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Discussion Starter #1
Does anyone know the bulb type or types used in the 95/96 Roadmaster stereos?

I would guess it must be quite a small bulb, as I have several individual buttons or buttom groups that have burnt out (e.g. Tune works, but Seek is dark) - how big are they?

Has anybody had success in replacing these with LEDs, especially in the bottom section where either the radio half or the tape half of the button row is lit?
 

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Bump on this as a few on my 1998 Tahoe are out. I'm ~guessing~ they may be a #74.
 

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if its anything like the chevy radios inside, it should look like these, and be soldered to the board
http://www.radioshack.com/pwr/produ...ack/p/2104023-12V-50mA-Incandescent-Bulb.html
I think those were the correct ones. You might want to google it though, it's been a while since I did it, and the link I used appears to be dead. Half of the ones I used looked like that, the other half didn't have the white plastic base, and they've all been fine for a couple years now

They were roughly the same size as an LED. if you know how to solder it's pretty easy to replace them.

This guy did a write up on how to change the chevy style radios to LEDs, you could most likely get it to work with your buick radio too
http://www.yorkspace.com/2006/02/35

i was going to add LEDs to mine last time i had it apart, but the only ones i had laying around only had about a 20° light pattern. i just lit one up and held it behind the faceplate and it didn't do a very good job of dispersing the light. if you ordered some with a wider light pattern it should work way better though
 

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Discussion Starter #4
I just bought 30 white LEDs, 10 each of 3 different angles. They aren't all that wide-angle, but they all look fairly bright off-angle and blindingly bright within the viewing angle, so perhaps they'd work with a spot of silver paint or black marker on the tip.
...though with what size resistor they'd dim appropriately (if at all) is quite a question.

Given the button arrangement in your link (vs. my pattern of burnt-out bulbs), I'd bet the Buick radio uses the same size bulb.
But how big are the bulbs exactly? Like 3mm (T1) LEDs, or 5mm (T1-3/4) LEDs?
 

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I think I still have the burnt out ones at home, so I'll check for you later on the size

As for what resistor to use, this is pretty handy for designing LED circuits
http://led.linear1.org/led.wiz

If theres room for it anywhere in there, hot glue makes a good light disperser

I'm not sure how familiar you are with this kind of stuff, so just incase you get a weird resistance value and don't mind a little algebra...
http://en.wikipedia.org/wiki/Parallel_resistors#Series_and_parallel_resistors
under the "theory of operation" it gives you equations to find the equivalent resistance. you can usually get pretty close to what you need by playing around with those

[edit] I reread that and I think you meant you want to dim them even more with more resistance... that I'm not sure how to go about offhand.
 

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Discussion Starter #6
No, I mean with what series resistance (the mimimum required for max current limit, or more) the LEDs' brightness would vary most appropriately with the interior light dimmer setting.
 

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well the bulbs from the radio appear to be between a 3 and 5 mm LED in size, closer to a 3mm though

I haven't tried using LEDs on anything with a dimmer, but from what I've read there's a very narrow range of voltages that will cause a change in light output. A conventional dimmer like you have for your dash lights would most likely work more like an on/off switch for your LEDs

they make LED dimmers, but they work by turning the lights on and off very quickly so it appears as though they're dimmer
 
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