Troubleshoot desk lamp

Jan 12, 2019 3 Replies

After the hurricane and power outage I had a defective radio, computer and desk lamp, all plugged into the same outlet. Nothing else electrical in the house was damaged. The lamp is fluorescent FML-27W-6500k it has 4 pins.


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The fixture has an electronic ballast. The ballast looks clean, nothing odd except a unidentified minor smell. Bringing my scope probe close I can tell it is oscillating. Although it looks like a thin pulse at 1,458 Hz, (that doesn't seem right). I have no idea what the output should look like. There are 4 pins and the driver has 4 wires out to the bulb, all from different connections. I want to know how to separate a defective bulb from a defective driver without buying a new bulb. Mikek

Test the bulb. - check the two filaments first. they should look like resistors.

When I tried casting out nines I made a hash of it.

OK, refreshed my memory. So this tube is like a long tube, a filament at each end, heats the gas, a high voltage strikes the arc and then the voltage decreases. One side measures 2.68 Meg ohms (not my fingers) and the other side is open. So, I'll splurge for a new bulb.

Thanks, Mikek

You could check the ballast first if you want by lashing up a 20w+ CFL tube to it.

NT

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