Hi all,
Unfortunately I cannot/don't know how to edit my last query, so I'll create another one instead.
So I've received this laptop to try and fix it. There were 2 blown components - small inductor and cap, both on Vin (main power rail) on the IN pins of the 0.75V chip (SY8388RHC). I've replaced that chip and the nearby 0.75V_DEEP_SUS (same type), and of course both of blown components. There was still a short on 3V coil, which went away when I replaced PI3DPX1207C chip next to usb-c port (as it was overheating). Luckily I have older non-working 455 G7 for the spare parts.
Now I'm at the point where I don't know how to proceed. All the voltages look normal to me, laptop charges the battery, but it just won't start up.
I've checked the PWRBTN, it has 3.3V and it does go to 0V when pressed, and this signal does go to EC chip (I've traced it around the board).
Most of the coils currently have high resistance, except V_core at cca 4 OHM, VDDCR_SOC coil at cca 12 OHM, and 1.2VSUS coil at cca 95 OHM.
When I connect just the battery, I have 3.3V on 3V coil (is this OK or too high?), 5.15V on 5V coil, 3.3V_alwaysON, 3.3V, and battery voltage on charging coil, nothing else.
When I connect just the charger (either barrel or usb-c), consumption is 7-10mA, I have the same volts as before, but also 1.8V on 1.8V_DEEP_SUS coil.
When I connect both battery and charger, the charging light comes on and battery charges (volts do go up).
My initial idea (as written in the last post) was that the EC chip is not working properly, but I don't know how to test it. Of course this might be completely wrong. 3V_alwaysON is present on EC chip, and there are no shorts on any of the caps around it.
Any help on what to check next or how to proceed is very welcome.
Thanks in advance!
Unfortunately I cannot/don't know how to edit my last query, so I'll create another one instead.
So I've received this laptop to try and fix it. There were 2 blown components - small inductor and cap, both on Vin (main power rail) on the IN pins of the 0.75V chip (SY8388RHC). I've replaced that chip and the nearby 0.75V_DEEP_SUS (same type), and of course both of blown components. There was still a short on 3V coil, which went away when I replaced PI3DPX1207C chip next to usb-c port (as it was overheating). Luckily I have older non-working 455 G7 for the spare parts.
Now I'm at the point where I don't know how to proceed. All the voltages look normal to me, laptop charges the battery, but it just won't start up.
I've checked the PWRBTN, it has 3.3V and it does go to 0V when pressed, and this signal does go to EC chip (I've traced it around the board).
Most of the coils currently have high resistance, except V_core at cca 4 OHM, VDDCR_SOC coil at cca 12 OHM, and 1.2VSUS coil at cca 95 OHM.
When I connect just the battery, I have 3.3V on 3V coil (is this OK or too high?), 5.15V on 5V coil, 3.3V_alwaysON, 3.3V, and battery voltage on charging coil, nothing else.
When I connect just the charger (either barrel or usb-c), consumption is 7-10mA, I have the same volts as before, but also 1.8V on 1.8V_DEEP_SUS coil.
When I connect both battery and charger, the charging light comes on and battery charges (volts do go up).
My initial idea (as written in the last post) was that the EC chip is not working properly, but I don't know how to test it. Of course this might be completely wrong. 3V_alwaysON is present on EC chip, and there are no shorts on any of the caps around it.
Any help on what to check next or how to proceed is very welcome.
Thanks in advance!
