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820-00875 PPDCIN_G3H at 5v

A

arash

Member
Corrosion was on U2890, U8400, Q8401 and in that area (Possibly under U2800 too). And very little corrosion around U3100.

I get 5.2 Volts on PPDCIN_G3H_CHGR
and 0V at PPBUS_G3H

It doesnt have a short at PPBUS_G3H.

It probabbly is U3100 or U3200 right ?
 
J

JohnB8812

New member
Reflowed U31/200 already? Replace U2890 as it can cause this as well. If no change, inject 3.3 volts into PP3v3_G3H and see if you get any current draw. If so, figure out what is heating as often one of the CD3215s pulls some current (U31/200). If no current draw, do a diode mode reading around both U3100 and U3200 on the 3v3 1v8 etc LDO rails to see if either chip gives a lower measurement.
 
2informaticos

2informaticos

Administrator
Staff member
Be sure all resistors and traces around U2890 are OK.
U2890 needs donor board to replace; is USB-C SPI chip (like a BIOS).
Corrosion could break communication between U2800/90.
That is sufficient to get dead board...
 
A

arash

Member
I did reflow U3100 and U3200.. seems not to have improved anything. I dont have Donor board right now, ill get one and replace U2890 asap and will let you know
 
A

arash

Member
I just noticed, that PP3V3_UPC_XB_LDO (measured near U2890) is constant 3.3V with the USB-C connected to the first connector. However if i connect it to the second one, PP3V3_UPC_XB_LDO Spikes to 3.3V and drops gradually untill it hits zero. Then it gets another Spike and repeats that over and over.
 
2informaticos

2informaticos

Administrator
Staff member
You must be sure about all traces of U2890.
The big problem is some trace goes to U2800 inside the board.

You may also need to change an USB-C controller (CD3215).
 
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