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Old 02-21-2014, 08:18 AM   #39
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Join Date: Nov 2012
City & State: Philadelphia, PA
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I'm a: Hobbyist Tech
Posts: 108
Default Re: Inverter tester using old CFL

Budm wrote in another thread:
Originally Posted by budm View Post
Thanks for the follow up. So what kind of 5W CFL lamp did you use? T5 type?
Yes, I scavenged a 4W T5 bulb from an old Coleman Powermate. I should've gotten 6 more of those along with 7 pairs of alligator clips. The monitor that I was troubleshooting had problems in two inverters at the same time. That's why this single bulb when connected to them one by one would still result in the two seconds to black.

Since we are on this subject.

A while ago I took apart a non-working fluorescent bulb with a spiral tube like in the OP. The bulb was merely a week old and the tube looked brand new w/o any dark spots, so naturally I suspected the electronics. The circuit was comprised of several discreet components and I tested every one that had a p-n junction - they all checked out fine. Next I took apart an identical brand new bulb - fortunately this particular type had the easy to open snap-in cases. I swapped out the tubes with the electronics. After that they both lit up fine.

In this particular bulb (picked up on HD sale: $2.97 per pack of 4, Soft White 2,700K) the spiral tube pins are simply inserted into the two pre-tinned eyelets in the PCB. The pins on this tube were dark of oxidation. My guess is the pins gradually lost contact with the soft tin in the eyelets and the bulb stopped working. I scraped the pins with a knife, reinserted the tube into the circuit and the bulb fired right up. In the hindsight I should've taken apart 3 or 4 dead ones that I had tossed into trash a few weeks ago. I bet they were fine as well.

Yesterday I finally received that $8 CCFL tester from China. Below is a picture of the 4W T5 bulb connected to this tester in front of the newly repaired Dell monitor.
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