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Replacing Fan and Air Temperature Sensor
I brought my Optiplex 745 to local repair place because it was having issues turning on. They pinpointed the issue as the fan needing to be replaced. Instead of paying them $70 to do it, I took the CPU back, found a new one online (for $12), and replaced it myself. The workers didn't replace the temp sensor off the I/O panel, and after talking about it with them, they said it didn't need the sensor. However, the new fan was very loud, so I put the sensor back in.
It booted up fine w/o an error and was very quiet at first--then the fan revved up to a consistently loud speed. Now, when I boot up, I receive a "temp sensor not found" alert. I'm wondering if I put the sensor in wrong; however, I can't find a schematic or any documentation online of how it should be inserted. The worker at the shop I went to just said it attaches "to the case," but I'm doubting that's correct. The user guide seems to cover replacing everything except the fan and this sensor. Can someone spell out explicitly where the sensor is supposed to connect?
Thank you!
osprey4
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March 27th, 2012 18:00
Hi Ryanhlane,
See if this page from the owner's guide helps. Here is the service manual section on the I/O board.
ryanhlane
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March 29th, 2012 12:00
Thanks for your help, Osprey4. I see where the pins for the sensor cable attach to the I/O board, but there's nothing in the user's manual about where to attach the other end of the sensor (the black part that looks like a clip). Is there a specific place that's supposed to go?
Also, I'm wondering if something is up with the I/O panel in general. At first it detected the sensor when I booted up the computer, but now it doesn't. Is there a test I can run to check that out?
Thanks again!
osprey4
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March 31st, 2012 04:00
I don't know if the diagnostics will test the I/O board, but you could try.
Let me see if I can get some help on the connections from one of the Dell mods.
DELL-Chris M
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March 31st, 2012 22:00
Temperature Sensor
Mini-tower = Integrated into the front I/O panel. Shared with the I/O ribbon cable
Desktop = Integrated into the front I/O panel. Shared with the I/O ribbon cable
Small form factor = Snapped into the front grill of the chassis in front of the fan. Two-wire signal cable connects to the I/O board
Ultra small form factor = Integrated into the system board. No cable necessary
If the temperature of the sensor rises above 42C (107.6F), the system logs an error (Air Temperature Out of Range) in the Event Log accessible through System Setup. The air entering the customer’s system has exceeded the 42C standard, and the system must now compensate with increased fan activity and noise. This is a normal design function.