Lenovo B590 Laptop Does Not Turn On

Laptop Model : Lenovo B590

Board Number : LA58 MB 11273-3 48.4TE05.031

Fault : Does Not Turn On

Repair Process :
　　Start disassembling the Laptop, connect the red Probe of the multimeter diode to ground and start to read the resistance value.

The measured CPU value is normal (since the diode value of this MOS tube is very low, it is normal as long as it is not exactly equal to 0).

The memory power supply value is normal.

The 3V5V values ​​are normal.

The bridge is normal (I also thought this value was abnormal at first. I removed the electrical sensor and found that the value was normal. But if the bridge is broken and I don’t have the parts to replace it, I will just assume it is good).

            Finally, when the common point was tested, it was found that the common point value was abnormal and short-circuited. If the problem was determined, use the burning method taught by the captain to burn the computer! ! There is no need to worry about it breaking down. The customer had to turn on the power all night before it broke down.

Plug in my DIY CNC power supply, the voltage is 10V and the current is 10A.

            After some operation, I found that the bridge power supply capacitor was broken. After removing it, I measured the common point value and found that it was still short-circuited. So I then burned and found that the VIN chip capacitor of the CPU main power supply PWM chip was also broken. After removing it, the measured value was no longer Back to normal.

        After repairing the broken chip capacitor, the power supply started up and the screen turned on. After installation, there were no problems and the repair was over. 

Happy Repairing !!