Stage Line PA-3000

[Audio Tech]

Hello,

I am looking for schematics or at least bias adjust description of that amp.

Many thanks in advance!

[Netlist]

A nice way to set the bias is applying a low input signal, looking at the distortion with a scope and adjust till the sine wave looks neat. Usually I turn the pot even a 'little' higher.

/Hugo

[edl]

Dear Audiotech!

STA-700 schema attached, maybe it helps...

Regards,

[Audio Tech]

Hello,

thanks both for replies. This stage line has made driver stage with BF757 and BF 760. End transistors are mosfets 2SK1058 and 2SJ162 (two in rail).

After repair of one channel (one broken 2SK1058) and switching on drivers of both channels get hot and I think too hot.
I measure the heatsinks temperatures (on each driver heatsink separate) and are 2-3 minutes after switching on about 55-60 degrees Celsius.

It seems too hot and that the bias is set to high.
It will be nice If someone has schematics with these transisitors used or at least datasheets of the BF drivers where I can see If this is normal.

There is no distortion on sound and the sound is clear to his maximum output.

Regards,

Audio Tech

[Audio Tech]

Hello,

I found out that the drivers working temperature is around 82 degrees Celsius meausered directly on his heatsink.

After that I set the bias properly.

Regards,

Audio Tech