1. Home
  2. Electronics Repair
  3. I Need a Scheme for Pioneer VSX-4900S

I Need a Scheme for Pioneer VSX-4900S

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

Reply to
Sparkey
Loading thread data ...

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

Reply to
Arfa Daily

On Thu, 16 Apr 2009 05:27:26 -0700 (PDT), Sparkey put finger to keyboard and composed:

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

--
Please remove one \'i\' from my address when replying by email.
Reply to
Franc Zabkar

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

Reply to
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.

Reply to
Mark Zacharias

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

Reply to
Rick

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.