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820-00281: Not powering up. PPDCIN_G3H is 5.19v

M

macRepairAmb

Member
Hello
any help will be much appreciated. 820-00281 logic board not powering up.
PPDCIN_G3H measures 5.19V
Found corrosion on CC773,CB211,CC772. Replaced all with the same result. Also replaced U7000.
PP3V3_S5_SMC_VDDA: 3.4v
PP20V_USBC_XA_VBUS: 5.19V

No other corrosion seen anywhere else.

Any suggestion.
 
2informaticos

2informaticos

Administrator
Staff member
The board has 4 USB-C controllers (CD3215A).
SMC needs to talk with all 4 before activate the full charger voltage.
U2800 and UB000 also should work.
If SPI chip U2890 cannot be accessed, you can't get more than 5.2V.
Bad thing is that SMC will not allow U7000 to generate PPBUS_G3H, even it can work with only 5V.

Compare resistance to ground on similar lines around the 4 CD3215A.
Not only power rails, compare data lines too.
Probably only one port is damaged...
Try first to reflow affected areas, using quality flux, to burn crap.
 
M

macRepairAmb

Member
There was corrosion near U3100. When i plug the charge to that port, PP3V3_UPC_XA_LDO starts to cycle between 3.4v and 0.9v. When i plug to the second usb-c port on the same side, PP3V3_UPC_XB_LDO
holds at 3.39v.

And resistance reading not finding any shorts. But going to keep checking the lines.
 
J

JohnB8812

New member
Yeah best to check now for signals near U3100. Compare PP3v3_G3H, PPDCIN_G3H and all of the LDO signals 3v3 1v8 etc around U3100 to the other 3 CD3215 chips. My guess is one of your lines will be being pulled low near one of the chips by either a cap or a CD3215
 
M

macRepairAmb

Member
Sorry took so long to respond. Was out of town.

In diode mode:
U3100 and UB400
PP3V3_UPC_TB_LDO/PP3V3_UPC_XA_LDO has a zero reading. Resistance mode measures about the same with the other 2 chips, high resistance in the 1M range.

Wondering if i should replace U3100 which is close to the capacitors i found corrosion on?
 
2informaticos

2informaticos

Administrator
Staff member
"PP3V3_UPC_TB_LDO/PP3V3_UPC_XA_LDO has a zero reading."
Do you mean 000, or OL?
You cannot read high resistance in a zero reading line...

Crap under U3100 can block the controller.
But you must compare readings for all controllers in more points, not only two.
 
M

macRepairAmb

Member
Correction it was OL. And i did check other lines and compared them between all 4 CD3215, and they were all comparable except the two mentioned.
 
2informaticos

2informaticos

Administrator
Staff member
OL doesn't mean zero at all...

You get differences at U3100 for that two lines comparing with the other 3 chips?
In such case change U3100.
You can try a reflow with quality flux first.; in case there is crap underneath.
 
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