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Fluorescent Ballast Caps: FAIL

After converting another fluorescent shoplight into an LED fixture, I tested its capacitors:

Fluorescent ballast capacitors - one failed
Fluorescent ballast capacitors – one failed

The ESR02 reports one as a 4.8 µF capacitor, the other as a “defective part” with a 4 kΩ resistance. Having a cap fail by turning into a resistor is surprising; I’m more surprised it didn’t simply burn up.

They’re visually indistinguishable, of course.

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  1. #1 by RCPete on 2019-04-22 - 11:23

    I have enough LED tubes to deballast and relamp a few more shop lights, with 5 left after that. I’ll use the swapped out fluorescent tubes until another ballast fails, then order another case of LED tubes. FWIW, the T8 fluorescents seem to fail faster than the older fat tubes.

    The Home Depot stocks tubes that want a working ballast, which kind of defeats the exercise…

    For new fixtures, so far the FEIT LED shop lights from Costco are doing the job. We’ve had three failures of first-generation LED screw-in bulbs in the house. These hit at 6 years on high usage lights.

    • #2 by Ed on 2019-04-23 - 08:41

      A six gallon bucket now holds all my remaining fluorescent tubes, so the endgame is nigh.

      Years ago, I bought a couple of “nice” T8 fixtures to replace the crappy T12s, but it’s exactly as you say: little tubes and fixtures fail faster than the bigger ones.

      One of the incandescent spots over the fireplace just failed, whereupon I discovered our ancient X10 dimmer can’t quite turn off the new Philips LED spots. We’ll use the manual kill switch until something else goes wrong, because I don’t want to disturb the wiring. [mutter]

  2. #3 by david on 2019-04-22 - 15:50

    I”m more surprised those things ever acted like actual capacitors…

    • #4 by Ed on 2019-04-23 - 08:36

      The mylar (?) tape peels apart easily enough to be scary and I straight up do not understand how they solder / weld / glue the leads to the edges of the foil.

      They’re definitely not built for looks!

  3. #5 by steve on 2019-04-26 - 17:07

    I use the LED tubes that require a ballast for use around rotating machinery. The reset I just replace the entire fixture with a $20 one from Walmart. The $20 ones flicker at 120 Hz making it unpleasant around rotating machinery. The rest I replace the ballast with a solid state ballast so they now flicker in the kHz range. Good thing I don’t need to operate any IR devices in my garage…

    • #6 by Ed on 2019-04-26 - 19:33

      I absolutely didn’t think of that when I ordered the no-ballast LED tubes, but they worked out perfectly: no visible flicker and no effect on the lathe that I can see. Whew!