I Need a Scheme for Pioneer VSX-4900S

[Sparkey]

Hello there;

I was replacing the spkr relay in my Pioneer VSX-4900S and it worked
for a moment but the main board was not mounted yet and it moved
enough for one of the temp compensating transistors to touch ground
and it popped something. Now, the receiver in in protection and the
relay won't even fire.

I checked all the B+ and B- and they're all there. Check resistors,
diodes and transistors. Can't find anything bad so far.

I'm hoping some kind soul has a schematic for this model.
Thanks,

Spark

 

[Arfa Daily]

Hello there;

I was replacing the spkr relay in my Pioneer VSX-4900S and it worked
for a moment but the main board was not mounted yet and it moved
enough for one of the temp compensating transistors to touch ground
and it popped something. Now, the receiver in in protection and the
relay won't even fire.

I checked all the B+ and B- and they're all there. Check resistors,
diodes and transistors. Can't find anything bad so far.

I'm hoping some kind soul has a schematic for this model.
Thanks,

Spark

Oh dear ! Don'tcha just HATE it when some little mishap like this, turns
what was a nice simple job into a DC coupled amp nightmare ... d|:-\

As one engineer to another, you have my sympathies - not that that helps you
much at all ...

Arfa

 

[Franc Zabkar]

I was replacing the spkr relay in my Pioneer VSX-4900S and it worked
for a moment but the main board was not mounted yet and it moved
enough for one of the temp compensating transistors to touch ground
and it popped something. Now, the receiver in in protection and the
relay won't even fire.

I checked all the B+ and B- and they're all there. Check resistors,
diodes and transistors. Can't find anything bad so far.

I'm hoping some kind soul has a schematic for this model.
Thanks,

Spark

I have circuits for a VSX-3700S. Perhaps the audio power stage is
similar. Can you let us know the part numbers of your output
transistors and some circuit references?

I have used the above circuit to troubleshoot other Pioneer receivers.

- Franc Zabkar

 

[Rick]

I appreciate it Franc;

The finals are the 2SC3281 and 2SA1302 pairs
The driver pairs are the A3206 and C3298.

Its got two 3-legged emitter resistor paks.
and both comp trannies and located right next to each other, in the
middle
between the left and right finals.

Thanks and let me know,
Spark

 

[Rick]

If you wind up replacing these, be sure not to use fakes. They're all over.
The 3281 and 1302 are discontinued from Toshiba but the replacements 2SC5200
and 2SA1943 can be had from B & D Enterprises. 800-458-6053

Any "new" 1302's and 3281's branded "Toshiba" are FAKE!

Also, Onsemi sells a Motorola version of the 3281 and 1302. Not sure of the
part number.

B & D also sells these, and I believe MCM does also.

Mark Z.

I will appreciate the heads-up on the "fakes"
I buy a lot of my semi's from B&D. I've had good luck with them.

Spark