Pentium 3 machine

Quadko · Post by **Quadko** » Tue Sep 23, 2014 12:23 pm

Yes, those pics came through fine. Looks sharp, hope you can get it working!

I don't see anything obviously wrong (unlikely that we would!), only new suggestions I can think of:

1. Unplug every cable, make sure contacts are clean (blow with canned air for sockets and pin connectors, carefullywipe with qtip and rubbing alcholol for card edge connectors like memory and cpu and let dry) and plug firmly but gently back in

2. I second Rwolf's comment about trying without the memory; MBs are supposed to give an error but still at least minimally power on without memory stick.

3. if possible, try a different PSU just in case

4. Replace the battery and make sure the old one didn't leak - dead battery <i>shouldn't</i> stop bios boot, but you never know

5. The power supply connector looks odd to me, but it's been a while since I've peeked into a case from that generation. Normal double-check "stupid" questions: is it plugged in backwards (if even possible), firmly, and all the pieces plugged in?

6. Another "stupid" double-check question - any chance the 'reset button' pins are shorted, so it's waiting "for the user to let go"? That can also potentially happen if power and reset buttons are swapped, depending on the type of buttons... Again, it's been a while for me.

7. And is the pc speaker plugged in? I can't tell. If the motherboard is reporting a "boot beep error" but no speaker, you might not hear it.

Longer list than I expected.

I didn't check, have you tried asking the hardware experts over at http://www.vintage-computer.com/vcforum/forum.php - it's an even better forum for this question and I highly recommend it. Well worth waiting through the newbie post approval process.

Derps · Post by **Derps** » Tue Sep 23, 2014 12:56 pm

Well, thanks again for the quick response.
The problem is the cpu cooler fan doesn't even try turning on and there's a light in the power button itself so even if you press it, it should turn on right? I also tried unplugging the front io and manually shorting the pins for power. Nothing happened. The battery also didn't leak. I'm going to try using canned air to clean the connections. Thanks a lot for your help, i appreciate it.

Rwolf · Post by **Rwolf** » Tue Sep 23, 2014 1:47 pm

I see it's an actual PIII, so then the spec page I found was wrong for the model of PC.

(I think DELL also used to reconfigure their high-end machines without changing the designation, so the exact specs varied a bit through the years, maybe this is why.)

I know that DELL at about that time had custom power supply pinouts for their motherboards back then, so getting a replacement PSU could be tricky; not sure the fittings were compatible with standard ATX supplies either, but there might be a blown fuse inside if the PSU won't start.

I'd look at the power supply first, to make sure it's in working order, then the rest.
You need to find out the power-on pin on the PSU connector, and have a load hooked up, like a harddrive on its own, only used to give a minimum +5V load.
Grounding the power_on should start the PSU if it's not broken.

Try to identify the correct pins by looking at the images matching your connector.
this is the standard ATX, 20/24 pin versions:
https://en.wikipedia.org/wiki/ATX

This is a DELL ATX pinout, which seems to match your setup, notice the red/black alternating layout for +5V:
http://pinouts.ru/Power/dell_atxpower_pinout.shtml

The power_on is the grey wire according to the latter webpage.

If the PSU won't power up, you may need a replacement.
(messing inside a PSU is not recommended, as it's high voltage)

There were 3rd party adapters to replace the DELL psu:s with standard ones...though power requirements has changed a lot since these were the norm, an off the shelf psu from today may not work in that chassis due to too low +12V loading, which is the main rail nowadays - I haven't tried such a mix myself, as I tend to keep old spares.
(Back them, the main rail was +5V)

ps: this post may belong in the hardware section

Derps · Post by **Derps** » Wed Sep 24, 2014 6:41 am

Thanks, and I know it should have been put in the hardware section. I just didn't see there was one...

Derps · Post by **Derps** » Wed Sep 24, 2014 6:42 am

I'll have a look at it once i get home.

Derps · Post by **Derps** » Sat Sep 27, 2014 5:35 am

Sorry for the late reply, i didn't have any time.
I connected the grey and black wires and it turned on(tested with cd drive) but when i try turning on the pc, still nothing happens.

Rwolf · Post by **Rwolf** » Sat Sep 27, 2014 11:43 am

Did you try it with everything taken out, even the single memory stick?

At least the power supply is not dead, so it's a start.
(If you have a DC voltage meter, you could verify the respective voltages too, with the power supply on it's own, just to be sure)

ESD (static discharges) is a common killer for electronics, or overheating from failed cooling.

There could be a short on the motherboard as well, sometimes the electrolytic capacitors start swelling & leaking when they age, but that is often visible as goo around them.
(On your pics they look fine though)

There could be something shorting it on the underside, or something that has fallen off due to poor soldering - mind you, most small components gets glued on in addition to soldering. Mechanical stress on solder joints can cause breakups, but are hard to spot without a microscope.

I assume you have not removed the motherboard completely, and the fastenings for it are original, check that the snap-fasteners are ok, otherwise these are grounding points that can cause shorts if misaligned.

Worst case, you have a dead motherboard, though similar retired PC:s would not be too expensive to find, maybe ask some local company if they have something ancient they are planning to retire?