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I have an A1989 820-00850 that came in with no power. Liquid damage near U3200 and beneath it on the other side of the board. Lots of corrosion inside of the ports. Both charging ICs shorted on this side. Replaced U3200 and UB400.
Power restored and I now have three functioning ports. The rear...
For UP701 I have
3.8V on PP3V8_AON and PPMDB_AWAKESW_TCON
1.8V for a few seconds and then 0 on EDP_PANEL_PWR_EN
For UP730
3.8V on PP3V8_AON
1.8V then 0V on EDP_PANEL_PWR_EN
.6V then 0V on FB_BLKT_2D
3.2V then 0V on PPBCON_AWAKESW_BKLTCONN
I have an A2779 820-02841-05 that came in with no power, not charging, some corrosion on bottom side of board.
Unable to find a schematic so I’m using 820-02098 which appears to be almost identical.
Relieved a short on PP3V8_AON_SPMU_ISNS by removing C771C. Obvious liquid damage in this area...
Let me know if this is the wrong place to post tablet questions.
Customer did his own digitizer replacement. Now, backlight only works with Apple during boot. Image is still there and device is on setup screen as he apparently restored it.
Replaced LCD and digitizer.
Replaced LCD connector...
The device was sent to me by a shop that is not 100% certain that it was working when the customer gave it to them but the display was definitely damaged.
USB-C meter shows 20V and .08 amps for about 15 seconds before dropping to 0 and then goes back to .08 before repeating this sequence.
So...
Thanks for the welcome and for assisting me with this issue. R7020 was in fact the problem and now I have a functional charging system! For some reason though, the fan does not work. I tested it using a power supply and it is definitely capable of spinning. PP5V_S0 is present at the connector as...
I have an 820-4924 that came in with no power, not charging. R7020 was visibly burned so I replaced it along with C7091 which was dead short and appears to have been at least one of the problems. Now when I plug in the charger I get 16.5 volts on the PPDCIN_G3H_ISOL side of R7020, but only about...