HELP need advice on late 70s dumble or schematics

[bole1]

hello i am a newbie with a dumble problem my output or power transformer blew and problaby the caps around it i need schematics or help on what to replace it with so my guitar tech amp guy can fix the problem its a late 70s overdrive special combo 50watt i am not a tech so i need to relay all the info to him any info help would be great i am in dire need it was my main amp so anyone please help thanks john

[Luthierwnc]

There are a bunch of them on the Dumble Files pages. I'm sure the tech is a great guy but he'd better get on here himself if there are questions about the model and components. You might take a picture of the guts and post it. There are people here who can identify it (or close enough) with a glance.

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[oldmacman]

For '70s, https://tubeamparchive.com/viewtopic.php?t=398 might be your closest bet.

As far as the power section goes, many of them came with Fender transformers, so a replacement should be fairly easy to find.

The thing to keep in mind if anything in the power supply has gone is that the voltages are critical to getting the sound. Changing filter caps or dropping resistors can have a noticeable impact on the feel of the amp.

Is it 50 or 100 watts?

[bole1]

it is a 50 watt amp combo made in the late 70's

[bole1]

what my tech has asked me to do is try and get a schematic of the amp 50 watt combo and he has a bunch of old parts but not alot of info on the dumble amps so any help is so appreciated so please keep the info comming thanks alot john

[Normster]

I don't know about your tech's qualifications, but if it's a real Dumble, you've got an investment to protect. Ideally, he should be talking to HAD. I think Andy Fuchs also used to service Dumbles so maybe your tech should contact him. Since Dumble referred to each of his amps as "prototypes" you may be hard pressed to find the "correct" schematic for your particular amp.

BTW, what's the chassis number?

[Luthierwnc]

+1 Considering the value of the head, you want to be sure that is stays as original as possible. You need a tech who is familiar with these guyss. If it is a blown trannie, make a point of writing down the code numbers stamped on the housings. It may be possible to find Fender or Music Man transformers of the period that are drop-in replacements.

I would also consider having the trannie rewound rather than replaced. There are several reputable custom winders who could do the work and would probably enjoy the chance to replicate the original.

All this should be at the behest of the aforementioned qualified tech. It won't be cheap but a cheap job could be really expensive. Fortunately, there are some very good back-up amps available from members of the forum.

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PS Post clips!