Burning transistor

Thread Starter

DavidCH

Joined Feb 2, 2023
3
Hi

I’m trying to repair an old Philips record deck. T5 in this circuit was smoking, so I replaced it (and F1 which had blown) but on power up the replacement T5 (2N2222) fried immediately as well. Can anyone tell me what I should look at next?
 

Thread Starter

DavidCH

Joined Feb 2, 2023
3
Hi

I’m trying to repair an old Philips record deck. T5 in this circuit was smoking, so I replaced it (and F1 which had blown) but on power up the replacement T5 (2N2222) fried immediately as well. Can anyone tell me what I should look at next?
image.jpg
 

Ian0

Joined Aug 7, 2020
9,671
Check the preset. If it's old it might have lost connection between wiper and track, and it's not designed to fail safe.
If it loses connection it turns the bias up to full and destroys the output stage.
 

bassbindevil

Joined Jan 23, 2014
824
Check the output stage transistors and emitter resistors for open or short as well; in my experience they're the usual failure points in power amps.
 

Thread Starter

DavidCH

Joined Feb 2, 2023
3
Thank you all. The preset checked out OK. I suspect as mentioned above that the problem has cascaded, I'm now looking at the probably simple option of replacing the amp completely ....
 
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