Sign in with
Sign up | Sign in
Your question

power on problem with ASUS K8N mother board

Last response: in Motherboards
Share
August 26, 2007 12:08:22 PM

Coming back from vacation my computer doesn't start up any more (no beep, no fans, nothing). Three weeks ago everything was still fine.

Here is what I found:
1. the power switch appearantly doesn't work
2. short cutting the "pwrsw" connector pins on the MB doesn't work
3. BUT: short cutting pin 14 & 15 on the MB power supply connector starts the system as usal

(The third I found here: http://www.bluemax.net/techtips/ATXPowerSupplyWiring/ATXPowerSupplyWiring.htm).

So, there seems to be something wrong between the power switch and the PSU power on.

More details:
- as I said everything worked great for quite a long time
- I get 3.3 V between the "pwrsw" pins on the MB

Thanks for any hints
August 26, 2007 12:32:10 PM

tempox said:
Coming back from vacation my computer doesn't start up any more (no beep, no fans, nothing). Three weeks ago everything was still fine.

Here is what I found:
1. the power switch appearantly doesn't work
2. short cutting the "pwrsw" connector pins on the MB doesn't work
3. BUT: short cutting pin 14 & 15 on the MB power supply connector starts the system as usal

So, there seems to be something wrong between the power switch and the PSU power on.


How do you figure that? The problem IS the power-on connectors on the motherboard since directly bridging those pins doesn't work. Measure continuity with an ohmeter of the power switch. Try connecting the power switch to ATX connector pins 14 and 15 instead.
August 26, 2007 3:38:14 PM

Here I was not completely clear and forgot another detail:
I already tested the power switch button itself with an ohm-meter and it is ok, just that it doesn't do anything (like short-cutting the "pwrsw" pins doesn't do anything).

> Try connecting the power switch to ATX connector pins 14 and 15 instead.

Well, as far as I understood, the MB would permanently switch on the connectrion of pin 14 of the PSU connector (pin 15 is ground) as a consequence of a short connection of the "pwrsw" pins (via the power switch).
So, directly connecting the power switch to pin 14 & 15 would probably run the computer as long as I push the power switch button and stop as soon as I release it (as it currently runs as long as I short cut these pins with a piece of wire).

But, what happens between the "pwrsw" pins and pin 14 of the PSU connector? Here seems to be the actual switching mechanism that is broken, no?
Related resources
!