Lenovo rescuer Y7000P does not show maintenance when starting

Lenovo rescuer Y7000P does not show maintenance when starting.

Machine model: Lenovo rescuer notebook Y7000P

Fault phenomenon: the customer describes that Lenovo rescuer Y7000P does not display when it is turned on.

Maintenance process:

Received a Y7000P from the customer, and the fault reported by the customer was that it was turned on and not displayed. When the machine was turned on, it was found that the current did not move to 0.6. According to experience, there was definitely no CPU power supply. The multimeter hit the CPU power supply resistance, and there was nothing unusual. It’s useless to brush a BIOS on the three axes. Check the working conditions of the power supply chip honestly.

When checking the working conditions of the chip, it is found that it is possible to start the machine once out of 10 times, without connecting the screen, and the current reaches 1.2. Then tell the customer to dry the bridge and inform the risk.

It’s the first time I came into contact with this kind of vinyl, and I have no experience. After drying, I went to BGA, and then I found that all four feet of the chip had tin balls, and the power supply was short. There was no way, so I continued to dismantle the bridge. Because I haven’t removed this kind of vinyl before, I thought to myself at that time, no matter how to ensure the integrity of the pad, the chip is dry, and it’s a big deal to lose one.

In the first line, the BGA is set to the temperature where the CPU is often dismantled before, and then it is dried. When the temperature is reached, because of the vinyl, we can only pry into the two feet around us first and then cool down. After cooling, turn the motherboard over and pry the other side. Finally pried it off.

But when I saw the pad, I lost almost 20 points. With a magnifying glass and a bitmap of points, they were all empty points. I’m lucky. Drag the bridge clean, hit the capacitor of the chip, there is no short circuit, but fortunately the chip doesn’t have to pay. Then began to plant the ball, solder the chip, and explode the tin.