Problem is with EPA900 which powers on and all front mixer works well but not any sound. Speakers tested separately works perfect, output connectors tested and are good.
So, working with the PSU18 (PCB827110REVB/01) separately (disconnected it from the mixer and amp modules power connectors, there is no any High Voltages power supply (+-40/80DCV), but the Low side voltages supply (+-15VDC, V15, +5V, +48) all are working good including the fan is working.
The VREF for U4-U5 is +4.8V, the +16V is measuring +12.8V only, and pin 10 of U5 is On with +3.8V.
When powers the PSU on about 4 seconds later the relay (K1) clicks on but inmediately clicks off, the thing tryed to start up but quickly kills itself.
All the rectifiers diodes tested ok, including the High Voltages secondary diodes D1-5. So ?????
Appreciate a lot all your amiable suggestions, will waiting. THANKS!!!