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ElectroMan wrote:

Here is the power connector specs for the mobo: (Remove) Also, according to the mb guide, it complies with ATX12V 2.01 standards […]
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fitzpatr wrote:

Any chance that this board requires -5V? It is an early ATX implementation, and Intel could be a stickler.

Here is the power connector specs for the mobo:
(Remove)
Also, according to the mb guide, it complies with ATX12V 2.01 standards, and the PSU has backwards compatibility with 2.01+.
Nothing on -5v specifically, but have it on my "the last resorts" list, though seemingly a few people confirmed this (very similar) board works for them with a new PSU no probs.

I'll ask the seller what exact PSU he used to test it.

This is a tough one! I did read both of those documents.

Incidentally, you're right about the nice features of the board. With a fully featured one, throw in a Voodoo1 and you're done!

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ElectroMan wrote:

fitzpatr wrote:

This is a tough one! I did read both of those documents.
Incidentally, you're right about the nice features of the board. With a fully featured one, throw in a Voodoo1 and you're done!

Thank you very much for trying to help with it. It's like I felt each and everyone's pat on my shoulder in these sorrowful days of mourning.

Yeah, the damn thing is nice, makes my tears that much bitter. Voodoo1 - that was the plan.

Happy to help. Hope isn't lost, yet. I've found reference online that normal modern PSUs should work fine.

J9C1-A should probably be set to 2-3, rather than 1-2.

You'll need someone more knowledgeable than me to get you farther, though. For what it's worth, you've done a lot of very good steps.

To summarize for anyone else that views this thread:

Specifications:
Motherboard: Intel AN430TX
CPU: Pentium 233MMX (also Pentium 133)
Power Supply: Multiple, both tested good.
RAM: Multiple Tried.

Situation: No signs of life when shorting PS_ON. PSU fan does not spin.

Actions Taken:
-Testing on wood, bare minimum configurations.
-Jumpers verified correct.
-Multiple processors and multiple PSUs made no difference. Verified correct in other system.
-CMOS Battery replaced.
-Changing CPU Voltage setting.
-Tried with and without CPU fan

My suspicion: A short is causing the Power Supply to enter a Short Circuit Protection state.
Alternate is that there is no voltage at PS_ON to begin with.

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ElectroMan wrote:

Alright, something new. While I'm expecting to get a multimeter this week, I tried this trick - shorted PS_ON with HDD activity diode from ATX case. To my amusement it turned red. Can I extract any meaning from the experiment? Is it better or worse for the overall forecast?

I understand that I probably more or less have 5V on PS_ON after all. Does it mean something is likely shorted on the board? I looked all over it with a magnifying glass for over an hour.

It most probably means that means that
- there is no ground on one of the PS_ON pins on front panel connector
- or the multiIO chip is dead, or almost dead
- or something in wrong with the traces connecting PS_ON pins to multiIO chip or ground
or combination of above.

Try shorting PS_ON pin from front panel connector directly to the ground from your PSU with a wire. There are 2 pins so try both, one of them is supposed to be ground, the other one is the PS_ON signal from multiIO chip, pulled up to +5V

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ElectroMan wrote:

Direct Ground does not help.

This actually is very interesting. So your computer DOES power on when you connect PS_ON and HDD_LED pins, but not to ground?
Can you measure what is present on a HDD LED pin you connect PS_ON to when starting the mobo?
I still think multiIO is dead, but the fact that it powers on from HDD_LED is really interesting!

GPA wrote:

This actually is very interesting. So your computer DOES power on when you connect PS_ON and HDD_LED pins, but not to ground? Ca […]
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ElectroMan wrote:

Direct Ground does not help.

This actually is very interesting. So your computer DOES power on when you connect PS_ON and HDD_LED pins, but not to ground?
Can you measure what is present on a HDD LED pin you connect PS_ON to when starting the mobo?
I still think multiIO is dead, but the fact that it powers on from HDD_LED is really interesting!

I believe that he meant that he could illuminate an LED by connecting it to the PS_ON +5V and the ground of another pin, not that the system powered up.

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There are 3 main reasons why motherboard would not start by shorting PWR_ON pin on it:

1. CMOS jumper set to CLEAR;
2. Bad southbridge (82371AB in your case) which has all the power control circuitry integrated in it;
3. Something is shorting.

You can check wether something is shorting or if southbridge is bad by connecting PSUs PS_ON wire to ground while it is connected to motherboard, that will force PSU to start no matter what. If southbridge starts heating up to the point where you won't be able to hold your fingers on it - it's dead, if southbridge is OK, try tracing other parts that might dissipate a lot of heat.

It's also possible that CPUs linear power regulator (thing on a big heatsink) might be shorted.

Did you end up getting that multimeter you mentioned earlier?

SSTV2 wrote:

There are 3 main reasons why motherboard would not start by shorting PWR_ON pin on it: […]
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There are 3 main reasons why motherboard would not start by shorting PWR_ON pin on it:

1. CMOS jumper set to CLEAR;
2. Bad southbridge (82371AB in your case) which has all the power control circuitry integrated in it;
3. Something is shorting.

You can check wether something is shorting or if southbridge is bad by connecting PSUs PS_ON wire to ground while it is connected to motherboard, that will force PSU to start no matter what. If southbridge starts heating up to the point where you won't be able to hold your fingers on it - it's dead, if southbridge is OK, try tracing other parts that might dissipate a lot of heat.

It's also possible that CPUs linear power regulator (thing on a big heatsink) might be shorted.

I had read elsewhere that the voltage regulator did run exceptionally hot. That is actually what my instincts are telling me is the culprit here.

The power supply still would not power up if there is a short, even if you bypass the southbridge. I concur with proceeding in this manner.

fitzpatr wrote:

The power supply still would not power up if there is a short

It would, as long as PSU would be able to handle the load.

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You were supposed to test motherboard using this method completely bare 😳. Test it again without any other component in it and see if CPUs voltage regulator still heats up, if it does - there is your problem, because it should not heat up w/o load (CPU).