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Fluorescent lamp circuit board

Discussion in 'Electronic Repair' started by rv31rv, Feb 10, 2007.

  1. rv31rv

    rv31rv Guest

    I have an undercabinet fluorescent lamp fixture that suddenly quit
    working. After verifying the tube works in another fixture & pulling
    the board out of the housing, I checked all components & they seem to
    be OK except for a component that looks like a black diode without a
    band. It appears to be open & has DB3 printed on it & the PCB next to
    it. I looked on line & have not been able to find the PCB name for a
    "DB" device. Any help? Thanx.
     
  2. James Sweet

    James Sweet Guest


    Not sure what that is, but if all else fails you can probably pull the
    ballast circuit out of a cheap CFL.
     
  3. rv31rv

    rv31rv Guest

    Found it. It's a Diac, which fires the scr.
     
  4. Jamie

    Jamie Guest

    which does not mean it's bad just because your meter
    said it's open.
    you need to apply the level of voltage required to
    switch it on.
     
  5. It takes about 32 V to switch on.
     
  6. Prior to the electronic "ballasts" and prior to designs that
    were "self-starting" -- there are typically only 2 parts --
    the ballast transformer and the "starter"

    So, we presume this item is the starter. Such starters
    were originally in aluminum cans and had two prongs for
    replacement.

    If this is the starter, get a starter from a hardware store for
    the same wattage flourescent lamp.

    Presumably, if you just solder that starter in place, it should work.

    Or, you might let some smoke out of something.

    Curtiss
     
  7. Eeyore

    Eeyore Guest

    That makes sense. DB = diode (breakdown).

    Graham
     
  8. James Sweet

    James Sweet Guest

    This is obviously a newer electronic ballast rather than the old choke
    and starter arrangement. Reliable as that is, it's not seen as often
    anymore.
     
  9. Franc Zabkar

    Franc Zabkar Guest

    It crosses to an NTE6408 "bilateral trigger diode", ie a DIAC. As
    already mentioned, the breakover voltage is 32V.

    See http://www.nteinc.com/specs/6400to6499/pdf/nte6407.pdf

    - Franc Zabkar
     
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