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    Need help with IC/electronics problem

    Last night I screwed something up and I don't know what happened. I was trying to wire two leds into my stock HU, to light the LCD display. The display has two incandescent bulbs lighting it originally, one on either end. I wanted to hook the leds into the power source the bulbs were using, so they would turn on and off and dim the same way.

    First I tested it (after waiting 20 MINUTES!!! for my pos soldering iron to warm up) by soldering a couple of wires to the board on one end of the display, and feeding them through a hole on the board. Then I took it into the car and plugged it in without its housing, and just held the led to the wires to make sure it would turn on and make sure I got the polarity right. It worked perfectly.

    Then I went back and removed the wires, and soldered the led into the same spot. I also soldered the one on the other side in, without testing the polarity (I assumed it would be the same, but that was probably a mistake). After both of them were soldered I took it back to the car and plugged it in again. The whole thing lit up for maybe half a second and then both the leds and the stock bulbs shut off (behind the display only, all the rest worked fine). I thought maybe I had just wired the second one wrong so I took it off, and it still didn't work. Then I took the first one off also, and the bulbs still won't light up.

    As far as I can tell there are no fuses or breakers anywhere in the circuit, and nothing seems to have actually burned through. It doesn't make sense to me. I didn't remove anything from the circuit, I was adding the two leds, which would increase resistance. But they shouldn't need enough power to burn anything out. What did I do wrong?

    #2
    Originally posted by jnorion
    What did I do wrong?
    you ****ed with something you shouldn't have...LOL

    did you test the voltage of that circuit? if it's 12volts, did you use 12v LEDs? FYI, alarm LEDs work with around 2-3volts. Cause if you used say, a 2volt LED, it would do just that, light up for a second and then go poof.

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      #3
      I always **** with things I shouldn't... what fun would life be otherwise?

      My voltmeter is broken, so I didn't test it. My test was soldering the wires in and then just touching the LED to them to see if there was a problem. The circuit is coming off the board in the face of the stock HU, I'm fairly certain it's not 12v. The LEDs are rated 6v max, 5v typical, 30mA. It worked perfectly with one of them, but when I put the second one on it screwed up. I am positive I didn't short anything out when I soldered them in, the only issue is that I might have reversed the polarity on the second one (I didn't test it, I just assumed it was the same), but even if I did it just should have not worked, right? Also, everything else works fine, all the other lights and the stereo itself.

      It just doesn't make sense to me that one would work and two would be a problem, I would think adding the second one would just decrease the output to both of them. Also, even if I did use LEDs rated too low for the application, that shouldn't also burn out the bulbs, should it?

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        #4
        Bump for any more suggestions? I'm completely lost here. I can easily jury rig it so it'll work, but I would like to do it right if I can.

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