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iMac 27" Late 2009 A1312 New Installation Problem - Keyboard flakey and Mouse not connecting


macrumors newbie
Original poster
Mar 29, 2011
Good day!

I was hoping that I could find some help here, am new to this forum.

The above device seems to work, but the HDD crashed and I replaced it with a new SSD (Samsung 850 EVO 500GB). At the moment, the temperature sensor cable is not terminated with a HDD temperature sensor.

I am trying to install High Sierra on this machine using a wired Apple keyboard, which does connect. However, during the installation process less and less keys work and when it gets to the High Sierra target disk selection, no keys work at all. I am not able to connect a Bluetooth mouse.

I have reset the SMC / PRAM but no change. I also tried to run ASD 3S138, but here none of the keys work correctly - in fact I need to press "Command-T" to start the test (which fails at the HDD temperature sensor of course).

Does anyone have an idea what is going on here? Happy to provide more info if needed.

Many thanks.

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