Preventative maintainence for an AU-9500

[Ionesque]

So I have an AU-9500, that I bought a few decades ago as a garage stereo system. And for giggles I looked it up on eBay today and I had no idea it's value had shot up so much. I just love the mids and highs it produces. I'm not an audiophile by any means, but it just feels so right to listen to it and I never bought something newer.

It's pretty much in perfect working order, bit of static at with no signal, and the left channel has always been a tad weaker on the highs. But it's always worked in a less than ideal enviroment that would probably make most people rather upset on here.

But that said I want to change that, to my knowledge it was only repaired once back in 2004, and most everything else is likely factory original. Besides a recap, are there any other preventative items that should be sorted to ensure the longest life possible?

 

[playittwice]

Hello Lonesque,
That’s a very nice amp you have there. I have one myself and after following the thread posted by AK member Leestereo, I gave mine that same treatment. It has transformed the amp to a whole other level. If you want an amp that will belt out some serious music I feel this is the one that will do it with authority. There is a good reason they are bringing the prices on the market. Sonics, build quality and nostalgia to mention a few.

After doing the restore on this amp it may even find a way into your living room as a mainstay in your set-up.

Good luck.

 

[blhagstrom]

I have one here for a repair and restore.

The output transistors are suspect. The 2sa679 seem to blow on that one and everything else that uses them. The 2sc1079 seem to last.

I am thinking 2sa679 and 2sc1079 should be replaced with mj21193 and mj21194 whenever found.
Of course the amps should be adjusted after the replacement.

Pioneer SX-1010 suffers from those failing.

Just a hunch based on how many dead 2sa679 I've seen on many different units.

 

[Ionesque]

I'll look up Leestereo's threads and see what all he did, wouldn't mind freshening it up overall. As for the amp its finding its way back inside soon as possible, I've had it for a long time and I paid nearly nothing for it initially so I didn't think much of it. I apparently did sign up here to resolve a protection mode issue years ago, but I never did more than I needed to get it running again.

If the 2sa679s fail does it typically end up taking anything with it, or is just a likely cause of light static?

Regardless, I hugely appreciate the recommendations I'll be taking better care of it from here on.

 

[quadklipsh]

balhagstrom,
if 21193 and 21194 are used in place of the originals, would they sound better than the original ?
i have successfully located and purchased the 21193/94s but my amplifier has its original transistors up and running just fine . just curious how would the sound differ if 21193/4s are used ? thanks

 

[kevzep]

balhagstrom,
if 21193 and 21194 are used in place of the originals, would they sound better than the original ?
i have successfully located and purchased the 21193/94s but my amplifier has its original transistors up and running just fine . just curious how would the sound differ if 21193/4s are used ? thanks

They will make absolutely no difference to the sound.

 

[quadklipsh]

wow , thanks kev. you saved up a weekends hassle ..
This essentially means that if the originals get damaged then the 21193s can come to the rescue rendereing complete originality .

 

[kevzep]

wow , thanks kev. you saved up a weekends hassle ..
This essentially means that if the originals get damaged then the 21193s can come to the rescue rendereing complete originality .

Yes they can, output transistors have the least influence on the sound of an amplifier, as long as they meet or exceed the specifications of the originals.

 

[slimecity]

If you have a slight drop in highs on one channel i would start simply - by cleaning all controls thoroughly with a good contact cleaner.