Project to change the backlighting on a car radio to use blue LEDs. I orginally wrote and posted this on my blog and can be found at:


The radio is the Delco AM/FM/CD model that appeared in many GM models anywhere from 1996 - 2002. The buttons and labels on the faceplate are backlit with a number of 12V incandescent bulbs. I initially set out to do a direct replacement of the bulb on the circuit board. In the end, the implementation was a little different. Due to the space constraints, right away I knew I would need to find an LED with an integrated resistor. They do exist, but they are quite expensive and I could not find any in blue. So at this point the best thing to do was to remove the incandescent bulbs and glue the LEDs into the faceplate, creating wire leads to solder to the circuit board.

Step 1: Disassembly

For this particular radio, the faceplate essentially snaps on to the front of the body. A flat screwdriver easily pries it off. Four screws remove the bottom of the body that exposes the two connectors that interface to the faceplate. Those easily disconnect and the new faceplate can be removed. Additional hex screws attached the circuit board to the faceplate. Remove these, and the front of the circuit board is now exposed. The incandescent bulbs are removed very quickly and easily with some solder wick.

The first image shows the front of the circuit board. The second image is the back of the faceplate where the circuit board connects to.
So what happens when you dim your dashboard lights? I figure at some point the forward voltage of the LEDs drops and they just shut off?
assuming the dimming mechanism is a pot that varies a voltage divider, that would be correct
On my 98 Pontiac the dashboard lights dimmer is actually a pulse-width modulated signal, so it actually dims like one would expect. The only problem is that the "brightness curve" is not quite the same for the LEDs and incandescents. The dimmer is designed to give a fairly linear brightness change for the stock bulbs, but for the LEDs this ends up being more of a curve so they stay quite dim from 0 to half way, and then ramp up to full brightness in the last 3rd of the dimmer's range. It's still not too bad though.
I was going to try this with my Sony XR-4750RDS, but the LEDs are integrated into the buttons in the faceplate, so that mucked up that idea... :(
Looks great. Blue LEDs look awesome on like, almost everything. +5/5 stars.
Looks a whole lot like my Chevy Blazer. If I hadn't gotten a new stereo this woulda been perfect for my blue color scheme. Nice job.
I want to do this to my dash instrument panel, any one know how to do that?
uhh, same way?
Sand the LEDs with very fine sandpaper (800+ grit) to diffuse the light.
My friend did this then decided he wanted to have matching under glow for th dash and back seats, choices were leds those ligth strings or cold cathodes... we had a bunch of leds (blue superbrights) the same as the ones in the radio (they were diffused with a wire brush wheel on a dremel,) we made the led strings and found a really great diffusion solution we used bits os the plastic cover for fluorescent strip lighting. Another good one was a friend that was a complete xbox nut green lighting for radio and the xbox sign of the drive bay bay put into a blank spot on teh faceplate...
Nice job on the radio, but i noticed they had bright and dark spots, this can be fixed with either a little hot glue, paper, or just by cutting the led a little to diffuse it. I do this kind of thing every weekend! If you need help just ask me, I love working on interiors! Good luck on future projects!
I've done the same thing in my honda prelude dash. you should do your a/c controls to. i converted every light in my car to blue leds. it's kick arse :)
Nice neat job :) I hate the way manufactures make things to be disposable... Why would they permanently solder in the original lamps! At least other socketed bulbs can be changed out with these style easily now:<br/><a rel="nofollow" href="http://www.eautoworks.com/html/ORD-1-1-1-38138.cfm">http://www.eautoworks.com/html/ORD-1-1-1-38138.cfm</a><br/><br/>If you only need a handful of Blue LEDs check here:<br/><a rel="nofollow" href="http://alan-parekh.vstore.ca/product_info.php/cPath/4_6/products_id/15">http://alan-parekh.vstore.ca/product_info.php/cPath/4_6/products_id/15</a><br/>

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