Lenovo T430s notebook can’t be started for repair

Lenovo T430s notebook can’t be started for repair

Machine model: Lenovo T430s

Main board number: LSN-4 UMA 11263-2

Fault phenomenon: The customer described that Lenovo T430s notebook could not be turned on when it was powered on.

Lenovo T430s notebook can't be started for repair

Lenovo T430s notebook can’t be turned on. Maintenance Figure 1

Maintenance process:

Disassemble the machine and power it on. Test the isolated circuit without standby. Check Q9.

Lenovo T430s notebook can't be started for repair

Lenovo T430s notebook can’t be turned on for maintenance Figure 2

There is no voltage output at pin 8765, and the G set is 0 V..

Lenovo T430s notebook can't be started for repair

Lenovo T430s notebook can’t be turned on for maintenance Figure 3

Tracing -RWRSHUTDOWN, it was found that it was issued by Toshiba chip TB62D515.

If the chip is to issue -RWRSHUTDOWN, the voltage must meet three conditions.

The test found that 100 pins, BAT_VOLT voltage is about 0.35V, the voltage is wrong, and the fault point should be found at about 7V under normal voltage.

Test that the resistance values of R531 and R528 are not infinite.

So the resistor was replaced and the fault was solved.