Lenovo Ideapad 3 15ALC6 motherboard issue
Hello,
I have a Lenovo Ideapad 3-15ALC6 computer that I'm trying to repair.
Initially, the computer wouldn't start, and there was no power consumption from the charger. The board itself is reference HS261&HS561&HS761 NM-D521 rev 3.0, where you can find the schematic and board view here: https://www.badcaps.net/forum/troubl...-hs761-nm-d521
When I opened it, I noticed three burnt components near the headphone jack. I removed them, but they weren't shorted.
Then I noticed that a MOSFET on the charger line side was shorted, so I replaced it. It wasn't any better, and I also had to replace the BQ24780S controller. Now I have 20V (B+) on the board, and I'm now seeing a slight 40 mA consumption on my power supply.
But there are other problems because I can't get 3.3V. In fact, I have 3.3V on +3VL (LDO output of the SY8386B controller) but only 0.9V on +3VALW. The Power Good signal is at 0V; I think this is normal, but I'm not sure.
I don't have 5V either. I have 5V on +5VL (LDO output of the RT6258C controller) but only 0V on +5VALW. If I remove the PJ5702 jumper to eliminate the components downstream of +3VALW, I do indeed get 3.3V instead of 0.9V. I deduce that a component is drawing too much current on this line.
Looking with my small thermal camera, I see that the SY8386B component that generates the 3.3V is heating up a little, about 50°C, as is the IT8227VG-128-CX SIO chip, but very slightly, about 25°C.
There are many components connected downstream of the +3VALW signal. Do you think it's the SIO chip that's faulty, or could it be other components, given the measurements I've taken?
Thank you in advance for helping me solve this issue.
I have a Lenovo Ideapad 3-15ALC6 computer that I'm trying to repair.
Initially, the computer wouldn't start, and there was no power consumption from the charger. The board itself is reference HS261&HS561&HS761 NM-D521 rev 3.0, where you can find the schematic and board view here: https://www.badcaps.net/forum/troubl...-hs761-nm-d521
When I opened it, I noticed three burnt components near the headphone jack. I removed them, but they weren't shorted.
Then I noticed that a MOSFET on the charger line side was shorted, so I replaced it. It wasn't any better, and I also had to replace the BQ24780S controller. Now I have 20V (B+) on the board, and I'm now seeing a slight 40 mA consumption on my power supply.
But there are other problems because I can't get 3.3V. In fact, I have 3.3V on +3VL (LDO output of the SY8386B controller) but only 0.9V on +3VALW. The Power Good signal is at 0V; I think this is normal, but I'm not sure.
I don't have 5V either. I have 5V on +5VL (LDO output of the RT6258C controller) but only 0V on +5VALW. If I remove the PJ5702 jumper to eliminate the components downstream of +3VALW, I do indeed get 3.3V instead of 0.9V. I deduce that a component is drawing too much current on this line.
Looking with my small thermal camera, I see that the SY8386B component that generates the 3.3V is heating up a little, about 50°C, as is the IT8227VG-128-CX SIO chip, but very slightly, about 25°C.
There are many components connected downstream of the +3VALW signal. Do you think it's the SIO chip that's faulty, or could it be other components, given the measurements I've taken?
Thank you in advance for helping me solve this issue.