Crimson 640D overheating

Hi there

Can anyone help me pin down what may be the problem with my Crimson 640D mono Amp.

Symptoms

The amp runs very hot when switched on but playing any music. The fan kicks in after about 5 mins but it keeps getting hotter and shuts off after another couple of mins. Playing music through it just makes it worse.


History

The problem began today as I was swapping speaker cables about. Have I shorted something and caused the problem? Or is is a parts deterioration issue and a common problem with these amps?

They are not worked hard, play at low to medium levels and the right channel mono is working fine.

I've access to multimeters etc but don't want to mess about inside whilst it is switched on.

 

Did you change the speaker cable? I think the Crimsons are a bit like Naim in that they need the right speaker cables to balance the circuit or something. Or is it possible there's a short across the terminals?

 

I did change the cable but on both monos, the other side is fine. I've done it a few times and there has been no problems. I've swapped back now.

The amp runs hot even when there is no source or speakers connected, just switching it on causes it to overheat and shut off. Bollocks.

In amateur speak it seems like there is nothing regulating how hard the output devices (mosfet / transistors?) are actually working. I switch it on, they get very hot, transfer it to the heat sink, that gets very hot, sensor shuts off power.

 

In my experience and others I know of with these amps, its just what they do.

They did it with DNM speaker cable and that's what they are wired with.

 

Double bollocks, that doesn't sound good. Any ideas as to why they do it?

I'll try and e-mail them but on previous experience I won't get a reply, ever.

 

Im not an expert but it sounds to me that you have a or more faulty output transistors/fets etc or the insulation on the output devices has broken down.