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Old 1st April 2013, 01:08 PM   #1
diyAudio Member
Join Date: Jan 2013
Default Help with repair of kac-x621

I have a kenwood kac-x621 that had 2 of the power supply fets blow on it so I replaced all 8.

When I power it on the LED blinks and I get LCD screen but something isn't right still -- after the mute delay and the amp kicks on there is 25 amp or so current draw -- I quickly shut it down.

It seems the fets even when clamped t the heatsink get warm really fast so I am using current limiter now.

I cannot seem to find out what is drawing the extra current. I checked the driver transistors "Q119" and "O120". Took them out of the circuit and found they are at Hfe of 141 and both test fine in diode check.

No shorts on any of the output transistors.

I read Perry Babins amp primer and purchased a cd... I think the protect maybe coming on for a good reason... perhaps the failure in the power supply took something out with it... any ideas on how to isolate it?

Thanks for your help!

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Old 1st April 2013, 02:36 PM   #2
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Location: Louisiana
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