plz give me full description about the ckt " dancing led",as i have to
make a detailed report on it.

Hi everyone,

I'm sorry for my low level knowledge about electronics. I hope this group
can help me. I use a compaq Tower PC from 1998.

It still functioned admirably, but I had connected a fan to one of the 4
cable (red black black yellow) plugs
which also go into hard disk and cdrom drives, using wires I put loosely
inserted into the plug.

Unfortunately, I caused in this plug a short circuit by pulling the loose
wires which connected
this fan to the plug and had the red and black ones touch each other for a
second.

However stupid this may be, I first thought no damage was done to the power
supply. However, the ATX motherboard power switch did not start the computer
no more. I thought the motherboard was gone as well by then.

I bought a new power supply, and the problem is over, for now.

I still hope I can fix the first, older power supply, because the new power
supply
stated on the box that there was protection against short circuits.