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Is it me ???????????
Have a utility area with 6 halogen downlighters, fitted many years ago.
Once in a while a bulb fails and a simple job to replace.
Each light is fitted with a transformer reducing voltage from 230V AC down to 12V AC.
This time light fails but bulb found OK - advised that the transformers are quite unreliable and indeed found no voltage in to bulb socket.
Replaced the transformer, new, like for like.
No luck, bulb still not powered.
Checked the new transformer, voltage on input, but no output measured (using a Fluke multimeter).
Set the transformer up on a bench, powered it and checked OK, but nothing measured on output.
Checked with another spare new transformer, just the same, nothing on output.
(I am planning to replace the lot with LEDs at some point later ...)

Have I got a few duff transformers or am I missing something ?
Any words of wisdom much welcomed !

Yes, you have missed something, those are NOT transformers. They are electronic voltage droppers. (A transformer is two coils of wire, (or more) wound on a former)
Some only work when they have "something to do" a meter is not enough for them to notice, so they do nothing, connect a known working lamp to them, or it could be they have failed.

Thank you (again) for your help 'Someone-Else', and so promptly.
I had wondered that and in situ had put in a new/working bulb (checked it on another fitting before and after).
I have read/google that there could be a short/fault in the wiring to the bulb holder, so can replace those.
I will check, on the bench first, connecting up a 'good' bulb and see what happens !
Will update ....

FYI, look at this "transformer"
Just under the name it says "Electronic transformer 20-75 w"

That means the maximum wattage it can supply is 75, BUT anything less than 20 w it will not work. It's common for people to take out 35 watt halogen lamps, install a 3W LED lamp, and wonder why nothing happens, It's because the new LED lamp is too low in watts, its better to change the whole lot to a GU10 mains LED light.

One does not show range, the other 10-60 VA so must have a 10 VA load or they will shut down. You can now get zero to rated output, but an electronic transformer output is often in the khz range.

Toroidal transformers only have a max output and are normally round, heavy, and often will not fit through hole for lights.

There are two reasons for extra low voltage, one where there is a danger using low voltage, and two the quartz bulbs had thicker filaments so lasted longer. With LED the latter is no longer true, so changing to low voltage means one can also used smart bulbs, so better in most cases to change to GU10 and low voltage.

Only reason not to change to low voltage (230 volt) is when there is no earth and it would need rewiring.

I think you should seriously consider replacing those fittings with GU10 led lamps. Then all you will have to go wrong will be the bulbs

I am now planning to change over to GU10 led fittings.

I see that these come in 12v and also 230v - for general areas I am guessing 230v is appropriate, but should only 12v be used in kitchen/bathrooms out of interest ?? (and hence needing step down transformers ?)
Many thanks

ChippyJoe wrote: ↑Sat Feb 10, 2024 12:48 pmI see that these come in 12v and also 230v

Where did you see that?