NAD 7250PE Intermittent Distortion - diyAudio
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Old 24th April 2004, 11:57 PM   #1
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Default NAD 7250PE Intermittent Distortion


I've been trying to get to the bottom of the problem with my NAD 7250PE receiver. The right channel (only) often lapses into a strange distortion where the channel all but drops out with the main musical "hits" straining through. I replaced the 4 main big filter caps, which seemed to help, but the problem is still occuring, albeit less frequently. Of course, it could just be luck that it hasn't happened as much, but the old caps looked worse for wear anyway.

It would make sense that it is a transistor (it sounds like a switch being turned on and off very quickly at the loudest current spikes) but I do not have the schematics for this model. Does anyone know the location of the possibly problematic transistor, or at least the location of the bias pot, which could also be causing this problem? Apart from this problem, I'm quite enjoying the sound of this unit.

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Old 25th April 2004, 08:11 AM   #2
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Default Re: NAD 7250PE Intermittent Distortion

Is the soft clipping turned on?

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Old 26th April 2004, 06:25 AM   #3
soma is offline soma  China
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You can remove right channel Q501(2SK363) or changed D501 from 1S1588 to 10meg resistor.Maybe can solved this problem.
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Old 27th April 2004, 08:01 PM   #4
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The soft clipping does not seem to effect the distortion.

Soma, I'll give that a try, thanks!

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Old 29th April 2004, 03:10 PM   #5
eLarson is offline eLarson  United States
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Some other, even simpler things to check:

Have you tried reconnecting your cables (dirty connection somewhere)?

Is your volume control or balance control dirty (noise when it is turned)? This one afflicted my parents' 7250PE.

Would a woodchuck bother to chuck MDF?
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Old 1st May 2004, 09:08 PM   #6
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The distortion appears on every input, so I don't believe that it is a dirty connection. It happens to phono, aux, cd, video, etc... Also, the volume and pan pots do not crackle when I turn them, so they seem fine.


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