cant start pc with switch...

G

game14

[H]ard|Gawd
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Nov 8, 2006
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got some strange issue with my biostar G31 mobo. I will not start if i connect the regular switch to the mobo. But it starts perfectly fine if i shorten the 2 pins with a screwdriver. A connector with 2 loose wires works fine too with only short contact. If i connect any switch to it it will not start at all... any ideas ??? :confused:
 
Should go without saying but check the switch in question, super easy and quick.
 
bad switch was my first guess too. I connected that switch to another mobo and its working just fine. I got like 30 spare switches in a bag and trying most of them always gives me the same problem. Yes i used different wiring too.
That mobo really "doesnt like" any switch...never seen something like that happen before , its really confusing.
 
Has to be something to do with your front panel connection. I couldn't imagine how it would break though.
 
second guess was that either the switch connector or the pins on the mobo was bad. Switch works fine with another mobo. So connector must be fine.
Right now i got a connector plugged in with 2 wires hanging out of the back of my case. Got tired of opening the case every time i want to start up my computer to shorten the pins.
Works fine with those 2 wires so the pins must be fine too.
As soon as i hold or solder a switch to them it refuses to start.
kinda really givin me headache...
 
All I can think of is check the resistance between the power switch pins on the mobo (with the power disconnected).

Get a multimeter, set it to 100kilo or 10kilo (ohms) and go crazy.

Most of my random mobos show 8000-9000 ohms between the pins (motherboard side).

You can check your power switch the same way - attach the probes to the ends of the switch wires - should show '1' meaning 'infinite'. Press the switch and the multimeter should show 0.

Good simple test imho.
 
michalrz said:
All I can think of is check the resistance between the power switch pins on the mobo (with the power disconnected).

Get a multimeter, set it to 100kilo or 10kilo (ohms) and go crazy.

Most of my random mobos show 8000-9000 ohms between the pins (motherboard side).

You can check your power switch the same way - attach the probes to the ends of the switch wires - should show '1' meaning 'infinite'. Press the switch and the multimeter should show 0.

Good simple test imho.
Click to expand...

so what you mean is that maybe the switch is adding too much resistance to the switching circuit on the mobo. While just holding together the 2 wire endings still let enough voltage pass to trigger the start.
Since i used 3 different PSU on that same board in the last month and still got the same problem i can rule that 5V connection out.
That basically means the switching circuit on that mobo must be faulty, something is adding more resistance as supposed to.
Am i right ??

Bad luck my old multimeter is brick, so i cant really test it right now.
 
Well in weird situations like yours I usually just check the basics with a multimeter while it's all in the chassis. Unpowered.

- if it shows odd (near zero or like megaohms), resistance between the mobo pins then there's a short on the mobo and this should be addressed first,

- if it shows, in chassis, that the resistance between the case switch wires (disconnected from mobo, insert a pair or thin uninsulated wires into the connectors to reach the pins) shows 'infinity' when 'off' and '0' when you hold it down, you know it's not a localized small short to the case somewhere.

If it shows some resistance in ohms or kiloohms (or hundreds of kilos) then that'd mean you have a bad switch or swithc wire (while it's in chassis)

- using a soldering iron on the motherboard is risky :p
 
power switch on most cases just shorts the two PINS on the mainboard

take switch out and test for continuity when the switch is closed with a digital multi meter
 
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