low voltage transformer needed, help please

happyhero

Hi can somebody help me please, my Mother has given me her lamp to repair. It is a LV ceiling lamp with 10, 10W, 12V lamps in it and inside the ceiling cylindrical bit is a round 105W transformer. This surrounds the center threaded stud.

I have checked inside as there was 240v in and nothing out and it is totally burnt out (also brown wire on LV side was very loose so this may have not helped). I think I have no hope of matching this transformer but my Mum loves the lamp and wants it fixed. She bought it too long ago to have any luck with any shop.

The diameter of the cylinder is 100mm and it is 50mm deep bearing in mind any transformer would have to go to one side of the center spindle (I'd like to try and avoid cutting the spindle if possible). I have searched the internet for a 105W transformer that will fit and it seems they are all over 100mm long so I am on to a loser straight away. Ideally I would like it to be 75mm or even 50mm long so it would fit comfortably. So anyone know where I can get such a tiny transformer?

I am a retired electrician and I am aware of all the current regs.

But I do need help with this one. Any bright sparks out there?

Any help appreciated.

Mr_Proctalgia

This is about the nearest toroidal transformer I can find

http://www.tlc-direct.co.uk/Products/TLT100slash1.html

or a better price and fit is here go to RS Components and search for item 257-4840

I cannot link to RS as it is in frames, but also have you checked to see if it has a thermal fuse that might have blown??

HTH

bullspeaking

Sound like you have got a normal LV transformer but you are looking for a matchbox type (you not said if it need to be dimmable or not) try speaking to youre nearest electrical wholesaler WF Electrical is a good one if you can take it to there trade counter they should be able to help you

HugoSP

Could the transformer sit outside the lamp?

If so, a normal LV source from inside the ceiling then LV wire down to the lamp could be in order.

H

raymond

Modification or repair using anything but a genuine replacement part will invalidate your home insurance if it goes on fire.

happyhero

Mr_Proctalgia wrote:

This is about the nearest toroidal transformer I can find

http://www.tlc-direct.co.uk/Products/TLT100slash1.html

or a better price and fit is here go to RS Components and search for item 257-4840

I cannot link to RS as it is in frames, but also have you checked to see if it has a thermal fuse that might have blown??

HTH

I noticed when I took the existing transformer apart, apart from the fact it has melted plastic all over the place, it has a tiny (about 30mm diameter)
round transformer amongst all the electronics. Is this a teroidal transformer? If it is how come it is so tiny compared to every teroidal transformer on offer such as the RS one you suggest?

Also can it be assumed that all teroidal transformers are dimmable or not?

happyhero

HugoSP wrote:

Could the transformer sit outside the lamp?

If so, a normal LV source from inside the ceiling then LV wire down to the lamp could be in order.

H

I did think of this but I am leaving it as a last resort because I don't fancy making a big hole in the ceiling since the fixings holding the light would be very near to this bigger hole making it more likely that the fixings would break the ceiling away.

I tiny transformer is favourite still if possible.

24_hour_sparks

will a smaller transformer fit into it ?, and then perhaps downgrade the lamp wattage to suit the new transformer?.

Wig

How about 240V low energy (7 Watt) GU10 bulbs or R50 bulbs (depending on what sort is currently fitted) and run it from the mains, definately not dimmable.

24_hour_sparks

wig, by making the fitting from selv to 230v be carefull that the intended insulation is sufficent, and either its earthed and/or doulble insulated.

happyhero

Wig wrote:

How about 240V low energy (7 Watt) GU10 bulbs or R50 bulbs (depending on what sort is currently fitted) and run it from the mains, definately not dimmable.

Cheers wig for the answer but I could not do this because as with many LV fittings part of the fitting is live, ie there are bending bars to each lamp holder which act as the return path for the LV. So each lamp has a bendy bar to it and a wire wrapped round it too - one of these modern thingys.
So making it 230 is out I'm afraid.

I was sure someone on here would know somewhere to get a tiny transformer, surely there is a demand for them, I can think of many situations where tiny would be a benefit.