Which led bulbs to replace multiple halogen bulbs?

I have a lighting fixture made of 20 halogen bulbs rated 20W, connected to a dimmer. For obvious reasons, the dimmer is always set to minimum values,else these lighting fixture would draw 400-500W!
I’d like to replace its bulbs by led bulbs, but after attempting with 5 different types of led bulbs (randomly selected/boight) with no luck, now I’d like to do something more scientific…

Unfortunately, I don’t have any specification for the lighting fixture; all I know is that:

- it has 20 halogen bulbs rated 20W

- it is connected to a dimmer

- if one bulb fails, whole lighting fixture will turn off, and a small led close to the failed bulb will light up

  • bulbs have 2 small pins (I guess it means “G4” connection)

All led bulbs I tried burned/exploded!

Now I just discovered that there are several types of led bulbs: 12V DC, 12V AC, 12V AC/DC, 220V AC…

So which one do I need?!?

Can I replace just ONE halogen bulb by a led bulb to figure how if it works, before buying 20 possibly useless bulbs and wasting 100$?

Nobody knows?

If those 20 halogen bulbs are connected in series, and it sounds like they are, this fixture is probably using 12V halogens.
I am going to guess that you have 220V mains. 20 - 12V halogens in series relies on each bulb being identical so that each bulb has a voltage drop of approximently 220V/20 bulbs, or approximently 11V each. If all bulbs are not identical, the voltage drop across each one would not be identical.
Replacing just one halogen in a series circuit like that with an LED will not work. That 1 LED will most definitely see too much voltage and immediately blow.

Actually under any circumstance I don’t think replacing all 20 LED’s would work in a series circuit either. I don’t think the associated electronics in each of the LED’s would do well in a series configuration, and you would probably blow all 20!

the information provided would indicate that you would need the 12v ac/dc led bulb as it appears that your fixture is working with ac. 20 of them in series would not be preferred but they should work in theory.

Also a lot of LEDs are none dimming so that may be an issue.

How can I be sure? Which is the cause?

Do you mean “led bulbs in series are not dimmable”?
Which is the cause?

Jumpjack, I should retract my comment as there are many variables. If you try one led at a time, you should try the 12vac version as in appears that your supply is full 240vac. Sorry, I cannot give a good enough answer.