Dell Inspiron 5435(12213-1) Laptop Power Problem Does Not Turn On

Laptop model: Dell Inspiron 5435

Version number: 12213-1

Fault : Laptop Power Problem Does Not Turn On

 

Repair Process:

 

    Directly connected to an adjustable power supply. The standby current is 0.016. If it is triggered more than 0.04, it will drop to 0.016. When I turned it over and disassembled it, I found that there was soldering oil next to the memory slot. 

I took out the bare board and looked at it front and back. Except for the side of the memory slot, there was no abnormality of water corrosion. Immediately after triggering, I used a meter to measure other voltages except 3-5V. When I checked the next voltage in sequence, the fault changed a little.

Originally, the current dropped off immediately after triggering, but now it stays for a few seconds before falling off, which just happens to eliminate the need for an oscilloscope.

When measuring, I found that 3.3v changed to 3.7V. I thought I measured the wrong inductor. PL4101 repeatedly measured it and found that it was indeed 3.7V for a few seconds when the current went up, and then it changed to 3.3V again when it dropped. 

What is the situation? Could it be that the FB feedback resistor is broken, causing the voltage to become high, or is there something wrong with the chip? 

However, when the current dropped to 3.3V, it became normal again. I felt that 3.3V was pulled up after triggering. 3D3V_S5 went to many places. I couldn’t figure it out even though I measured it against the drawing.

Finally, I went back and saw that 5V was normal. unusual.I found that the 5V was a little lower after triggering, and a little higher when it fell off.

If I don't care at all, because I measure 5V on different boards, sometimes it will be 4.9V or 5.1V, which is normal.

My multimeter is like that, but this time it is low. I had to check it carefully. They found this chip together and took it apart to try another one

The current ran up, and then the standby current became 0.007. Could it be that the original standby current was wrong? Find a memory and connect it to the screen cable.

When the current jumps, it feels like the phone is about to turn on. As a result, the Didi alarm beeps 8 times. The screen is not detected. This machine has been repaired and the screen lines on the board are still the same after cleaning.

After removing the screen, the alarm stops flashing on the other end. It’s time to turn on! However, the screen is still black, and both upper and lower case letters are illuminated.

I can see English when I shine it with a flashlight, but the screen is now dark. The screen interface signal at this end of the motherboard: 2 3-pin LCD DVDD screen power supply 3.3v, 35-pin LCD_BRIGHTNESS brightness adjustment 3.3V, 36-pin BLON_OUT_C ​​backlight enable 3.3V, 38 39 40 DCBATOUT_LCD backlight power supply. 

I measured the end behind the screen and found that the backlight power supply was 0V. After swiping the screen wire a few times and checking the value, I confirmed that the screen wire was broken.

I looked closely and saw that it was not broken. It seemed that it was broken in the middle. Please connect the following wires.

This is the end of the repair.

Happy Repairing !