I got a Fujitsu T4020 Tablet PC for free, secondhand, and it was pretty nice.... but then I made the mistake of updating the BIOS (from 1.03 to 1.05). This changed the fan control, so instead of turning on to maintain a sane temperature, it let the laptop get scalding hot... and a tablet you can't hold is useless.
I then went poking around and managed to blow out the MOSFET (I assume -- http://picpaste.com/a5v0d.png) that powers the CPU fan... so it changed from bloody hot to mind-numbingly loud (zero resistance between the three pins). I then proceded to remove the MOSFET from the board, but it took part of the traces with it.
For now, I'm thinking I may have to just use a hideous hack: an analog or PWM fan controller knob. I'm worried that even if I replace the surface-mount component, the thing that controlled the gate may have gotten fried as well. Also, even if I fix the control circuitry, it does me no good to go right back to scalding hot -- I'd either need the old BIOS, or a MOSFET with a different behavior curve to increase low-end speed (if it's even analog, and not PWM).
To make matters worse, the thing doesn't even offer any ACPI or SMBus temperature sensors at all! I know the thing won't let itself totally die, at least... and it reaches too hot for the user long before it reaches too hot for the chips.
Anyway, does anyone have any really high-resolution pictures of the front of an intact motherboard from that laptop, right near the CPU fan connector? Even better would be some pictures of the back, so I could find the fan controller chip. Also, does anyone know how to identify that little surface-mount component? Note that the bottom-left leg is broken off.
I then went poking around and managed to blow out the MOSFET (I assume -- http://picpaste.com/a5v0d.png) that powers the CPU fan... so it changed from bloody hot to mind-numbingly loud (zero resistance between the three pins). I then proceded to remove the MOSFET from the board, but it took part of the traces with it.
For now, I'm thinking I may have to just use a hideous hack: an analog or PWM fan controller knob. I'm worried that even if I replace the surface-mount component, the thing that controlled the gate may have gotten fried as well. Also, even if I fix the control circuitry, it does me no good to go right back to scalding hot -- I'd either need the old BIOS, or a MOSFET with a different behavior curve to increase low-end speed (if it's even analog, and not PWM).
To make matters worse, the thing doesn't even offer any ACPI or SMBus temperature sensors at all! I know the thing won't let itself totally die, at least... and it reaches too hot for the user long before it reaches too hot for the chips.
Anyway, does anyone have any really high-resolution pictures of the front of an intact motherboard from that laptop, right near the CPU fan connector? Even better would be some pictures of the back, so I could find the fan controller chip. Also, does anyone know how to identify that little surface-mount component? Note that the bottom-left leg is broken off.
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