repairing the NAD 502 display
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CPL593H

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I'm posting this as information for those with NAD 502 CD players with a dead display. The repair is fairly easy. The display is backlit by two incandescent light bulbs that burn out. Replacing them restores the display. I measured the voltage on the bulbs to be about 15 volts so I replaced them with 18 volt bulbs rated for 10,000 hours life. The brightness is adequate (just barely) with these bulbs and they draw less current (based on info from the web) than the original bulbs so should run cooler and last longer. You could use brighter bulbs but I wanted them to last longer than the rest of the mechanicals.

To get to the bulbs you have to open up the case and remove the white plastic cover on the back side of the display. Have to remove the front panel and detach the main board to solder the new bulbs in. I got the bulbs from Mouser. Here's the part number: 606-CM7220
 
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Shosta

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Thanks for the information. My old NAD512 cost me 50€ for that repair five years ago.
Now it has again just one bulb. It's a typical fail of these machines.
 
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amb

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Thanks for the tip. I have a NAD C520 and its display is very dim. I'll have a look at fixing the backlighting too.
 
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CPL593H

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On the 502 the display is just some type of active mask that uses the backlight as the only light source. The backlights shine through the mask to create the digits.
 
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n_maher

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I'll have to crack open my dusty 513 (wacky 3-CD changer) tonight and see if this looks like it'll work. It definitely has a fried display I can only hope it's as easy as you describe. Thanks for the post!

N
 
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amb

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I finally found time to open up my NAD C520 to have a look. Unfortunately, there is no obvious replaceable backlight bulb on the display. The (electroluminescent) display is soldered to a small PCB which is mounted on the front panel. If there is any backlighting on this model, it's probably integrated with the display itself. When powered up the display shows a very dim readout (barely readable). I tried checking the voltage at all the pins of the connectors to the display pcb (as well as the solder points of the display), most of them read 2.5V, a couple of 5V and a couple of 0V (DGND).

I think the only "fix" would be to replace the display, but that is probably not worth doing...
 
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n_maher

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The unfortunate part for me is that the display on my 513 is mounted beneath the transport (the whole thing slides) so I literally have to disassemble the entire player to get at the back of the display. I'll still give it a go at some point since I had this player in college and then recently reacquired it so it's got some sentimental value.

If anyone has any ideas for fixing a short in an NAD integrated amp that'd be sweet since I have a busted one of those sitting in the attic as well.

N
 
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