PC power button problem

BMp3W · 10-11-2002, 02:24 PM

Hey, I'm finally a registered user though I've been regularly reading all kinds of helpful mp3car.com posts for over a year-thanks. Also, after a year or more of the on/off work of planning and tracking down the right components, I've finally gotten my project to the point where I'm troubleshooting the final unit.

The problem:
I've built a case using one of these pretty sturdy aluminum tool briefcases like you find at Lowes (about 12"x16"x6"). I've got a PC power button on this case that, of course, comes from the little motherboard header power switch pins. However, the case will be in the trunk of my car so in order to power on the PC I've also run a power button up to the front seat. This power switch's wires are run through a ribbon cable and connect directly to the power button on the case, and that case power button then connects to the mobo pins-if you get my drift. So, I figure, and I've tested it for continuity with a multimeter, that the circuit closes when either power button is pushed. The problem is that, as soon as I turn on the rocker switch on the *power supply*, the PC starts up before I even hit either PC power button.

I'm no electrical genius so...Why is this? Is the wire run from the trunk to the front seat of my car (about 10 feet) too long for some reason? Is this (serial??) circuit not appropriate for this situation? Could there be some kind of grounding issue?

The relevant stats for my system appear in my sig. Thanks for any insights and sorry this post is so damn long.

felix99 · 10-11-2002, 02:59 PM

I'm not a genius but some things to check:

- try with only one switch.
- sure you got the good pins on mobo ?
- no shortcontact ( hope this traduced right) ?

A general thing i remarket during my install / developement

Power button and reset :
on my mobo's

GND---------/ ---------o powerpin
GND--------/ ----------o Resetpin

that means that one of the 2 pins is GND and by pressing button you are grounding" so if there is a leak on the line it is probable that the pc starts.

If I understood you you have this ???

..................................-----------/ ---------------
o---pwrpin1mobo----/...................................\-------pwrpin2---o
.................................\______/ __________/

the dots are only to display my ascii art the right way. ( see them as like they wheren't there

)
sorry ascii art is not my really my favorite way of painting

If you have the above shematic I don't see why the mobo turns on without pressing on of those switches -

If I'm wrong please correct me !

For expressing my self I tried my best

Hope it helps

Felix

mp3hombre · 10-11-2002, 06:10 PM

----
0|0
| |
| |
| |
| |
| |
----
0|0
| |
| |
| |
| |
| |
x x
To MOBO

The switches should be connected in parallel.
Also, you should check your BIOS settings. There's an option to reboot the PC in case of a power failure (for example if you turn the PC off just by flipping the rocker switch).
Otherwise you might have a short somewhere or you are picking up some noise. Try using insulated wire.
Hope this helps
Cheers!!!

albysure · 10-11-2002, 06:14 PM

yeah...check your bios. i have had that happen to me sometimes. just let it boot up and then try your switch

BMp3W · 10-12-2002, 03:36 AM

Thanks for the replies. Problem solved.
My circuit is in parallel so that was fine but when I checked each and every connection on my home-made ribbon cable, there was a crossed wire.
I have one of those port extenders which is used to put your mouse, usb ports, game port and sound card plugs up on the front panel of your PC case. What I did was run this port extender box up to the front of my car by my front seat. This port extender has a DB37 connection (which are actually quite hard to find and pretty expensive) which is only a couple feet long. So, to get the length I needed I bought some bulk floppy cable which is 34 pin but it worked out since this port extender only uses 31 wires. Then, since I'm not using the game port (DB15), I ran the power and reset switches and the HDD and PWR LEDs through the game port and mounted them on this port extender box. So, I can power up/down the PC even though it's way back in the trunk.
I hope to get some pics up soon someplace b/c it's coming together quite well.

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