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MP 1,1-5,1 Mac Pro 5,1 not starting

D

dmtr

macrumors newbie
Original poster
Nov 14, 2023
7
0
I have a Mac Pro 5,1 that stopped booting. (no fans, no chime)
plugging / unplugging PSU make red LEDs quickly blink as it is expected.
DIAG button only shows yellow 5V LED
Power button doesn't do anything.
Shorting sys_pwr (vertically or horizontally) doesn't do anything also

What I've tried already:
removing RTC battery
pressing power button for a long time without PSU powered
removing all RAM
removing everything and trying to boot at minimum configuration
cleaned up boards

I'm wondering if it is the corrupt bootrom issue.
Any ideas?
Thank you

PS: Thanks @tsialex for all the info shared in this forum, I've been reading a lot in the last few days.
I have some skills in electronics, I'm able to desolder rom chip, retrieve info and re-record it if needed


Code: 
  Model Name:	Mac Pro
  Model Identifier:	MacPro5,1
  Processor Name:	Quad-Core Intel Xeon
  Processor Speed:	2.4 GHz
  Number of Processors:	2
  Total Number of Cores:	8
  L2 Cache (per Core):	256 KB
  L3 Cache (per Processor):	12 MB
  Memory:	56 GB
 
From what you wrote, seems more a dead PSU. Did you tested the PSU with a known working Mac Pro?

Did you tested the CPU tray with a known working Mac Pro?

Did you removed or disconnected all SATA drives including the DVD? Defective/short circuited SATA drives can make the Mac Pro behave as a defective PSU.

If the PSU works with another Mac Pro and the EFI_DONE diag LED is not lit when you press the DIAG button, could be a dead SPI flash or worse.
 
Thanks. I live in a remote area. no other Mac Pros 5.1 around to swap parts.
I've checked again DIAG Leds and there is no EFI_DONE LED.
I've removed all drives including DVD. I'll inspect the connectors.

I've been using 10.13 and Ubuntu prior to the crash. I've tried installing Windows once but I didn't know it was a problem. didnt succeed.
it used to work OK, but the last 6 months before stop the computer refused to boot intermittently. Some days it would just work, others not.
 
dmtr said:
Thanks. I live in a remote area. no other Mac Pros 5.1 around to swap parts.
I've checked again DIAG Leds and there is no EFI_DONE LED.
I've removed all drives including DVD. I'll inspect the connectors.
Click to expand...

I'm afraid that you won't diagnose it correctly until you get a working Mac Pro to test each part one at a time to eliminate what is working or not.

dmtr said:
I've been using 10.13 and Ubuntu prior to the crash. I've tried installing Windows once but I didn't know it was a problem. didnt succeed.
it used to work OK, but the last 6 months before stop the computer refused to boot intermittently. Some days it would just work, others not.
Click to expand...

This seems a PSU or power related issue.
 
Ok I've turned the PSU on outside of the computer, and jumpstarted by shorting two pins (2.7v and switch wire) so I can hear the solenoid clicking on and off.
When PSU is ON I can hear a faint "cricket" sound from inside the PSU (very high pitched as in old tube television, about 4 chirps per second)
With the PSU on it reads 12.2, 12.3v in the main bus.
I know it doesnt mean a lot but I'm puzzled about why the main board doesn't even turn on the solenoid (not by power button or shorting terminals on board)
 
SMC manages the PSU, if anything is wrong, it will not power on. Anyway, it's practically impossible to test a Mac Pro PSU without a working backplane/load. Get yourself a cheap working Mac Pro, test everything and sell the parts that you not going to use, you will probably make money with that.
 
tsialex said:
SMC manages the PSU, if anything is wrong, it will not power on. Anyway, it's practically impossible to test a Mac Pro PSU without a working backplane/load. Get yourself a cheap working Mac Pro, test everything and sell the parts that you not going to use, you will probably make money with that.
Click to expand...

So the problem can be other than the PSU in this case right? maybe the bootrom issue you addressed many times before?
 
dmtr said:
So the problem can be other than the PSU in this case right? maybe the bootrom issue you addressed many times before?
Click to expand...

Unless the SPI flash memory is dead, it's not the BootROM that is causing this, since most Mac Pro with a corrupted BootROM can still power on with the power button/pads.

It's not impossible that is the BootROM/SPI flash, but it's unlikely. Can be anything, that's why it's easier and cheaper to buy a test mule. Defective CPU tray, PSU, south bridge dead…
 
I'm ok with taking the risk of shipping.
I have the original box with styrofoam which protects. anyway it is not working.
Is there any way of contacting you directly here?
 
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