Crest Audio FA1201 repair - Sanyo LA2500?

[xefe]

I replaced a few burnt resistors, a few burn 2sc3281 and a few 2sa1302 in one of the channels. I the the end i found that the LA2500 chip is also burnt. The other channel is working right.
Where can i get a LA2500? Seems that sanyo stop making them many years ago.
Can i run the amp without this chip? It's function is to polarize the output stage to class A.

Or how can i replace it with a equivalent circuit?

Thanks.

Schematics below:

 

[PRR]

> Can i run the amp without this chip?

No!

I did find a datasheet but I'm unclear what is really inside.

http://datasheet.octopart.com/LA2500-Sanyo-datasheet-14143825.pdf

"LA2500" is readily available through dubious sellers.

http://www.aliexpress.com/w/wholesale-la2500.html

http://www.ebay.com/itm/LA2500-Original-Pulled-Sanyo-Integrated-Circuit-/121136472341

 

[JohnRoberts]

The data sheets I found were in japanese and as PRR mentioned they do not reveal the inner circuits. It looks like a very nice part to manage the class A output stage bias for a class A/B output stage.

You could make a crude simple substitute using a single transistor Vbe multiplier but it would not likely work as well as that dedicated IC that probable does some extra tricks, like internal V ref, thermal compensation, perhaps even current limiting and maybe more...

If you can get the real part by all means do that.

Have you tried the obvious  Crest/Peavey Service?

JR

 

[xefe]

Have you tried the obvious  Crest/Peavey Service?

JR

Email sent! Waiting for an answer.


also i have another question.

I bought a bunch of 2SC3281 and 2SA1302 at a local store. They were cheap (2$ each) Do you think they could be fakes? I know these aren't made in several years.
Or will i do better finding modern replacements?

 

[JohnRoberts]

I have no idea... It probably takes some effort to make and brand counterfeit parts, not sure it's worth it.

Only you know where you live and what your local merchants are like.

JR