I purchased a used AUDIO Research D115. I turned it on once, the green leds flickered and I heard a faint crackle through my speakers. Now the amp will not power up at all. I checked the tubes and determined that they are fine. The fuses are also fine. I examined the inside of the amplifier and everything looks fine. Any help would be greatly appreciated, thank you!
start with verifying all connections, check for burned parts, and then powering it up and measuring voltages at each stage from the wall to the rest of the circuitry. Best done via variac or a dim bulb tester.