I bought a gooseneck type art specialty co. lamp on ebay.  What a great lamp.  It had twin F15T8 tubes in it but one of them stopped working.  I bought two new tubes online Verilux F15T8 VLX.  I was attempting to get tubes with a high CRI and higher color temperature for doing artwork.  These new tubes will not fire up in the lamp.  The ends flicker but won't catch.  After searching online it appears the art specialty co. lamps are pre-heat manual start lamps which will not necessarily work with newer tubes.  Is this the case?  Am I doing something wrong?  Should I try to replace the ballast with a newer ballast or should I search for some different tubes which will work in this pre-heat lamp?  I'd love to be able to use it.

I don't know.
I have always used a floating Dazer for this type of work.
Like this one.
They have been around for ever.

http://www.ebay.com/itm/mh-20-Vintage-Dazor-2-Tube-Fluorescent-Swing-Arm-Clamp-Mount-Desk-Table-Light-/121298872734?pt=LH_DefaultDomain_0&hash=item1c3df9e99e

I looked at the bulbs and as far as I can tell they look like the typical 15 watt T8 bulbs.
Do all the ends light up when you hold in the start button?
Is the indentations on the bulb end caps lined up with the center of the bulb holder?

Sometimes on new bulbs the button has to be held down for a while to heat up the filaments in the ends of the bulb so when you release the button the arc is struck inside the bulb.

I have a 1970s type two 15 watt desk fixture with new GE bulbs that I have to hold down the button for a while before releasing the button to get them to go.
Other wise it won't start.

If you get it to start, I would let them run in for a while.

If it was working before the bulb quit working it is my guess that the fixture is ok.

I would check all this above first before digging in to it.

If it uses the inductive ballast, it has to work. The onlyproblem may be the arc build up across the starter switch, so limitting the inductive kick, so it becomes insufficient forthe lamp.

What you can check, whether there is the capacitor parallel to the starting switch and if it is OK. If there is nothing, try to connect there ~4.7..10nF rated at 1000V.It should be sufficient to extinguish the arc in the switch, so allow the voltage peak to become higher for the lamp ignition.

And with a new lamp you may need multiple attempts (preheat/start) before itcatches. Oce it does, let the lamp to burn about a hour uninterupted, this will precondition itso, next time it shouldignite way easier.
And of course really preheat the lamp (the filaments have to turn orange) before the ignition...

I'm realizing that I left something important out.  I live in Germany temporarily but this lamp is from the U.S.  So the lamp is a 120v 60Hz lamp and I am running it on a transformer that is putting out 120v 50Hz.  Does that make a difference?  The old Duro-Test tube works fine but despite my best attempts.  The new Verilux tubes won't light up.  I'm realizing the ballast is designed to work at 60 Hz and is probably not efficient enough at 50 Hz to get the job done.  But the old tubes work so I'm confused.

That could be a problem as 60 cycle ballasts don't work very well on 50 cycle current.
They may over heat and burn out after a while.
So it could have run for a while under adverse conditions before it finally gave up and quit.

Some parts of the world runs on 60 cycle current so 15 watt 50 cycle fluorescent ballast for your fixture may be difficult to find.
You may be able to adapt two 15 watt 50 cycle ballasts to your fixture if you are good at understand electrical devices.

May be some one here knows where to find some 50 cycle ballasts that would fit your fixture.

I understand the voltage is higher there and has to be reduced to 120 volts, but are you sure your power supply to the building is 50 cycle?
Also check your voltage reducer output as if it is made for 50 cycles and your power supply is actually 60 Cycles that could be a problem also.

I have seen some 50 to 60 HZ frequency converters, but they are not cheap.
You might check around locally and see what other people use to convert frequency from 50 to 60 HZ as I would guess it is would be a common problem with imported equipment that runs on 60 cycle current.


I would check all this out first to make sure before digging in to the fixture.

The lower frequency definitely mean higher current, so overheating of the ballast.
However for the 230V, you may use 2x "PL-S7..11W" chokes in parallel as a ballast directly at 230V.
Other option would be to connect 3.3uF/350VAC (assume the ballast is designed to operate the lamp at the rated 0.33A; check the label) in series with the "120V" coil and operate it then at the 230V/50Hz. The setup will become a lead type, but it should operate well


@Larry: I won't be as sure with your "majority of the world" statement...

The lower frequency definitely mean higher current, so overheating of the ballast.
However for the 230V, you may use 2x "PL-S7..11W" chokes in parallel as a ballast directly at 230V.
Other option would be to connect 3.3uF/350VAC (assume the ballast is designed to operate the lamp at the rated 0.33A; check the label) in series with the "120V" coil and operate it then at the 230V/50Hz. The setup will become a lead type, but it should operate well


@Larry: I won't be as sure with your "majority of the world" statement...

I changed it to some parts of the world.

I bought a case of Duro Test lamps made by Sylvania.  All they are,   are Design 50s.  The case was a whole lot cheaper than ordering a case of Sylvania D50s.  Well in the push to start lamps they would not start. I put them in a trigger start, it flickered and slowly started and swirled madly for 30 minutes.  After that they would light on the desk lamp, but would be a pain to start if you let the lamp sit awhile.
This may be the same problem here....