Dear friends,
I would like to help me solving the problem i have.
My favorite laptop Acer aspire 5942g motherboard is tottaly destroyed from my bad luck attempt to reflow the BGA chip. So the original m/b is off now.
Fortunately, i had bought another m/b with some problems and i decided to give a second chance.
The new m/b has the problem that with no RAM, no CPU placed and giving power 19VDC, it lights the 3 blue lights. Then, when i pressed the POWER button, it goes on for 3-5 sec and then goes off.
I 've found broken parts which i' ve replaced (PU7), a FET and a transistor, and then i clean the m/b well and put fresh thermopaste above the 3 main chips (CPU, BGA, VGA). I've measure +5VALW, +3VALW. After then, when i press the power button, it goes on and i have image through VGA cable.
I connect then the HDD and it goes into windows. I was very glad but unfortunately, the laptop goes off after 5 minutes.
I did that many times and the laptop goes off even into POST screen BIOS settings after 5 minutes no matter what.
I took off the RAM, the CPU and starting measures. So far i have:
No pressed power button:
+3VALW, +5VALW, +0.9V to PL11
After press the Power button:
+3VALW, +5VALW, +1.5V, +1.8V +1.1V (no battery connected)
A strange measure i get is the VGA_ON signal that has 3.3V without pressing the power button. Is that normal?
Also, i get +1.0V to PL7 which is strange too.
Looking the schematic, i noticed than the signal DGPU_PWR_EN is pressent with +3.3V. Is that normal too? What conditions must have to get this signal corectly?
I would apreciate any help.
PS. A good boardview file would be very helpfull to find points for measuring.
I give the circuit diagram for further help
Thanking in advance
I would like to help me solving the problem i have.
My favorite laptop Acer aspire 5942g motherboard is tottaly destroyed from my bad luck attempt to reflow the BGA chip. So the original m/b is off now.
Fortunately, i had bought another m/b with some problems and i decided to give a second chance.
The new m/b has the problem that with no RAM, no CPU placed and giving power 19VDC, it lights the 3 blue lights. Then, when i pressed the POWER button, it goes on for 3-5 sec and then goes off.
I 've found broken parts which i' ve replaced (PU7), a FET and a transistor, and then i clean the m/b well and put fresh thermopaste above the 3 main chips (CPU, BGA, VGA). I've measure +5VALW, +3VALW. After then, when i press the power button, it goes on and i have image through VGA cable.
I connect then the HDD and it goes into windows. I was very glad but unfortunately, the laptop goes off after 5 minutes.
I did that many times and the laptop goes off even into POST screen BIOS settings after 5 minutes no matter what.
I took off the RAM, the CPU and starting measures. So far i have:
No pressed power button:
+3VALW, +5VALW, +0.9V to PL11
After press the Power button:
+3VALW, +5VALW, +1.5V, +1.8V +1.1V (no battery connected)
A strange measure i get is the VGA_ON signal that has 3.3V without pressing the power button. Is that normal?
Also, i get +1.0V to PL7 which is strange too.
Looking the schematic, i noticed than the signal DGPU_PWR_EN is pressent with +3.3V. Is that normal too? What conditions must have to get this signal corectly?
I would apreciate any help.
PS. A good boardview file would be very helpfull to find points for measuring.
I give the circuit diagram for further help
Thanking in advance
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