820-00850 No 20V

[brunomotter]

Hello. Got this board here. It's a return actually. The first time this board came here it had been all poked by another technician and there were 2 CD3215B1 in place of C00. After a lot of work I made the board work again. It worked for 2 months and this week it came back again with no 20V on charger. All LDO voltages present and all LDO diode modes ok between all 4 chips, all reading close each other. PPBUS_G3H 12.27V indicating no communication with T2. Machine does not enter in DFU nor gets recognized on another computer.

 

[2informaticos]

Do you get 3V3_G3H_RTC?
Also check the AWAKE and SLPS2R voltages around U7800 (its small coils).

 

[brunomotter]

3V3_G3H_RTC Stable @ 3.3V
All SL2R and AWAKE voltages present. Only coils I don't get any voltage around U7800 are L7821/22/20/19

T2 chip gets a little warm. Not hot, but little warm

 

[2informaticos]

Then T2 should be able to enter DFU mode.
Unless it can't communicate with the host machine (AC2), through corresponding CD3215 chip.