Pioneer VSX-520-K Protection problem

[rievax_60]

Originally Posted by rievax_60

Ok, that helps to make sense of the voltages. The leakage has to be between collector and base pads of Q444. Try to clean it again. Do you have any information about the flux?

That was a mistake. The leakage would have to be between collector and emitter.

[srt1]

Originally Posted by rievax_60

Ok, that helps to make sense of the voltages. The leakage has to be between collector and base pads of Q444. Try to clean it again. Do you have any information about the flux?

Flux shows neutral PH7+-0.3..so i think its neutral

[rievax_60]

Did the PCB get burnt under Q444?

[srt1]

Originally Posted by rievax_60

Ok, that helps to make sense of the voltages. The leakage has to be between collector and base pads of Q444. Try to clean it again. Do you have any information about the flux?

Flux shows neautral..its written ther PH+-.3

[srt1]

Originally Posted by rievax_60

Did the PCB get burnt under Q444?

Yes littile burn mark ther

[rievax_60]

Originally Posted by srt1

Yes littile burn mark ther

I would use a small drill bit to remove the burnt paper from between the collector and emitter pads.

[srt1]

Originally Posted by rievax_60

I would use a small drill bit to remove the burnt paper from between the collector and emitter pads.

I am.trying to remove the burn mark..and let you know the result

[srt1]

Originally Posted by srt1

I am.trying to remove the burn mark..and let you know the result

Hi.. i replace the 2sa684(q444) with a92 now problem soleved ther is no leakage current. I think 2sa684 for not suitable for this apllication as the maximum volatage on Vceo is 50 but in this circuit its 54volt i think thats why this leakage current but for a92 Vceo is 300 volt.any way thanks alot for your support i apriciate it..may be tomorrow i will get correct tramsistors ie. A992..then i wil replace it

[rievax_60]

The 2SA684 would not have had any leakage and there was no indication that Q443 was leaky. If the PCB was charred, you should confirm it. I like things to make complete sense where possible.
It is best to use the correct transistors.

[srt1]

Originally Posted by rievax_60

The 2SA684 would not have had that much leakage and there was no indication that Q443 was leaky. If the PCB was charred, you should confirm it. I like things to make complete sense where possible.
It is best to use the correct transistors.

Yes i done cleaning and same time i replaced transistor also ..i think you are right may be black mark cause leakage ..but any way i will replace with correct transitor tomorrow.because if i put back 2sa684 for testinfg freequent removal causing traces damage..

[srt1]

Today i got onkyo sr 313 and pioneer vsx 1122 both are ahutdown itself after power ..i will open another thread for discission..

[budm]

What Voltage do you have at the Base of Q437 compared to working channels?
What are the Voltages at the Collector of Q443, 444 compared to working channels?

[srt1]

Originally Posted by budm

What Voltage do you have at the Base of Q437 compared to working channels?
What are the Voltages at the Collector of Q443, 444 compared to working channels?

At base of q437 was around 49 volt with respect to ground.and cillector pin of q443 444 is -53volt .its almost same comoared to other channel..

[budm]

So those Voltage readings on all those 3 location as I request show about (within 1V) the same as in the working channels. There must be some readings in that section that is/are not the same as working channels.

[srt1]

Originally Posted by budm

So those Voltage readings on all those 3 location as I request show about (within 1V) the same as in the working channels. There must be some readings in that section that is/are not the same as working channels.

Yes that is at base of q443 q444 and at the emitter tied