The Keylock connector is also for the power led. The power led should be a 3 pin connector with a missing pin on the middle. The first two pins on the board I think are for the keylock, so pins 3 and 5 should work for the led. Check the polarity. If it doesn't work one way, try the other.

What motherboard are you trying to plug everything into? If we can get a picture of the board, or a schematic, I'm sure we can point ya in the right direction on what-to-plug-into-where.

Markk is right. Also, you may have burned out the LED.

Mobo is: Asus VL/I-486SV2GX4 Rev 2.0. Doesn't say anything on the schematics or user manual found online where to connect the power led (from what I've found)

I've found this while browsing. http://www.pcguide.com/ref/mbsys/mobo/comp_Connectors.htm . The keylock now works with using pins 4 and 5, but since I don't have the key to the case and it is in the "locked" position there is no point using it. Tried connecting the power led to 1 and 3 and then swapping them the other way, but to no luck. I'll try 3 and 5 as well, just to make sure.

The molex trick I read while googling for this problem, but that may have been for an 3rd party LED. So it might have gotten burned out? I didn't see anything when I connected it (like going extremely bright and then dieing). Thought they were supposed to run on 5V.

If you know how to remove the cables from the connector(as they should use 2 pin connectors instead of 3 like the power led) you can use either the turbo or hdd led to test and see if it's working when connected to those pins. If it does, then probably your original power led is burned.

edit: I had a motherboard and an AT Power supply handy over here, and started it in order to measure the power led voltage using my multimeter. It reads 5.05v while the 5v molex cable show 5.07v, so I guess it's not so likely to have burned the led by connecting it there.

I had a motherboard and an AT Power supply handy over here, and started it in order to measure the power led voltage using my multimeter. It reads 5.05v while the 5v molex cable show 5.07v, so I guess it's not so likely to have burned the led by connecting it there.

You're forgetting about current. If you feed an LED 5V direct from a molex without a current limiting resistor, you'll fry it in pretty short order. The LED headers on a motherboard, OTOH, usually have such a resistor built into the circuit.

Old Thrashbarg wrote:

The LED headers on a motherboard, OTOH, usually have such a resistor built into the circuit.

Usualy, lets hope so, they are for sure.
5v on the led will burn it for sure if not explode or short out on your power supply. Bad idea.

Old Thrashbarg wrote:

You're forgetting about current. If you feed an LED 5V direct from a molex without a current limiting resistor, you'll fry it in pretty short order. The LED headers on a motherboard, OTOH, usually have such a resistor built into the circuit.

Yeap, you're right. First I thought that it would be ok, as I have seen some of those speed displays that feed directly from the molex, and the turbo led goes on them instead of the motheboard. But after a second thought, it's obvious that some sort of limiting resistor as you mentioned has to be on the display's small board.
Anyway, I thought I should test this just for fun. I connected a green led on the molex 5v rail, and it lights up, but it's color changes to yellow... I had it powered like that twice, and about 7-8 seconds each time. It didn't burn but it's clear that it's not meant to be used like that. Sorry guys, my mistake.

Looks like I've burned the LED. I connected the turbo led cable to the power led pins 1 and 3 while at the same time connecting the power led cable to the turbo led. No light in the power led, while the turbo led stayed on even if I pressed the turbo button on and off.

Are these kinds of diodes hard to replace? I guess it will be hard to find a similar one so that the power led doesn't shine much brighter than the others.

They are cheap and easy to find. Any decent electronics store near you should carry a wide selection of colors, shapes and intensities. They usually have a working display or let you test them individually so you can pick one that suits your fancy.

The problem is finding a decent electronics store in this day and age.

Farnell / element14 and RS Components are good online options for components.