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Krell Evo 302e amp shutting down afeter about an hour!!

Hi, as per the title my Krell Evo 302e amp shutts down after about an hour of use. Before shutting down the amp emits a series of two red flashes, which according to the owner's manual means there is "excessive DC out in the output".  I should mention that when I turn the amp on or when I turn it off I got some brief thumping noise coming out from the left speaker (not really loud).

The amp is connected directly to the wall outlet.
I guess the other audio components and cables are in order since this is the only piece of equipment I have change recently. 

The questions I have are:
1. How can I measure the DC offset? I mean what is the procedure to do this?
2. Is there a pot o pots that I can adjust to lower the DC offset?
3. Any other things I should check o do to correct this problem?

Any help wold be very much appreciated.
Thanks in advance for your help!
tiofelon
erik_squires
16,041 posts
 
Depends on the design, with some DC coupled amps this can happen because there is DC on the input.  First thing to do is disconnect the inputs and see if the problem continues.

You can use a DC meter.  With no input, the DC voltage should be 100 mV or less.
imhififan's avatar
imhififan
2,180 posts
 
1. How can I measure the DC offset? I mean what is the procedure to do this?
https://www.wikihow.com/Measure-DC-Offset
2. Is there a pot o pots that I can adjust to lower the DC offset?
You need a service manual or call Krell for the procedure to do it. But maybe it is not the root of the problem.
3. Any other things I should check or do to correct this problem?
Your Krell Evo 302e amp shutts down after about an hour of use and emits a series of two red flashes which indicate there is "excessive DC out at the output". I think it is thermally problem. My suggestion is clean all vent slots of the case and the circuit boards and heat sinks, make sure it's dust free.
If the problem still exists after cleaning, that could be signs of components start to fail, my advise is sent the amp for service before more damage happened. 
tiofelon OP
59 posts
 
The Krell Evo amp is capacitor coupled. So, should I measure the DC offset with the speakers connected?
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