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Old 4th March 2010, 12:27 AM   #1
diyAudio Member
Join Date: Mar 2010
Location: DC Area
Default Trying to fix HK930

Hey everyone,

I need some advice. My roommate and I bought a Harman Kardon 930 amp towards the end of last year. About 2 months after we bought it, it blew a fuse. Once replaced, the new fuse blew in about 2 seconds. Today I finally had the time to take it apart and try to fix it.

By disconnecting all of the boards from the power supplies, I determined that the two power supplies are fine, and that it is one of the boards that is causing the problem

I reconnected one of the two (the one that drives the right speaker channel amp, the lights, and all of the other boards). It still works fine in this configuration.

Ultimately, I have decided that it is either the left channel portion of the main amplifier board (maybe a capacitor died?) or that it is one of the power transistors.

I just need advice on how I should proceed, and whether or not my logic in determining the problem makes sense.

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Old 4th March 2010, 04:39 AM   #2
diyAudio Member
Join Date: Mar 2010
Location: DC Area

I managed to isolate the problem to one of two things. While I was trying to isolate the problem, I powered on the amp and one of the capacitors on the aforementioned (in my first post) board literally exploded. It sounded much like a gunshot, leaving the innards of the capacitor all over the board, and even 2 feet away from the amplifier (I'm glad I'm ok).

I think I'm going to order a new board (if I can find one), and replace the power transistors with the MJ21194G'swhich is also an NPN transistor, and was recommended as a good replacement for the original 2SC897's that the HK930 has right now. Does this sound like a good plan?
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