I'm repairing my 20+ year old McIntosh MC2125 poweramp.
I got the service manual already, so I have all the circuit details.
The problem with my amp is - occasionally, the left channel would gradually fade and starts to sound sniffy.
Many time, the sound will finally be gone. Lately, the right channel starts to have similar problem, but a lot less serious. The power guard light also turned red quite often.
The problem is I don't know where to start checking because it doesn't always happen. If I leave the amp off for a few days, it will normally come back to work properly for half and hour or more. Any suggestion ? I plan to have it overhauled anyway. But which parts of the circuits are most likely need to be replaced ? Thanks
I got the service manual already, so I have all the circuit details.
The problem with my amp is - occasionally, the left channel would gradually fade and starts to sound sniffy.
Many time, the sound will finally be gone. Lately, the right channel starts to have similar problem, but a lot less serious. The power guard light also turned red quite often.
The problem is I don't know where to start checking because it doesn't always happen. If I leave the amp off for a few days, it will normally come back to work properly for half and hour or more. Any suggestion ? I plan to have it overhauled anyway. But which parts of the circuits are most likely need to be replaced ? Thanks
Testing.
This sounds like a thermo-shutdown problem. So, one of the tubes or transistors is overheating (whichever this amp is?)
Try a can of Freon(sp?). Keep one component cold until the amplifier shuts down. Then you know it's Probably not that one. It's a slow process, but it will isolate the problem IF it is indeed a overheating problem.
Of course there's always the old standby... Ow! Yep it's that one!
pixie
This sounds like a thermo-shutdown problem. So, one of the tubes or transistors is overheating (whichever this amp is?)
Try a can of Freon(sp?). Keep one component cold until the amplifier shuts down. Then you know it's Probably not that one. It's a slow process, but it will isolate the problem IF it is indeed a overheating problem.
Of course there's always the old standby... Ow! Yep it's that one!
pixie
few questions?
Is that amp solid state ?
Is the power suppy regulated type ?
Is there current limiting in power supply ?
If yes to all find shunt resistor in current limiting circuit and the transistor used with it.
If the transistor is normally at cutoff with a high voltage ( emitter- collector ) across , it could produce your trouble.
Is that amp solid state ?
Is the power suppy regulated type ?
Is there current limiting in power supply ?
If yes to all find shunt resistor in current limiting circuit and the transistor used with it.
If the transistor is normally at cutoff with a high voltage ( emitter- collector ) across , it could produce your trouble.
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