I have a bunch of fluorescent fixtures hanging over my layout. These a cheap fixtures from Menards, 48" 2-bulb units. The fixtures are throw-aways when they fail since the ballast is sealed inside the housing.
Yesterday, both fluorescent tubes were unlit when I applied power to the fluorescent fixtures by flipping a wall switch. I tried the two fluorescent tubes in another fixture so the problem is the fixture, not the tubes.
My question is how to test the fixture for power. Since there are two tubes, each with two pins at each end, the fixture has four end clips to hold the two tubes. Can I use a multi meter to test these end clips for power and how would I do that?
Rich
Alton Junction
I would not recommend it for the casual meter user - it's high voltage. It's also a little complicated, in that they start with both pins energized to heat up the filaments and then switch over to just the single pin on each end once the lamp has heated enough to strike an arc. The old type sontrolled with this the starter, those little tubes you replaced periodically when they failed, it was little more than a bimatallic switch like used in Christmas light flashers, the modern ones do it by supplying a high voltage pulse electronically. With no bulb in the circuit you might not even get the steady state condition since it won;t see the load of the lamp to know it started.
Easiest (and safest) way to test them is to simply use a known good tube and swap it around.
Nifty animation on how it works:
http://www.edisontechcenter.org/Fluorescent.html#howitworks
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I have replaced a few hundred ballast over the years as an industrial worker. You don't test them. Replace them. Replacements are usally available. Sealed in a metal case. At one time, some would leak a little tar they go so hot.
Google the number on the ballast. Might be easier and cheaper to buy a new fixture.
Six wires to change. I still have a lot of the plastic wire nuts I used in some replacements.
Big box stores should have everything. Check Amazon. They sell some but maybe not for your lamp. If not familiar with electrical, might be safer to stay out of the fixture.
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I have many fixtures with one, two or four 48" tubes in the layout area. Many of them were from commercial installations and are good quality housings but the original magnetic ballasts and T12s were "noisy" (both hum and RF leakage) so I replaced the ballasts over time with smaller, more efficient electronic ballasts and T8 lamps.
Less hum but it was still there and in such close proximity (low ceiling) it could get pretty annoying after a while.
Then I discovered linear LED tubes. Dead silent, as bright as or in some cases even brighter than the fluorescent tubes. The first ones I bought were $25 each. The cost is about half that now and they're available in a range of color temps. Some are made to hot-wire, you need a NON-Shunt tube holder (tombstone) there are others you can just leave the ballast in but I don't have any of those. Some tubes come with them. Some have frosted diffusers, some clear.
These are similar to the ones I have been using, but there are other choices...
https://www.amazon.com/Hyperikon-equivalent-Qualified-Tombstones-Included/dp/B01DJT11AQ/ref=pd_sim_sbs_60_12?ie=UTF8&dpID=41rB1bkIivL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=3CE4N0EJN6YSSW19GJC6
Some wire from only one end, some both ends. Weigh the cost of a new ballast against the cost of these tubes and see what works for you.
Regards, Ed
LED is really the way to go. I doubt a LED bulb will work in a fixture with suspect ballast. Shop around for new LED lamp fixtures. No issue with mecury like FL tubes have now.
A local Snap Fitness I work out at, three years ago replaced LED for FL in about one hundred fixtures for quite a savings in electrical. No disposal issues either.
All my tube FL's and CFL's have been replaced with LED.
Thanks, guys, it sounds like the best advice is to toss the fixture and buy a new one.
The last time that one of these fixtures failed, I called the manufacturer and I was told that it would be best to toss it, that it was not designed to be repaired.
If the OP insist, Google testing fluorescent ballast. I just did. There are many links.
Good luck.
richg1998 I doubt a LED bulb will work in a fixture with suspect ballast. Shop around for new LED lamp fixtures.
But the ballast gets completely removed. You just retain the lamp holders or replace them with "non-shunted" lamp holders AKA tombstones.
Some LED replacement tubes are wired at one end with the hot and neutral going to each pin, others, like the example below, have the hot at one end and the neutral at the other.
Just sayin—it is a very easy retrofit and if the fixtures are of good quality and you don't feel like replacing the whole thing, this retrofit is easy to do.
Good points, Ed, but unfortunately these cheap fixtures are sealed and not fixable. I talked to the manufacturer about trying to open up the fixture to reach the ballast and was told to forget it.