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Anybody here ever worked on one of these? I had one on the bench recently, luckily it turned out to be a microphonic preamp tube.I say "luckily" because when I opened it up I discovered all the circuit boards covered in a thick black rubber of some sort preventing any access to the circuit boards without removing the goop.I also found both power tubes (EL34's) had the guide pins broken off.According to the owner the tubes are original and have been in the amp since he bought it new.Seems to me the builder coated the boards and even broke off the guide pins to prevent anybody from working on his amps.Now the kicker here is that he no longer makes these amps and will only perform repairs on amps under warranty.I feel bad for the client because he has had it here twice in the last year, both times was tube related and loose jacks,but if its anything more I cant get at the circuit board to repair it.Is there a safe way to remove this gunk from the circuit boards? Am I just being too cautious not wanting to peel this crap off? The amp seems fairly well built and best as I can tell seems to be a Boogie clone type amp.
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If you can peel the goop off I don't see any problem with that. OTOH why bother unless 1: you need to get at the board to repair something and/or 2: goop is already starting to peel or you found it not too difficult to remove. I would not try dissolving it with chemicals. Possibly shooting areas with freeze spray might make it easier to crumble & remove a few chunks at a time.Originally posted by stokes View Post
Looks to me somebody wanted to be the next Dumble, then found he doesn't have the chops to do it and gave up. FWIW there are octal tube locator replacement gadgets, I've seen 'em in catalog at antique = tubesandmore.com. By now probably wouldn't hurt to have some fresh output tubes anyway.
This isn't the future I signed up for. -
I recently changed the power tubes,as one of them was rattling causing noise problems.When he first bought it to me I discovered the missing guide pins and was able to reinstall the tubes and put a mark on the tube base and chassis so I could reinstall in the future.I have a bunch of those replacement guide pin devices I bought when I had a pin break off about 10 yrs ago.Thats what makes me think the builder did it on purpose.To see 2 broken guides in one amp is unusual and the owner says he never took the tubes out,I gotta believe him because he wouldnt be able to reinstall the tubes otherwise.That was the last problem he had with it,first time he had a loose return jack in the effects loop and a severely microphonic V1. My issue with removing, or trying to remove the plastic is that its a PCB and I'm concerned pulling the goop may pull the pads and traces off the board with the component. A lot of it looks like it flowed under the components and will take the component with it.The amp is fine now,but this guy is a good client and has actually become a good friend,I've worked on 5 other amps for him and if he has problems with this that require any more than a tube change I dont want to touch it.Comment
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From Carol Ann page:Originally posted by stokes View Post
Notice it was pre-Covid.Important Notice.
9/21/2019
Due to the declining guitar amplifier business I sadly had to make the decision to essentially shut down any new production of amplifiers and had to take a full time job outside of the business. I didn't want to completely close the business, but I am currently only able to support valid warranty work at this time.........
Given there are quite a few out there, he "should" at least post schematics and servicing data in his page, so faithful paying users at least can recourse on their own to some local Tech.
Juan Manuel FaheyComment
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From Carol Ann page:
Due to the declining guitar amplifier business I sadly had to make the decision to essentially shut down any new production of amplifiers and had to take a full time job outside of the business. I didn't want to completely close the business, but I am currently only able to support valid warranty work at this time.........
Reading "between the lines" - I'm not selling any amps, my business model is rubbish, Dumble I am NOT.
At least he got a full time job, hope it worked out for him. Wonder what it is he's doing?
And people wonder, why I don't make amps...
This isn't the future I signed up for.Comment
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"And people wonder, why I don't make amps..." I've been asked by a lot of people to build them an amp, I dont do it often except for my sons and a couple for very close friends.I figure once you build and sell an amp you are married to it for life.Dont want to be in that position.This guy took it a step further by making it hard/ near impossible for anybody else to work on his.Dont know when he built his last but I would assume the warranty period expired and now he has no responsibility for them.Comment
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Probably charges gold dust money to fix them at this point. Man's gotta earn a living y'know! And what happens if he conks out, who's gonna deal with them then ? ? ?Originally posted by stokes View Post
This isn't the future I signed up for.Comment
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No, he told my friend that he only does warranty work and his warranty was expired so he advised him to take it to a local tech.Originally posted by Leo_Gnardo View PostComment
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Did he supply a schematic?Juan Manuel FaheyComment
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No schematic.Comment
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Not that a schem would help with the "Dumble mod" he did to the circuit boards with that black tar.I tried to contact him via the website a couple years ago and got no reply.I might try again to see if he has a way to safely remove the crap.Right now the amp is fine, we were lucky with only tube issues so far but if anything else occurs I hate to not be able to help the guy but I dont want foul up a $2-3k amp.Comment
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What's the choices? You can play it & hope it never develops a problem and for your sake I hope it never does. Or sell it if you can get 2 or 3 grand and let it be someone else's problem. As a buyer, I'd have to say regardless of its supposed $$$$ value it is a pig in a poke without schematic support also with circuit all gooped up. Even Dumbles that are gooped - what are owners gonna do when the builder kicks the bucket? A headache nobody wants to deal with.Originally posted by stokes View PostThis isn't the future I signed up for.Comment
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First, its not my amp.The guy that owns it really loves it, it has been his main amp for a long time.He has a couple of really nice vintage Fenders that I think are much better sounding.To me it sounds and feels like a Boogie type amp.Selling it is not even an option for this guy, he likes it so much.There has to be a way to safely remove the goop.Maybe I should try to contact Dumble, maybe he'll tell me how to remove it since this guy seems to have copied his amps.Comment
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OK, sounds like a keeper then. If you do find out how to de-goop please let us know, TIA! In case any of us MEFsters run into one of these gems.Originally posted by stokes View PostThis isn't the future I signed up for.Comment
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