Vintage Modern Pilot Light Failures

Discussion in 'Marshall Amps' started by Wooferhead1, Jan 19, 2019.

  1. Wooferhead1

    Wooferhead1 Well-Known Member

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    I replaced the purple pilot light about a year and a half ago and it's burned out again. I'd like to replace it again but at $30 a shot is it worth the bother? I thought the problem was remedied with the newer led replacement ?
     
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  2. Micky

    Micky Well-Known Member VIP Member

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    Replace it with an LED...
     
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  3. Adieu

    Adieu Well-Known Member

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    There's surely cheaper ways than a $30 bulb

    And it's certainly a rebadged off-the-shelf component that costs <$1 wholesale, and can probably be found for a couple bucks plus shipping retail somewhere online
     
  4. Wooferhead1

    Wooferhead1 Well-Known Member

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    Isn't that what the purple light is ? or are you talking about an alternate version? I bought mine off ebay and it appeared to be a direct replacement - with the up-graded built in resister (which I thought was the fix for the original LED problems).
     
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  5. Linedrive

    Linedrive New Member

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  6. Kelia

    Kelia Well-Known Member

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    About time those are reasonably priced !.......they were like $34 on Evilbay where only one dude had them !
    I saw that Amplified parts have them also !
     
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  7. 67mike

    67mike Well-Known Member

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    I was having that issue as well. I just soldered a resistor ( researched it and found suggested values which i forget)...this solves the problem..
     
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  8. Kelia

    Kelia Well-Known Member

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  9. junk notes

    junk notes Well-Known Member

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    Is this the same 6v lamp that Plexi's have? If so, the two reasons I do not replace with the LED, is one that they are indeed a LED and not incandescent, and that I do not have to wear sunglasses on an LED that is as bright as the Sun. It is "these" that break down more often and that it has a micro diode, just as filimant is prone to failing.
    Do yourself a huge laborious fave and track down an incandescent bulb version.

    [edit: type O]
     
    Last edited: Nov 29, 2020
  10. marshallmellowed

    marshallmellowed Well-Known Member

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    The "Purple" LED's do not last, not sure why. I never cared for the purple myself, so I replaced mine with a standard red LED, which should cost you less than $5, no issues.
     
    Last edited: Nov 29, 2020
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  11. MajorMan

    MajorMan Member

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    You could solder a resistor to the pilot light like @67mike said. Or you change it to a different kind of pilot light. The current is to high so the light doesnt last that long. :shrug:
     
  12. marshallmellowed

    marshallmellowed Well-Known Member

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    There's a current limiting resistor built into the factory holder for the purple LED. I think it must have something to do with the composition of a "purple" LED that leads them to burn out prematurely, never had a red LED go bad. Just a guess.
     
  13. Thevenin

    Thevenin Well-Known Member Platinum Supporting Member

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  14. anitoli

    anitoli Well-Known Member Gold Supporting Member

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    Looked at a few data sheets and i am seeing similar numbers for red, green, purple, yellow.
    Peak forward current 100 - 150 ma
    DC forward current ( operational ) 25 - 30 ma
    Peak Forward Voltage 2 -3.5 MAX.
    Can anyone measure what voltage is hitting a factory purple?
     
  15. Linedrive

    Linedrive New Member

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    Soooo. Here's a real basic newbie kinda question. Would you wire the resistor in line with the purple wire going from light to pin 22. Or in line with the yellow wire going from light to pin 23? Or does it not matter? Or would you wire it a different way? Thanks!
     
  16. scott-colorado2016

    scott-colorado2016 Well-Known Member

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    It doesn't matter which side you wire it onto, it will reduce the voltage to the led either way.
     
  17. marshallmellowed

    marshallmellowed Well-Known Member

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    If you're using an original replacement, it has a current limiting resistor built into the housing (LED holder). If you're modding it to use a different lamp, will you still be using an LED?
     
    Last edited: Dec 10, 2020
  18. gkterry

    gkterry Member

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    Most LEDs use a 2.2k to 3k resistor for a reasonable non-suntanning brightness. A low value resistor will be BRIGHT and short-lived. No resistor is a guarantee for an instant burnout of the LED.
     
  19. mickeydg5

    mickeydg5 Well-Known Member

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    If using a 5V-6V LED go with replacing the stock 68 ohm inline resistor with a 330 ohm.
     
  20. marshallmellowed

    marshallmellowed Well-Known Member

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    I think the stock purple LED uses a 68 ohm resistor. They may have been trying to achieve a level of brightness out of the purple LED that was pushing it to it's limit, leading to premature failure. Just a guess.
     
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