Fred:
Well Fred...... I would dust off your DMM and start your troubleshooting
effort at checking the power supply for all the necessary voltages and
regulation, test the components in the power output and preamp circuitry and
look for any obvious blown fuses, burnt components, cold or crack solder
connections, etc. If all of that checks out then you will need to follow
the signal path through the amplifier circuitry to see where the problem
is...... an oscilloscope and signal generator would be of great assistance
in this effort.
For additional troubleshooting tips, repair procedures, component testing
methods and IMPORTANT safety information you should spend some search time
at the website for this newsgroup at
http://www.repairfaq.org/
However, based on the initial troubleshooting information that you posted
(or lack there of) I think you might be best advised to TAKE your PA Amp to
a service shop for at the very least a repair cost estimate so you can make
an intelligent repair decision with facts instead of internet or telephone
guesses.
