Can you also do the top side pictures too since you have the board out so the wires are not in the way?
I download a bunch of pictures from the link you provided, I will study them to see if they are good enough for me to do the circuit tracing.
OK, thanks!
I may ask for more pictures, I may have to create the virtual PCB since I do not have your board in front of me to do the reverse engineering for examples:
It will be time consuming.
So I download the diagram from DIY, it shows the output transistors as
C3519 (2SC3519) and A1386 (and 2SA1386) so it uses the same outputs as your board.
You need to check those Transistors I have marked in the pictures and need their P/N.
i think budm wants you too test these two transistors too like you did before
Set the meter to 200-Ohm scale.
You have 3-leg device, so looking from the top you can assign left pin as pin 1, middle pin as pin 2, right pin as pin 3, then do the combination resistance testing:
1 & 2 = xxx Ohm.
1 & 3 = xxx Ohm.
2 & 3 = xxx Ohm.
i think budm wants you too test these two transistors too like you did before
Set the meter to 200-Ohm scale.
You have 3-leg device, so looking from the top you can assign left pin as pin 1, middle pin as pin 2, right pin as pin 3, then do the combination resistance testing:
1 & 2 = xxx Ohm.
1 & 3 = xxx Ohm.
2 & 3 = xxx Ohm.
just incase these are bad too
+1, the circuit is using Darligton setup for the outputs so it will not take much to destroy those transistors.
OK, so they are not shorted out, now you need to use Diode mode on the meter to see if the Transistor junctions are not open between E and B, C and B. You will have to look up the spec sheet to get the pin out of those Transistors.
Meter in Diode mode.
For PNP:
Checking B-E junction: Black probe on the BASE, Red probe on the Emitter, it should show around 0.60V.
Checking B-C junction: Black probe on the BASE, Red probe on the Collector, it should show around 0.60V.
For NPN:
Checking B-E junction: Red probe on the BASE, Black probe on the Emitter, it should show around 0.60V.
Checking B-C junction: Red probe on the BASE, Black probe on the Collector, it should show around 0.60V.
Next thing you will need is the lamp fixture so you can put the 75W Incandescent lamp in series with the load which in this case your amplifier to limit the current automatically if you still have problem in the amp, the lamp will stay on bright if there is shorted circuit, but dimly lit if things are OK, we do not want to blow your new parts.
See what I use in post 112 when I do repair works. https://www.badcaps.net/forum/showth...t=25810&page=6
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