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8 foot fluorescent lamp trouble

1783 Views 20 Replies 9 Participants Last post by  fltdek
have a 2 bulb, 8' fluo fixture, replaced ballast, but on 2 new bulbs (tubes), and no light. So, took Ohms readings of both terminals (one blue/red wires, other blk/white), and one terminal 160+- ohms, other 80 or so. Are these good readings? What is ideal? Am I on the right track?
Thanks
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Checked for incoming power?
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Checked for incoming power?
Good point, joe, but yeah, it is in a SERIES - theres a working unit before AND after it. Thats what is getting me. Other culprit could be the main feed wire could be grounding on the metal case/box.....but doubt it.
Still could be a power problem. The wires on the ballast are smaller than the line wires and sometimes they don't connect even if the power wires do.
Still could be a power problem. The wires on the ballast are smaller than the line wires and sometimes they don't connect even if the power wires do.
OK, Joe, then what should I do? Check for voltage at the blk/wh low v wires? Or the red/blue wires? What should one get for V reading? What V should one see there? I already did ohms......
In other words, if I take voltage of those wires going to ballast, what should I expect?
Bad ballast.
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Bad ballast.
guess it could happen, (mentioned in my 1st post I replaced with new). Have you ever seen a "new" ballast be bad?
Many times.
Is the ballast warm to the touch?
We had this discussion in another thread.
Did you wire the new ballast like the old, of by the diagram?
Problem is, many times the new ballast needs to have the entire fixture rewired, or "creatively wired" for it to work properly. :huh:

One simply just can't replace the ballast and reconnect the wires as before, since many of the older ballasts are series wired, and the new ones are not. :no:
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Check voltage at the black and white (incoming power) wires on the ballast. Use a non-contact tester to check for voltage at the lamp sockets (voltage may be close to 1000V, so don't use a meter unless it's rated for that!). Test the lamps in the other fixtures next to it. Swap ballasts with another fixture. Do any other tests you can think of to isolate the problem.
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Wired wrong, wrong ballast, wrong voltage, no voltage, wrong lamps.....bad ballast...that's a few things that could be wrong. Is this a magnetic to electronic replacement?:wink:
OK, Joe, then what should I do? Check for voltage at the blk/wh low v wires? Or the red/blue wires? What should one get for V reading? What V should one see there? I already did ohms......
Tug on the power wire connections and see if they pull out. Undo the power wire connections and redo them.
Could also be a bad ballast.
have a 2 bulb, 8' fluo fixture, replaced ballast, but on 2 new bulbs (tubes), and no light. So, took Ohms readings of both terminals (one blue/red wires, other blk/white), and one terminal 160+- ohms, other 80 or so. Are these good readings? What is ideal? Am I on the right track?
Thanks
Is this a slimline ( single end pins useally either 60 or 75 watters ) or High Output ( recssed double pin useally 95 or 110 watts ) ??

That will make the differnce and if you have the ballast number if you can read it please posted to us we can indentify quick.

Did you check the incomming source to make sure you have power ?

With the slimline ( single pin verison ) look at the fixed end carefully to see if damaged concats or not.

Merci,
Marc
wow, so much help!! Thanks, guys! Im on my way to work, where I will post the specs on the ballast. Meanwhile, I will try switching it to another lamp that works......
The ballast is GOOOOOD!!! I verified it by wiring it up to a known good fixture!! (it was cold to touch when "on".)

So, now, I have bigger problems- its has to be voltage, right? I dont have a meter that measures 1000v....
Since you know the ballast is good, you don't need to measure the output voltage. Just reconnect it in the right fixture, exactly the same way it was connected in your test fixture. Make sure the input power connections and the lamp socket connections are solid. If it still doesn't work, check voltage at the input (probes under the wire nuts). If it still doesn't work, then use a non-contact tester to check for power on the output wires - if they are hot and the fixture still doesn't work then it's probably a bad lamp socket.
You don't need to measure 1000volts. You know the ballast is good so it has to be input power(120 volts) or the wiring between the ballast and the lamp holders. Or maybe a bad lamp holder.
Since you know the ballast is good, you don't need to measure the output voltage. Just reconnect it in the right fixture, exactly the same way it was connected in your test fixture. Make sure the input power connections and the lamp socket connections are solid. If it still doesn't work, check voltage at the input (probes under the wire nuts). If it still doesn't work, then use a non-contact tester to check for power on the output wires - if they are hot and the fixture still doesn't work then it's probably a bad lamp socket.
Whats the diffreence between the input wires and output? Is the input the white/blk? And output is red/blue?
Whats the diffreence between the input wires and output? Is the input the white/blk? And output is red/blue?
Yes:wink:
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