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.
Not sure what that is, but if all else fails you can probably pull the ballast circuit out of a cheap CFL.
Found it. It's a Diac, which fires the scr.
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.
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It takes about 32 V to switch on.
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.
That makes sense. DB = diode (breakdown).
Graham
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.
On 10 Feb 2007 08:05:58 -0800, "rv31rv" put finger to keyboard and composed:
It crosses to an NTE6408 "bilateral trigger diode", ie a DIAC. As already mentioned, the breakover voltage is 32V.
See
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