820-00163 2015 MacBook Pro 15" Restarting During Boot

bjf

Member
I can go to the drive-select page, select a known-good test drive, but a few seconds after going to the Apple and displaying the progress bar it restarts. Any idea what might cause a startup loop like this? Slight spill on right side of board toward the display connector, down by the headphone jack and some down by the battery connector. I can't see any sign of corrosion but the sensors are tripped red. No visibly-damaged components. Gave it an ultrasonic cleaning.
 
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bjf

Member
Yes, known-good test drive. The weird thing is that I figured out it boots fine if I disconnect the trackpad. I'm not sure what's happening here. It could be because there's an issue with the trackpad or the trackpad circuit on the board, or it could be that the computer is switching into a decreased performance mode that's changing the way the computer is booting or interacting with the hardware. No clue really.
 

ALB-Repairs

Member
These systems are horrible.

Are you using a 20V power supply?
When i saw this issue occur it was due to a bad battery/unplugged battery. The more items you disconnect the more likely it is to boot, it seems to boot when you unplug power hungry devices such as the trackpad and the screen.

But yeah, try it with another battery, will probably resolve the issue.
 

dukefawks

Administrator
Nothing horrible about them. Also no problems unless you use JUNK Chinese chargers...

Inspect trackpad cable and TP for corrosion.
 

ALB-Repairs

Member
Nothing horrible about them. Also no problems unless you use JUNK Chinese chargers...

Inspect trackpad cable and TP for corrosion.
I stand by what i stated

I actually use a bench supply (tektronix PWS2326) on original charger cables for most my testing. It allows you to easily see how much current is being drawn by the entire system, and quickly narrow down issues (similar to checking rails with diode mode). I see no problem why a good quality bench supply with original apple charger leads would cause any problems.

Anyhow we tested it using several original apple chargers (including the one it shipped with) and still ran into issues with it booting without a battery installed (IIRC)

It also wouldnt make sense that it was my power source as the 2015 15" retina pulls less current than 6Amps, yet it was shutting down during boot until i fitted a new battery.

unless you can state to me exactly why my setup would have caused this issue im not going to believe it.
 

bjf

Member
Thanks for the tips. I'll try working with both ideas presented. It's so hard for me to understand how I keep seeing this issue with this model. I posted this last time: https://www.rossmanngroup.com/board...63-2015-macbook-pro-15-restarting-during-boot

It feels identical. It feels like I have a perfectly good computer as far as measurements and everything else, and then, the restart during boot.

Using a standard 85W genuine adapter.

When it does boot (without trackpad plugged in) I'm seeing a bad battery. Stuck at 22%. Not charging and not working off of it. Weirdly, the keyboard stops working too when the trackpad is unplugged. Odd.

I'll update tomorrow. I have another 2015 Retina 15" showing up tomorrow so I'll have some more parts to mess with. Hopefully I'll have another battery and trackpad/cable to work with.
 

bjf

Member
Well, this is crazy. Using two EMC 2910 (820-00426-A) models I verified that these boards do indeed need a functional battery to work properly. Hard to believe, but here's what I have:
• Tested using 3 different genuine known-good 85W adapters
• 2 boards with no visible damage or corrosion that behave identically
• both fail about 20% into booting. they go into a restart loop. (I did see it boot once, but every other time they would stop booting and restart.)
• both will boot when trackpad is unplugged. (tested this with both trackpads.) also, the keyboard stops functioning for both when the trackpad is unplugged.
• both boot normally when plugged into a good battery

Thanks a ton for the tips. I would have continued to be completely confused about these boards.
 

tlough75

Member
I can confirm this issue is resolved by installing a known good battery. after my own testing, the computer will boot loop without a battery installed, but will boot fine without TPAD cable plugged into LB. Iv'e now had this on 3 devices. I know this is an old thread but I thought it may help someone else if they are having a similar issue.
 

Tony Tone

Member
Yes, known-good test drive. The weird thing is that I figured out it boots fine if I disconnect the trackpad. I'm not sure what's happening here. It could be because there's an issue with the trackpad or the trackpad circuit on the board, or it could be that the computer is switching into a decreased performance mode that's changing the way the computer is booting or interacting with the hardware. No clue really.
Ha, thanx. My trackpad was bad. LOL
 
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