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Latitude D620 CPU Fan problem
I have a Dell Latitude D620 that was a workhorse, until one day recently, the CPU fan stopped working and the CPU started overheating. I did a little diagnosis of my own and found that the fan worked fine while plugged into a stand alone power supply. I then took the laptop into a local laptop repair shop and they diagnosed it as a bad motherboard.
I located a replacement MOBO for the D620 on ebay that was represented to be a tested and fully operational and functional MOBO by a reputable seller. I received it yesterday and put my CPU and other components on it and much to my surprise, the laptop fan doesn't work. Everything else appears to work fine with it (it booted up to Windows and the CPU began overheating). I tested this fan too, and it worked plugged into a stand alone power supply.
What are the odds that I could have 2 laptop motherboards with the same exact fan issue? I've researched the D620 and it doesn't appear to be a widespread problem, like the nvidia video chips on them (mine has intel video, btw). Could it be that there is something else going on, like a failing CPU? Anybody have any ideas? I really need to get some feedback before I contact the ebay seller for a return authorization and start looking at other MOBOs.
ejn63
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July 6th, 2014 08:00
You haven't mentioned having changed the fan - that would be the next thing to do before you condemn the mainboard as the problem. Although the fan may work on DC12V, it has a third wire that is required to communicate with the mainboard - and it may be the cause of the entire problem.
rdkapp
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July 7th, 2014 02:00
Thanks for the reply, EJN63.
The fan has been changed out, once by me and once by the local laptop repair shop. The repair shop told me that they put in a known working fan on the board and it didn't work. Thus, they condemned the board and tried to sell me a replacement board.
As for me, I've swapped the fans from the original board and the replacement board that I bought off ebay, and neither one worked in either board.
And yes, in case you are wondering, both fans have the 3rd wire (the yellow one in the middle). Also, I didn't test them with DC12V. I tested them with DC6V and both were operational.
Finally, today, I put a multimeter to the red and black terminals on the fan plug on both boards, while powered up, and the readings were insufficient to power these fans, much less anything else. The readings on both boards were fluctuating between 0.05V and 0.07V.
Do you still think it could be the 3rd wire and that I should invest in another fan?
I am interested in any other thoughts you may have on this issue, and really want to get to the bottom of this problem.
Thanks again.