Laptop Model : Dell Vostro 5740(P41G)
Board Number : DAJW8CMB8E1
Fault
: Completely Dead Second Chance
Repair
Repair
Process :
After disassembling the Laptop,
I discovered that the EC had been tampered with. I guess the previous owner had
replaced the EC and it was still a death sentence for the Laptop without
triggering it. Check the EC first, check the picture and find that the EC
model is correct, then measure the common point 3/5V to ground, and no
abnormality is found.
Brush the EC with washing water
and check with a magnifying glass to find a short circuit. After
re-soldering and power-on test, 3/5V was normal. The switch of this Laptop
is inconvenient to operate on the keyboard. The 29th pin of CN16 in the picture
is the switch. Use tweezers to short it directly to the ground, and the light
will turn on.
The screen is on, and it
seems that the previous family has the same problem. After installing the Laptop,
it still didn't trigger, and the short contact triggered again.
It turned out that the
keyboard switch of this Laptop was disconnected, and the motherboard was good
at all. I started to want to change the keyboard, but the cost was high,
so I made a switch for it. It was just a 3.3V and a GND.
First cut off the
original switch. The original switch is made of carbon film and is difficult to
operate.
Align the position of the switch and solder the switch to the motherboard. Cut off the excess feet and leave them to be soldered to the motherboard.
It is recommended to
dismantle the left and right buttons of the touch panel on the motherboard,
because the shell of this switch also has grounding contacts and the soldering
is relatively firm.
Flying lead switch, CN16 pin 29
The switch feels much
better than the original keyboard. The only regret is that the indicator light
on the switch will also be cut off.
Happy Repairing !!
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