Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired

Machine model: Lenovo G480

Malfunction: Notebook Won’t Turn On, lack of CPU VCC

Maintenance process: disassembly, no obvious water damage, no trace of repair.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 1.

Looking for the drawings, the power-on is still the same. It falls off at 0.20, and it falls off very quickly. Press Switch several times before you can. The second time it is turned on, the current is obviously not as high as CPU VCC.

Memory VCC, system manager VCC, bus and PLL VCC are also normal at 1.8V These VCC are all normal, so it is normal to grab the graphics card VCC. Then the problem is obvious. Check the condition of CPU VCC chip directly!

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 2.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 3.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 4.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 5.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 6.

The arrows are all normal, and I guess it should be the problem of the bridge. Then blow first.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 7.

The result is still the same. First, check the conditions (6X and 7X timing is the same, if there is a CPU VCC, the previous VCC is OK, then the EC sends it to the bridge APWROK and PWROK, and after the bridge receives these two good signals from EC, it will read the BIOS, then the bridge will open and drain the output DRAMPWROK, then the bridge will send VCC and PROCPWRGD, and then the CPU will send SVID to control the CPU CLK).

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 8.

As for this signal, it’s hard to find the direct quantity EC 3.3V after seeing the resistance. If it comes out normally in an instant, the bridge will come out of DRAMPWROK, that is, this signal, all the way here.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 9.

The 3.3V that comes out immediately becomes 0.5V It seems that it is not normal here, so there will definitely be no PROCPWRGD in the back, and there is a great chance of the bridge. The front VCC and APWROK are also normal. It can be said that the PG of VCC is also normal. If you brush a BIOS first, you can’t dry the bridge directly, and then brush it directly on BGA Rework Station. Installation test,VCC.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 10.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 11.

Lenovo G480 laptop can’t be started up and needs CPU power supply for repaired Figure 12.