On Monday, April 30, 2012 9:58:27 PM UTC, Mike Easter wrote:
I have 3 identical fluorescent fixtures in the garage about 15 years
old, 2 bulb 4' rapid start. A clue to their usage is that none of them
had had any bulbs changed in their life.

One of the units showed intermittent flickering sometimes one bulb was
good/bright, sometimes dim, the worse/dimmest bulb had a dark spot at
the end.

So I changed the bulbs, with no improvement. Used another new bulb.
Same thing. Took two working bulbs from the other fixture and put them
in. No improvement. I began to suspect something was wrong with the
ballast, but I wasn't smart enough to do any troubleshooting. All I
have is a little volt/ohm meter I use to troubleshoot computer power
supply problems.

So, I went to Home Depot and bought a ballast aided by an experienced
sales person who understood what fixture and bulbs I had. The new
ballast was not as 'fat' as the other but was the same length and color
coding of the wires.

I disassembled the fixture/ballast and replaced the ballast using wire
nuts acquired during the ballast trip and reconnected, reassembled, and
resecured the ceiling fixture.

No improvement.

Now I don't know if my original ballast was good or bad and/or if the
replacement ballast is good or bad. I would like to do some of the
diagnostic testing I didn't do during my original guesstimation that it
was/ must be/ the ballast.

How can I:

- benchtest my old ballast I removed
- test the integrity of the new ballast installed
- troubleshoot my malfunctioning fluorescent

If I could satisfactorily prove to myself that the new ballast isn't
good, then I could return it; but under the present conditions I have no
clue what is wrong.


--
Mike Easter

I hadnt used the work bench in my garage for years after building a shop so when I tried the light over the bench the other day it worked about like yours. Flourescents are usually troubleshoot by the replace and see method. Not having any replacement parts I took off to the local hdwr store and came back with two new fixtures and lights for cheaper than I could buy parts..