Well OK, why not just replace the halogen bulbs then? If it's not the bulbs, find the fault and fix it.

The bulbs were replaced by LEDs, but when I switch them on, I see a brief flash at full intensity, then it immediately goes very very dim. Measured voltage at the LED pins at that moment tests to 0.9V instead of full 12V...so I figured it must be that the load is too low for the transformer, as is often the case when you try to use a dimmer with some type of LEDs.

 

The bulbs were replaced by LEDs, but when I switch them on, I see a brief flash at full intensity, then it immediately goes very very dim. Measured voltage at the LED pins at that moment tests to 0.9V instead of full 12V...so I figured it must be that the load is too low for the transformer, as is often the case when you try to use a dimmer with some type of LEDs.

OK, I need more details to make any sense of this. What were the original bulbs and what did you replace them with and what are the specifications? The output of your transformer is almost certainly AC for the halogen bulbs. Your LEDs almost certainly are expecting a current-controlled DC. Is there anything between the AC supply and the LEDs to account for this? From your description, I'm surprised you haven't ruined your LEDs.

 

OK, I need more details to make any sense of this. What were the original bulbs and what did you replace them with and what are the specifications? The output of your transformer is almost certainly AC for the halogen bulbs. Your LEDs almost certainly are expecting a current-controlled DC. Is there anything between the AC supply and the LEDs to account for this? From your description, I'm surprised you haven't ruined your LEDs.

The original bulbs were two 12V 20W halogens; I replaced them with 12V 3W COB LEDs rated for AC or DC. Hence why I thought this would/could be a drop-in replacement. Taking a look at the diagram, mains goes in a transformer, which then outputs to 12V and 9.5V on the processor board which then sends this to the bulb sockets.

I don't really have more info on the bulbs since they are cheap and were bought on Wish lol.

http://www.wish.com/c/5808857382152e213ab6deec

 

The original bulbs were two 12V 20W halogens; I replaced them with 12V 3W COB LEDs rated for AC or DC. Hence why I thought this would/could be a drop-in replacement. Taking a look at the diagram, mains goes in a transformer, which then outputs to 12V and 9.5V on the processor board which then sends this to the bulb sockets.

I don't really have more info on the bulbs since they are cheap and were bought on Wish lol.

http://www.wish.com/c/5808857382152e213ab6deec

Interesting, thanks. I don't want to sign in there but I get the idea.

Is it possible that the halogen system failed because that transformer has failed? I mean, the same root cause may be affecting both the halogen and LED systems. What happens if you apply the transformer's 12V output to a 12V incandescent bulb of similar wattage?

 

Interesting, thanks. I don't want to sign in there but I get the idea.

Is it possible that the halogen system failed because that transformer has failed? I mean, the same root cause may be affecting both the halogen and LED systems. What happens if you apply the transformer's 12V output to a 12V incandescent bulb of similar wattage?

You know...I didn't actually think about this but indeed the transformer might've crapped out...I could clearly see that the filament was broken in one of the halogens, but didn't bother looking at the other one. I don't have any spares, so I guess i'm gonna run a continuity test on that second halogen I just removed...if there is continuity, then the bulb is okay...and the transformer is done for. It doesn't light when I plug it in.

 

You know...I didn't actually think about this but indeed the transformer might've crapped out...I could clearly see that the filament was broken in one of the halogens, but didn't bother looking at the other one. I don't have any spares, so I guess i'm gonna run a continuity test on that second halogen I just removed...if there is continuity, then the bulb is okay...and the transformer is done for. It doesn't light when I plug it in.

If you're like me, you might have some 12V automotive lights on your shelf. Dome light, turn signal, brake light, any of them should work for testing. A headlight draws too much current, so I wouldn't use that.