Lenovo Z460 Notebook Won't Turn On repaired

Lenovo Z460 Notebook Won’t Turn On repaired

Machine model: Lenovo Z460

Malfunction: Notebook Won’t Turn On has no standby current when it is powered on.

Maintenance process: remove the mainboard to measure 19V at both ends of PF1 Fuse, 18V at G level of PQ27, 18V at D S2 level, and 0V at S level of PQ6. It seems that PQ27 is not fully turned on, that is,Current protection is not isolated.

Lenovo Z460 Notebook Won’t Turn On repaired Figure 1.

This is the ignition circuit of Compal. PQ6 needs to output 19V normally, and 4 pin is controlled by PACIN, ACON and ACOFF signals. Only when PACIN and ACON are at high level and ACOFF is at low level, PQ10 turns off PQ9 and PQ8 turns on PR29 to ground. PR30 series voltage divider VCC is 8.1V, which is lower than 19V of S pole. PQ6 is fully turned on to generate common point B+VCC.

Next, the 2nd pin of PQ9 is only 0.3V It seems that the problem lies in that the control stage of PQ9 can’t be turned on. At this time, there are three signals involved in controlling PQ9, and PACIN is the first test. Generally, PACIN is the problem. The 1 pin of measuring resistor PR37 has 3V VCC which is normal. Measure ACOFF at 0V, and this signal is also normal. It seems that the problem lies in ACON, and the measurement of 3 pin of PD10 is 0.3V

Lenovo Z460 Notebook Won’t Turn On repaired Figure 2.

This is schematic of ACON. If ACON wants to be high, only 7 pin of PU10 outputs high level, and ACON can be high level after PD10. Measure the 7 pin VCC 0.08V of PU10. It seems that the problem lies in PU10 or PD10. Remove PD10 directly. When the power is turned on, it is found that there is a standby current. When measuring the 7 pin of PU10, it is 5.24V VCC,PQ6 and the G level of PQ6 becomes 8.1V It is judged that PD10 is damaged. After replacement, ACON is 3.1V Troubleshooting. (Note: It can be turned on normally without PD10).