Fluorescent troubleshooting

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On 5/3/2012 2:24 PM, dpb wrote:

A grounded surface near the lamps is used to start the tubes. As far as I know a ground is not needed for the tube operation once the tube has started. Sounds like all the tubes are operating (but not bright enough).
I don't remember that the OP has verified that the sockets make good contact with the pins and that the wires make good contact with the sockets (for instance that the socket doesn't 'contact' insulation instead of wire).
As I wrote previously, a darkened end likely indicates that the filament at that end is not working (burned out or not receiving power).
--
bud--

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wrote:

The 34 watt bulbs take a different ballast than the 40 watt bulbs, don't they? I know I could not get the newfangled 34 watt "green" bulbs to light reliably with my "legacy" ballast.
"instant start" ballasts have a 600 volt (+/-) opern circuit starting voltage, and no "filament heat" voltage.
"Rapid Start" ballasts run about 500 volts (give or take) and have filament heaters - about 1 watt per tube end. (on a T8-32 or F32T8 system).
Programmed start ballasts precisely time and control the filament heat to extend life when occument sensor systems etc turn the light on and off a lot.
So, you check voltage from end to end with no bulb installed - 600 volts is instant start - 500 is rapid start. If there is any question what you have, measure voltage between pins on one socket. If you have any voltage it is not an instant start, and 500 volts should be expected end to end. If you have less than 600 and no filament voltage whatever ballast you have is toast. The filament voltage should be very close to the same on each end.
Also, instant start systems usually have the tubes in parallel, while rapid starts are more often in series (and more complex to follow the circuitry) Parallel wired units have 2 wires of each of 3 colours (usually red, yellow, and blue) while series will only have (usually) 2 blue and one red - with no yellow.
There is a pdf document available from Philips called "RT-8010-R03_ABC.pdf" that you should be able to find online by googling that will tell you all you want to know about ballasts and flourescent lighting in general.
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snipped-for-privacy@snyder.on.ca wrote:

My current new ballast lists both the 34 and 40W bulbs. My old ballast doesn't do that same type listing because it doesn't have that fine print.

I have rapid start.

Gotit. Thanks.
--
Mike Easter

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god, that is why I hate fluorescent fixtures.
so
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On Monday, April 30, 2012 4:58:27 PM UTC-5, Mike Easter wrote:

Mike, you stated that the ballast was smaller but is it a solid-state ballast? I find the smaller solid-state ones put-out a more reliable voltage, all things considered. (load,ground,type of tube)
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Bob_Villa wrote:

My understanding of ballast types is based on this
http://nemesis.lonestar.org/reference/electricity/fluorescent/trouble.html The Fluorescent Lighting System
... which distinguishes 4 sections, Pre-Heat-Start, Rapid-Start, Instant-Start, and Compact.
My concept of my rapid-start ballast is that they are iron or magnetic and look like this:
http://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Magnetek_Watt_Reducer_HPF_Rapid_Start_Ballast.jpg/800px-Magnetek_Watt_Reducer_HPF_Rapid_Start_Ballast.jpg
or previewable http://goo.gl/DP6BO +
... whereas solid state are instant-start, but I don't have a good example pic for that except maybe this one
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7f/EL_2x58ngn.jpg/800px-EL_2x58ngn.jpg
or http://goo.gl/rQlAT +
--
Mike Easter

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On Monday, April 30, 2012 4:58:27 PM UTC-5, Mike Easter wrote:

I use mostly 4ft 4 tube ones and the wires are correspondingly the same as their mag brothers. I have had the same problem as you, but with a 4 tube set-up. Replaced with mag-type and new tubes (T8) and they light dimly. A new electronic one and it worked as it should.
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Sure sounds like a ground problem to me.
Oversimplified a bit, current flows from end to end in a tube after the lamp has started.
But in a rapid start lamp, starting requires current to flow from one end a little way down the tube then TO the ground, this point works its way down the tube until full operation. Of course it isn't "connected" to the ground with a wire, it is a capacitative coupling.
15 years old? scrub the heck out of the whole fixture. Dirt can be enough to interrupt the coupling.
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Bob_Villa wrote:

Grrr. I will be irked if I have to eat a brand new non-working ballast.
I would also be more irked if I bought another new electronic ballast for an unknown problem and I had to eat it /too/ while the light still didn't work properly.
I really feel that I should make a diagnosis somehow.
--
Mike Easter

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What is it with this light. There are only a couple of things that can be wrong.
From what I have read, you have bought new bulbs and a new ballast.
Make sure the make sure the bulbs and the ballast are the same. You have two power wires, the black and white, then only about 4 more wires. Make sure the wires are going to the correct places, not just by matching the colors. Then the connections at the sockets the bulbs fit in could be bad. Also make sure the ballast case is grounded to the light fixture.
How many wires are comming out of your ballast and what color are they ?
If your bulbs are marked raid start, the ballast should have 8 or 9 wires. The green, black and white (standard house colors) and 2 each of blue, red, yellow.
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Ralph Mowery wrote:

I have also used working 'old' bulbs from the other fixtures with both old and new ballast. And I have observed the nature of what was wrong/dim/dark with the lighting using the old ballast compared with using the new ballast and they are the same when I use the same old bulbs which old bulbs light is very similar to the new bulbs light with the new ballast.

Done.
There are two power wires black and white. There are two yellow wires which go to one end of the fixture and there are two red and two blue wires which go to the other end of the fixture.

The ballast grounding is from its metal case being screwed up against the fixture on one end against tight prong/slot on the other end and metal case length against the metal fixture. However, the fixture and the ballast are painted, but there are bare metal edges all over the place. There is no specific ground wire for the ballast to the fixture, but there is a specific house power ground specifically bolted to the fixture.

6 two yellow to one end, 2 red and 2 blue to the other.

The ballast does not have a ground wire to the house or even coming out of the ballast. That grounding depends on the house wire bolted securely to the metal fixture and the metal ballast housing secured tightly against the metal fixture over many square inches of metal surfaces.
That was the same condition of the old ballast which worked for 15 years and I am sure it is the condition of the other two lights.
--
Mike Easter

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On 5/3/2012 3:12 PM, Mike Easter wrote: ...

In a case like this I'd scrape off some more paint from both and use toothed washer to be sure to get bonding through the paint to the base metal...
...
When did the change occur and has it been a gradual deterioration or a sudden failing? Again if it doesn't/didn't change characteristics w/ the new ballast it's almost certainly owing to something else, _not_ the ballast. And, if it was a gradual change that's indicative of a growing corrosion problem or similar at a connection or the bulb contacts. If it were a sudden step change that would be like the capacitance problem w/ a suddenly missing or moved reflector that causes bad starting. But, that generally is evident by the change in brightness when touch a bulb, etc., and you say these don't do that...
--

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wrote:

Then you have a "rapid start" ballast and there should be 500 volts between the yellow and the blue, and between the yellow and the red, and some low voltage between the two red, the two blues, and the 2 yellows. Checking with the ohmeter and the power off, you should have close to a short between each coloured pair, and equal and high resistance between the yellows and the blue and red. If you measure resistance of the primary (white/black) the secondary resistance should be something like a minimum of 4 times as high - possibly higher. If less than 4 times the primary resistance (on a 220 volt ballast) you have a shorted secondary (most likely, anyway)

fits to ensure a good ground connection. Still a bit dodgy in my opinion - check to be sure the connection is clean and tight - and also make sure the "reflector" or "trough cover" is installed and that it also is electrically connected to the main ground through it's mounting. Loose screws can cause starting problems. Without clean earth connections you are depending on capacitive linking not only from the bulb to the reflector/cover/sheild, but from there to the case and from the ballast to the case. The capacitance soon becomes way too high to be effective.

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On Monday, April 30, 2012 9:58:27 PM UTC, Mike Easter wrote:

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.
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JIMMIE wrote:

How I came to believe I could replace a ballast to fix a fluorescent:
Once upon a time my 20 y/o owned office had a false ceiling and lots and lots of 4 bulb ceiling lights that I was responsible for unless I wanted to call an electrician whenever a light bulb wasn't working, and I bought fluorescent bulbs by the boxful. In fact, one of those old boxes is what I'm using now.
Consequently over the years sometimes it was a ballast instead of a bulb or two, so I became 'accustomed' to occasionally removing and replacing a ballast without any testing or diagnostic efforts because replacing a fixture for a bad ballast certainly wasn't practical and it always worked out.
'All of a sudden' I'm mystified by fluorescent madness.
--
Mike Easter

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On Thursday, May 3, 2012 3:32:22 PM UTC-5, Mike Easter wrote:

For people who haven't been there this is maddening. I have replaced 2 ballasts (new) in a two tube fixture and wound-up changing out the entire fixture because it didn't fix the problem.
Can you buy a solid-state ballast and leave the wires long...hook it up...and if it doesn't fix it...take it back?
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wrote:

the mix. Infant mortality rates for electrical and electronic devices has gone up almost by an order of magnatude over the last 5 or 10 years. A known working used device is the best way to eliminate a bad device as a possibility - using an unknown new device as a benchmark only tells you if the old one IS DEFINITELY bad if the new one is good and solves the problem. If replacing with an unproven new device does not solve the problem you still don't know if the new one, the old one, or both are defective (or not). And 2 new ones out of the same batch only increase your chances by a little less than twice.
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