Lenovo Essential E E42-80 Laptop Does Not Power On Repair

Laptop Model: Lenovo E42-80

Board Number : DA0LV6MB6F0

Fault :Laptop Does Not Power On

 

Maintenance Process:

 

Looking at the current, I feel that the standby voltage has come out, and there is a voltage of 3V on the measured switch. When you press the switch, a 3V voltage will instantly appear on the 3V inductor, which is where the winding is. Please see me analyze it one by one.

There is no voltage on all the BIOS pins when the power is turned on, and everyone begins to wonder if the BIOS is not involved in triggering.

I just flashed the BIOS and there was voltage. Then flash it!. I did a bunch of flashing and the fault remains the same.

　　During the process of flashing the BIOS by accident, I took a test lead and measured the voltage of 3V on the soldering pad, and there was also voltage on the 3V inductor. It was amazing. What was going on? This is more definitely caused by the BIOS data. Continue downloading, continue brushing, still unchanged.

　　After calming down and thinking about it, after removing the BIOS, there was a voltage of 3V, but I never measured 5V. I decisively removed the BIOS and found that the 5V inductor had no voltage. 

 

Please note here why I measured 5V before it came up, because this board is not designed to be conventional. The 5V inductor is at the east end of the Motherboard, and the 3V inductor is at the west end of the Motherboard. They are far apart. The 3V inductor is next to the memory power supply inductor, which is strange.

　　Found that there is a problem with 5V, let’s start here!  I checked found out that the model number is SY8288. I found the model number and got the drawings .

First, measure that the power supply is normal, the linear turn-on voltage is normal, the linear output is abnormal, and the resistance to ground is measured and a short circuit is found. 

Using the burn-in method with low voltage and low current, it was found that the IC body was hot. After replacement, the linear voltage is normal, the standby voltage is normal, and the screen turns on when the switch is pressed.

　　Summary: The problem is a small one, and it is easy to ignore it. As a result, it took a long time to refresh BIOS and wasted so many download points. The current abbreviation for IC takes a long time to check the model number.

 Happy Repairing !