Fanless AAO shuts down. Any ideas?

I'm trying to remove the fan, but whenever I boot up with the fan unplugged, the machine shuts down after about a minute.
It has nothing to do with temperature.. Is there any way around this?

 

That's one of safety features: no fan = no boot... Someone mentioned that before...

 

Yea, I noticed

Maybe I can trick it with a resistor? Does anyone know the resistance of the fan?

 

No bright ideas? I threw away the fan already..!
It's getting annoying.. Thank god I don't actually use this thing

 

The computer could be looking for a couple of things accross the two pins feeding the fan.

Current flow
voltage drop
resistance (variable)
AC pulse (RPM)

The easiest solution would be to re-install a fan. Check ebay...

 

Indeed... but I don't want it there
I will force this POS to do my bidding..one way or another.. but no fans

 

Remove the fan blades so everything is still there but there's no actual fan?

 

A DC motor is an inductive+resistive load. I seriously boubt if the circuitry actually bothers to detect this. To keep thing simple (and cheap) I'm guessing its just looking at the speed pin. 0 RPM = shutdown. Just tested this with a multimeter, the speed pin seems to return a voltage proportional to the speed of the fan. I had a 12V DC fan, i ran it off a 9v source and mesured. 0rpm=0v. 0.3v = speed at 9v. I'm sure if u just fed a small voltage in there it would be fine. Probably not worth the effort though, shouldn't have thrown out the fan so hastily.

 

If I didn't take rash decisions I wouldn't own an aspire one ...

I had to take the fan out, because I installed a massive heatsink. I've noticed that the computer doesn't turn off if I play with the wires, occasionally brushing them against each other. It will, however, turn off a minute after I stop doing that.
How would I go about feeding volts back to the speed pin, and do you know which one is the speed pin?

 

(EDIT) Speed pin would be the gray wire.

Your observation of touching the wires together, enabling the CPU to continue running, would suggest the motherboard is measuring current flow. If that is the case, you could use a resistor.

 

Check your fan again, it does have three wires
I tried a resistor, but it didn't do much good.
Brushing wires together + fan control allows me to keep it running now, but it's an ugly workaround

 

OOPs, yes there is three wires. So gray must be the speed pin (Tach). It will be looking for a AC pulse.

 

How can I feed it an AC pulse?

 

Hook it up to a three wire fan and turn the fan on. (Sorry, I could not help myself)

Desktop computers have a bios setting to disable the fan inoperative warning (shutdown). You might google water cooled computer forums and search those forum on how to simulate a fan, because when you water cool the fan tach is a problem which certainly has been solved.

 

Hehe! I kinda solved it. I uninstalled my AV and disabled a bunch of start-up processes, so that fan control starts up just in time to prevent it from turning off =)
Not a great solution tho... I will look for a tiny fan unit to place somewhere inside
Now I just have to sit back and wait for my thermal glue to arrive.

 

What on earth lead you to believe the fan is outputting an AC pulse into the speed pin?? It's a DC fan, do you really think theres an AC signal generator in a simple computer fan? Lots of misinformation flowing around here. If you wanted to feed a small voltage into the speed pin id suggest getting the power from the voltage pin of the fan header. Throw in a resister in series to drop the voltage down to a couple hundred millivolts and see what happens. Using too large of a resistor will just make it behave like open circuit(same situation you're in now), too low resistance might fry something.

 

Thanks for you input zzzz. I'm waiting for his response, as I have no idea about which one of you is right.
In related news, my new heatsink is -awesome-. It's performing extremely well even without thermal glue/paste. I will post some results when I get it all glued and pasted together

 

The speed pin picks up the signal generated by the spinning magnets inside the motor. There is no way this signal could be DC (direct current) unless there was a rectifier or diode to convert the signal to DC. Believe what you will.

 

Lets settle this once for all.. it's not ac nor dc. It's pulsed or dodulated dc. It has characteristcs from both dc and ac.

 

In which case I would have to...?