Model A1224 / Mid 2007 and Early 2008 / 2, 2.4, or 2.66 GHz Core 2 Duo processor

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type of transistor used at hard drive thermal sensor inside iMac a1224

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Hello everyone's

Please answered somebody who know what type of transistors used in thermal sensors inside iMac a1224 a1225 mid2007-early2008.

I know that is exactly the transistor but what transistor?

I have not one of this thermal sensor at hands for check the transistor mark, but I need to know for built it by myself.

Thanks and regards.

Update (12/09/2017)

I think that the 2n3904 bipolar transistor was used. It costs in ma local shop 5 cents.

Cable costs nothing for me.

Connector - maybe 20cents.

And my own work)) I'll pay myself.

It so cheap for me. And I can do it for 15 min. Most cheapest original thermal sensor on eBay - 5.80$ plus the time that I will wait the parcel. I live outside from Noth America . Or 5 cents and 20 cents plus 15 min of my own time with solder station in hands.

I just want to clarify what kind of transistor it is.

Update (12/09/2017)


In the end, I found good quality photos in description of one of the lot on eBay. Transistor marking is clearly visible on one of the photos. It's Mps3904 - npn bipolar transistor. It can be replaced by 2n3904, 2n4401 etc

so, if you are have enough experience in soldering, you can easily produced that thermal sensor by yourself, I think it takes something about 15 to 30 minutes. And you can save 7$ per item and shipping costs if you are far from seller destination.

Update (12/19/2018)

One year later

Two thermal sensors which were soldered of 0,1$ transistors 2n3904 and wire works just fine.

Answered! View the answer I have this problem too

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artemsemon you are correct with your research about the 2N3904 You can also use a I used a 2N2907 TO-220 transistor. It has successfully been used as sensor replacement in multiple different machines. The only way to know which one Apple uses is by trying to take it apart and hoping that it is marked. Go with your research and I am certain you already recognized that you will have to tie the Base and Collector of the transistor together.

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Here's the needed part already made: Cable, HD Sensor - Apple P/N 922-8196 ($4.45 US) Which I think would be easier than trying to make it. If you search on 'Apple 922-8196' You might even find a source closer to you.

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It doesn't easy for me, otherwise I would have bought it.

And still wait answer from anybody.


artemsemon - By the time you pulled all of the parts needed together I'm sure it would cost you more. Given how old the system is I doubt anyone knows off the top of their head.

Where are you located country & city?


Which is your system the Mid 2007 you've listed here or the Mid 2010 you linked? These are very different systems and use different parts.

Where do you live? If you give me a clue here I might have an alternative for you.


But the thermal sens construction are the same.

There are answers In that discussion in which write about transistors and model we are looking...


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Has anyone (besides OWC) reverse engineered the sensors required to make the 2009-2012 iMacs work with 3rd party hard drives? The OWC in-line digital thermal sensor products work great but they cost almost as much as a 120 - 240 GB SSD that are affordable to keep these old machines going. If someone could make and sell these for half their cost or less I think there would be a lot more people keeping these old iMacs going. They’re still useful.

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artemsemon will be eternally grateful.
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