Desk light problem

[gordon stephenson]

Hoping somebody can help me out.My computer desk light is one of those anglwpoise type with an 11w U shaped 2 pin fluorescent lamp. Light stopped worling(It's done this before and a new tube cured it) Tried 2 new lamps and still no go.It just seems to have a transformer in the base and a switch on the head. I put a meter across the lamp socket terminals an got 16-17 volts, What sort of starter do they have?is it maybe incorporated in the bulb unit? My electrical knowledge is pretty low so hoping your replys will save me having to buy a new one.(particularly as I now have 2 new bulbs and no light to fit them in to.
Thanks Guys..

 

[Shox Dr]

It will have a ballast inside somewhere. you can buy replacements for around a fiver.


edit, that transfromer is the ballast

 

[gordon stephenson]

Thank you Shox Dr, Not being electrically inclined where will be the sort of place I need to find a new one? I will strip it again and look for any markings on the Transformer/ballast.

 

[Shox Dr]

ebay is your best bet

 

[gordon stephenson]

Hi Shox, I have looked at the ballast, It's a Helvar, Looked on the web and ebay, can't find the same one. Mine is just what appears to be the coil unit without the built in base plate that all other have. My details are:
Helvar L11L 240v 50Hz tw130
lamp is single turn 11w 2pin fluorescent tube.

 

[Engineer1964]

Hi Shox, I have looked at the ballast, It's a Helvar, Looked on the web and ebay, can't find the same one. Mine is just what appears to be the coil unit without the built in base plate that all other have. My details are:
Helvar L11L 240v 50Hz tw130
lamp is single turn 11w 2pin fluorescent tube.

Gordon, I used Farnell for all my electronic bits, Fast Next Day Delivery

Take a peek at some ballasts on there and see if yours are similar http://uk.farnell.com/jsp/search/br...=flouresant+ballasts&Ntx=mode+matchallpartial

 

[gordon stephenson]

Many thanks chaps. Still can't find one thats identical,It is quite a small space it has to fit into,Have rigged up a different light for now and will keep looking/

 

[Engineer1964]

Many thanks chaps. Still can't find one thats identical,It is quite a small space it has to fit into,Have rigged up a different light for now and will keep looking/

They may be just custom made for that particular lamp, make sure you don't spend more than the lamp is worth, have you thought of looking at replacements??

 

[GeorgiePorgie]

The lamp is £20 new on ebay,does it have an heavy oval base and is black in appearence?

I have one,pretty coold lamp for a desk.

http://www.ebay.co.uk/itm/Kanlux-HE...0?pt=UK_Home_Garden_Lamps&hash=item53ee24f166

 

[Engineer1964]

The lamp is £20 new on ebay,does it have an heavy oval base and is black in appearence?

I have one,pretty coold lamp for a desk.

http://www.ebay.co.uk/itm/Kanlux-HE...0?pt=UK_Home_Garden_Lamps&hash=item53ee24f166

Now that is cheap

 

[gordon stephenson]

Looks like the same as mine except for the swivel base might just have to bite the bullet and order one,
Thanks again,

 

[MattF]

Nick the PCB out of any of these crappy energy saving lightbulbs you can get these days, (they're cheap enough), else the unit out of a standard fluourescent striplight.

 

[gordon stephenson]

Thanks for the above post, So if I strip a low energy bulb of the same wattage (11w) it shold work in my fitting,as long as I do it safely etc,

 

[MattF]

Yup, that's about it. As long as it's a 11W or above bulb, it should be fine. Never personally phaffed about with one, but I'd just split the sacrificial bulb unit, whip the board out and then do a quick test using flyleads to the mains and recipient lamp from the board. You know for definite then before you fit the board into the unit as to whether it'll cope or not. Easier to check before you do the phaffy bit.

 

[gordon stephenson]

Hi MattF, Took a lamp apart, Nice little circuit board inside.Now I'm puzzled again.It has 2 pairs of wires. each pair with a tungsten filament between, I single bend 11w tube for my light only has 2 pins that fit into the holder.Any idea's anyone?

 

[MattF]

Do you mean there are two pins either end of the bulb/tube on the donor unit you've dismantled?

 

[gordon stephenson]

Yes, 2 pins at each end bridged by a small filament.

 

[Engineer1964]

Be careful you don't create a fire risk, For the sake of £17 get a new one with guarantee.

Seems to be an awful lot of fluffing about for a desk light, you deserve a treat Gordon, get a new one

 

[gordon stephenson]

I have already ordered a new one,Just running on pure curiosity now,Simple electrics I don't mind,but electricity in general scares me to death!!!
Just wondering why do these florescent dest lamps need a chunky solid transformer/ballast, and a 230v florescent low energy bulb runs on a circuit board as big as a postage stamp?

 

[brightspark]

I have already ordered a new one,Just running on pure curiosity now,Simple electrics I don't mind,but electricity in general scares me to death!!!
Just wondering why do these florescent dest lamps need a chunky solid transformer/ballast, and a 230v florescent low energy bulb runs on a circuit board as big as a postage stamp?[/QUOTEheres the answer it saves me explaining the advantages / http://ateam.lbl.gov/Design-Guide/DGHtm/electronicvs.magneticballasts.htm