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Florescent light fixture gone bad

I have a "Lights of America" Florescent fixture (4 ft - 2 bulb shop light).

Only one bulb would light. New bulbs did not fix it. Only one side of the fixture worked. (Always the same side).

I finally tore it apart.

I have repaired and replaced ballasts in a lot of fixtures, but this one is unique. Instead of having one ballast for the entire fixture, this one has thick plastic ends, with one ballast on each end. These ballasts look more like a small transformer or a choke used in power supplies on electronics. Across the wires on each ballast is a capacitor and a resistor. The choke on one end looked ok and that fed the bulb which worked. As soon as I opened the other end, I found the problem. That capacitor literally had a hole in it, and there was black burnt markings around it.

The good capacitor is not labeled like a normal cap, so I dont know what value it is. It says K 505J 250. (I am guessing its 250 volt, but I am clueless about the uf value).

Either way, I am sure that finding a capacitor that will work, would only be a guess...

But I am posting this for another reason. The wires that cross over to the defective side, are joined in the middle of the fixture with a sealed plastic box, which can not be opened. I put my VOM across those wires and there is no reading (on the ohm setting). Is that a fuse, or what? Like I said, I have never seen this type of setup. Every fixture I have ever opened just had straight thru wires, or used wirenuts to join splices.

I can only guess that when the cap shorted, it blew the fuses or whatever is in that thing...

Have any of you ever seen this type of setup?

I'm only asking this because I am curious. I do not intend to buy a new ballast, which would probably cost as much or more than a new fixture. However I may convert this fixture to 4 ft LED replacement bulbs, which means removing all ballasts and directly wiring the sockets to the AC line (only one one end of the bulbs). I was kind of thinking of converting the fixture to LED anyhow, so now I have more reason to do so.

Reply to
oldschool
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I did figure out one thing on my own (using Google).

505J is a Japanese way of marking a cap. In this case, it's 5uf. So it's a 5uf at 250V cap. I can only guess the "J" means Japan.

Why they cant label their caps like normal people, is frustrating, but that's how they do it. Just more complication for no advantage. Kind of like metric bolts.... The SAE bolts were just fine, but they had to complicate matters and force everyone to buy and own TWO sets of tools.

Reply to
oldschool

Only if you still cling on to your bushels and pecks...

Mike.

Reply to
MJC

J=+/-5% tolerance.

That is a standard marking. You need to study the basics, instead of constantly complaining.

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

Be careful you don't bite your tongue while it is firmly planted in your cheek. Eric

Reply to
etpm

Oldschool-

You caught my interest, since I have been slowly changing some old fluorescent fixtures for LED.

I'm thinking your capacitor may use a standard method of marking: significant digits 5 and 0 followed by 5 zeros, and a J to indicate 5 percent. This is in picofarads, so the result would be 5 microfarads. I agree that the 250 would be voltage. I would expect such a capacitor to be non-polarized.

I once found a similar fixture, but the two sides were just independent. Each had an inductor for ballast, but used a starter for each. I think yours may be the modern equivalent that does not use a starter.

My thought would be to replace the entire fixture, not just convert it. The cost may be similar, but the result may look and work better.

Fred

Reply to
Fred McKenzie

Your right about those caps. Funny thing, I began working on electronics around 1965. I have never seen a cap marked like that till now. All I have seen all those years were either marked uf, MFD, uuf MMFD, or PF. And some of them real old ones with colored bands and dots that make them look like a domino.

Yep, both sides are independent on this fixture. I think those 5uf caps replaced the starter.

I looked at the cost of a new fixture. The LED ones complete with bulbs are around $60. I can get the bulbs for about $7.50 each. Theres no sense spending the extra $45, when this fixture is just fine. Except for the socket ends and the cord, all I am re-using is the metal/plastic shell. And since I ripped out the guts, I gave it a good hose cleaning and it looks almost like new.

Besides that, I think the NEW fixtures are all plastic. I like metal better.

Reply to
oldschool

On Saturday, April 1, 2017 at 12:14:12 PM UTC-4, snipped-for-privacy@tubes.com wrote: I can only guess the "J" means Japan.

Americans make up less than 5% of the world's population. We consume 25% of the world's total natural resources. By any reasonable or unreasonable measure, we are hardly "normal" people.

Get over yourself.

Peter Wieck Melrose Park, PA

Reply to
pfjw

I wouldn't bother it because if a fire results afterward, then the insurance might not pay. I'd call a lighting retailer to send someone out to fix or replace it.

Reply to
bruce2bowser

1967, North High School, Earth Science class, Mr. Hillier. Points to the letter W on the periodic chart, "John, what element is this?" "Uh, water?"

This *is* how normal people label capacitors:

I work on vintage radios along with "new" stuff. How they marked things has changed over the years.

Paper dielectric capacitors for example were marked

0.002 MFD 400 WVDC | value, voltage and which end was the outside foil. The only "not the same" ones were the Sprague "Bumble Bee" black plastic bodies which didn't matte, because they all need to be replaced anyway. Back in the '70s when I first started work in the aerospace industry, capacitors that we used were all marked with the number system, 104 for example for 0.01 uF. (And that was uF, not MFD.)

I remember reading a mil-spec definition for some capacitors where then specifically assigned random numbers in place of the values. This way you had NO idea what the value was unless you had the "secret Captain Video decoder wheel." This was supposed to cut down on employee theft of components.

During the early '30s, just to make things a little more interesting, they used the letter M instead of K for "thousands of ohms" on the schematics, so a 47,000 resistor was marked 47M, not 47K. The Meg was used to bigger values, 1,000,000 was 1 Meg. But I'd get the occasional questions, "Where can I get a 120 meg ohm resistor?"

--
Jeff-1.0 
wa6fwi 
http://www.foxsmercantile.com
Reply to
Foxs Mercantile

J is quite likely to be the tolerance code.

Electronic starters can improve a flaky fitting - but I'd just rip it out and fit electronic ballasts, you get more light and/or less electricity bill. The tubes also last a lot longer.

LED "tubes" are starting to appear on the market - you can probably expect better than half the electricity usage.

Leaving the PFC capacitor in can take the edge off mains spikes, but to protect an electronic ballast, a MOV is worth the effort.

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Reply to
Benderthe.evilrobot

My thoughts too - but 5% seems a bit too good for a PFC capacitor.

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Reply to
Benderthe.evilrobot

1% would be excessive, at 5 uF. It's easy to make 5% film capacitors. 
--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

Use two 60M focus resistors in series. :)

--
Never piss off an Engineer! 

They don't get mad. 

They don't get even. 

They go for over unity! ;-)
Reply to
Michael A. Terrell

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