| jasonlaronde |
The fuse had burt out on the PS of my NAD 510 CD Player that I had closeted some time ago. I got around to running down to the electronics store and picked up some 630mA 250V fuses so I could get 'er going again. Popped a new one it totally expecting it to blow again because knowing my luck, some transistor was stuck somewhere but YAY! Plugged it in and it fired up without a problem... Except one thing.... The backlights on the display had burnt out. So I pull the display apart to check out what I need to trot down to the electronics store to buy and low and behold. Incandecent lamps... I hate these bastards... Always burning out at the most retarted times and a bastard to replace too.
So I meter the line and it's 24v... Screw these damn bulbs. I'm going to convert to LED.
The backlight board has locations for three lamps, but the 510 only has two. The third in the middle is soldered over. I guess the original design in London way back in December of 1995 called for three but they figured it was too bright... Bright is good!!!
I was going to splice in a resistor in the V line from the mainboard to the front panel and heat shrink it to further drop the voltage to the 3.3V that I need for by blue LED's (Blue is so much cooler than white lamps) but that would have looked like ***. Even thought no one will ever see it... I'll know it's there...
So I traced back to the mainboard and a big *** 3W 10-ohm resistor takes care of the current limiting for the front panel display. Luckily the backlight and the display itself run off of two differed power lines so I pulled out the 10-ohm and am going to put a 390 in its place... That should drop the v to what I need give or take since I'm putting three LED's instead of the original two lamps.
That's where I'm at now... I'm off to the store to pick up the resistors and LEDs and will do the mod tonight.
I'll keep everyone posted.
Jay |
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| bigwill |
Crazy coincidence - I was googling for the NAD 510 today because the backlight on mine had died - and found this thread which was also posted today!
It has been like it for months and I'm getting tired of not being able to see anything on the display :D |
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| jasonlaronde |
you can just replace the 24v lamps with the soldering iron and a beer but they're just going to burn out again.
The resisitor that controls the 24v is just in front of the 2-pin connector near the rear left of the main board. The resistor is hard to miss... It's the big one with insullating fabric tubing on each of the exposed leads.
You have to remove the two screws from the mainboard on the right, the retaining clips on the left and the screw between the RCA jacks on the back panel. You should be able to pop it out with a little gusto.
Desolder the big resisitor and replace it with a 390-ohm 2W. You can then replace the lamps with LED's. This calculation was based on three blue LEDs. The value will change a little bit depeding on if you want to use just two LEDs or a different color as different LED's have a different forward voltage but at a 24v supply just about every color with just use a 390-ohm.
Good luck and let me know how it goes. I still havent gotten to the electronics store. Probably monday.
Jay |
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| jasonlaronde |
All done!
Ended up using a 330-ohm 2W resisitor as I chose blue LED's which use a higher draw and not as much resistance is required. Do your own math if you chose other colors.
Also I found that the LED's create spots of light. I diffused them by giving each LED a light sanding with 300-grit sandpaper. But you could just buy diffused LED's... I had already installed the clear ones so I couldn't return them obviously. Just a hint.
I also purchased 2500mcd LED's which is just bright enough. If you want something that is readable from across the room.... Go brighter than that.
Cheers! |
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