Fan control on a Lombard

#1 Sun, 31 Aug 2008 - 14:19 68kMLA

I finally have my Lombard up and running (mostly). However it will overheat if left alone since the cooling fan never comes on. Currently I'm using one of those PC slot fans to draw air through the openings in the side of the case, but a more elegant solution would be greatly appreciated.

The TemperatureMonitor program only shows 1 sensor and that is located in the hard drive.

#2 Sun, 31 Aug 2008 - 17:04 68kMLA

Perhaps you can find a 5V point somewhere and connect the internal fan directly to that. Maybe on the USB port. It won't be temperature controlled, but at least it'll run.

It would be worth checking that the fan runs at all while you're in there.

#3 Sun, 31 Aug 2008 - 19:46 68kMLA

You can test the Lombard internal fan by itself. Disconnect it and make a drawing of the three wire colors and where they go into the plug housing. Then if necessary remove the connector pins temporarily from the plastic block with a jeweler's screwdriver and power up the red and black to +5VDC and ground respectively. The fan should run at full speed. Mine starts up with as little as 2.3VDC. The yellow is a square wave TTL tachometer output. View it on a scope or counter and slow down the fan with your finger to verify the frequency tracking with RPM, constant amplitude, and that it stops completely when you stall the fan.

If the fan checks out ok you can also check the Si9933 motor driver FET pair nearby and maybe the LMC6462B opamp U20.

#4 Wed, 3 Sep 2008 - 14:40 68kMLA

The Lombard is up and running again and seems to be cooler even with the original 400mhz processor. The only issue I have with it is that FireFox 3 will not run-Opera was installed instead.