Lenovo ideapad Y500 notebook computer often restarts for repair

Machine model: Lenovo IdeaPad Y500

No.: LA-8692P

Type of CPU: I5-3230M

Description: After DC power supply is powered on, the startup current is 0.3, and the computer often restarts.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 1.

Maintenance process:

1. visually inspect that the CPU may not work, the motherboard does not have VCORE, and the VCC, such as the memory graphics card VCCSA, has been removed without VCORE. There is no bump mark of water damage mainboard maintenance, and CPU replacement is fruitless.

2. Check schematic, turn directly to the end, and find that this graph has time sequence.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 2.

According to the time sequence, check that VR_ON 3.3V is normal. According to the forum, it is said that VCORE needs to be sent out after H_CPUPWRGD. After testing H_CPUPWRGD, there is no VCC. Check that PM_DRAM_PWRGD is normal.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 3.

After checking PM_DRAM_PWRGD_R according to the drawing,VCC can’t be found, U1′ s 5 pin+3VALW is normal, and 1 pin+3VS is only over 1V, which seems to be the fault.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 4.

Check drawing +3VS is converted by +3VALW through U47.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 5.

The input is normal, the output is low, and the control pole of U47 is only 0.35V.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 6.

The drawing shows that the conduction condition needs to meet 10V. Check R1086 Diode value is normal, and there is no VCC at both ends. Tracing +VSB, it is found that VCC 19V of +5VS +VSB is normal, and the problem has been clarified here. It may be that PCB circuit defect caused the abnormal control electrode of +3VS +VSB VCC and the low output, which caused a series of subsequent problems.

Lenovo ideapad Y500 notebook computer often restarts and repairs Figure 7.

According to the drawing, it is found that the circuits of +3VS and +5VS are similar. Directly from the end of +VSB Jump wire to R1086 at +5VS, the machine is turned on again, and the machine lights up.