Lenovo G40-70 notebook is unresponsive according to Switch, so it is not powered on for maintenance

First, look at EC_RSMRST#, then look at PCH_PWR_EN. It turns on +20VSB, and then guess that RPC8 has poor performance. 4 pin exposes VCC, which causes EC 2 pin to output 2v pin abnormally when it is in standby, and 0v when it is in standby. When RPC8 is replaced, it turns on normally

[Machine model] Lenovo G40-70 notebook

[motherboard model] NM-A271 REV1.0

[Fault phenomenon] The notebook does not respond according to Switch, and it is not powered on.

[maintenance process]

Send a Lenovo G40-70 notebook to my colleague. The notebook does not respond according to Switch, and there is no water damage without disassembly or repair. At first, the fault is turned on, that is, it doesn’t show. After the BIOS is OK, there is no problem in the test. When the customer came to pick up the machine,no booting was up, but there was no response when pressing Switch. When my hand did not power up, I disconnected the battery, powered up the LOGO Switch, and never powered up again.

Remove the machine, check that the main board 3 / 5V is OK, there is no Short circuit, EC VCC is also normal.

Lenovo g40-70 notebook press Switch no response, no power up maintenance Figure 1

After brushing the EC program and changing the EC program, the fault still remains.I played it all night and tried again the next day. I turned it on and hung up after several repetitions.After checking the EC circuit honestly, we found that EC_RSMRST# PCH_PWR_Abnormal en, pbtn_Out ා without current of change, EC_Rsmrst ා to be 0V, PCH_PWR_EN jump unstable, first look at EC_RSMRST#。

Lenovo g40-70 notebook press Switch no response, no power up maintenance Figure 2

Lenovo g40-70 notebook press Switch no response, no power up maintenance Figure 3

Enter the CPU through rc182. Rc85 is a directly connected resistor. If it is disconnected, it is not pulled low by U. look at PCH again_PWR_EN is to open + 20vsb.

Lenovo does not respond to g Switch when it is powered on

Lenovo G40-70 notebook is unresponsive according to Switch, and is not powered on for maintenance. Figure 5

No matter if Q2 and Q30 are empty, disconnect the connected resistor PR220 R162,PCH_PWR_EN is still unstable, and even pull PQ202. 3/5V is detected and 5V is found.

Lenovo G40-70 notebook is unresponsive according to Switch, and it is not powered on for maintenance. Figure 6

SY8208C’s 5 pin+5vVCC is 3v, which doesn’t feel normal. After a while, the 5V chip was changed. pc1062 Capacitor,+5VVCC is still 3v. It was later confirmed that+5VCC 3V is normal. Maybe the data generated is different depending on the board frame and standby (+5VVCC is purely personal understanding). The fault is still not powered on. The wooden method was thrown into the oven and baked for half an hour. Amazing things happened, and it was turned on. After verifying some information, a conclusion was reached. There was a standby EC_RSMRST# PCH_PWR_EN 3.3v standby. There was a 2 pin that detected EC with changed data before.

Lenovo G40-70 notebook is unresponsive according to Switch, and it is not powered on for maintenance. Figure 7

There is an VCC of 2v or so when it is not powered on. At that time, I didn’t know whether it was normal or not, but it was detected. After it is normal, EC_LID_OUT# stands by for low VCC. After judging, it may be that EC_LID_OUT# is abnormal, which leads to the abnormal work of EC. It is detected that EC_LID_OUT# is directly connected through a resistor RC96 of 0 ohms.

Lenovo G40-70 notebook is unresponsive according to Switch, and is not powered on for maintenance. Figure 8

Lenovo G40-70 notebook is unresponsive according to Switch, and is not powered on for maintenance. Figure 9

Connect RPC8 to get rid of it.

Lenovo G40-70 notebook is unresponsive according to Switch, and is not powered on for maintenance. Figure 10

Guess it’s the poor performance of RPC8. The exposure of VCC by 4 pin causes EC 2 pin to output 2v pin abnormally when it is in standby, and it is 0v when it is in standby. Replace RPC8 and turn it on normally, so as to avoid the same failure and disconnect RC96. Both ends are 0v when it is in standby, and both ends are 3v after 0v,or so, which has no influence. Just one standby problem, test it again and again.

【 maintenance conclusion 】

Lenovo G40-70 notebook has no response, no power on, and sleeps, which is caused by abnormal standby of EC_LID_OUT#. Replace RPC8 to solve the problem.