it.

[nosaj]

A 2000 dollar amp is only worth what someone is willing to pay for it. If it doesn't work well it aint worth 2000 anymore.

nosaj

[35L6]

Is piracy that big a problem and does gooping it up help ? Somebody with alot of spare time degooped that pedal . A giant corporation could X-ray it . And a couple of online enthusiasts cloning it isn't competition . They all seem to get out anyway , but only after they are successful .

[Leo_Gnardo]

As for that pic JM posted of the successfully degooped "miracle" pedal I'd be damned if I called that successful.Maybe ok for a 100 dollar pedal but a $2000 amp, not so much.

IF, like Mr. Dumble, you knew where the trouble spot potentially is, you degoop only that part of the circuit. If it doesn't look pretty enough to meet your standards, consider those gooped up Dumbles often trade in the $50,000 - $100,000 range, ugly, pretty, or in between. And you can always regoop it if nobody wants to see the ugly truth below the goop.

To the tune of "He Ain't Heavy, He's My Brother" - - it ain't ugly, it's my fuzz tone...

[stokes]

IF, like Mr. Dumble, you knew where the trouble spot potentially is, you degoop only that part of the circuit. If it doesn't look pretty enough to meet your standards, consider those gooped up Dumbles often trade in the $50,000 - $100,000 range, ugly, pretty, or in between. And you can always regoop it if nobody wants to see the ugly truth below the goop.

To the tune of "He Ain't Heavy, He's My Brother" - - it ain't ugly, it's my fuzz tone...

If it was my amp I wouldnt care what under the hood looks like,who sees it anyways? But having been dealing with people and amps for so many years I've found that many guys with an amp in this price range want everything perfect,regardless of whether they will ever see the inside.I once changed caps on an old Boogie amp that was sounding like crap.When the guy picked up the amp he couldnt have been happier with the improvement.A week later he's back and wants it re-done because when I changed the caps I opted to clip the leads from the old filters and then neatly twist the pre cut leads on the new caps to the lead and solder them together so as to avoid heating the PCB.Tried to convince him that it wasnt a problem but he insisted it just doesnt look right.That was the last amp I worked on for him.So, while I agree that if a scarred board is the worst that happens,no big deal, but I dont want to be the guy that has to replace a board after I fix it.

[The Dude]

I would just have a conversation with the customer before the repair. Make him aware of the situation and potential solutions and cost. Let him decide. That gets you off the hook if he doesn't like the outcome.

[stokes]

I would just have a conversation with the customer before the repair. Make him aware of the situation and potential solutions and cost. Let him decide. That gets you off the hook if he doesn't like the outcome.

We have talked at length about this amp.I've had it twice and both times I've told him I will not try to remove that crap.If I try and break the circuit board or some other serious damage occurs I wont be "off the hook" as I'll be the "guy that broke the amp" when he talks about it with others.Even if he says he knew the danger beforehand, it wont matter to anyone else, I still broke the amp.

[stokes]

Okay, a new development with this amp.The owner found the users manual and sent me this excerpt: Note: Circuit boards may contain areas covered with an insulating non-epoxy compound to help reduce induced noise from sources such as fluorescent lights, stage lights etc. This potting compound can be easily removed in the event of Amplifier service by using an electrical heat gun on a low setting to make the compound pliable.
I assume the noise from lights he is referring to is 60 cycle hum.I've never heard of using an insulator like this to reduce such noise, only grounded shielding as far as I ever knew.Now if it is indeed a method to reduce this hum, I would think it would have to be replaced afterwards.Anybody ever hear of using this to reduce hum? Any thoughts you guys have are welcome.