Linked by Howard Fosdick on Mon 31st Dec 2012 20:26 UTC
Hardware, Embedded Systems Last month, I explained why I use generic desktops and laptops running open source software. They're reliable and inexpensive. But this presumes you can fix them. I believe that even those with no hardware training (like me), can identify and fix most hardware problems. To prove it, here's a quick guide. Feel free to add whatever I've missed.
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RE: The Bane of Laptop Repair ...
by Doc Pain on Tue 1st Jan 2013 03:19 UTC in reply to "The Bane of Laptop Repair ..."
Doc Pain
Member since:
2006-10-08

Comparable problem here while trying to resurrect a IBM Thinpad T60p: FAN ERROR, machine powers off. I've replaced the fan with a new one, same error. Because the fan doesn't even spin up, I checked voltages with a scope and could see that the power for the fan isn't present on its power pin (3 pin connector with gnd, power, sensor). Unplugging the power and carefully (!) powering the fan with an external power supply at approx. 3V makes it spin properly, and the machine boots, so the sensor tells the truth.

Diagnostic options are:

1. The wiring to the power pin is damaged somewhere. This is hard to tell when a multi-layer PCB is used.

2. The "power generating complex" (that generates all the different voltages needed inside the machine) does not provide the base voltage which is then leveled as required to control fan speed.

3. The unit that actually controls the fan speed - probably a component within the "chipset" chip - is malfunctioning.

Big question: How to find out, and how to cure it?

I'm almost doing this - and kids, don't try this at home (except you are considered insane already): Get 5 volts from a "nearby" USB port inside the laptop, apply a resistor powerful enough to bring the voltage down to 3 V (or something like that - needs testing!) and install it inside the machine. The fan itself is confirmed for 5 V at 300 mA. Close the device and let it run for longer time, make it perform hard work and be idle. Watch the temperatures (for example by using healthd and mbmon). Yes I know, resistors are stupid, a proper voltage control circuit is better. Also having the fan run all time shortens its overall lifetime. But that's still better than having bought the spare parts and now throw that nice laptop into the dumpster.

I know this is not a hardware support forum, but my problem is so exceptional that only the exceptional participants of this forum might have a pointer for me to deal with this problem-

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