Trying to fix an old Fluorescent lamp


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Old 02-27-19, 05:53 PM
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Trying to fix an old Fluorescent lamp

Hi. I have this old Fluorescent lamp. When I put a bulb in, it partly lights up. If I twist the bulb, removing one pin on each side, it lights up well.

I replaced the ballast but the lamp acts exactly the same. The only piece left to try changing is the yellow part in the photos. Can you help identifying it? I don't know much about electronics.

Thanks!

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Last edited by PJmax; 02-27-19 at 07:12 PM. Reason: cropped/resized pictures
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Old 02-27-19, 07:20 PM
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It is a .006 microfarrad 1500 volts DC capacitor.
 
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Old 02-27-19, 07:24 PM
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Welcome to the forums.

Just hate to part with an OLD friend......

That's a .006ufd @ 1500vDC capacitor. Probably find one on ebay.
In the second picture..... the white button is the off button and opens the black and white wires on the left side. The orange button is on and start. When you push it in it is supposed to allow the black and white wires on the off switch to connect and at the same time short the two right hand wires to start the filaments glowing. Once the filaments start to glow the start button is released and the capacitor is left inline to allow the high voltage to pass.

That cap could be dried out from age but a more common problem is that the tubes available today don't have enough mercury in them for these old systems to fire them.
 
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Old 02-28-19, 05:24 AM
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What type bulb does the lamp use? What shape is the shade? If you can't get the fluorescent working you could convert it to LED's.
 
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Old 02-28-19, 10:54 AM
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The hood was partially visible but couldn't see a tube size.
I can see a single tube so if it's a T-12 lamp...... it would be a 15" tube as that is 14 watts.

A more likely prospect..... F14T8/CW - T8
Possible LED replacement.... LED tube
 

Last edited by PJmax; 02-28-19 at 11:12 AM.
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Old 02-28-19, 06:16 PM
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So that light has a manual push-to-start switch, I presume. The behavior described (lamp partially lighting at ends, but works if one pin disconnected) suggests the light is stuck in starting mode.

That means either the switch or the capacitor has a short. I'd try removing the capacitor. It's unnecessary and assuming it's the culprit, taking it our will fix the problem. By the way, some automatic glow starters also contain capacitors (condensors), and can sometimes be fixed simply by removing them. The cap provides EMI suppression, but that's about it.

Update: I more closely read @PJmax's description of the circuit. That sounds exactly right, except possibly the role of the capacitor. I was going on the assumption that it's merely an RF suppression cap. There certainly are manual start desk lamps without caps, so I'm pretty confident it isn't necessary. There's no harm in removing it, considering it's probably bad anyway.

By the way, this is the circuit diagram for this kind of fluorescent light.
 

Last edited by pjcpc1; 02-28-19 at 06:45 PM. Reason: clarification
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Old 02-28-19, 08:28 PM
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Thanks!!

Hi. I removed the capacitor and now the lamp works!! I re-connected the 54 year old ballast and that works as well. I can send back the one I bought ($30).

Everything you all said about the lamp was correct, Button functions, lamp size etc. I'm really impressed by and grateful for your knowledge!

It is made by Mobilite Japan. The ballast says 1964 on it.

This was my dad's lamp and I remember it working when I was little. Dad isn't with us anymore but his lamp lives on!

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