Perreaux 9000B schematic?

[still4given]

Hi Guys,

A friend of mine has this Perreaux 9000B amp and one channel is not working properly. I checked the low voltage leg of the power outputs and all are the same except for the -side of the left channel. The good channel and positive side of the left all read .499v. The -side of the bad channel read .348v. I need a schematic to maybe see what component might be causing this unless one of you happen to know.

Thanks, Terry

[still4given]

Bttt,

I could really use some help with this. This is a great sounding amp when it is working properly.

Thanks, Terry

[kiwiandy]

Hi Terry,
I haven't got a schematic I'm afraid, but you might try contacting the company for a copy (www.perreaux.com). The amp is over 20 years old now, so there are probably no trade secrets hidden in there.

There's a schematic for the 3000B model on this forum somewhere, that you should be able to search and find. It looks like a fairly generic version of Hitachi's original app. notes, and I suspect the the 9000B is very similar, but with a few more mosfets on the output.

Good luck, but be careful inside the amp. They have high voltage rails that can give you quite a belt. I suggest that you keep one hand in your pocket when it's powered up.

Andy

[still4given]

Hi Andy,

Thanks for that. I found the 3000B schematic here .

Now I just have to figure out what is causing the low voltage at the outputs.

I'm going to do some voltage checks and maybe post them here if I can't figure it out first.

Thanks so much, Terry

[still4given]

I just wanted to say thanks again to Andy for the suggestion. I received the schematic from Perreaux in an email yesterday. It even has some reference voltages on it.

Blessings, Terry

[ztan]

Just opened up my blown 8000c:

One 2SK176 FET blown with Gate to Source short reading 500 ohms. I see these are quite difficult to get.

How critical is matching the output devices: can I replace just one of the five FETS with a good used 2SK176 or Exicon/Semelab new one; or do I need five new matched FETs?

Alternately, can I just take out 1 FET from each group and run with a RMS power of 400W rather than 500W? I probably never come close to using even 50W on account of neighbors and wife.

Does anyone have a bias adjust procedure for these amps?

Thanks,
Ezekiel