Counterpoint SA-100 Fix

genther · 10th April 2010, 11:59 PM

Hello,
I first will admit I am self taught in electronics and have many holes in my knowledge base. That being said, I would greatly appreciate any direction sent my way.

I have an SA-100 with a blown channel and was able to find a matched set of MOSFETS from an other SA-100. I installed them in the channel that was working on mine and they worked fine. When I install them on the blown channel I am experiencing a problem. I replaced the 10v zeners and the gate resistors and triple checked everything. I have a 1 ohm resistor over the positive rail fuse clips and am getting 40mv across the resistor at 25% nominal voltage with the gates shorted to ground. I'm not sure where to look for the problem.

Thanks,
David

genther · 12:45 AM

Hold on, I just took a reading of 0.00 ohms between the source & drain on the P side. I will report my findings...
Sorry, I neglected to properly drain the main caps and there was enough voltage to keep the MOSFETS turned on. The problem stated above still persists.

genther · 11th April 2010, 02:57 AM

Never mind. I found the problem and I won't embarrass myself by explaining.

10th April 2010, 11:59 PM	#1
genther diyAudio Member Join Date: Sep 2006	Counterpoint SA-100 Fix Hello, I first will admit I am self taught in electronics and have many holes in my knowledge base. That being said, I would greatly appreciate any direction sent my way. I have an SA-100 with a blown channel and was able to find a matched set of MOSFETS from an other SA-100. I installed them in the channel that was working on mine and they worked fine. When I install them on the blown channel I am experiencing a problem. I replaced the 10v zeners and the gate resistors and triple checked everything. I have a 1 ohm resistor over the positive rail fuse clips and am getting 40mv across the resistor at 25% nominal voltage with the gates shorted to ground. I'm not sure where to look for the problem. Thanks, David

11th April 2010, 12:28 AM	#2
genther diyAudio Member Join Date: Sep 2006	Hold on, I just took a reading of 0.00 ohms between the source & drain on the P side. I will report my findings... Sorry, I neglected to properly drain the main caps and there was enough voltage to keep the MOSFETS turned on. The problem stated above still persists. Last edited by genther; 11th April 2010 at 12:45 AM. Reason: New info

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11th April 2010, 02:57 AM	#3
genther diyAudio Member Join Date: Sep 2006	Never mind. I found the problem and I won't embarrass myself by explaining.

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