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820-00928-A A1707 15" TouchBar pulling [email protected]

Melvinzill

Melvinzill

Member
Hi, have this Touch Bar Board here I'm having trouble diagnosing. It pulls a steady 0.015A at 5.2V but never jumps to 20V. PP3V3_G3H is missing, but the Enable on Pin 10 of U6903 is present at 5.4V. Anyone know how to proceed? This is one of my first TouchBars I'm working on so I'm not that experienced with them at all...

Thanks!
 
2informaticos

2informaticos

Administrator
Staff member
Missing 3V3_G3H, board will never start.

Check diode mode at 3V3_G3H first.
If no short (nor low value), post U6903 voltages.
 
Melvinzill

Melvinzill

Member
Diode Mode on PP3V3_G3H measured at R6923 is .397 and Voltages at U6903 are:


Pin 1 - 0V
Pin 2 - 0V
Pin 3 - 0V
Pin 4 - 0V
Pin 5 - 0V
Pin 7 - 0V
Pin 8 - 0V
Pin 9 - 0V
Pin 10 - 0V

It in fact doesn?t have the enable on Pin 10. I think I confused R6920 with R6921. Sorry! Mistakes sometimes happen though...
 
2informaticos

2informaticos

Administrator
Staff member
All pins MUST have the same voltage.
Do you really have 0V at R7022???

Check R6920 and D6902.
Post diode mode to ground at C6905/06.
 
Melvinzill

Melvinzill

Member
Correction: Its 5.1V. Don't know what I did there...

At R6920 its 5.3V at D6902 its 5.3V at Pin 1 and 3, Pin 2 (PPBUS_G3H_R) is 0V
 
2informaticos

2informaticos

Administrator
Staff member
Try now...

"Voltages at U6903 are:
Pin 2 - 0V
----------------------
D6902 its 5.3V at Pin 1 and 3"

"Pin 2 - 0V
------------------------------
5.3V at Pin 1 and 3"

"Mentioned points are in the same power rail."

Sorry for confusion; I forgot to mention pin 3/D6902 before...
 
Last edited:
Melvinzill

Melvinzill

Member
Remeasured everything....


D6902:
Pin 1 - 5.4V
Pin 2 - 0V
Pin 3 - 5.3V

Very interesting, the board briefly went to 20V at .161A for 60sec before going back down to 5. But now its no longer drawing .020A but 0.15A...

While it was at 20V I got these readings:
U6903:
Pin 1 - 0V
Pin 2 - 5.2V
Pin 3 - 3.5V
Pin 4 - 0V
Pin 5 - 0V
Pin 7 - 0V
Pin 8 - 5V
Pin 9 - 1V
Pin 10 - 2.78V


Also I noticed these reads vary a lot depending on which port I use that's why my readings are so inconsistent


I found out:

1st Port - [email protected] - Initially also 0.155 with a warm CD3215 but after letting it sit it went to this
2nd Port - [email protected] and a warm CD3215 chip
3rd Port - [email protected] and a warm CD3215 chip
4th Port - [email protected]


Also the Voltage on D6902 and U6903 vary depending on the port. Should I post the voltages for D6902 and U6903 for every one of the 4 ports?

Any idea what could be causing this big mess?
 
2informaticos

2informaticos

Administrator
Staff member
Different behaviour on USB-C ports indicates that one CD3215 chip is damaged; the most probably reason.
Compare diode mode readings, on their LDO outputs, between all them.
 
2informaticos

2informaticos

Administrator
Staff member
There are 3 types of LDO outputs; check all them.
Use external names for these lines, not the ones inside chip marking...
 
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