I'm trying to repair a JVC JA-S22 amplifier. It's a class AB amplifier with Darlington output transistors. The power transistors are blown in one channel.
The transistors are contained in a module called an STK-0040, which has an internal circuit of this:-
It's TR4 and TR5 that have blown and are shorted collector - emitter.
There are lots of STK-0040 module on ebay, but I am fairly sure that they are all copies. The original STK-0040 has semiconductor dies bonded onto a circuit board, so it would be quite easy to make an equivalent with a very different technique, but it's likely that the copies don't perform properly.
This video (
which is in Spanish) show someone repairing the same amplifier and uprating the transistors on a copy STK-0040.
I have opened up the blown STK-0040 and think everything except the big transistors is working. I think that I could cut the base and emitter connections on the big transistors, and mount equivalent NPN and PNP transistors in T0220 packages somewhere else on the heatsink, and run wires to the module or the circuit board.
So I've got a choice of:-
1) use existing module with the big transistors fitted remotely.
2) use a module from ebay that is probably a copy and hope for the best.
3) get a module from ebay and change the output transistors, as in the video.
Has anyone got experience of these or any suggestions?
The transistors are contained in a module called an STK-0040, which has an internal circuit of this:-
It's TR4 and TR5 that have blown and are shorted collector - emitter.
There are lots of STK-0040 module on ebay, but I am fairly sure that they are all copies. The original STK-0040 has semiconductor dies bonded onto a circuit board, so it would be quite easy to make an equivalent with a very different technique, but it's likely that the copies don't perform properly.
This video (
I have opened up the blown STK-0040 and think everything except the big transistors is working. I think that I could cut the base and emitter connections on the big transistors, and mount equivalent NPN and PNP transistors in T0220 packages somewhere else on the heatsink, and run wires to the module or the circuit board.
So I've got a choice of:-
1) use existing module with the big transistors fitted remotely.
2) use a module from ebay that is probably a copy and hope for the best.
3) get a module from ebay and change the output transistors, as in the video.
Has anyone got experience of these or any suggestions?
