Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

MP 1,1-5,1 I need help, I have a problem that I don't understand.

A

AlejandroPeralta2019

macrumors newbie
Original poster
Oct 31, 2019
10
3
Argentina
Hello everyone, I need help to understand what's happening to me.

I have a Mac Pro 5.1 mid 2012;

This Mac Pro forgot the time every time I unplugged it from the power cable, and it also turned on by itself without pressing the power button.

Then it is most likely that the motherboard battery is expired.
It occurred to me to replace the battery with a new one and when I put it in the motherboard the Mac didn't start anymore. I put the old battery back in and it turned on.

I measured the batteries with a multimeter to see if I found anything strange.

The original battery was 0.48 volts, clearly expired.

The new battery that I had inserted had 2.80 volts, which means that it is in optimal condition. ..

However, the Mac turned on only with the battery it came with from the factory.
Looking at the original battery I noticed a detail, the original battery had the following written "BR2032" from the "Panasonic" brand; However, the battery I bought had "CR2032" written on it.

Researching on the internet I read that the difference is the compound with which they are made.
My question is why it does not work with a normal battery, or one that is easy to obtain like the "CR" ones since they are the same volts, 3 volts.

After searching throughout my city for a battery similar to "BR2032" I did not find anywhere that has them.

To my surprise, I returned home, put in the original battery and the Mac did not turn on. At that moment I thought that the problem was something more than the battery, but when I measured it I realized that it had discharged more (0.28 volts), so Leave it on the motherboard connected to the power;

I discovered that the motherboard, even if it is turned off, charges the battery.

So I think that the battery has to have a minimum charge for it to turn on the device?

The question is what is happening to me,
Should I get a battery exactly the same?
I see that a "BR2032" is not common

PS: I read the Mac Pro 5.1 manual; Keep in mind that there are a series of diagnostics to determine faults in the computer, I don't have any, when connecting Enegila the red LEDs turn on briefly as they should.
Also press the diagnostic button on the motherboard and an amber LED lights up, which is correct, and I don't have any red lights on the second board with processors, etc.

The device turns on randomly. Now I can get the device to turn on. Maybe the battery is charged? Or is the voltage balanced? I don't know. ..


Thank you very much, I await answers.
 

Attachments

  • 129825107-40.jpg
    129825107-40.jpg
    100.1 KB · Views: 123
AlejandroPeralta2019 said:
The new battery that I had inserted had 2.80 volts, which means that it is in optimal condition. ..

However, the Mac turned on only with the battery it came with from the factory.
Looking at the original battery I noticed a detail, the original battery had the following written "BR2032" from the "Panasonic" brand; However, the battery I bought had "CR2032" written on it.
Click to expand...

A Mac troubleshooting website I follow, TidBITS, has a recent discussion about PRAM batteries you might find helpful:
talk.tidbits.com

Waking up a dead old iMac?

I’m trying to help a friend with an old iMac. I’m not exactly sure how old it is, but from looking at old emails my best guess is that it might be from 2009. He rarely used it (he mostly uses his iPhone and iPad) but had been turning it on regularly until 6 months ago. I’m not sure what for and...
talk.tidbits.com talk.tidbits.com
 
  • Like
Reactions: AlejandroPeralta2019
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
  • Like
Reactions: MarkC426 and AlejandroPeralta2019
A CR2032 will work ! Make sure it’s a fresh unused device. Your old battery is gone south eons ago.
The current needed by the NVRAM is pretty low and the BR2032 battery type will deliver the needed current way longer - it has the ability to do this at higher temperatures.
The CR2032 will only last for 1 to may be two years depending on the usecase.
Most IMPORTANT is to reset the NVRAM ! Likely it is corrupted because of undervoltage. Do a DEEP NVRAM RESET - you should hear the boot chime FOUR TIMES.
The NVRAM battery is not charged by the logicboard/PSU.
If you have to measure the voltage of these batteries, you should do it under load (only if you are used to work on pcbs like the logicboard). 2,8V are a low voltage for a new CR2032 with no load.
 
  • Like
Reactions: AlejandroPeralta2019
You should find the Apple Technician Guide for you cMP5,1. Do a search for it. Not being smart because you wont find it here. It has detailed steps to troubleshoot your mac Pro. Invaluable. Read why you wont find it here.

forums.macrumors.com

Apple Documentation links for all the Mac Pros

Today Apple reformulated the support and documentation pages for all Macs and started to consolidate all the documentation and downloads for each one of the Macs to it's own page, making it easier to find all the pertinent info like tech specs, firmware updates, user guides, service manuals and...
forums.macrumors.com forums.macrumors.com
 
For what it's worth, I am able to buy these from a local Interstate Batteries store for $3.99 ea. (in the U.S., at least). Not sure where you are, but this store has saved me many, many times! They also carry the old 3.6v Lithium PRAMs for my vintage Macs. Good luck!
 
After many hours of thinking and reading the manual, I have come to the conclusion that it is possible that my problem has more to do with the Power Supply.

One question, in the manual it talks about a button called (Diag LED), when you press it, LED lights come on that tell us if certain protocols work.

When I plug the Mac Pro into power and press the button with the computer off, only the 5V STBY LED (amber) lights up.

The PSU PWROK LED (green) does not light up.

It is normal?


As I told you, the computer turns on almost randomly, on one of those occasions I also pressed the diagnostic button but with the computer on, and the green LED lit up along with the amber one; but the equipment was on. ..
 
Have you done a parameter reset (NVRAM)?
I suspect that with the drained battery the system evaluates the stored data as invalid and ignores it (perhaps using factory default). With a new battery it might happen that garbled contents are taken as boot/initialization parameters and system will not even turn on.
Try the following: Insert new/fresh battery, unplug power AC cable, press "on/power" button for >20s, hold button and reconnect AC cable while power button still pressed. Release power button an press it again.
(Alternatively, you can try the second mainboard button (not the diag but on upper right corner near PCIe slots) while AC is connected).
 
  • Like
Reactions: AlejandroPeralta2019 and Macschrauber
AlejandroPeralta2019 said:
After many hours of thinking and reading the manual, I have come to the conclusion that it is possible that my problem has more to do with the Power Supply.

One question, in the manual it talks about a button called (Diag LED), when you press it, LED lights come on that tell us if certain protocols work.

When I plug the Mac Pro into power and press the button with the computer off, only the 5V STBY LED (amber) lights up.

The PSU PWROK LED (green) does not light up.

It is normal?


As I told you, the computer turns on almost randomly, on one of those occasions I also pressed the diagnostic button but with the computer on, and the green LED lit up along with the amber one; but the equipment was on. ..
Click to expand...
Larsvonhier said:
Have you done a parameter reset (NVRAM)?
I suspect that with the drained battery the system evaluates the stored data as invalid and ignores it (perhaps using factory default). With a new battery it might happen that garbled contents are taken as boot/initialization parameters and system will not even turn on.
Try the following: Insert new/fresh battery, unplug power AC cable, press "on/power" button for >20s, hold button and reconnect AC cable while power button still pressed. Release power button an press it again.
(Alternatively, you can try the second mainboard button (not the diag but on upper right corner near PCIe slots) while AC is connected).
Click to expand...
Do a DEEP NVRAM RESET ! Use a fresh (known good battery - CR of BR won’t matter).
The deep NVRAM RESET will toggle the SMC to be reset too.
A corrupted NVRAM because of battery undervoltage is a known behavior of a Mac Pro of that era.
The GREEN PWROK LED will only light up if the PSU is powered up - all voltage rails are checked by a logic circuit under load.
A faulty PSU can occur after the years - most likely because of dried out electrolytic capacitors.
The computer will most likely shut down or show erratic behavior under higher load.
The symptoms you described are a typical for a corrupted NVRAM and a confused SMC (the SMC controls the power on sequence with parameters stored in the NVRAM).
 
  • Like
Reactions: AlejandroPeralta2019
Larsvonhier said:
Have you done a parameter reset (NVRAM)?
I suspect that with the drained battery the system evaluates the stored data as invalid and ignores it (perhaps using factory default). With a new battery it might happen that garbled contents are taken as boot/initialization parameters and system will not even turn on.
Try the following: Insert new/fresh battery, unplug power AC cable, press "on/power" button for >20s, hold button and reconnect AC cable while power button still pressed. Release power button an press it again.
(Alternatively, you can try the second mainboard button (not the diag but on upper right corner near PCIe slots) while AC is connected).
Click to expand...

Ladies and gentlemen, we have a winner, thanks to this sequence of steps that my colleague described, I have managed to get the Mac to start with the new battery.

I want to emphasize that nowhere does the sequence described by the colleague appear. Not even in the Mac Manual..

Thank you very much, you really saved me.
 
  • Like
Reactions: macsforme, Larsvonhier and leifp
AlejandroPeralta2019 said:
Ladies and gentlemen, we have a winner, thanks to this sequence of steps that my colleague described, I have managed to get the Mac to start with the new battery.

I want to emphasize that nowhere does the sequence described by the colleague appear. Not even in the Mac Manual..

Thank you very much, you really saved me.
Click to expand...

Seems you missed page 32:

Screen Shot 2024-03-31 at 15.36.35.png
 
  • Haha
Reactions: AlejandroPeralta2019
priorytools said:
Can you please make available as pdf for download?
Click to expand...

Sorry, not allowed, more info here:

forums.macrumors.com

Apple Documentation links for all the Mac Pros

Moderator Note: Just to follow up on what @tsialex mentioned, the public Apple URLs in the OP are fine, but posting links to non-publicly released Apple tech docs would violate the forum rules. If anybody has more questions about this, please use the contact us link. Thanks
forums.macrumors.com forums.macrumors.com

If you search enough you will find it.
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back