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signal after power switched off
signal after power switched off
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Old 6th August 2014, 02:43 AM   #11
Enzo is offline Enzo  United States
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I tend to not think both channels have the same problem, so I look to something they share.

Sorry, but you don;t have the mute button on do you? My first thought is a mute circuit hanging up.


Isolate the problem. The block diagram seems to say there is a preamp out jack and a couple power amp in jacks. So with the amp running and showing the silent symptom, plug a signal into the power amp in jack, anything come out the speakers? Likewise put a signal into one of the source jacks, and set the controls as you would, then monitor what comes out the preamp out jack. Those two tests should tell usw which half of the amp has the problem.

Elektrotanya has the schematic, though some of the scan is poor. When you get to their page, look just under the cover image and it says "processing". Wait 30 seconds until it changes to "Get Manual" and then click there. All those big green DOWNLOAD buttons are for other stuff.

NAD 3140 Service Manual free download, schematics, eeprom, repair info for electronics
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Old 6th August 2014, 04:07 AM   #12
shredhead is offline shredhead  United States
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If the power rails are good with no offset I'd guess it's a messed up protection circuit.
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Old 6th August 2014, 04:32 AM   #13
rettedm is offline rettedm
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Default No sign of life

The plot thickens. Protect kicked in and now no power.
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Old 6th August 2014, 06:09 AM   #14
djk is offline djk
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Check the muting circuit with the J-FETs.
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