Crown Macro-Tech Schema & Bias


I fixing a Crown Audio Macro-Tech 601 Amp.

Multiple problems here. Firstly, I have replaced 2 of the 4 main transistors of the right channel to get it working, and it works fine.

Now, the left channel then... it works, but distorts really easily.
I have a service manual with some tests to be run. The second test to measure bias already fails. There are 2 points to measure and adjust the bias and they are both way off the limits.

Im strugling to find a schema for this amp, and thus it's quite hard to continue the investigation.

Anyone, any tips where to find the schema or experiences what could be wrong?

Thanks :) regs Timo from Finland
If the output transistors were blown, chances are the drivers, pre-drivers and bias transistors may also be blown. Also check the bias diodes and emitter resistors.

If I have the board out I usually replace most of the components. They're all cheap compared to the labour.

If you swap the output boards over you can isolate the fault to the output board or main board.