M4 output transistors??

ferninando

Lunatic Member
Hi all.
I have an M4 power amp with a major problem. Right ch. output heatsink gets super hot while the left one stays room temp.
So I'm thinking Output transistor short.
But before any disassembly to indentify the types of output trans. visualy, I would see if anyone here can tell me
what their type #s are. 4 per ch. And even if they are still available or good substitutes.
Any info is welcome and appreciated.
Thanks.
 
ferninando, does the amp make music on the hot channel? If so, then I'm thinking bias just needs to be adjusted on both channels so both get warm, but not hot/cold. If there's no sound out of the right channel, then maybe the output transistors are bad.

I'll take a look to see if the bias setting procedure is available.
 
thanks Cap for the link and svc mnl.
Once I discovered the hot heatsink I didnt go any further . stopped all doing till I can find out more on the transtrs.
so do not if it plays on the hot ch. do know its too hot to touch.
Its the M4 amp I bought when I bought the C4 preamp.
 
Hi all.
I have an M4 power amp with a major problem. Right ch. output heatsink gets super hot while the left one stays room temp.
So I'm thinking Output transistor short.
But before any disassembly to indentify the types of output trans. visualy, I would see if anyone here can tell me
what their type #s are. 4 per ch. And even if they are still available or good substitutes.
Any info is welcome and appreciated.
Thanks.
Check the bias adjustment !
 
I have an M4 power amp with a major problem. Right ch. output heatsink gets super hot while the left one stays room temp. This mean for me that you have sound on both channels
So I'm thinking Output transistor short. No ! if 1 output transistor is shorted you can't get sound on the right channel because the fuse burn
But before any disassembly to indentify the types of output trans. This not necessary to delete anything to get this info , it is in service manual
visualy, I would see if anyone here can tell me read the SM (2SA1050 Toshiba and 2SC2460 Toshiba )
what their type #s are. 4 per ch. And even if they are still available or good substitutes. Why are you talking about replacement of rare working output transistors ??
Any info is welcome and appreciated. Here is what you need to know : if one channel is overheating this is because there is something wrong with the bias circuit (this do not mean that you just need to re-adjust it ) ! I think that you are in front of a defect parts in this bias circuit and you have to find which one .
Once you have replaced the bad part you can switch the power on and re-adjust the bias but only after that .
Re-adjust a bias is not normal because the factory adjustment can't moove alone and that's why I tell you that you have something wrong in your bias circuit !
I am pretty sure that if you don't want to follow my advice and make a bias re-adjustment without doing anything else inside this unit , you will not be able to get the recommended value

 
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