Working on a Hartke HA5000. Had 3 blown power transistors and both drivers on right amp. Replaced those with exact part numbers and also replaced the six .47 ohm resistors. The amp works fine in mono mode and in bi-amp mode through the high output jacks. When plugged into the low output jacks the relay opens after 30 seconds or so and cuts the sound. I can't find any info or setting the amp (there is 2 trim pots on the board) just a schematic. Both channels have equal B+ voltage going to them. Anything else I should check?