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Installing the UpTone Audio MMK in a 2014 Mac mini


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10 hours ago, johndoe21ro said:

Hi! First of all I'm a big fan of UpTone products. These guys are great!

Secondly - I've recently installed the MacMini DC Conversion/Linear Fan Controller Kit (MMK) in my Mac Mini Late 2012. 

I have to mention that in the same time I also installed a brand new SSD (Samsung 860EVO)...

Today I hooked up an SMPS (12V, 5A) and was planning to install the MacOS... but something happened. When I plugged in the wall the SMPS the fan in the MacMini already started to spin very fast and noisy (MacMini wasn't turned on). When I've turned the thing on everything seemed to be ok... The USB stick with the OS was recognized but I decided to stop and investigate the FAN problem... Any suggestions? Why did it start to spin (full speed) even if the MacMini was turned off?

 

The fan control coming from the Mac Mini is a series of pulses, these are not voltages coming out of the Mac, they are called a "pull down". The destination (in this case the MMK) has to put a voltage on the wire and the Mac "pulls it down" when it want to be low.The length of time the signal is pulled low determines the speed of the fan. If it mostly low with just a little time high, then the fan speed is low. If it is mostly high and only low for a short time, the fan is fast.

 

When the Mac is turned off or the fan signal from the Mac is not connected, the signal is always high, which means "run the fan as fast as it can go".

 

So the fan running fast when power is applied to the MMK and the Mac is turned off is normal. Note this is not a normal configuration. Normally things are setup so the Mac turns on when the power is applied to the MMK so you would not see this. I'm not a Mac person so I don't know how this is done.

 

John S.

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12 minutes ago, johndoe21ro said:

I appreciate the effort to write down an answer but that doesn't help me much. The fan speed is high and it's high without it even being turned on. When it's on it remains high... Looking for an answer from a Mac Mini owner... 

 

P.S. John, you wrote: When the Mac is turned off or the fan signal from the Mac is not connected, the signal is always high, which means "run the fan as fast as it can go". The fan signal from the Mac could be the problem. Is it the white ribbon cable? And, if so, is this a DS4 14 pin power switch ribbon cable? In case I break it down trying to stick it better into the connector... 

There are three cables involved with the fan:

 

1: the long white one from the big board to the little board.

2: black from little board to the fan

3: black from little board to the MotherBoard

 

The white cable carries both the signal from the MB and the power to the fan. Since the fan is running this seems to show that #1 and #2 are working, which points at #3 as the problem.

 

So try removing and re-inserting both ends of the #3 cable, this is the black cable that is plugged into the connector on the small board labeled "TO MB".

 

John S.

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