Krell KSA-250

My design slaves the DC protect relay to the soft start. When the soft start has the bulk caps near terminal voltage, it clicks in both the resistor shorting relay on the soft start circuit and the output load relay.

In that manner you take longer for the amp to come on but you do not scorch boards in the process. It would appear that the shorting relay failed at one time or another and the amp was running with the resistors in series all the time...
 
My design slaves the DC protect relay to the soft start. When the soft start has the bulk caps near terminal voltage, it clicks in both the resistor shorting relay on the soft start circuit and the output load relay.

In that manner you take longer for the amp to come on but you do not scorch boards in the process. It would appear that the shorting relay failed at one time or another and the amp was running with the resistors in series all the time...

I think the excess heat caused the failures and


Marvin2.jpg
 
The board is so cooked now, it's either replace it (none available), reproduce the board (maybe), or part out the amp which is a waste as they still go for good money when finished. But...... What can ya do...........
 
I can give it some time to give you some suggestions but not right now. I don't know how long you can wait on it. Is that small auxiliary always on?
 
I can give it some time to give you some suggestions but not right now. I don't know how long you can wait on it. Is that small auxiliary always on?


The protection in is always hot since it monitors each channel.


If you come up with anything, let me know.
 
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