question about mac2105

[kise007]

hi everybody,ive got a mcintosh 2105 vintage amp that seems to wofk fine except the left side heatsinks get warm when powered on even with no input or speakers hooked up while the right side stays room temperature,no sign of heat.the amp is 1971 and never been serviced or worked on.the left side that gets warmer with all things equal seems to sound a little clearer with better highs.volume souds about the same.my concern is the one side getting warm (not hot)while the other is cold to the touch,any replies that can help me understand this would be appreciated.

[gearheaddruid]

Hi, it sounds like the bias has drifted on the channel that is cold. If the bias is not set properly, there will be distortion in the output. I have one of these amps and the heatsinks should become warm (not hot) to the touch after the unit has been on for a while.
I honestly cannot remember if there are adjustment pots on the top but I would bet they are dirty and need to be cleaned and re-adjusted. Regards, Steve

[sakis]

all and i mean all electrolytics on this amp is a must !!!!!!

also except trimpots that might be dirty or warn there is a very good chance that resistor value is sifted up or down especialy if the amp was "stocked" in a wet area .....

all this will update also the amp considering how well it sounds