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Old 29th December 2005, 06:30 AM   #1
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Default Nad 314 broken\protection circut active

Hey guys!

i reccon some of you are serveice technicians and so i wonder if any of you have been in the guts of a nad intigrated and seen the problem i have, before?

bought this amp for 25bucks, broken, hoping to fix it, so i'l have something to lend my ear to when everything else i have is in peices awaiting inspection and potesial improvement (yes, this is quite the problem for me )

the thing is that when i turn the amp on, the led in front is red, and when i enable the "direct" function, it plays happily.
leads me to beliving the fault could be in the VAS, perhaps the VAS power suply? it appears to have a dedicated VAS suply, something which i have not seen before at least.

i read on another thread conserning the 304 that nad uses transistor based regulation, and that those transistors are prone to faliure?
i'm not at my apartment right now, so i have no multimeter or such, but hope to get some tips before i start going through the whole amp, so i hopefully wont have to

If anyone could supply the repair manual for the unt, it would be great as well!

appreciate any feedback!
-Marius
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Old 30th December 2005, 11:32 AM   #2
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Bump??

no one?
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Old 30th December 2005, 12:06 PM   #3
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The direct function should have no effect on the VAS stage, it merely bypasses any preamp/tone controls. What exactly are the symptoms, and what test gear do you have to troubleshoot with?
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Old 3rd January 2006, 12:52 PM   #4
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yeah, offcource, you'r right

i'm home again now, here i have the usal deal, multimeter ect.
i'm gonne check the obvious, transistors, diodes, fuses ect.

but have any of you seen this problem in this amp before, and know how to fix it?

-Marius
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Old 3rd January 2006, 01:20 PM   #5
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Scope?
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Old 4th January 2006, 11:29 PM   #6
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I'm sorry, I just have to ask this. Nothing but accolades for their perfomance, while alive, but two friends who've owned them frequently had their NAD amps in for repair. I thought at the time that, well, you just can't nail down anything general based on two examples. But this is the second request I've seen this week here for help repairing an NAD amp. Anyone else out there have tales of woe?

I'm always on the lookout for good used equipment. I'd like to know if there are brands that should be avoided.
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Old 5th January 2006, 12:37 AM   #7
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Hi Marius,
You are therefore looking at the tone stage. Check supply voltages, one may be out. Then check center voltages at the outputs. It's possible the circuit has a DC offset.

-Chris
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Old 5th January 2006, 03:30 PM   #8
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hey guys.

i feel so stupid, yet so lucky..

the thing is that i had missunderstood the old owner of the amp, i thought that i had to enable tone deffeat, but who and behold, it was that only the "main in" innput worked, he had discarded the pins that go from the pre out to the main in.

my teacher and i looked at it for an hour or two, than he all of a sudden sees the name of the two phono's, and starts laughing, no wonder we couldn't track the sinus wave into the amplification part itself.

so, i got myself a fully functional nad for 25bucks
almost mint condission to!

thanks for your effort to help me out though guys!
appreciate it!

-Marius
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Old 5th January 2006, 10:01 PM   #9
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Hi Marius,
Excellent! Don't feel bad about this. I have had many units over the years brought in by their owners missing those jumpers.



-Chris
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Old 5th January 2006, 11:04 PM   #10
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Tee Hee. That was so obvious that none of us even thought of it!

Happy listening.
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