Nad 412 Display does'nt work from ebay!

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Marc

Hmm weird... this is the third(!) time in about two weeks that I hear/read about s/h NAD tuner display's not working. kinda suspiscious.

sorry, don't know the solution for the problem though...

regards,
Alco

Matthew,

The NAD412 is a fantastically musical tuner, so it's worth doing a quick check first.

Are you sure the display isn't working?

The unit is backlit with some lamps, and these are common failures. Shine a torch at the front to see if you can discern the numbers - if you can the fix is a really simple job - I can supply the part number of the lamps for you.

If you fancy peering inside, the board that holds the lamps is behind the display - it just clips out - remove it, place it somewhere safe where it can't short to anything, and shine a small torch behind the display.

On my NAD402 (basically the same unit) I fitted a big bunch of LED's - they're slightly less bright (which is no bad thing) and they'll last forever.

Andy.

P.S. the NAD link is only for connecting to other NAD components.

My Father-in-law has a NAD Receiver of a similar vintage, and the tuning display on that has gone - it disappeared segment by segment.

Repairing does not seem an economic option, so

I am looking for a thin receiver to replace it, but very few manufacturers make audio only machines - they all seem to come with 87 A/V modes / features.

DS

ITC - V/A - Escape from Cologne

Andrew,

About 1-2 years ago the display on my NAD 502 CD player also stopped working - but when I shined a torch onto it from in front the display was in fact discernable. At the time I did not consider repair on the grounds of cost/ hassle/being without music, besides it prompted the purchase of a CDX player for which I was awaiting an excuse!

You mention in your reply above that it is a really simple repair - could you perhaps outline LED ratings/part numbers and a brief method please? It would be nice to have the NAD working properly in my 2nd system.

Thanks in advance for your help in this matter.

Kevin.

FWIW, a NAD salesman himself told me that their CDP and Tuner displays tend to break after a 2-3 years.

This was about 5 years ago, back when the 314 and 317 were their integrated amps.

Urm, so how long is my NAD 4225's display likely to last? It's segmented LED, and only one segment is (very) slightly dimmer than the others'.

Ah - it only cost me £12 as well - good old Smack Generators

Any idea how old the 4225 is?

Back on topic - so the 402 has an backlit LCD then? Interesting - I'd have thought LED would have been cheaper to make...

When the music's over turn out the lights

quote:

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You mention in your reply above that it is a really simple repair - could you perhaps outline LED ratings/part numbers and a brief method please?

---

The first job is to measure the voltage across the lamps. IIRC on my 402, there's a small resistor in series with two festoon bulbs, I don't remember if they were in series or parallel, I did this years ago!

Once the voltage is known, let me know and I can work out a a string of LED's + a resistor to do the job.

I'll check the 402 manual tonight, if I remember.

Andy.

Hi Andy,

Just checked inside the nad and the bulbs are blown but the display works.

Both bulbs are soldered together at each end but the resister is only joined to the bulbs at one end(series/parallel?)

I will borrow a voltage tester tomorrow and get back to you on that.

I also noticed that the two largest capaciters (25v 2200uf) have translucent, light brown stuff around there base, it is quite hard.

Could they be leaking? or maybe Flux residue?

Excellent news - that sounds familiar - two bulbs in parallel and a series resistor - usually looks a bit 'cooked' round there too!

I've seen loads of people complaining the display has packed up, it's almost always the bulbs!

The brown stuff is glue to secure the caps - quite common on these units.

Andy.

Andy,

I Checked the voltage today and it is 11.69 v

I would be extremely grateful if you could explain how to solder all the parts together. I can solder and de-solder but i don't know a lot about electronics

Matt

Mathew,

If you contact me off-line (andrew at alw-audio.co.uk) I will connect the necessary parts together and send them to you.

Better still, if you note the polarity of the connections to the lamp PCB, then desolder it (making sure you've noted where the wires go!) and then post me the backlight PCB, I'll arrange the LED's for you - you can just refit the board then.

Mark + / - on the board with a permanent marker, and note the wire colours / polarity your end.

Andy.

Andy,

I just looked through my maplins catalogue and noticed they sell led's with built in resistors, What do you think?

I Don't know how many i could get in the board, maybe 6?

As long as i fit them the right way round (At least they won't explode if i do) i should be able to do it myself

Maplins only do this type in yellow, red and green, I think i may try yellow

Many thanks for the help & the offer to do it for me

Matt

Mathew,

You have two choices re: connection, maybe about 5 in series with a small R to limit current, or the ones that work from any voltage in parallel.

Yellow is what I use, and it works well, but is dimmer than the lamps (which I find pleasing for late-night in the dark listening).

Mine sit close to the PCB, but getting them towards the display will help brightness.

Any problems, drop me a mail.

Andy.