Power issues with my Acer Aspire tc-780, when I turn it off, cannot get it to turn back on.

iamsiaho

I have this old TC-780 that I wanted to do something with.
The problem is, I can power it on and use it, but when I turn it off, I cannot get it to turn back on.
This has happened twice, where I turn it on, use it, and turn it off. And then it won't turn back on. A few days later, I try again, it works, I use it, I power it off, and then it won't turn back on, once again.

I was worried it was a cooling issue, but after removing the cooler, repasting the CPU, and booting it up and running a stress test, temps were fine. So, I turned it off, came back to try something else… and it won't turn on.

I know the issue is not the SSD in it or the RAM, as I have used both in a different system of the same age. I know it isn't the GPU, as it works just fine in other systems. That means it is either power supply, or motherboard.

I'm hoping it's power supply, so I swapped in another (admittedly old) power supply. Same thing. On, working, off… and won't turn on again.

Is this a motherboard issue and is it fixable (maybe a dead CMOS battery or something? I don't know, I'm reaching here, and my hardware knowledge is limited), or should I look at scrapping the system rather than trying to find some way to breathe life into it and keep it out of a landfill?

[Edited the thread to add issue detail]

StevenGen

https://community.acer.com/en/discussion/710766/power-issues-with-my-acer-aspire-tc-780-when-i-turn-it-off-cannot-get-it-to-turn-back-on

The TC-780 comes with either a 220W or a 300W Acer proprietary PSU and its mainboard has the Standard 24-Pin ATX power connector plus an additional 4-Pin ATX power connector. Test the desktop with a new type 24pin PSU that works to assure you that it’s the actual mainboard and not the PSU. Change bios battery and reset CMOS too see if that helps like below:

Clear CMOS

So unplug ALL of the wiring coming from the case front I/O and switches to the motherboard, after unplugging and switching off the PSU, then, plug the PSU back in and switch it back on. Now, attempt to start the system by jumping the two power pins that the switch from the front of the case WAS previously connected to. Once it powers up and boots, shut it back down and try to power it up again WITHOUT switching off the PSU, by jumping the pins again. You can jump the pwr pins to turn and to turn off, if you don't wish to complete the boot process each time just for verification. If the system does not want to power on, even with those connections unplugged, by jumping the power pins after the first try, without switching off the power supply again, then it could be a bad switch on the front of the case, if not then it would have to be either the PSU or the motherboard and unfortunately in order to determine which of those it is you pretty much have to swap in a different PSU or motherboard to eliminate one of them, bench testing the mainboard can be very helpful too for this faulty. Try all the above out and see if you can diagnose the problem. Good luck and hope this has helped you out.

Here is the TC-780 mainboard layout so it can assist you what to check, I've highlighted the ATX power plugs:

If this answers your question and solved your query please "Click on Yes" or "Click on Like" if you find my answer useful👍