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SOLVED - 820-01521 (A1932 2019) 5V 0.16-0.20A

J

jadao

Member
Got this logicboard with liquid damage, initially both CD3215 were shot, first one with one LDO shorted and second one with PP1.8V_SLPS2R shorted and an LDO shorted. First port was 5V 0A, second port was 5V going 0.2 to 0.43A. Replaced both CD3215 and I have no more short.

Board is now stuck at 5V 0.16-0.20A

Tried a DFU but the board is not detectable.

Here are all the voltages I noted:

PPBUS_G3H 12.3v
PP3V3_G3H_RTC 3.3V
PP3V3_G3H 3.25V
PP5V_G3S 0V
PP3V3_G3S 0V and P3V3G3S_EN missing
PP1V8_G3S 0V

L7806 0.771V PVDDCPUAWAKE_SW0
L7807 0.753V PVDDCPUAWAKE_SW1
L7808 0.753V PVDDCPUAWAKE_SW2
L7809 0.753V PVDDCPUAWAKE_SW3
L7810 0.822V PVDDCPUSRAMAWAKE_SW0

L7811 0.845V P0V8SLPDDR_SW0
L7812 0.822V P0V8SLPDDR_SW1
L7813 1.802V P1V8SLPS2R_SW0
L7814 1.1V P1V1SLPS2R_SW0
L7815 1.1V P1V1SLPS2R_SW1
L7816 0.905V P0V9SLPDDR_SW0
L7817 0.901V P0V9SLPDDR_SW1

L7819 0V PVCCPCOREPRIM_SW0
L7820 0V PVCCPCOREPRIM_SW1
L7821 0V P1VPRIM_SW0
L7822 0V P1VPRIM_SW1

L7823 0V P0V9SSD_SW0
L7824 0V P1V8SSD_SW0

Thanks in advance
 
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J

jadao

Member
No liquid at all on the audio board/flex and I also tried with another audio brd/flex just to discard any issue but no difference.

While I was going to measure the diode mode as you asked me to do I charged the battery with another test board and surprisingly the patient board is now booting correctly with a charged battery...
However my usb adapter is not lighting on at all, no external usb mouse or external keyboard.

So my issue now is non charging board and no usb/accessory detected ports. I don't know if it's simply related to my CD3215C00 soldering job (although diode mode readings seem fine). when booted in macOs the system/report/power doesn't show any AC charger information:
Connected: no
Charging: no
20V 0A with battery plugged and charged at 75%
5V 0.16-0.20 without battery plugged
 
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2informaticos

2informaticos

Administrator
Staff member
Do you get 1V1 LDO on CD3215 chips?

Inspect U2890 area for corrosion,
Check all resistors and traces from its area; around U3100/200 too.
 
J

jadao

Member
Hi 2informaticos!

I inspected U2890 and there was absolutely no corrosion, checked all the spi/rom resistor and traces one by one from U2890 and the one for CD3215C00. And yes I do get 1V1 LDO on each CD3215 when the corresponding port is plugged in.

I decided to check the scl/sda bus between SMC (SoC) and XA and XB Ports and found out I2C_UPC_SDA full short at R5200 pin2.
So it's either U3200/U3100/U3900 (T2). If it ends up to be the T2 chip I guess it's game over :)

Before starting to remove U3200 and U3100 I will try to do a backup with battery fully charged.
Since I have no way to connect an external device on usbc I plan to use some airdrop/cloud thing to transfer manually important files. Do you have a better suggestion to backup wirelessly?

I will of course report for the short after the backup
Thanks
 
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J

jadao

Member
So I started by removing U3100 because on this chip I2C_UPC_SDA corresponding ball is sitting next to 2 GND balls and indeed that was the bad soldered chip.
Reballed again cd3215 and it is good to go now.

I learned at least that a shorted I2C_UPC_SDA line will cause these behaviour:
  • 5V 0.16-0.20A fluctuating
  • no XA and XB USBC ports usage at all (no detection, no charging, no usb accessory, no DFU and no thunderbolt)
  • will work fine from a charged battery
And of course not to be too much confident with soldering, this one was very tricky, all the U3100 surrounding components were reading good diode mode values and had expected LDO voltages but still, it took only 1 ball merged with the gnd...

Thanks as always!
 
J

jadao

Member
Sorry I was unclear in my previous post.
I meant it is solved :cool:
20V is back battery is charging now and all ports working now.
 
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