[Amps] Alpha 87A - strange power related issue

[Eric Dobrowansky]

It's been a long time, and I'm not sure if there is a dedicated Alpha 87A related mail list in existence any longer, so I will go ahead and ask here.

I have an 87A that started exhibiting a strange problem.

When the amp is plugged in, the blower automatically starts, and various band and segment LEDs illuminate, but the amp does not start up. The LEDs which illuminate vary each time the amp is plugged in. 

If I try to push the POWER OFF switch, the amp will turn off the blower and LEDs, but as soon as I release the switch, it returns to the state where the LEDs and blower are on.

If I push the POWER ON switch, the amp starts up normally. The amp works fine once it completes the warm-up period. 

If I then press the POWER OFF button to turn the amp off from when it is fully running, it shuts down properly. IE - all the LEDs turn off, and the blower stops.

However, if I leave it plugged in, out of nowhere sometime later the above symptom repeats, and I have to pull the AC plug to get it to shut down completely. 

Any recommendations as to where to start troubleshooting?  Maybe a cap going bad somewhere is pulling down a particular control circuit?


Eric
K2CB