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A1989 820-00850 Fan spin, no boot

A

adrko

Member
820-00850 board, zero signs of corrosion or any damage

Without the battery:

20V 0.135A - slowly rising to 225-230mA as the fans spin faster
Nothing heating up, CPU not even warm
T2 doesnt warm up

PPBUS_G3H 12.58V

PPVDDCPU_AWAKE goes as follows when plugging in power:
0.75V --> 0.51V --> 0.89V --> 0.51V
Stays at 0.51V

With battery connected:
1-2 seconds of fan spin then stop
power cable plug in sound
PPBUS_G3H drops to 12.30V and rises slowly to around 12.45-12.54V eventually goes back up to 12.60V
It was left to charge earlier for around 20-30 min so its not completely flat
Fans do not spin this time
Judging from power consumption the battery is being charged

I have tried another topcase and battery


What am I missing here?
Or should I just leave it and move on?
 
A

adrko

Member
Hello
Thanks you for your reply, I have tried dfu in every possible configuration and option, error messages stating that there’s a problem with communicating with the chip - which is T2 from what I understand

and if the voltage powering T2 doesn’t go to values specified in the schematics the chip doesn’t power on?

I’ve compared voltages with identical board which is probably also having issues that require restor(but I’m getting in that one other error messages)

volatges on the other board go to 0.75V which is a value that’s specified in the schematics and on this one T2 warms up slightly
 
A

adrko

Member
Also I’m waiting for the usb chipmunk to arrive, I don’t know any other way to check for usb activity
 
2informaticos

2informaticos

Administrator
Staff member
Read this first; about DFU and USB activity...

HOW TO collection

I hope this "How to" collection will help our members. I will possibly modify this post in time, if updates available. Trigger SMC_ONOFF_L (PMU_ONOFF_L): It reffers to simulate power button function, when the keyboard is not connected. We need to do this when we work with the board...
boards.rossmanngroup.com
 
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