Author Topic: A Troubled Fixture.  (Read 3121 times)
wattMaster
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A Troubled Fixture. « on: June 25, 2016, 10:19:23 AM » Author: wattMaster
I have been having problems with the free fixture with tubes I got, the rapid start ballast just makes the ends glow forever, which is a bad sign. When I first got it, I made a quick fix by removing the reflector and playing around with Aluminum (I accidentally spelled it Aluminium, but I fixed that) and that's how I got the photo, but after putting the reflector back on, it worked, so I put it in storage. Now when I tested it out again, the ends glow, which indicated bad grounding. The reflector is painted white and held in with 2 screws, which should be making contact. Should I test continuity with the reflector and the main body? (I can't test continuity between reflector and ballast, because the ballast is inside the fixture, which means removing the reflector, which would disrupt the test. What's a good fix? It would optimally be without Al Foil because that is sloppy, clunky, and bad looking. In case you don't know, It's a Lithonia Lighting 2-lamp F40T12 fixture with 2 Philips Soft White Kitchen & Bath 40 Watt tubes. Could it be the tube's problem? I tried it out with 2 F32T8 tubes, but it didn't help. Another anomaly with this is when you pull the switch after the ends glow, the tubes flash very quickly once. If it can't be fixed, it's not a big loss because I got the fixture and lamps for free.
Update: I'm looking at the ballast and it says 06-08-01. Is that a date code?
Update again: I am testing it out with more foil, and only 1 tube is lighting up dimly, what's the problem? The same effect happens when I remove one of the tubes, in my experience.
« Last Edit: June 25, 2016, 11:27:20 AM by wattMaster » Logged

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Ash
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Re: A Troubled Fixture. « Reply #1 on: June 25, 2016, 11:37:28 AM » Author: Ash
The current going through the capacitance to the reflector is tiny, so even very slight reference between it and Earth is sufficient to make it function. I doubt there is possibility for a problem there

Measure the voltage between lamp ends and between each lamp end to the luminaire body. It is possible that they are wired so the voltage splits more or less in half, so the voltage between each end of the lamp and the reflector is too low to provide starting - In which case something like swapping Phase and Neutral in the supply might help
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Re: A Troubled Fixture. « Reply #2 on: June 25, 2016, 11:39:41 AM » Author: wattMaster
The current going through the capacitance to the reflector is tiny, so even very slight reference between it and Earth is sufficient to make it function. I doubt there is possibility for a problem there

Measure the voltage between lamp ends and between each lamp end to the luminaire body. It is possible that they are wired so the voltage splits more or less in half, so the voltage between each end of the lamp and the reflector is too low to provide starting - In which case something like swapping Phase and Neutral in the supply might help
What do you mean by lamp end? End cap? Power pins?
Are there any other fixes? Swapping wires could mean a deadly device.
Update: I don't have my meters right now, so I can't take any measurements.
« Last Edit: June 25, 2016, 11:47:48 AM by wattMaster » Logged

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Re: A Troubled Fixture. « Reply #3 on: June 25, 2016, 11:57:58 AM » Author: Ash
The end cap of the lamp is electrically floating, so there is no sense measuring voltage to it (except in lanterns intended for lamps with starting strip, where a tab in the socket connects Earth to the lamp cap). In this case i meant the lamp pins

The luminaire body is connected to Earth by an Earth wire, which is separate from the Neutral wire. Swapping Phase and Neutral supply to the ballast changes the voltages present from the lamp to the luminaire body, but the luminaire body Earthing is not changed

Swapping Phase and Neutral in an appliance can be dangerous where the appliance body was connected to the Neutral instead of Earth, or generally any electrical systems where the installer did not have a clue what is the difference between Neutral and Earth (so for example, "bright sparks" who implement "Earthing" in old 2 wire systems by jumpering Earth to Neutral inside receptacles). This is never the case in any properly assembled 120V appliance (Exception : some older 240V appliances in the US, like clothes dryers). For the luminaire in question, you can open and see how it is wired
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Re: A Troubled Fixture. « Reply #4 on: June 25, 2016, 12:18:42 PM » Author: wattMaster
Checked it, black to black, white to white, ground to fixture. Don't see anything wrong, maybe a wire isn't connected to the tube connector, but I can't check easily because I don't know where my meters are right now.
Maybe I can make a circuit to light up an LED, But there aren't any connection points for the wire.
« Last Edit: June 25, 2016, 12:20:56 PM by wattMaster » Logged

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Re: A Troubled Fixture. « Reply #5 on: June 25, 2016, 01:21:40 PM » Author: Ash
For each end of each lamp, if it is heating up properly, then there is good connection for the 2 wires

This would be ok (assumng the ballast is made properly), have you checked the polarity in the wall receptacle ?
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Re: A Troubled Fixture. « Reply #6 on: June 25, 2016, 01:22:26 PM » Author: wattMaster
For each end of each lamp, if it is heating up properly, then there is good connection for the 2 wires

This would be ok (assumng the ballast is made properly), have you checked the polarity in the wall receptacle ?
I have one of those 3-light receptacle testers, would that help?
Update: I just tested it, it says the receptacle is OK.
One of the tube ends is not glowing, could the electrode be broken? How do I test?
« Last Edit: June 25, 2016, 01:25:40 PM by wattMaster » Logged

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Re: A Troubled Fixture. « Reply #7 on: June 25, 2016, 01:54:32 PM » Author: wattMaster
Update: I found my meters! They were roasting in my mother's car, but I cooled them down.
Slight Problem, I can't measure the tubes because if they probes went in there, the power would transfer to the end caps, which I don't want.
« Last Edit: June 25, 2016, 01:59:44 PM by wattMaster » Logged

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Re: A Troubled Fixture. « Reply #8 on: June 25, 2016, 02:37:07 PM » Author: Ash
Inspect the meter and test leads before you use it, to verify that they were not damaged from the heat in the car

You can poke the meter into the lamp pins in a way that connects the caps too, simply dont touch the caps yourself while measuring. (Unless there is a special tab in the sockets that connects Earth to the caps, in which case dont measure it this wy as you would be shorting the ballast output)

Alternatively splice an additional short wire to the lamp socket's connections, add a terminal on that wire, and measure between that and Earth

Anyway, dont short the 2 pins of the lamp end together while measuring, as this would short the heating output of the ballast
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Re: A Troubled Fixture. « Reply #9 on: June 25, 2016, 02:39:54 PM » Author: wattMaster
Inspect the meter and test leads before you use it, to verify that they were not damaged from the heat in the car

You can poke the meter into the lamp pins in a way that connects the caps too, simply dont touch the caps yourself while measuring. (Unless there is a special tab in the sockets that connects Earth to the caps, in which case dont measure it this wy as you would be shorting the ballast output)

Alternatively splice an additional short wire to the lamp socket's connections, add a terminal on that wire, and measure between that and Earth

Anyway, dont short the 2 pins of the lamp end together while measuring, as this would short the heating output of the ballast
The meters look OK, it wasn't actually really hot, but it could have got hotter, and it was in for I guess  day.
I will have to test it now.
Update: I checked the lamp-lamp (One probe on lamp pin, other on other end of same lamp, on another pin) voltage and it was a whopping 2.6 volts.  ::) But is that normal?
Update: I checked the lamp-ground (One probe on lamp pin, other to ground) voltage, and it was 163 volts! Is that normal?
Update: There is continuity between the screws that hold the reflector in and ground, but no continuity between the reflector itself and ground. The part of the reflector that is unpainted happens to have continuity, oddly enough. I guess the paint could be part of the problem?
« Last Edit: June 25, 2016, 03:21:00 PM by wattMaster » Logged

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Re: A Troubled Fixture. « Reply #10 on: June 25, 2016, 03:34:50 PM » Author: wattMaster
Awesome news! It works! The problem is you need lots of Al foil connected to the screws, which is ugly, clunky, and not a real solution. Any fixes? It looks like the problem is with the reflector paint.
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Re: A Troubled Fixture. « Reply #11 on: June 25, 2016, 04:18:14 PM » Author: Ash
Some reflectors actually have a tab on the back to connect Earthing wire to. If yours does not, use a spikey washer on the screws, that punches through the paint, or scratch a bit of the paint off. You can do this in a tiny spot that will normally be hidden by the screw head anyway, or on the back sode of it

2.6V across a lamp's length does not look normal, however :

 - What is across the other lamp ? Some ballasts are made so that most of the voltage is applied across one lamp before the other, so if you were measuring the other lamp, this could actually be normal. We dont have any comparable gear over here so i can't tell if 2.6V is about right for the "2nd" lamp or not

 - 2.6V is about the voltage of the heating supply. Is your lantern by any chance miswired, so that heating voltage is applied beteen 2 ends of a lamp instead of between 2 pins on 1 end ? Are all 4 ends of 2 lamps heating properly and equally ?

What is the voltage from each side of each lamp to the reflector (after repairing its Earthing) ?

Do you have a well starting luminaire to compare the voltages with ?
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Re: A Troubled Fixture. « Reply #12 on: June 25, 2016, 04:24:34 PM » Author: wattMaster
Some reflectors actually have a tab on the back to connect Earthing wire to. If yours does not, use a spikey washer on the screws, that punches through the paint, or scratch a bit of the paint off. You can do this in a tiny spot that will normally be hidden by the screw head anyway, or on the back sode of it

2.6V across a lamp's length does not look normal, however :

 - What is across the other lamp ? Some ballasts are made so that most of the voltage is applied across one lamp before the other, so if you were measuring the other lamp, this could actually be normal. We dont have any comparable gear over here so i can't tell if 2.6V is about right for the "2nd" lamp or not

 - 2.6V is about the voltage of the heating supply. Is your lantern by any chance miswired, so that heating voltage is applied beteen 2 ends of a lamp instead of between 2 pins on 1 end ? Are all 4 ends of 2 lamps heating properly and equally ?

What is the voltage from each side of each lamp to the reflector (after repairing its Earthing) ?

Do you have a well starting luminaire to compare the voltages with ?
1: The screws that attach the reflector to the main body to go through the paint, so that's not a problem.
2: I did not measure the voltage between 1 heating electrode, so I assume it is all OK.
3: I don't have anything comparable right now. (Although I do have a F15T8, but I'm not going to use that, for the wire's durability)
4: I measured the voltage between lamp-ground with Al foil, and it was almost exactly 40 Volts.
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Re: A Troubled Fixture. « Reply #13 on: June 25, 2016, 05:12:44 PM » Author: wattMaster
Also, would not running these tubes much impact the starting capability?
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Re: A Troubled Fixture. « Reply #14 on: June 25, 2016, 05:31:02 PM » Author: Ash
If there is no continuity, then there is no continuity. And you do what have to be done to make it

If the electrodes heat equally then they get the same voltage, which is probably the correct one

Voltage to a "floating" foil capacitively coupled can be anything weird. It is voltage to Earthed reflector that got to be measured, and there i would expect way higher. I'd expect on the order of 200V+ for starting of lamp.... Verify this with other US members

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