Hello everybody,
One of my friends brought me his brother's laptop to repair, I'm the third person who put the hands on this laptop (he tried to convince his brother to take it to me for the ram upgrade, dust cleanup and thermal paste replacement but he wanted to make it to his university friend... sorry if I say that, but we saw the result).
The laptop is a Lenovo IdeaPad Gaming 3 15ARH05 with AMD Ryzen CPU and Nvidia GPU.
I'm going to give a quick recap of what happened before I got this laptop for repair to make clear the situation.
A friend of his brother tried to make a ram modules upgrade, his friend said it booted up correctly but it suddenly turned off (by checking on the event viewer, it was installing Win11 updates). It didn't power on again, and power/charging leds were dead.
They after reinstalled original ddr4 ram modules because they thought it was something about ram compatibility. No power/charging even with original ram modules installed.
Another person checked it a said it was a charger problem (he didn't see the +20.5V), he also cut in half the charger cable to check voltages (i still don't understand WHY he did cut the cable) and then he tried to solder the cable back.
After all of that, my friend took his brother's laptop and gave it to me for the repair.
I repaired the charger cable, tested and it works, so I removed the solder and crimped the cable back to make a better connection.
The battery at this point had an output of 0.14V.
Then I checked the motherboard and quickly found a shorted capacitor on the CPU power rail (capcitor PC3001). I replaced it with another one from another board and the motherboard now power on again.
After power on, the battery had output of 10,1V (so the battery internal circuit protected it from power rail short)
Another problem which I can't find the solution is that the battery doesn't charge.
I checked the capacitors and mosfet near the battery connector area and noticed that the mosfet PQ104 receive the +20,5V on Drain pins but it doesn't make any output when battery is connected (I read the actual battery voltage, 9.7V right now).
With battery disconnected, on PQ104 I read: Drain +20,5V, Source 4.2V, Gate 5.4V
There is another mosfet, PQ105, that doesn't have any output power, I read 0V on both gate and source pins. the gate pins are connected to the source pins of PQ104.
I'm sure I'm missing something, but I don't know what (another short?). Anyone has any advice?
I already have the boardview and schematics (I found them here in the forum), but both boardview and schematics refer to the rev 0.2 motherboard. in this specific laptop I found the rev 1.0 motherboard (there are minor differences between the two revs).
Thank you to anyone who will help.
One of my friends brought me his brother's laptop to repair, I'm the third person who put the hands on this laptop (he tried to convince his brother to take it to me for the ram upgrade, dust cleanup and thermal paste replacement but he wanted to make it to his university friend... sorry if I say that, but we saw the result).
The laptop is a Lenovo IdeaPad Gaming 3 15ARH05 with AMD Ryzen CPU and Nvidia GPU.
I'm going to give a quick recap of what happened before I got this laptop for repair to make clear the situation.
A friend of his brother tried to make a ram modules upgrade, his friend said it booted up correctly but it suddenly turned off (by checking on the event viewer, it was installing Win11 updates). It didn't power on again, and power/charging leds were dead.
They after reinstalled original ddr4 ram modules because they thought it was something about ram compatibility. No power/charging even with original ram modules installed.
Another person checked it a said it was a charger problem (he didn't see the +20.5V), he also cut in half the charger cable to check voltages (i still don't understand WHY he did cut the cable) and then he tried to solder the cable back.
After all of that, my friend took his brother's laptop and gave it to me for the repair.
I repaired the charger cable, tested and it works, so I removed the solder and crimped the cable back to make a better connection.
The battery at this point had an output of 0.14V.
Then I checked the motherboard and quickly found a shorted capacitor on the CPU power rail (capcitor PC3001). I replaced it with another one from another board and the motherboard now power on again.
After power on, the battery had output of 10,1V (so the battery internal circuit protected it from power rail short)
Another problem which I can't find the solution is that the battery doesn't charge.
I checked the capacitors and mosfet near the battery connector area and noticed that the mosfet PQ104 receive the +20,5V on Drain pins but it doesn't make any output when battery is connected (I read the actual battery voltage, 9.7V right now).
With battery disconnected, on PQ104 I read: Drain +20,5V, Source 4.2V, Gate 5.4V
There is another mosfet, PQ105, that doesn't have any output power, I read 0V on both gate and source pins. the gate pins are connected to the source pins of PQ104.
I'm sure I'm missing something, but I don't know what (another short?). Anyone has any advice?
I already have the boardview and schematics (I found them here in the forum), but both boardview and schematics refer to the rev 0.2 motherboard. in this specific laptop I found the rev 1.0 motherboard (there are minor differences between the two revs).
Thank you to anyone who will help.
Comment