Marshall parts

[Valvehead]

Im going to try partsisparts Monday for this , but i doubt they will have this .

Maybe someone here can get one for me ?

Its the small pcb in a Marshall AVT 150H that has the output tda7293 chip on it .

the number on it is AVT50-62-00

can anyone get these? Mine is burnt beyond recognition...

[Twist]

Mouser electronics sells the TDA7293. Unless you have several burnt traces you should be able to replace the chip. Sometimes you have to replace some components in the mute section of the amp also.

[Valvehead]

i know.


i already have all the parts. the board itself and the traces are destroyed.

[Enzo]

The part is

KITS00003 dealer net is $36.27, and list price is $65.95

There are several versions of the little 7293 board, and that is the one you want. The connectors are the variation.

I'd be interested to know what they sell them for. I would be surprised if they DIDN'T have them on hand, they are a common repair need. Unless they are out of them.

Are you sure it isn't worth fixing with wire? CHances are that once the soot is removed, there are only a couple damaged traces.

$65 is a lot of money for a $6 chip.

[Valvehead]

ill give it a try. Half the traces are damaged and the soot doesnt want to budge-even with rubbing alcohol.

[Enzo]

I use a wire wheel in my Dremel or sometimes a bristle brush in the Dremel, when Qtips and alcohol don't work. I don't like using wire wheels on circuit boards, since the wheels throw little bits of wire. But on this little thing, held away from the amp, there is not a lot of places for a wire bit to hide. Especially with the chip off the board.

No I don't use alcohol when Dremeling. I don't want to chance setting the stuff on fire.

[Nemesis]

Hello, this is my first post here. Okay, I'm not too knowledgeable on electronics lingo and stuff, but I can wire and actually DO electronic work.

I too have a Marshall AVT150H head and BOTH chips are blown. After a close look and some searching I came here and it seems that they are in fact the TDA7293 chips.

They are both bad, one has a blister and the other one has a big hole. This is the SECOND TIME they went. I had this repaired last october, and then they blew again in Feb. It cost me $80 to have it fixed, but it also took 3 weeks cuz the shop had to send it out.

I found the Mouser site and the chips HERE.

but which ones do I need? one of each? and if so, which one is which on the board.


And in further reading it seems that they blow due to heat. So I think some new fans are in order. Where can I grab those online?

The amp has lasted me since May of 02, and I guess the stuff is just worn out.

Thanks for the help!

[mykey]

Originally Posted by Nemesis

Hello, this is my first post here. Okay, I'm not too knowledgeable on electronics lingo and stuff, but I can wire and actually DO electronic work.

I too have a Marshall AVT150H head and BOTH chips are blown. After a close look and some searching I came here and it seems that they are in fact the TDA7293 chips.

They are both bad, one has a blister and the other one has a big hole. This is the SECOND TIME they went. I had this repaired last october, and then they blew again in Feb. It cost me $80 to have it fixed, but it also took 3 weeks cuz the shop had to send it out.

I found the Mouser site and the chips HERE.

but which ones do I need? one of each? and if so, which one is which on the board.


And in further reading it seems that they blow due to heat. So I think some new fans are in order. Where can I grab those online?

The amp has lasted me since May of 02, and I guess the stuff is just worn out.

Thanks for the help!

those things blow really often and you can add heat sink or fan but the best is to just get another amp. the TDA chips are not reliable.

[Enzo]

You need the TDA7293V, the TDA7293HS has its lead wires formed for horizontal mount. You want the V version for vertical mount. Note that Mouser doesn't stock the HS anyway.

If one of those blows, ALWAYS replace both anyway. Usually both fail at once. Both modules use the same IC. Both modules are identical.

These do blow up a lot, if your fan is noisy, replace it. Chattering axle bearings will slow the fan down. But pay close attention to the jacks. Use the correct one for your speaker. Always connect the speaker with power off. These are sensitive to sudden load shifts - I don't know why. Always use a real speaker cord, do not ever use a guitar cord for speakers.

[Nemesis]

Okay, I know I'm gonna sound stupid, but what does IC stand for?


And where can I grab a pair of the circuit boards the the TDA chips are on.

My plan is to always have a spare set of boards ready to be tossed in whenever they blow. So I swap in the good set then replace the chips off the bad ones, so I have minimal downtime. I really miss playing that amp. Alot of people that say they suck don't give it a chance. Alone they are not great, but once you hook some tone enhancing pedals and such, it really starts to develop a fantastic tone!

Thanks, you have really helped me!

[mykey]

Originally Posted by Nemesis

Okay, I know I'm gonna sound stupid, but what does IC stand for?


And where can I grab a pair of the circuit boards the the TDA chips are on.

My plan is to always have a spare set of boards ready to be tossed in whenever they blow. So I swap in the good set then replace the chips off the bad ones, so I have minimal downtime. I really miss playing that amp. Alot of people that say they suck don't give it a chance. Alone they are not great, but once you hook some tone enhancing pedals and such, it really starts to develop a fantastic tone!

Thanks, you have really helped me!

the IC is an Integrated Circuit.
The TDA chip IS an integrated circuit.
It's a power amp on a single chip.
you can put two together to get more power.
also there are small black ones for use in preamps.
about 1/2" by 5/8" with 8 legs, four on each side.
The TDA has a habit of blowing, not just in Marshall amps
but in every amp it's used in.
they overheat really easily and blow.
they need more heat sinking, or a fan...
lots of companies use them in amps.
you can keep replacing them or would it be easier to
buy another more reliable amp?
no it's not a stupid question.

[Enzo]

If you want to have the whole little boards complete with 7293, any MArshall deale or Marshall parts dealer can order them for you.

[Mark Black]

On the subject of soot removal I'd like to share something that works very well for me: oven cleaner.

Obviously you don't want to just go spraying it all around inside an amp, but a little bit on a Q-Tip works wonders. On big/bad sooted areas I routinely get the PCB out and spray oven cleaner all over the afflicted area, let it sit a few minutes, work it with a paintbrush, and then wash the whole thing off in the sink under running water with a little help from the paintbrush.

[Valvehead]

anyway.....i just hard wired the bad traces and the amp lives