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How to repair Led Bulb

  1. Nov 25, 2015 #1
    I am trying to repair a A15 LED Bulb rated 5 WATT 46 MA 120 Volt. It runs on 30 Volt DC it has 5 cells inside one is not working so based on this information each cell needs 6 volts so the remaining 4 good cells will burn with 24 volts which I applied and my ammeter says 90 MA I know not how accurate this is. If one puts 2 Led's rated 20 Ma at 3 volts in series this would handle the volts, but how many of these sets would one need to handle the amps maybe 5 I am thinking or could one put a 1 Watt resistor rated 40-70 ohms?
  2. jcsd
  3. Nov 25, 2015 #2
    I don't know your exact set-up, but LEDs are commonly powered by a current source. Your 30VDC reading was probably a measurement made when there was no LED load. Take another measurement when the LEDs are lit.

    There's a good chance that you can simply put the remaining four LEDs in series with the "36VDC" supply - because that supply is actually a current supply. But verify this first to avoid damaging you lighting.
  4. Nov 25, 2015 #3


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    This is a battery powered lamp right?

    If it has a replaceable bulb rated at 120V but is powered by a 30V battery then is there a circuit that steps up the voltage?
  5. Nov 25, 2015 #4
    The power supply puts out 43 volts DC when not connected to Leds when connected to Leds it drops to 30 volts DC. I soldiered two wires on each side of the bad led and connected them to 8 - 20 ma 3 volt T5 style leds and it seems to work how long I do not know. I have know idea what is in the base of these lamps I do know they get warm down on the base so electricity is wasted as heat.
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