Crown DC300A One Side Overheating

[rf7]

This Crown DC300A amp goes into thermal shutdown a lot earlier on the Left side. Everything seems to be ok with that channel, no DC on the output and it's biased a touch colder than the Right side. What could make that side run hotter than the other side?

[Leo_Gnardo]

Biased a bit colder, but runs hotter? Does seem odd. Are you fan cooling the heatsink fins? It doesn't take a whole lot of power to trip thermal switches on the DC300A (I've done it with only 40W per channel), and even modest fanning can allow you to run them to hi power without thermal shutoff.

[rf7]

Finally got back to this. Yeah, I guess he could fan cool it. He says this problem is a new development. Why would one side run hotter than the other one? Should I swap output devices and see what happens?

[The Dude]

Does one side run hotter even if the amp is run unloaded (no speaker load)?

And, FYI, every one of those I've ever worked on has been full of cold solder joints. It would be a good idea to give it a once over and make sure solder connections are all up to snuff.

[Enzo]

ANything is possible, but it is probably not the outputs, it is more likely they are being turned on too hard.

How did you decide they were biased cooler?

here is a simple dirty trick. Turn both biases cold. Monitor mains draw. Now slowly advance one channel bias until the mains current JUST starts to rise as you turn it up. Stop and back off a hair. Now do the same to the other channel. Now both channels shpuld be set just below the point exstra mains current starts to flow.

Noww does it still over heat?

[TimmyP1955]

Fed by a 9V battery or wall-wart as each channel's input source, those amps make nice power supplies.

[rf7]

I'll go thru this thing again tomorrow. I'll check the solder joints and follow Enzo's biasing instructions.