Pioneer GM-X962

2pist · 12th February 2008, 05:45 AM

The amp had shorted Mos-fets which I replaced. At idle, it draws about 1/2 amp and appears fine. After about 2 minutes it gradually increases current draw and the left channel output transistors get hot at which point I shut it down. I pulled the output transistors and they check out fine. I even replaced them as I had some NTE equivalants and the same thing happens. Any idea where to go from here?

sdoom · 12th February 2008, 09:16 AM

Probably some bad solder joints. When I have a broken amp I always start re-soldering all joints first. ( even if they look fine, they dont have to be).

Perry Babin · 12th February 2008, 10:08 AM

sdoom is probably correct. Look closely at the biasing circuit components. The connections often fail on the bias transistors (Q565 in the left channel).

2pist · 12th February 2008, 02:39 PM

Thanks, I'll give resoldering a shot.

12th February 2008, 05:45 AM	#1
2pist diyAudio Member Join Date: Jun 2004 Location: Utah	Pioneer GM-X962 The amp had shorted Mos-fets which I replaced. At idle, it draws about 1/2 amp and appears fine. After about 2 minutes it gradually increases current draw and the left channel output transistors get hot at which point I shut it down. I pulled the output transistors and they check out fine. I even replaced them as I had some NTE equivalants and the same thing happens. Any idea where to go from here?

12th February 2008, 10:08 AM	#3
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	sdoom is probably correct. Look closely at the biasing circuit components. The connections often fail on the bias transistors (Q565 in the left channel). __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

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12th February 2008, 09:16 AM	#2
sdoom diyAudio Member Join Date: Mar 2004 Location: Heidelberg	Probably some bad solder joints. When I have a broken amp I always start re-soldering all joints first. ( even if they look fine, they dont have to be).

12th February 2008, 02:39 PM	#4
2pist diyAudio Member Join Date: Jun 2004 Location: Utah	Thanks, I'll give resoldering a shot.

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