Denon DRA-350 heat buildup

mpena93 · 17th October 2004, 03:28 AM

I purchased a Denon DRA-350 unit in good condition. It had a blown output fuse on one channel. I replaced the fuse and both channels work and the sound is excellent. My concern is the heat build up in the chassis. I am talking very hot to the touch. Even when it gets this hot, the sound is good. Is this normal or what should i be looking for? Any hep will be greatly appreciated.

djk · 17th October 2004, 12:06 PM

If I remember that unit correctly it has a tripple emitter follower output stage. It is possible for one of the driver or predriver transistors to short b to e and still have the amplifier sound OK, just get hotter than blazes.

Check all the b to e voltages on all the outputs, drivers, and predrivers, replace any that are bad, then adjust the bias pot for about 10mV~20mV across the emitter resistors in the output stage.

mpena93 · 17th October 2004, 08:04 PM

I had the same issue with a Scott 477 receiver. The problem was the bias adjustment. I noticed this Denon had two pots for bias adjustment. Since I do not have the equipment to do an intrument adjustment, I thought perhaps they were only dirty. I marked the original location and rotated them several times making sure they were retunrned to its original setting. The amp works just fine with very little heat build up even when driving speakers at high levels. Thanks very much for your advice. It came in handy.

17th October 2004, 03:28 AM	#1
mpena93 diyAudio Member Join Date: Oct 2004	Denon DRA-350 heat buildup I purchased a Denon DRA-350 unit in good condition. It had a blown output fuse on one channel. I replaced the fuse and both channels work and the sound is excellent. My concern is the heat build up in the chassis. I am talking very hot to the touch. Even when it gets this hot, the sound is good. Is this normal or what should i be looking for? Any hep will be greatly appreciated.

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17th October 2004, 12:06 PM	#2
djk diyAudio Member Join Date: Feb 2001 Location: USA	If I remember that unit correctly it has a tripple emitter follower output stage. It is possible for one of the driver or predriver transistors to short b to e and still have the amplifier sound OK, just get hotter than blazes. Check all the b to e voltages on all the outputs, drivers, and predrivers, replace any that are bad, then adjust the bias pot for about 10mV~20mV across the emitter resistors in the output stage.

17th October 2004, 08:04 PM	#3
mpena93 diyAudio Member Join Date: Oct 2004	I had the same issue with a Scott 477 receiver. The problem was the bias adjustment. I noticed this Denon had two pots for bias adjustment. Since I do not have the equipment to do an intrument adjustment, I thought perhaps they were only dirty. I marked the original location and rotated them several times making sure they were retunrned to its original setting. The amp works just fine with very little heat build up even when driving speakers at high levels. Thanks very much for your advice. It came in handy.