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Somebody plz help me with rheostat.

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Apr 17, 2001
I purchased a rheostat from radio shack today and connected it to the black wire on my delta.
The rheostat does what its supposed to do, it changes the speed of my fan when i turn the knob.
The only problem is my computer wont boot up when the rheostat is connected.
Just a black screen.
It works fine if i bypass the rheostat.
Can anybody tell me how i can get this to work.
My delta is a 3 pin type with the rheo on the black wire.
Did i do this wrong?
Yea its plugged into the fcpu header on my Iwill kk266 and the fan runs, but the screen doesnt boot.
Do you have your computer set to turn off if the CPU fan fails?? if so that's probably why. Adjusting the speed slower causes the tac to malfuntion and either report 0 [cuts off the computer if you have it set to] or really high due to the timing changes.
The Correct Answer:

Never put the Rheostat in the black lead if your fan has a tachometer output and your motherboard needs it to boot up. The added resistance in the return (black) can screw up the tachometer reading. Put it in the plus (yellow) lead.

Actually, I believe in the case of the Delta, it's the RED lead. But Hoot is correct. The ground is not the one you should be messing with. Except, the KK266 doesn't even need to have a fan hooked up to boot (at least mine doesn't). Strange.
Hey guys thanks for your info, but whatever i did i screwed up my motherboard :-(. Thats why it wont boot up. I just hooked up a regular 92mm fan on top of my heatsink and it still wont boot up. I took my chip to a local computer store and it tested out fine. I transfered my power supply to a different computer and it powers up. I switched my video cards and my computer still has a black screen. Im totally convinced i killed my motherboard. It was such a high quality motherboard it never locked up once. Im not gonna mess with rheostats anymore. Now im just gonna wait and see if I can get the iwill exchanged, If not ill just buy another one.
Look around for a piece of conductive debris, that may have fallen on the motherboard, or some other reason it is appearing to fail now.

Read Carefully: There is no, repeat no possible way that simply putting the Rheostat on the minus lead to your fan, that it would damage your motherboard. I've been troubleshooting electronics for 30 years. Trust me.

If you went to put water in your cars radiator and mistakedly put it in the crankcase, blew up the engine and had to replace it, would you swear off adding water to your radiator? Think about cause and effect.
Good Luck resolving whatever your problem is.

Did you possibly mess with the voltage or multiplier in the BIOS before this happened? Before you write off the motherboard (and these KK266's are pretty darn robust), try changing the jumper for FSB (133 back to 100 -- the one located between the CPU socket and the memory slots) and see if that works. If not, then reset the BIOS as outlined in the Iwill manual. I'll bet one of those will get you back in the saddle. Good luck.