Mac Pro Late 2013 (Trashcan) No/Intermittent power

Hi all!

So, I have a 2013 Mac Pro that is currently not powering on on most occasions.

Started off with the obvious, changed power lead, checked RAM was seated, checked that the magnetic cover sensor was working correctly.

The issue manifests in a way where the button usually does nothing, no lights on the panel when power applied and no fans or lighting up when pressing the power button.

There are occasions where you can turn on at the wall (without moving power cable or anything like that - so not a connection issue in the lead) and it’ll suddenly work fine. If direct power from the wall is lost while the machine is off though, then once again you can’t turn it back on when mains is turned back on and it’ll take a while of power cycling from the wall and discharging capacitors by holding the power button down before it’ll start responding.

I did initially think it may be the PRAM battery as it was previously in a studio where at end of night the mains was turned off, so there were a fair few occasions where it would have no main feed.

But, after tearing down and replacing that battery, the issue still persists.

Now i’m thinking it’s potentially either the PSU or the full IO panel itself that is having the issues.

Has anyone had a similar issue before like this and found a cause I may have missed?

Also, does anyone have any values I should be expecting when I get around to testing the PSU properly?

Any insight appreciated.