Mac Mini constant fan issue

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didoman

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I just picked up a used mac mini, want to do some upgrades to it but first I have a problem to fix... It's a Core Duo 1.83, superdrive (high end of 2nd gen Intel I believe), 80GB HD, 1x1 GB RAM.

The guy I bought it from said he had an issue with one of the RAM sticks (was 2x1GB before), but has been running fine since he pulled it out about 3 months ago. I've had it for a day, and the only problem I've run into is that the fan is constantly blasting at max (not a runaway process, CPU usage is 2-3%). The fan is full blast about 3 minutes after boot.

A Google search leads me to believe that he probably forgot to plug in the fan cable when he swapped out the RAM... anyone here experienced this before? Is it pretty easy to see where this cable should be plugged in? Can anyone link to a good take-aprt guide? Also, could it be anything else? An SMC reset did not fix it.

My plan is to take it apart this weekend to upgrade the memory, and I'll try to fix the fan problem at the same time. Also, just want to check that 2GB is the max this mac can handle... it can't be pushed to 3 like the core2duos right?
 
It's not that difficult -- just have steady hands and patience as to not scuff anything up.

http://letmegooglethatforyou.com/?q=mac+mini+take+apart+guide

Yes, 2GB is the max RAM. If it's a Core 2 Duo, then I believe you can shove 4GB in there (2 x 2GB).

As for the fan issue, did you reinstall OS X when you took possession of the computer, or are you using the OS X the original owner installed? Did he, perchance, install SMCFanControl, which allows the user to set the minimum fan speeds?
 
The HD temp sensor gets disconnected when you open up to replace RAM. It's very easy to miss. The tiny connector is near the battery. It can't be plugged in until you are ready to put the cover back on. If that is left disconnected, then the fan runs at high speed..
 
I haven't re-installed OS X yet (came with original 10.4 disks as well as retail 10.5), I'm waiting until I upgrade the ram (in case I get to the computer store and decide pick up a new hd too haha). But he erase/installed leo before selling so I don't think he would have installed anything. Thanks tho, I will definitely check that before I take it apart.

DeltaMac said:
The HD temp sensor gets disconnected when you open up to replace RAM. It's very easy to miss. The tiny connector is near the battery. It can't be plugged in until you are ready to put the cover back on. If that is left disconnected, then the fan runs at high speed..
Click to expand...

Thanks deltamac, this is something that the guide I was looking at did not mention. I'll definitely keep an eye out.

ElDiabloConCaca said:
Yes, 2GB is the max RAM. If it's a Core 2 Duo, then I believe you can shove 4GB in there (2 x 2GB).
Click to expand...

Thanks eldiablo. I know the more recent ones can take 4gb, but i just remembered one generation being able to address 3.3 even tho apple stated 2 as the max. I guess not mine, o well :)

By the way, i do know what google is... I was only asking if anyone had a good recommendation on guide, from experience. Like how the one I was looking at did not mention that HD sensor...

Ok so thanks for your help so far, I'll be doing the take-apart when I get off work in a few hours so I'll post back with results. I really hope its as simple as that fan cable being unplugged...
 
Okay good new and bad news... really really bad news...

First off - took the case apart, immediately saw that the fan cable was unplugged - an easy fix. So I install the additional RAM (now at 2x1GB), put it all back together, and voila, works like a charm. "About this Mac" reports 2GB, looks good. Browsed the internet for a while without problems, and the fan issue is fixed now that the cable is plugged in. OK, time to clean install 10.5.

I put in the dvd. It popped up in the finder just fine. I restarted, held option, selected the Leopard DVD to boot from, pressed enter, and walked away. Came back 15 minutes later to a grey screen... no boot from leopard disk. OK no big deal I thought, I held the power button on the back to turn it off. Re-started, this time not holding any keys (thinking it would default to the HD). went out for dinner, came back an hour later, still at grey screen...

So i power down manually again. power up again, this time holding my mouse button (thinking it will eject). Now, I don't get any video output, and there is no startup chime! The dvd spins in the drive, then it stops after a few minutes and all I can hear is the quiet whir of the low-speed fan (and maybe the HD). Also, the sleep indicator light is on.

Took it apart again, thinking the ribbon on the back was loose or something. Adjusted it, turned back on (case is still off), same problem. No video, no chime.

PLEASE HELP!!! My girlfriend is gonna flip if she finds out i spent a few hundred $ on fancy paperweight... What is the next step? pull off the top unit and re-seat it? take apart the optical drive (is that hard?) to get that dvd out? surely it's not the new ram, it was working just fine...
 
Ok more results... Adjusted the ribbon on the back again. this time it booted up just fine! I was able to eject the 10.5 dvd no problem. but still no startup chime hmmmm, so I check the volume settings in sys prefs, and sure enough there is nothing listed under output - no "line out" or "built-in"... definitely had sound before!

I'm convinced it's a problem with the ribbon... When you slide it in, is it supposed to stay in there firmly? because mine seems to want to pop out at the slightest nudge. it doesn't feel right. I almost want to glue it down or something.
 
You should take back apart. Make sure the interconnect board is seated firmly. That's the long connector that runs into the logic board from the drive frame. Check all the little connectors that attach to that interconnect board. You should be concerned about the connection for that ribbon cable. It secures in the connector with a locking bar. That should be the lighter piece of plastic that runs the width of the ribbon. It should lock the ribbon in place, and the ribbon should not just 'pop out at the slightest nudge'.
If you can't figure this out, you might take it into an Apple service shop, and pay someone to help you out....
 
DeltaMac said:
It secures in the connector with a locking bar. That should be the lighter piece of plastic that runs the width of the ribbon. It should lock the ribbon in place, and the ribbon should not just 'pop out at the slightest nudge'.
Click to expand...

That's exactly what I was thinking, that it should slide in firmly! well after taking it apart again I noticed a small piece of plastic sitting loose on the logic board - guess what, it was the locking bar! Looks like the guy I bought it off broke it at some point.

For anyone with similar issues, here how I fixed it. The idea is to wedge the thin end of the locking bar between the back side of the ribbon and the inside of the slot. I got it in there by holding one end with needle nose pliers (really small ones!) and nudging the other end into place with a tiny screwdriver, then repeating on the other side. and by being VERY careful! The result is a very tight connection that I am happy with. Since the locking bar is broken, it's possible that it might get knocked out if the mini is whacked or something... I'm considering adding some glue or thermal tape to be safe.

DeltaMac said:
If you can't figure this out, you might take it into an Apple service shop, and pay someone to help you out....
Click to expand...

Well it's a good thing it didn't come to that, who knows how much apple would charge to diagnose and fix. reports on other forums of $200 just for the new sound board (b/c they'd replace the entire thing, not just the little piece), plus labour! Anyway, I'm up and running again, fresh leo install. Thanks everyone!

To summarize issues for others:
- Mac mini Core Duo 1.83 takes 2 GB ram max.
- Constant high fan speed after take-apart is likely due to the fan cable being left unplugged. Simple fix.
- Audio issues (and possibly related issues) after take apart likely due to the ribbon cable being improperly seated. It should slide firmly into the holder, and then be locked into place by a small plastic locking bar.
 
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