VOGONS


First post, by JonathonWyble

User metadata
Rank Member
Rank
Member

I recently dug up a Pentium II custom build, which still works as I tested it out for a brief amount of time. I then took it apart to clean it out, and then put it back together. But I'm having one little problem. I can't seem to get it to turn on, and I know why. It's because I can't seem to remember where two Power SW pins go on the motherboard. I already connected the speaker, H.D.D. LED, power LED, reset SW and speaker pins successfully, but not so much for the power SW pins. So, about this motherboard, it's an Intel E139761 model, and it has a Pentium II CPU. I'll show you what I'm talking about with where certain pins go...

1550413005.th.97690.JPG

As you can see on the bottom of the motherboard, it has most pins assigned to specific ones, but not the power SW pins.

Here are these two pins I'm trying to locate,
1550413124.th.76484.JPG

So yeah, I'm having this problem where I can't locate the pins for the power SWs, which are required for this PC to boot, because there are no assigned pins for them on the motherboard. I guess I don't know how to work with older hardware components very well. Any comments would be appreciated.

1998 Pentium II build

1553292341.th.19547.gif

Reply 1 of 7, by gerwin

User metadata
Rank l33t
Rank
l33t

The two pins on the far right are marked "PWR ON". Try that?
This manual may apply to your motherboard:
http://www.elhvb.com/mobokive/Archive/Intel/S … 2/se440bx-2.pdf

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 3 of 7, by JonathonWyble

User metadata
Rank Member
Rank
Member
gerwin wrote:

The two pins on the far right are marked "PWR ON". Try that?
This manual may apply to your motherboard:
http://www.elhvb.com/mobokive/Archive/Intel/S … 2/se440bx-2.pdf

Thanks for the manual. And no, I did not try the PWR ON, because this PC doesn't include that type of pin.

PTherapist wrote:

Have you tried placing them on the pins marked Sleep & Power On? I can only assume that's why there are 2 plugs marked Power SW.

Edit: Beaten to it. 🤣

Yes, I did insert the sleep pin, but the power pins are what I'm having trouble with.

1998 Pentium II build

1553292341.th.19547.gif

Reply 4 of 7, by tincup

User metadata
Rank Oldbie
Rank
Oldbie

Assuming the PDF manual that was linked is the correct one, page 55 shows the front panel connector layout. The 2 pins on the far right is the Power Switch connection (as pointed out already). The manual diagram indicates pin 1 is 'hot' and pin 2 is ground. Check the plug and there should be a small triangle in the black plastic next to one of the plugs - this indicates the 'hot' plug. Align it with pin 1.

Curious that you have two Power connectors though. Are all the connector accounted for? Maybe one of the power connectors is actually for reset or sleep? can you trace the wires back to the front panel to see what they may service?

Hope this helps

Reply 5 of 7, by JonathonWyble

User metadata
Rank Member
Rank
Member
tincup wrote:

Assuming the PDF manual that was linked is the correct one, page 55 shows the front panel connector layout. The 2 pins on the far right is the Power Switch connection (as pointed out already). The manual diagram indicates pin 1 is 'hot' and pin 2 is ground. Check the plug and there should be a small triangle in the black plastic next to one of the plugs - this indicates the 'hot' plug. Align it with pin 1.

Hmm, I guess I would have to check that part of the motherboard. I'm assuming the builder of this PC probably didn't know what they were doing. It might be because when it comes to custom-built PCs, sometimes you don't end up having everything matched with an associated component.

EDIT: I forgot to add that I don't think one of the Power SW pins is for the reset pins, because I already have a Reset SW pin, as well as an HDD LED, Power LED and Speaker pins separated from the two Power SW pins. I don't have a Sleep pin nor an Infrared pin, but the pins on the right side of the front panel connectors section are labeled "PWR ON", so I think that's where one of the Power SWs go, and I might just leave one Power pin unused.

Last edited by JonathonWyble on 2019-02-17, 16:08. Edited 1 time in total.

1998 Pentium II build

1553292341.th.19547.gif

Reply 6 of 7, by gerwin

User metadata
Rank l33t
Rank
l33t

For indicator LEDs: These do require proper plug orientation. Plus on the side of the colored wire.

For an ATX style power switch: the plug orientation is not of any consequence. You can turn it around and it is still technically the same. To illustrate that point: You can even use a screwdriver to toggle these "PWR ON" pins, by touching and connecting both of the pins with the metal screwdriver tip. ( Just don't accidentally touch the other pins for LED / Speaker / infrared etc. because that can short out things )

--> ISA Soundcard Overview // Doom MBF 2.04 // SetMul

Reply 7 of 7, by tincup

User metadata
Rank Oldbie
Rank
Oldbie
gerwin wrote:

For indicator LEDs: These do require proper plug orientation. Plus on the side of the colored wire.

For an ATX style power switch: the plug orientation is not of any consequence. You can turn it around and it is still technically the same. To illustrate that point: You can even use a screwdriver to toggle these "PWR ON" pins, by touching and connecting both of the pins with the metal screwdriver tip. ( Just don't accidentally touch the other pins for LED / Speaker / infrared etc. because that can short out things )

Correct! pin orientation isn't required for the power switch, screwdriver test is good.

Other reasons the rig may not be powering is an improperly seated CPU or the ATX power plug. Also it might not fire up without a fan attached to the CPU fan header (item "L" on the motherboard diagram in the manual).