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-   -   Nad 705 Receiver Pre Amp faulty? (http://www.diyaudio.com/forums/solid-state/228248-nad-705-receiver-pre-amp-faulty.html)

pmpants 20th January 2013 12:49 PM

Nad 705 Receiver Pre Amp faulty?
 
Hi everyone, thanks in advance!
I'm looking at my friends Nad 705 it powers up fine, the protection relays click and the display works, however there's no speaker output.
I've removed the links and connected a source to the power amp sections input, and there's output on both sets of speaker outputs so I imagine the fault is with the pre amp, if I connect a source to say "aux in", and loop an output from either of the tape "rec outs" to the power amp input you get output, but of course the volume control doesn't function.
Has anyone got any ideas where to start looking? The amp has service stickers inside from 3 dates in 1997, and looks to have had some dry joints repaired.
Thanks ever so much
Paul

chicks 20th January 2013 02:03 PM

I've had several NAD producrs from the '90's and '00's, every one of which had issues, and were a PITA to work on. Bad solder joints, poor quality caps that dry out. One huge PCB that requires disassembly of the entire chassis to reach the bloen caps.

I prefer '70's gear that uses multiple PCB's, far eaier to work on, and far better build quality than NADs of a certain vintage, in most cases.

pmpants 20th January 2013 05:41 PM

Quote:

Originally Posted by chicks (Post 3334415)
I've had several NAD producrs from the '90's and '00's, every one of which had issues, and were a PITA to work on. Bad solder joints, poor quality caps that dry out. One huge PCB that requires disassembly of the entire chassis to reach the bloen caps.

I prefer '70's gear that uses multiple PCB's, far eaier to work on, and far better build quality than NADs of a certain vintage, in most cases.

I know what you mean, I've recently been busy recapping Quad 405s and 33s and 70's Japanese integrated amps, loving every minute, learning as I go! This Nad is a diffrent beast altogether :(

TANDBERGEREN 20th January 2013 08:02 PM

Theese receivers often have the PSU for the preamp and tuner placed on the preamp-PCB.
The PCB itself often was rubbish, with exremely thin paths and ultrasmall solderpads.
Lots and lots of dried out solderjoints aswell as dried out caps.
But start with the often +/- 18V PSU. Find a way to mount the regulators away from the PCB, and change those caps wich mechanically is tight mounted up to the regulators.

Should be relatively fine when finished.

pmpants 20th January 2013 09:00 PM

Thanks Tandbergeren, I have a schematic so I'll take a good look tomorrow, I hope I can revive it for my friend, he really loves it :o)


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