DIY Audio Projects Forum

NAD Stereo Receiver 701 - Display Kaputt
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Author:  Gilf_tronic [ 30 May 2014, 19:08 ]
Post subject:  NAD Stereo Receiver 701 - Display Kaputt

Hi everyone,

My first post here, also brand new to the art of DIY audio.

I was gifted an NAD receiver and plugged it in. The first thing I noticed was how bright the inside of the display was (looking inside of the receiver from the top), but thought nothing of it. Soon after it put itself in 'protection mode' and basically shorted out. It responds to being turned on but turns itself off within a couple of seconds. I took it apart and found the back of the display had melted thus why it was so bright inside of the machine.

This seems like a good project to finally get my hands dirty with some DIY and maybe to start to understand the intricacies of the art. Though I am completely new to everything relating to working with electronics so perhaps this is too large a step to begin from; especially where I likely have very few tools.

If I were to take on the task my goal would be to divert whatever energy was going to the display so it doesn't force the machine into protection mode. I do not want to replace the display as I want to keep the cost to minimum and I do not really need it.
That being said, I do not know if something else was damaged and if I knew how to, that's probably what I should check first.

I realize this sort of question has likely been asked many times on the forum but I thought at the least someone may be able to point me in the right direction of where an explanation for this sort of issue and solution already exist.

I'm wondering any information you guys would be able to divulge into helping me decide if I should take this on at all, and if so, what sort of process and tools would be necessary to solve the problem.

Thank you in advance

Author:  Peter W. [ 09 Aug 2016, 15:15 ]
Post subject:  Re: NAD Stereo Receiver 701 - Display Kaputt

Welcome to the Wonderful World of NAD Audio.

You will need a schematic. Register with HiFi engine, likely they will have it.
You will need some basic diagnostic skills - eyes, nose and fingers for a start. Following the schematic next.
NAD was/is notorious for wretched build-quality and absolutely the lowest price-point components and parts possible.

Most NAD failures are due to bad caps. Look hard and see if you see any swollen, leaky, deformed or burnt caps anywhere in the system.
Other failures are due to cold-solders. Look VERY carefully at the boards, even with a bright light and optical quality magnifying glass, and see if you find any evidence of a broken trace (white fuzz, burn marks and such).

You did not mention any sound artifacts - does it sound OK right up until failure?

Good luck with it, and, as you seemed to imply, the alternative is land-fill, so that gives you much more freedom to take risks and experiment!

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