Trouble with an old Shuttle

[Kealy]

Hey guys,

I've been searching for an embarrassingly long time trying to find the right answers to fix my old Shuttle SN25P. A few years ago, the system started fading (I thought it was the video card) and inevitably stopped working all together. By stopped working, I mean that I had similar issues to those voiced by many in which the motherboard starts up, all attached fans, including the video card fan, start spinning, but no video output is observed on the monitor. I have no idea if it is POSTing as I cannot hear any bios beeps.

I am by no means an expert on computer hardware, but through searching many forums I have tried many things to solve this, such as:

Purchasing a replacement motherboard (pain in the butt considering its this MicroATX mobo)
Purchasing a system speaker and attempting to Breadboard the entire system (although I couldn't figure out where to plug the speaker in, which if anyone knows, would be great).
Testing all parts separately, with exception to the PSU and CPU with heatsink.

At this point, I want to fix the computer just so that I can conquer this stupid thing, but I need some help.

As best I can remember, the specs are (other than outdated)
Shuttle SN25P
FN25 socket 939 AMD Athlon 64 motherboard
EVGA nVIDIA GeForce 7950
2x 1gb Corsair xms3200 DDR400 RAM
Stock PSU (I believe it is 350 Watts)

I know there are a lot of moving parts here, but any help to any of my questions would be greatly appreciated. (Especially the one about where to plug in an external speaker...)

Thanks in advance

 

[Wolfshadw]

More than likely, your power supply has failed. I'm surprised a 350 watt PSU would ever run an old S939 system with a Geforce 7950 installed!

-Wolf sends

 

[Kealy]

I agree that it sounds like a PSU problem, it's just weird that it used to run this system just fine. Also, it does not POST even with just the bare minimum (no video card, ram, optical drives, etc...). Is it still a possibility that the PSU is the issue?

I will try to hunt down a spare PSU, although, I don't think a normal one will work and who knows if anyone has one of these lying around.

 

[Wolfshadw]

According to the information I've been able to dig up, you're running the stock SilentX 350 watt PSU. This is a standard ATX power supply, so you should be able to put any standard power supply in there.

-Wolf sends

 

[Kealy]

I think any ATX PSU will work, but now I'm running into an issue with the connectors. The shuttle motherboard has 2 connections, labeled ATX3 (8-pin connector) and CN5 (6-pin connector). These do not seem to be standard connectors. Is anyone aware of a way to connect standard ATX PSUs to these types of connections?

I searched and found that others have had the same question, but with no answers, so hopefully it is possible.

Thanks again.

 

[Kealy]

I've been doing some investigating and have learned alot (thanks to the users here). Here's where I'm at.

So the CN5 connector was just a 6-pin PCI-E connector with the connectors inverted (also called ATX1 pin assignment). The ATX3 connector is an 8-pin slot but this is where I get confused.

Everyone is saying that the ATX3 connector slot is just a typical 8-pin ATX connection, but when I re-wired the PCI-E plug to match the original PSU from the shuttle's 6-pin slot to the "CN5"/"ATX1" (This pinout is 1-3 ground/4-6 +12VSB) and used the 8-pin ATX connector, this wouldn't even power the motherboard.

SO, I got frustrated and started looking for ideas, and thought I would attempt to re-wire the new ATX PSU's plugs, since I read that the stock SN25P PSU has proprietary plugs. Well long story short, someone had posted that the yellow/blue wires can are the same as the yellow only wires and I re-worked the 8-pin ATX connector to match the colors on the original shuttle PSU (substituting yellow wires for the shuttle PSU's yellow/blue ones, which was probably stupid). Now I had my matching 6-pin ATX1 connector and my matching (kind of) 8-pin ATX connector, so I'm totally pumped and ready to go. Everything is great right? WRONG.

I plugged in the newly wired PSU to the motherboard and flipped the switch. There was some crackling and I immediately shut it off. The motherboard still receives power (although is probably shorted, but that's no big deal since I already pointlessly bought another one) but it now immediately starts up the fans, whereas before the power button would need to be pressed.

So essentially I don't care about fixing the motherboard, I'm just wondering if I re-wired things correctly. The PSU from the shuttle (which does not have a pinout map in the manual or anywhere for that matter) has a pinout as follows (from what I can tell from looking at the colors of the wires):

1: PS_ON (green) 5: Ground (black)
2: +12v/-12v (blue/yellow) 6: Ground (black)
3: +12v/-12v (blue/yellow) 7: Ground (black)
4: +12v/-12v (blue/yellow) 8: NC (No wire plugged in)

So I rewired the new 8-pin ATX from 1-4: +12v (yellow) 5-8: Ground (black) to

1: PS_ON (green) 5: Ground (black)
2: +12v (yellow) 6: Ground (black)
3: +12v (yellow) 7: Ground (black)
4: +12v (yellow) 8: NC (No wire plugged in)

And that was when things fizzled and got weird. If nothing else, can someone please tell me what the yellow/blue wires are for and if/why they will/will not substitute as plain yellow wires?

I SHOULD HAVE LET THIS MYSTERY DIE. It is driving me insane and your help would be IMMENSELY appreciated.
Also, sorry for the wall of text.

THANK YOU SO MUCH in advance,
Joe