fluorescent tube driver

[solis365]

Hey all

I had a dead 22" LCD panel (it fell and cracked) so the other day I decided to take it apart. The backlights are four small fluorescent tubes but I can't figure out what the markings on them mean. They look usable.

The writing was extremely small and located on the wires connecting to the tubes. Everything I could make out (with a magnifying glass) is thus:
AWM 1A 10SC 300V FT1/FT3 SUMITOMO-Y (the S in the 10SC could be a 5)
SUMITUBE F34 CSA 125³C VW-1 SUMIPAC (the superscripted 3 there is a placeholder for a degree symbol)

so theres some obvious things, like 1A, 300V, and 125degC, but...

the writing is on the wiring/heatshrink so im not even sure if it applies to the tubes.
I looked up SUMITUBE F34 and it is the heatshrink, not the tubes.

I googled "300V FT1" and found that it is a type of wire, so that also does not relate to the tube. "SUMITOMO-Y" also returns the cable, and SUMITOMO appears to be a cable manufacturer.

this means that the "AWM 1A" is probably for the wire as well.


anyone have any ideas how to identify and/or drive these fluorescent tubes?

 

[timsvb]

From the size of the screen you took apart, I would assume that tubes would be in the vicinity of 11W-15W. They should hook up the same as any other tube. Apology for the crappy drawing. Haven't learnt Multisim yet. Be sure to earth the chassis of the light you assemble as the mains can be fatal and the HV of the ballast as well. Haven't taken a screen apart myself, but the tubes should be just low wattage for backlighting. Hope it helps.

 

[Hero999]

It's possible to power the tubes using the driver from the laptop's screen - I've done it before.

The trouble is you need to find out what part of the board is the inverter.

Be warned: the inverter produces a high voltage, 300V to 2kV depending on the type of tube, it won't kill you, it's low current and high frequency but it can give you a nasty burn.

 

[solis365]

It's possible to power the tubes using the driver from the laptop's screen - I've done it before.

The trouble is you need to find out what part of the board is the inverter.

Be warned: the inverter produces a high voltage, 300V to 2kV depending on the type of tube, it won't kill you, it's low current and high frequency but it can give you a nasty burn.

well since the wiring is labeled as 300V I assume that the tubes will be driven by something lower than that.


might there be some way to measure the voltage and frequency using an oscilloscope or some other piece of lab equipment? I have a 0-100kHz spectrum analyzer, a cheap digital scope (tektronix TDS2024B, 200MHz if i remember correctly), and a fairly insanely fast scope, tektronix tds8000b might be the number on it)... of course I don't want to break these devices as it would mean my head on a platter?
how high frequency are we talking? possible to attenuate with carbon film resistors and measure frequency and peak voltage and using the voltage division calculate the original voltage level?


using the inverter from the board might not be an option as I'm not sure I want to rip up the driver circuitry (its all intact, the only thing that broke on the monitor was a gigantic crack in the LCD part). Basically I have a nice aluminum box with a couple plugs coming out of it, two for the tubes and one for the row/column divers on the panel. its got DVI and VGA connectors and an AC plug still, works fine...

 

[Hero999]

'scope it.

Use a x10 probe but check that the probe can handle 300V first and do it with the tube connected, not disconnected.

 

[Boncuk]

You might use the complete inverter/driver circuit of a salvaged battery operated fluoescent lamp. (Available at camping accessories shops)

I used mine for a light table with dimming the lamps just by using an adjustable supply voltage.

Amazingly the dimming worked over the entire range from faint glow to full brightness without flickering.

Boncuk