Nice cooker hood in teh kitchen, but thought it best to swap the 2 (12v) halogen g4 lamps to leds. As they use half as much juice as the entire kitchen...

So some LED discs turn up. I change one, and indeed similar brightness to the old halogen. Take the 2nd halogen out, led goes dim. Put the 2nd LED in, and they are both dim. Change the other to halogen, all good.

So anybody got any ideas why this is? I am really confused, as I assumed it was just a 12V supply in the hood. Or is the current draw so small it is partially shutting down?

TIA
Clive

(more a want to know, and will change something if viable, sort of question than a how do I fix it. If that makes sense)

I have seen this before, where the circuit driver needs a bigger load than just the leds, - ie will work so long as there is one conventional bulb in circuit.

probably just change the 12v supply to an led one

edit:
http://www.locostbuilders.co.uk/viewthread.php?tid=195532

[Edited on 24/11/15 by gremlin1234]

it is I believe an effect of load on the switch mode power supply, it is designed to run at 100W say and is now being presented with maybe only 10% of that

hth

Hmm, thanks chaps. Looks like my hunch was right about the psu.

I suspect it is all part of some circuit board that controls the fan speeds as well as the lighting, but will have a look when I get the chance (think it a PITA to get to the board!)

Ignore the existing board & assuming you can get to the 240V supply, just put a driver into that feeding the 2 lights separate to everything else, leave the existing supply from the circuit board disconnected, insulated & tucked away