ASUS X421IA R2.0 Boardview

[mcplslg123]

Need boardview

[mcplslg123]

Re: ASUS X421IA R2.0 Boardview

case solved. Couldnt find boardview/schematics/repair guide anywhere. Problem was 01.battery not charging
02.Doesnt work on adapter alone(battery disconnected)
03.Doesnt works on battery alone(adapter disconnected)
04.But works fine when both adapter+battery connected.However, doesnt charge battery.

Troubleshooting Part#1
I checked resistance on the dc-in fets out of circuit and on pcb-Healthy readings in M ohms range. Soldered the 1st dc-in fet but didnt soldered the 2nd dc-in fet. got 19V on Source/Drain and 24.6V on gate. My experience says its usually problem in fets connected to charging coil/discharge fets. So replaced all the 3 fets around charging coil and soldered the 2nd dc-in fet. Now gate voltage is ok on 2nd fet,19V reaches CLR and motherboard started working on Adapter Alone.

Troubleshooting part#2
Still battery doesnt charge. On investigating voltage on battery pins connector, I found that Either SDA or SCL(cant say which one as no BDV) was pulling low to 0.18V while the other pin was 3.3V. measured resistance to GND on pin with low voltage-it reads 0.3K ohms while the pin with 3.3V reads more then 20K. So something wrong here. manually traced the pin with low voltage to a 6 PIn IC(dont know what it was and the resistance was low here as well. Removed this IC ,still same low resistance. Now SDA/SCL on charging circuit is connected with charging IC also(BQ24780S used here)-so went ahead and removed the charging IC but no change in resistance. Soldered back charging IC/6Pin device. This SDA/SCL communication goes to SIO-so traced the pin on SIO and it reads same 0.3K ohms.Lifted this particular Leg of SIO(ITE5XX) and resistance returned to normal on battery connector. So replaced the SIO and it starts charging and working on adapter only/battery only/adapter+battery.

Just posted for members who gives up in absence of schematic/boardview. Hope this will encourage them to not give up without fight. Just stick to basics.

[alas3376]

Re: ASUS X421IA R2.0 Boardview

well done

[hedong7655]

Re: ASUS X421IA R2.0 Boardview

X421IA R2.0.cad