how to connect fan to always on? (connected)

[chilipuca]

I have a T21 and the fan cooler switch itself on only a for few seconds during the boot time... then, it doesn't turn on again even on 60° CPU.
I have sporadic shuts downs and since the tpfancontrol doesn't work for my laptop, I want to try this "fix" as first step.

How/where do I wire the fan?

[jamiphar]

If you knew the voltage and current draw of the fan (may be listed on the label), you could wire it to the USB 5v+ pin and use a resistor to get the correct voltage. This will make the fan stay on as long as the T21 is powered on.

[Nick Y]

If you knew the voltage and current draw of the fan (may be listed on the label), you could wire it to the USB 5v+ pin and use a resistor to get the correct voltage. This will make the fan stay on as long as the T21 is powered on.

If the T21 uses a 3 wire fan as does the T43 and T41p, the simple link suggested may not help. The third wire is, I assume, a feedback link indicating fan speed. I assume, again, that it is this that causes the T41p to shutdown on power up if the fan no longer works.

Have you tried blowing cold air in to see if that stops the T21 shutting down?

[jamiphar]

@Nick Y

Actually, it should work if he does it that way, as long as he connects the power to the positive contact. He may or may not get the RPM readings, but it shouldn't matter if the laptop isn't controlling the speed anyway.

@chilipuca

A couple of more things you can do if you have the time; you can test it with different resistors until you get a voltage that is keeping the fan on, but only enough to sufficiently cool the CPU. That way, it doesn't necessarily have to be at full blast. You could also add a potentiometer into the mix and you could adjust the FAN speed whenever you want. Just a reminder; if you hardwire it like this, you'll probably have a fan error every time you start up.

[chilipuca]

Thank you guys... I connected the fan the way jamiphar said...
everything working fine so far.