Mac Pro 4.1 Won't Power On

[TECCS]

I've done a bit of work with Macs before but not a huge amount first time working on a mac pro. A customer asked me to look at a Mac Pro 4.1 "that was booting then shutting off and now won't boot at all". I have taken the side panel off to have a look and nothing seems out of place. when i plug the power in the diagnostic lights flash red. i press the power button on the front no signs of life at all. Pressing the diagnostics button makes the 5v light up orange. Any ideas please? I also don't have many apple components to do testing with and can't afford to be buying lots of components in just for diagnostics

thanks in advance

 

[Markverhyden]

Heading out the door so I cannot give you more. Do a search for testing Apple power supplies. They have issues where the trickle voltage dies which prevent the machine from powering up. Similar to testing an ATX where you short a couple of pins to test the rest.

 

[TECCS]

OK Thanks for that

 

[Dustin Hennis]

Having a couple Macs here, make sure the the PSU adapter is connecting properly. Depending on the model, the adapters themselves have a habit of getting the pins/probes pushed back in.