Reviving old computer - PSU works but computer won't turn on.

[Gyppy101]

On my MacBook Pro I can access everything on Windows XP, running in VMFusion, that I can access on the Mac

[Snowwolflair]

On my MacBook Pro I can access everything on Windows XP, running in VMFusion, that I can access on the Mac

You cannot toggle the polarity of bit 4 on the parallel port   

This hardware level control is used by a lot of legacy equipment.

[Bealman]

Having reread the OP, I have a feeling that he does not want to muck around with the household Macs, but wants a stand alone machine for railway purposes.

Perhaps some clarification?

[Snowwolflair]

I use these simple PCs to run parts of my workshop. At £60 they are very good value.

https://www.ebay.co.uk/itm/Thin-Client-T5740-Computer-Pc-Atom-N280-Windows-XP-Embedded-SSD-2GB-Rs-232-VGA/323018824746?epid=14025075583&hash=item4b356c1c2a:g:-U0AAOSwv-xb6bTS

they also do a version with a parallel port.

[Paul-H]

Also check thst the on button is actually working, with a meter.

Paul

how do I test this?

Follow the two wires from the switch to the motherboard, unplug the wires from the motherboard, then with the meter on Continuity (Buzzer) or low resistance put one probe to one wire and the other probe to the other wire at the plug, then press the button, sounder should sound or meter show low resistance, if not then the switch has failed.

If the switch has failed shorting the two pins on the motherboard should fire up the PC.

[Black Sheep]

Having reread the OP, I have a feeling that he does not want to muck around with the household Macs, but wants a stand alone machine for railway purposes.

Perhaps some clarification?

Sure,

Regarding the macs:
The Macbook dates from late 2011 and isn't in the best of health so might have to be replaced (hence not wanting to put too much into an old machine)

The other mac is from 2006 so is obsolete but handy to have (has full Adobe suite)

I'd like to keep as a standalone machine so that I don't muck up another computer or get down a route of setting things up to find something somewhere doesn't do what I need / want it to.

It'd also be nice to see what files etc are on this machine.


Will try testing the switch at some point this week, thanks all for your help so far.

[Black Sheep]

I couldn't get it to fire up bridging the switch wire, however, the IT chap at work suggested stripping out all the extra cards and disconnecting drives so that it's simply power supply and motherboard and see if we get any life

we didn't

so, removed the CMOS battery and popped the multi-meter on it, it happily gives out 1.5v and having put it back in we do have life, it powers up, fans spin, lights come on and long beeps happen

and the long beep keeps happening and I don't seem to get much further!

[Snowwolflair]

I couldn't get it to fire up bridging the switch wire, however, the IT chap at work suggested stripping out all the extra cards and disconnecting drives so that it's simply power supply and motherboard and see if we get any life

we didn't

so, removed the CMOS battery and popped the multi-meter on it, it happily gives out 1.5v and having put it back in we do have life, it powers up, fans spin, lights come on and long beeps happen

and the long beep keeps happening and I don't seem to get much further!

The beeps are a code sequence.  If you can get the manual for the motherboard it will tell you what it means.  No monitor, no keyboard, program the CMOS memory. etc.

Try variously F8, F9, F10 etc as soon as the first beep happens when you power it up and it may load the BIOS configuration screen.

[Black Sheep]

swapped the ram to the adjacent slot and we're up and running

[Railwaygun]

might be worth running a bit of contact cleaner over the memory chip connector- alternatively just leave it alone and make a full disk backup ASAP!! (use a disk cloner (freeware))

[Malc]

Just as a matter of interest, the POST (power on self test) beeps are a function of the bios, not the motherboard. Phoenix bios, AMI bios etc have different combinations of short and long beeps.