cobra 25 s/rf meter light bulb

Discussion in 'CB Radio Forum' started by Leeworthy, Sep 18, 2013.

  1. Leeworthy

    Leeworthy Bobtail Member

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    Jul 8, 2012
    Belleville, Ontario
    0
    Hey ya'll. Anyone know how many watts the bulb needs to be to replace on the cobra 25 that lights up the s/rf meter. I pulled one out the other day that was burnt out. Found an LED that was in one of my garden lights wired it in, and then it burnt out rather quickly, assuming it couldn't handle the voltage going to it. Anyone know what watt I need to replace it with?
     
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  3. Ridgeline

    Ridgeline Road Train Member

    20,659
    100,393
    Dec 18, 2011
    Michigan
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    The LED couldn't handle the current that was going through it, not the voltage. You have to put a resister in line with the LED to limit the current. Try a 560 ohm resister.

    Those bulbs are hard to find.
     
  4. 6string

    6string Bobtail Member

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    Mar 24, 2013
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    no thier not you can order it online or go to radio shack and get a 12v lightbulb part its not much

    I know cuz ive replace mine before i bought mine from radioshack

    otherwise you have to run a 3mm-5mm LED bulb to the radio plus a 470 ohm resistor 1/2 watt no lower

    if you skimp on the resistor it will blow everythime
     
  5. Ridgeline

    Ridgeline Road Train Member

    20,659
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    Dec 18, 2011
    Michigan
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    Yes you are right, rs has them, they didn't when I went there but they also have 3d printers now too.

    by the way you don't need a 1/2 watt resistor, 1/8 watt will work just as well.
     
  6. BTShepp

    BTShepp Blue Demon

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    Oct 31, 2015
    Chicago, IL
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    Other then personal preference, is it advantageous to change stock bulbs to LEDs?
     
  7. Turbo-T

    Turbo-T Road Train Member

    1,953
    702
    May 31, 2009
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    Nope it's super easy to change the bulbs to LED's. Biggest thing you need to know is the polarity. LEDs don't work on reverse polarity like typical incandescent bulbs do. Most times the meter lamp bulb wires will be the same color. You'll need to use a cheap multimeter to determine which wire is positive and which is negative.

    And you can get the LEDs on ebay. Easy to find.
     
  8. Lowboy456

    Lowboy456 Light Load Member

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    Mar 14, 2017
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    If I take a working light out of a Cobra 25 and put it in a Cobra 29 will it need the resistor?
    Theres not one installed currently
    in the 25.
     
  9. Lowboy456

    Lowboy456 Light Load Member

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    127
    Mar 14, 2017
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    Turns out my Cobra 25 had a blue Led in it. It had a resistor covered in heat shrink which on that radio reduced voltage from 11.5 to 3.1v
    The cobra 29 read 12 .5 v on the meter light circuit before the resistor and I assume it read 4.1 after the resistor. It worked fine in the 29.
    Looking at the radio from back to front the light plugs into the meter down on the left side. The light was inside a soft rubber square plug that fits so nicely with 2 red wires going through it, it didnt look like it could be popped out. This thread helped me to solve my issue and was literally the only thing I found that had just the right info.
     
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