My Big Mistake, Marshall Hybrid

[killivolt]

Long story short, started with 2 cheese balls playing with my amp, plugged into the back with another amp, impedance difference I explained to them would damage the amp, e.g. Knuckle Heads didn’t listen.

That led to me destroying the outputs, 3rd Knuckle head, was working on it with several people in my office that day, my probe slipped measuring the voltages pre-amps TDA7293 which let the magic smoke out.

Help please, got the schematics need to locate physically in my mess later, currently on the phones working, I’ll post a link, if I can find it or if someone else does first.

M-2001-11-0833-B on the back, front is Advanced ValveState Technology AVT 150 then the other side of head Valvestate AVT 2000. Just need to know my starting point, I do have limited knowledge with my scope if necessary.

kv

Edit: Second big mistake, I purchased it second hand.

[nosaj]

Read over this thread.
nosaj

[Jazz P Bass]

It's possible that the only failure is the TDA chip.

A few pointers:
-Clip off the IC leads and tap out the cut leads (the less heat applied to the pcb the less likely it is that you will damage it.
-Before reinstalling the power leads to the repaired module make sure the power rails are drained off.

[killivolt]

Just realized I can’t double qoute? Lost all my previous content trying to respond to both of you. Still learning. Tried to tag you that didn’t work either, did the same thing.

I’ve read content referred to in Post # 2 and will follow ascribed pointers in Post # 3, I will tell you pisses me off I spent time responding an lost that content lol even though I restored previous content wasn’t my original post comments. Arrrrrrrrrrrrrg.

Letting out the Neanderthal in me. Ug must hit something with rock, smash.

Untill I rediscovered this forum, I was going to take the amp to the desert and shoot it with my .45 and .243 film it with my discontent and put it on youtube. That would have been a mistake, but who knows might still do it.

kv

[nosaj]

Letting out the Neanderthal in me. Ug must hit something with rock, smash. Till I rediscovered this forum, I was going to take it to the desert and shoot it with my .45 and .243 film it with my discontent and put it on youtube. That would have been a mistake, but who knows might still do it?

kv

You will definately do that if you DON'T follow Jazz's tips to a t. They are the key to sucess with this amp.. The thread I posted is supposed to increase the longevity of the repair.. Look at the end of the thread post followup by MARS amp tech I think.

nosaj

[killivolt]

It's possible that the only failure is the TDA chip.

A few pointers:
-Clip off the IC leads and tap out the cut leads (the less heat applied to the pcb the less likely it is that you will damage it.
-Before reinstalling the power leads to the repaired module make sure the power rails are drained off.

Just simple comment, I thought this was more detailed. Apparently this is all done in the TDA? Duh. I have never studied an amplifier for a guitar, thought I would be messing with biasing, is their adjustments I need to make biasing issues? I’ll get them out won’t damage the circuit board, not my first rodeo. With the amp down just insure I don’t have any caps loaded on the power rails, as pertaining to the compatibility same chip should be same same, I’ll look at the data sheet on the TDA’s I purchased. If I have any questions I’ll get back to you guys.

Should I look into and isolated power supply, any reason I can’t just plug it into an outlet to power up? What is proper, in the TV shop I worked in the boss handled all the regular stereo amps and would sometimes put a light bulb in series somehow, just been to long to remember, like been 30 years ago working there.

When I was at the Uni a guy in the next office blew out one of his channels gotta chance to do some troubleshooting, got pretty technical, never had time to complete it, they force me into retirement.

Thank you for your response,

kv

You will definately do that if you DON'T follow Jazz's tips to a t. They are the key to sucess with this amp.. The thread I posted is supposed to increase the longevity of the repair.. Look at the end of the thread post followup by MARS amp tech I think.
nosaj

Your Sig is funny, good one.

Ya, don’t want to shoot it anymore.

kv

[g1]

the TV shop I worked in the boss handled all the regular stereo amps and would sometimes put a light bulb in series somehow, just been to long to remember, like been 30 years ago working there.

This is the basic sketch, the lower the wattage of the bulb, the better the protection, so 40 to 60W are the ones usually used.

[killivolt]

This is the basic sketch, the lower the wattage of the bulb, the better the protection, so 40 to 60W are the ones usually used.

Yup thats it, thx man.

kv