How to set idle current with old STK modules

[Orit]

Hello,
after replacing the output modules on the amplifier as attachment, I noticed that idle current is too low. Am I right saying that idle current depends on voltage difference between pins 0 and 1 of the output modules, hence on VAS collector current ?
Thanks in advance, have a good day

Orit

 

[sregor]

Yes - but the bias circuit is internal to the module and inaccessible. I suppose increasing the VAS current would increase the idle current, but would affect other things too. There is no simple fix to adjust the current. Are you measuring the current by the voltages on the output resistors? Is it different from the other channel? Have you checked the value of the .22 resistors? Parts change in the thirty years since this amp was originally range. Good luck with it.

 

[Orit]

Steve,
thank you for your reply. Yes, there should be 20 mV on each output resistor, but I measure only 6 mV, and the resistor values are Ok.
Orit

 

[EchoWars]

There's a lot of bogus STK modules out there (probably from China) that have virtually no bias circuitry (or at least circuitry that isn't doing what it's supposed to).