2008 Grand Prix stereo display backlight

[sgcb]

Hi all

I hope I'm not abusing the system too much by posting something that may not be strictly under the description of "computer display"...

The problem is the display in my 2008's grand prix radio quit working some time ago. The radio works fine and the buttons seem to perform their functions, it is just the display that is supposed to allow me to see the tuned station/time. Though if the sun strikes the display at the right angle, I am able to make out what is shown, so my first thoughts were backlight issues.

I cracked open the radio casing and disassembled the thing in order to get to the front panel board and found three unidentified type lights driving the display (pictures should be attached) At first I thought these were LED but after removing the rubber sleeves, they now look like some type of miniature incandescent lights. Would I be able to order replacement lights of this type?

[budm]

Re: 2008 Grand Prix stereo display backlight

They are incandescent lamps, more likey to be connected in series. Do you have Ohm meter to find out which bulb is burnt out?
I use this kind of lamp for repair, but you need to find out the voltage feeding them first.
http://www.radioshack.com/product/in...ductId=2102814
http://www.mcmelectronics.com/product/25-1365
http://www.mcmelectronics.com/produc...m_term=25-1370

[sgcb]

Re: 2008 Grand Prix stereo display backlight

I do have a multimeter, but it looks like all three are burnt out (all three fail continuity test). Does this mean determining voltage across is impossible now? Or should I still be able to obtain voltage with a reading across a burnt out bulb? Testing will have to wait until tomorrow since I need to reconnect to car to power the board

[budm]

Re: 2008 Grand Prix stereo display backlight

OK, so this thing is for car, so more likely to be 14V lamps.

[kc8adu]

Re: 2008 Grand Prix stereo display backlight

i would use my 3mm diffused white led's and a 470ohm 1/8w resistor in place of each.
or whatever color you want.
just sand the led if clear or non diffused.the boots are diffusers.maybe reuse?
i did several of these a while back and just used whites.find the board ground and beep out the ground to each lamp.led's are polarised.

[sgcb]

Re: 2008 Grand Prix stereo display backlight

thanks for the replies budm and kc8adu. I have some more information:

• The bulbs look to be wired in parallel - left pins are shorted together and right pins are shorted together.
• left pins seem to be wired to ground - shorted to blue wire which runs back to main logic board. Assuming blue == ground
• right pins are connected to a 3.6 Ω axial resistor. I'm not sure what the circuit looks like on the other side of the resistor due to goop, but it looks like a cluster of surface mount components

Not sure if this changes anything, but I thought I should post it anyway.

Any recommendation on where to get 3mm white diffuse LEDs? (voltage, other specs?) How should I best wire an LED + resistor given only two through-hole slots on the board? Please be descriptive. I'm faily new to 'DIY' electronics.

[sgcb]

Re: 2008 Grand Prix stereo display backlight

It looks like the voltage is 9.8/11.3V when taking readings across the broken bulb. I'm wondering if this changes any of your thoughts on bulb replacements (incandescent voltage or LED + resistance value)?