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I have a JBL/Urei 6215 amplifier that has a bad STK2240 output chip that I am going to replace. I have a copy of the owners quasi service manual, but I cannot find any information on how to bias the amplifier. It looks like there is a bias pot for each channel, but again no information on where to connect a meter, what the reading should be etc.
Below is a link to the manual that I have:
http://www.jblproservice.com/pdf/Vin...5%20manual.pdf
Any help would be greatly appreciated.
Thanks
I can't help with your question, but I was told there are lots of fake STK chips for sale. My tech tried two different suppliers of STK chips in a couple of 6215s, and he said they were all fakes.
Try diyaudio.com forums
It appears that the pots offer adjustment to the DC offset circuit. See section 4.6 in the manual for a description of Q1 and Q2.Quote:
Originally Posted by kazarkazam
For the amplifiers that I have working, I was able to adjust one channel that had a small offset back to zero.
It is my understanding that most stk modules are biased internally. Let me know if you find anything different as I didn't find a clear and complete schematic for the stk-2240.
If you can figure out the test points, the attached file has a column for typical/max quiescent.