Why do McIntosh SS amps cut out?


I have known quite a few old SS Mac's. My main amp is a 2205 and I've just picked up a 2505. These, and every other old Mac I've run across seem to have issues with shutting off one or both channels. Switching on and off will usually get it to stay on. Is it just bad switches? It seems more like it is seeing static/noise and going into protection.
mr_work

Showing 1 response by rontube

Meisterkleef,

You are correct in this sounds like a relay problem. If the amps are being overdriven or have poor ventilation they may thermally shut down. The MC2505 does not have power guard as it was not invented until the MC2205 by Ron Evans, the current head of McIntosh engineering.
All Mc amps have the sentry monitor circuit which will protect the amp if the load exceeds the safe operating area of the output transistors. A defective speaker or one with a shorting voice-coil will trigger this also.

Thanks,
Ron-C