Lenovo G40-80 ACLU3 ACLU4 NM A362 not charging

[mon2]

Ok. Measure the voltage to ground of:

5VALW
+3VALW

with:

1) only the power adapter
2) with only the battery
3) with both, adapter and battery

[G_sene]

Ok. Measure the voltage to ground of:

5VALW
+3VALW

with:

1) only the power adapter
2) with only the battery
3) with both, adapter and battery

1) 3.4v and 5.1v
2) 0v the both
3) 0v the both

[mon2]

Is there a charge on the battery? What is the voltage?

Assuming, yes:

measure the voltage to ground of PQ303 (battery mosfet)

source (1-2-3)
gate (4)
drain (5-6-7-8)

With only the charged battery - this mosfet must be ON to pass the battery voltage onto the main power rail of B+. This B+ rail then should be able to create the missing +3VALW and 5VALW rails.

PQ303 is a P-channel mosfet so the gate pin must be a lower voltage than the voltage being passed between the source / drain pins to enable.

[G_sene]

Is there a charge on the battery? What is the voltage?

Assuming, yes:

measure the voltage to ground of PQ303 (battery mosfet)

source (1-2-3)
gate (4)
drain (5-6-7-8)

With only the charged battery - this mosfet must be ON to pass the battery voltage onto the main power rail of B+. This B+ rail then should be able to create the missing +3VALW and 5VALW rails.

PQ303 is a P-channel mosfet so the gate pin must be a lower voltage than the voltage being passed between the source / drain pins to enable.

Only battery

source 13.92v
drain 13.92v
gate 0v

[mon2]

Is the laptop ON or OFF? Press the power button. EC_ON should be a logic '1' to enable the ALW rails.

When you attach the power adapter, what are the voltages present on PQ303? At this time, gate voltage should be higher to DISABLE PQ303.

[G_sene]

Is the laptop ON or OFF? Press the power button. EC_ON should be a logic '1' to enable the ALW rails.

When you attach the power adapter, what are the voltages present on PQ303? At this time, gate voltage should be higher to DISABLE PQ303.

Whether on or off, it stays that way.
With the adapter, the voltage rises to 14.09V drain and source, 0.018V gate (battery and adapter).

[mon2]

Flux and remove mosfet PQ303. Test again without this mosfet on the board.

1) Confirm if PR304 is present on the board. Test the voltage on each side of this resistor. One side should be the raw adapter voltage. With no power, measure the resistance across PR304 and the value should be close to the schematic value of 47k ohms.

2) with both the adapter & battery, what are the voltage to ground measurements of PQ308B? It is ok if you have removed PQ303 off the board - we are only testing as to why this mosfet remains enabled for both cases. With the power adapter connected, this mosfet should be disabled. Only if operating off battery, then PQ303 will be enabled.

[G_sene]

Flux and remove mosfet PQ303. Test again without this mosfet on the board.

1) Confirm if PR304 is present on the board. Test the voltage on each side of this resistor. One side should be the raw adapter voltage. With no power, measure the resistance across PR304 and the value should be close to the schematic value of 47k ohms.

2) with both the adapter & battery, what are the voltage to ground measurements of PQ308B? It is ok if you have removed PQ303 off the board - we are only testing as to why this mosfet remains enabled for both cases. With the power adapter connected, this mosfet should be disabled. Only if operating off battery, then PQ303 will be enabled.

I removed PQ303 and it still has 0V at the gate.

PR304 has 47kV and no voltage from the adapter.

PQ308B
Pin 3 - 0.200mv
Pin 4 - 0v
Pin 5 - 0.230mv

[mon2]

According to the schematics, the one side of the resistor at PR304 should be the Vin adapter voltage.

Remove all power. Meter in resistance. Measure the resistance from this one leg of PR304 to anywhere on the board that is mating to Vin voltage rail. This should be ~0R ohms.

Is it possible that there is a broken pcb trace to this resistor? Do you know the history of this board? Any liquid damage?

BTW, this missing Vin voltage here could be the root cause of your issue.

[G_sene]

According to the schematics, the one side of the resistor at PR304 should be the Vin adapter voltage.

Remove all power. Meter in resistance. Measure the resistance from this one leg of PR304 to anywhere on the board that is mating to Vin voltage rail. This should be ~0R ohms.

Is it possible that there is a broken pcb trace to this resistor? Do you know the history of this board? Any liquid damage?

BTW, this missing Vin voltage here could be the root cause of your issue.

It arrived and wouldn't turn on. It seems it was out of order because it stopped turning on and only the LEDs were on.
The PR306 is also in line with the VIN, from what I saw.

[mon2]

Yes, PR306 should also have the VIN voltage. You can measure from this area of the board to the drain pins (5-6-7-8) on PQ301. This should be ~0R ohms resistance between the 2 test points. Otherwise, to me, this is a broken pcb trace and needs to be manually jumpered by wire. Double-check that your board is identical to the schematic but appears to be the case.

[G_sene]

Yes, PR306 should also have the VIN voltage. You can measure from this area of the board to the drain pins (5-6-7-8) on PQ301. This should be ~0R ohms resistance between the 2 test points. Otherwise, to me, this is a broken pcb trace and needs to be manually jumpered by wire. Double-check that your board is identical to the schematic but appears to be the case.

I just measured from PL706 (VIN) to PR304, I got 3Mohm

[mon2]

To me, this is a broken trace between these 2 points of interest.

Confirm that there is a trace between PR304 & PR306. Once this is confirmed, suggest to place a wire between this common junction to PL706 and then test again. Be sure that your board is matching the schematic but otherwise, there is a broken connection that is required on this board.

[G_sene]

To me, this is a broken trace between these 2 points of interest.

Confirm that there is a trace between PR304 & PR306. Once this is confirmed, suggest to place a wire between this common junction to PL706 and then test again. Be sure that your board is matching the schematic but otherwise, there is a broken connection that is required on this board.

One side of PR306 continued with PR304.
Hitting 200k as shown in the diagram.

But one question remains.
How is the battery voltage getting to the charger connector? The input MOSFETs shouldn't allow this to happen, due to the internal diode, right?

[mon2]

With the missing Vin, the gate voltage on the battery mosfet is always a low voltage. The battery mosfet is a p-channel mosfet so this mosfet is always enabled. This mosfet should disable when the adapter is connected but is not due to the missing Vin.

[G_sene]

With the missing Vin, the gate voltage on the battery mosfet is always a low voltage. The battery mosfet is a p-channel mosfet so this mosfet is always enabled. This mosfet should disable when the adapter is connected but is not due to the missing Vin.

So what can I do to see if I can resolve the VIN issue, is it a jumper from a component in the VIN loop to the PR304 resistor?

[mon2]

Based on the details to date, yes. According to the schematics, this connection should be there from the factory. Very odd that it is not. Do not see an issue for you to test this manual wiring of Vin to the PR304 resistor. This wire will elevate the voltage on the board at that junction and cause the gate voltage to increase. Then that P-channel mosfet will disable (as it should) when the power adapter is connector. In theory, could solve your issue. Test it and share your feedback.