No power to MB

[wmn]

I purchased a Shuttle ATX MB, AK39n. The processor to be used is a AMD Athlon 2800+. I purchased an atx case with 300 watt pwr supply at PC club to house MB. The AMD is good and running at the moment on a Compaq board.

My problem is that I cannot get power to the MB. The pwr sup is ok as I have installed in another computer to check. Installing a different known good ps was no help. I still do not get power to the board.
The only thing I can find is that the ak39n install instructions call for a 3 pin PLD connector, whereas I have a single +PLD connector and a single -PLD connector and a two pin pwon connector to the front panel. I have not connected any of the other front panel options pending this power problem.

Any suggestions? I live near your Pomona and your City of Industry facilities. Can you check this MB problem at one of those places?

Thank you for a reply,
Bill Noyes

 

[mechBgon]

Welcome to the Forums I will download the manual for that board and see where they want you to plug in your case's power button. You may wish to re-inspect all of the case's front-panel wiring to ensure that you're plugging in the actual power switch wire to the motherboard's corresponding pins, and not the Power LED or something.

Back in a while (56k dial-up, so downloading manuals takes a while).

 

[mechBgon]

All rightie, if you look at page 16 of your motherboard manual, they show the front-panel pinout. On the bottom row, the PWON pins are the third and fourth pins from the right. Your case's power-switch wire goes on those. It could be labelled all sorts of things depending on who made the case, it might say ATX PWR or PWR SW or who knows.

If that doesn't help, then I have a pretty complete no-POST / no-run checklist you can consult, first link at the top of this page. The top items in my mind would be

1) is the motherboard on standoffs like it should be

2) is the secondary power plug hooked up (on this board it's the same type that a hard drive or CD-ROM drive uses, and the receptacle is at the top of the board above the memory slots)

3) is the power supply any good, or is it the typical feeble freebie junk that comes with cheap cases Powering an AthlonXP 2800+ is not something I'd ask of a typical freebie 300W unit.

4) check the rear ports to ensure that the springy finger things on the I/O shield didn't sneak into the USB ports or LAN port.

5) maybe the case's bezel button is not actuating the actual electrical switch behind it. Take the bezel off and push the power button itself. If it doesn't react, hook up the Reset button to the mobo's PWON pins and hit the Reset button. If that works, then your case's power switch is faulty, happens sometimes.


All this and more, in that first link to the full list o' problems

 

[wmn]

Thank you for the rapid response. To further explain the front panel setup,
Red LED- r&w wires - female connector marked HDD LED.
Green LED - 1 green wire -F/conn marked- (+PLED), 1 white wire -F/conn marked- (-PLED)
1 Switch - orange/white wires -F/Conn marked - (Power Sw).
1 Switch - blue/white wires - F/Conn marked - (Reset SW).
(Speaker) - 4wire conn not used..bad hearing
On the MB, this leaves 2 pins for (EPMI) and 3 pins for (12c). Neither of which I know what they are for.
To reply,
Yes, both pwer plugs from supply connected correctly to MB.
Brass standoffs used, have considered using nylon ones.
Switches check ok with Ohm meter.
I understand about the 300 PS, however, fans and processor run ok with original 240 watt ps on compaq A7V8X-LA MB. (I can't handle Compaq proprietary BS.)
Hmm...no springy things on IO shield, shield does not actually touch anything mounted to board. Even so, at least the fans should function when PS is on and case switch is on, right?
I'll check out the no power list from your site and/or bite the bullet.
Thanks for your time and effort. This 70yr old really appreciates it.

 

[mechBgon]

Another thing that can help narrow down the list of possibilities is to take the motherboard out of the case and operate it laying on cardboard (the motherboard, not you ). That eliminates the case as a possible cause of short-circuits.

Good luck!

 

[wmn]

Been done..
Thanks again.

 

[wmn]

Ah-ha..
By getting down to the very basic; Mobo out of case, with only the two power supply to board connections made and ONLY the PWON connection to the front panel header connected, I have power. At least to the fans. Evidentally one of the connectors to the Mobo is causing a shutdown of power to occur. Will keep you posted, and thanks for the mental reminder to start with 1,2, 3, etc.

Bill