MP 1,1-5,1 Mac Pro 5,1 (2012) does not start

[moszio]

Dear Friends,

I've had a problem with the mac pro not starting... Only the fans are spinning, there is no start-up sound, when you turn it on, a red led lights up on the memory card for a moment, but then it disappears, I've attached a picture showing that there is a yellow led which is constantly lit. Is the power supply or motherboard cmos battery dead?

5,1, 2012 mac pro

thanks in advance to anyone who has encountered something like this

Best Regards,
Roland

 

[tsialex]

Remove the RTC battery and see if the Mac Pro does anything different. Also, check the BR2032 voltage with a voltmeter.

 

[moszio]

Hi,

I replaced the new battery, nothing happens, I recorded the start-up and the shutdown, these LEDs flash. the yellow led always : 5v stby

Best Regards,
Roland

 

[tsialex]

Hi,

I replaced the new battery, nothing happens, I recorded the start-up and the shutdown, these LEDs flash. the yellow led always : 5v stby
View attachment 2306543



Best Regards,
Roland

All CPU trays does lit that LED on power up.

Did you tried to power up WITHOUT the RTC battery? Also, disconnect all SATA devices, including the DVD and check if you have anything on the display.

If you have access to another Mac Pro, start to test components, first the CPU tray, then the GPU, PSU, etc.

 

[moszio]

Yes, I tried disconnecting everything, but nothing, I'm looking for a donor and will start to find the fault

Thank you very much
Best Regards,
Roland

 

[tsialex]

Yes, I tried disconnecting everything, but nothing, I'm looking for a donor and will start to find the fault

Thank you very much
Best Regards,
Roland

You did not answered if you did removed the RTC RTC battery and tried to power on, doing that bypass the Mac Pro BootROM NVRAM.

Assuming that everything hardware wise is currently working fine, if you remove the RTC battery and then power on your Mac Pro to a grey screen, you have a corrupt BootROM.

 

[moszio]

You did not answered if you did removed the RTC RTC battery and tried to power on, doing that bypass the Mac Pro BootROM NVRAM.

Assuming that everything hardware wise is currently working fine, if you remove the RTC battery and then power on your Mac Pro to a grey screen, you have a corrupt BootROM.

I tried it by taking out the battery and starting it, but it's the same, black screen, no boot sound, and what you can see in the video

 

[moszio]

What is interesting is that I plugged the keyboard in, and after switching it on, the green LED Caps Lock does not turn on, as if the keyboard is not receiving power

 

[tsialex]

A working Mac Pro won't have any DIAG LEDs lit when powering up. All DIAG LEDs are powered off.

While a 5V LED lit could make you think that the PSU is the real culprit, if the CPU tray is bonkers or the BootROM is corrupt, the DIAG LEDs will not work correctly and the LEDs will not give you a reliable indicator of the real fault.

Could be the PSU, could be something connected/installed that is defctive and taking the 5V line off, could be the backplane, could be the CPU tray, could be the BootROM and etc. Get a cheap working Mac Pro and test each one of the parts one of a time.

USB controllers only give power to connected devices if its initialized correctly. For example, some types of BootROM corruption can make the POST fail even before the USB is initialized, so, no power to the USB devices.

 

[moszio]

is there such a thing as a psu tester? or with a voltmeter?

 

[tsialex]

is there such a thing as a psu tester?

Only for standard ATX PSUs (Mac Pro PSU is not ATX) and it's pretty unreliable.

or with a voltmeter?

PSUs can't be tested with just a multimeter, you need load. The only thing that you can see with a multimeter is if a voltage is still present.

The way to test a Mac Pro PSU without lab equipment, like a load and a scope, is installing your suspected one to a working Mac Pro and the working PSU to your defective Mac Pro.

 

[moszio]

Thank you,

is the 4.1 and 5.1 cpu tray compatible?

 

[tsialex]

Thank you,

is the 4.1 and 5.1 cpu tray compatible?

No. You can't use an early-2009 CPU tray with a mid-2010/mid-2012 backplane or vice-versa - SMC firmware mismatch:

• early-2009 = SMC firmware 1.39f5
• mid-2010/mid-2012 = SMC firmware 1.39f11

Both the CPU tray and the backplane have System Management Controllers and the secure microcontroller is not upgrade-able. A mismatched SMC firmware will make all fans to run at max speed all the time and without any software control.

If your intention is just to test the CPU tray with a working Mac Pro, even with the mismatched SMC the Mac Pro will power on - with all fans running like a jet engine on take-off, but it's useful for checking if a CPU tray/backplane still works.

 

[moszio]

Hi, Happy End

The cpu tray was faulty, solved with a replacement
Thanks for the tips