I have an original ADA Microtube 200 (circa late 80's/early 90's), that has no output. I'm not sure when it died, as it's been in storage for years. But, I remember how nice it sounded, and decided to bring it out and use it for a little stereo 8" cab I'm building...if I can get it to work again.
It powers up fine, drops out of protect mode after a minute or two, and the fan is running. Both tubes are glowing (replaced just for the hell of it with no change), all three fuses look good (main power and each channel), and the neon lamp is also glowing.
It just doesn't have any output sound or LED indications, no matter which inputs are used, volume, etc. It's as if it never goes out of standby. I've worked the knobs, standby switch, and jacks to clean any residue or gunk, but no change. I can't find anything obvious with a visual inspection; nothing burnt or discolored, no loose connectors or wires, no funky smells, etc.
Whatever it is, it seems common to both channels. Any ideas, or a known issue that causes these symptoms?
I can get around a circuit with a multi-meter and can read a schematic (which I downloaded), but I know nothing about the theory of these amps or where to start in troubleshooting. Any help greatly appreciated, as I'd really like to get this amp cooking again.