Downlight Mystery

[AndyTheSpark]

Hi Folks,

I had a job today for a faulty downlight. It was a 12v with a 50w lamp run through a transformer rated up to 60w, there were only two lights runs off a one way switch, the other light worked fine and the light in question had been working fine previously. I tested for supply and got 230v going into the transformer, nothing coming out. Simple, I thought to myself, new transformer and all is well. After trying 3 brand new transformers I was still getting nothing coming out the other side. I rigged up a pendant to the 230v supply to see if the lamp did anything odd but it worked fine. Has anyone come across anything similar? I can replace the 12v with a 230v fitting but this seems to be skirting the issue!! Any help would be much appreciated!!!

AndyTheSpark

 

[Octopus]

Did you replace the cable between the tranny and the lamp?

 

[AndyTheSpark]

Did you replace the cable between the tranny and the lamp?

The lamp holder is connected to transformer leads using connector blocks - I didn't replace the lampholder but tested at the connector block so there was no previously existing cable between test point and transformer that could have been damaged.

 

[Rauer]

Was your meter set to dc?

 

[Shropshire]

MR16 type lamp ? if so pin holders are ****

 

[Richard Burns]

If you are trying to measure the voltage on the output side of a standard downlight transformer then you will not get a reading from a standard voltmeter. The transformers need a minimum load to start operating and once they do they are running at very high frequency that your meter is unlikely to pick up.
Easiest way to test a transformer is to connect it to a light bulb and see if it lights!
You could also clamp one of the output cables and see if you are getting the expected current.

 

[oba]

New lamp holder / lamp required

 

[i=p/u]

make sure there isnt a thermal cut out, try 20w 12v

 

[Fin170]

New lamp holder / lamp required

Second probably this

Take the thing apart and look at the point where the lamp connects, on the back where the wires connect you'll probably see a big burn mark

 

[ruston]

Second probably this


Take the thing apart and look at the point where the lamp connects, on the back where the wires connect you'll probably see a big burn mark

Probably as above your tranny may not show an output without a load depending on type.


Sorry missed Richards post .

 

[One_of_them]

did you try a new lamp?

 

[Rauer]

Did you turn the breaker on?