Problem with Mac Mini Not Powering On All The Time And Shutting Down Unexpectedly

macwise · Jun 16, 2012

Hello, I hope someone can figure this out because I am at my wits end. I was just typing this post on Boot Camp XP on the Mac Mini in question when before I could save or post, it shut down, so now I"m typing it up on my laptop. Ok here's the problem we have a used late 2006 Mac Mini Intel 1.8 GHZ (no audio, since the ribbon is broken, we just use a USB sound card, but we don't get chimes since no on board sound) with Snow Leopard when we bought it did not have a Power Supply Unit so we bought a new one online we went with the 110w rather then 85w since that's what the specs called for, it worked fine for a few days and then it started shutting down. The only way it would start up again was to leave the PSU connector disconnected from both the mini and the AC outlet. I should add though I don't think it's a factor I misplaced the power cord it came from and I'm using one from a different adapter. Anyhow So I started to wonder if this could be a bad PSU, I didn't really think much of it since we were getting ready for a RV cross country trip. The mini was in storage for about 2 months till I recently hooked it up again, the problem persisted and I started to wonder if maybe the mini was overheating so I recently installed SMC Fan control, as far as I can tell the temps are well within the acceptable parameters, one odd thing happened yesterday though, it booted up and the LED light did not come on and the Fan was at full speed, SMC Fan control showed the Fan speed at 0 and I'm not sure what the temp was, since yesterday the white light would only come on and then off and no power up. Also when you hold in the power button the White light will flash but it won't start up. Lately I started wondering if something was wrong with the Logic Board since it's behaving very erratically if that's the case I give up. Today I was ready to throw in the towel since it just wouldn't start no matter what, As in the past I tried and I tried everything, re seating the RAM,
(oh I should mention the white light will blink correspondingly when no RAM is detected since I tested it by taking out the two RAM modules), I tried to reset PRAM and SMC PMU and everything else suggested, the only thing that seems to work is disconnect and reconnect the PSU and the longer it stays disconnected the better chance it has of starting and staying on I just tested the PSU with a multimeter and the output show around 18.7 it should be 18.5 no surprise the mini just started up after I left the PSU disconnected for about an hour or so, I am going to wait till it shuts down again and test the PSU output again, I will post the results as soon as I can. Well I'm on it right now on mac side and SMC fan control shows 55 Celsius about 3900 RPM, the PSU brick doesn't seem hot to touch at all, I haven't noticed in past shutdowns if it seemed like it was overheating, it's too bad sensors can't monitor the PSU temp. I'm waiting for it to shut down like it usually does to test the output, we shall see soon I hope. just tried to put it to sleep and it won't do it it keeps waking up could it be a bad PMU? UPDATE, I shut it down and when I tried to startup the boot screen loaded but then as usual it it wouldn't stay on, the brick didn't feel hot at all, I tested the output and at first it read 18.7, but I tried again and it read 19.2, this seems like a sign that the brick is overheating, it would seem that way to me. I am going to wait about an hour or so and test the output again and I wouldn't be surprised if the mini starts up again with no problem. I'm on it again, the output reads 19.3 last checked, that seems way to high, I read somewhere online the the brick has some kind of a switch inside that if it overheats it will shutdown the Mac Mini, Sleep is working fine now, waiting for next shutdown to happen
On a side note, last week it stayed on for nearly two days straight and then the next days very bad,, Could it be the PSU is bad and is overheating and that's why it only will start after being disconnected, and that's why It shuts down with no warning? System log reports as of today as you can see " Jun 16 09:27:20 localhost DirectoryService[13]: Improper shutdown detected" meaning "Uninstalled Interrupt", if I'm not mistaken whatever that means since after an extensive search online I found little to no information on that. I'm not sure what to think. If the PSU is bad, no big deal I will just replace it and buy another one,but since they aren't cheap I don't want to buy it and then find out the problem was something else and if it's the logic board, then it's hasta la vista baby.
Thanks for any help.

BSD Meister · Jun 16, 2012

I'm a little bit leery of the idea that the sound cable was cut. An old, dishonest auto dealer trick: if the check engine light is on, pull the bulb or disconnect the cable - problem solved, or so it appears. If you accidentally cut the sound cable yourself, no big deal, but if the unit was beeping once in a while, one sure way to make that go away is to cut that cable.

You can have several possible problems:

1. PSU is defective
2. Battery needs replacement
3. Logic board is bad.

If I were you, I would try to address the PSU's apparent problem first. They have a thermal cutoff switch in them and if it's bad or poorly calibrated, it will cut off prematurely. The first time I ran into this problem was in a lab. We used to have a facility with lame AC, and the temp would go from about 70 deg F to 78 deg F, then back down, and cycle like that. One unit kept erratically going out on us. I noticed every time it did it, I seemed hot, because it was. That temperature variation in the room was just enough to cause the faulty thermal regulators to shut off. You might have a similar problem.

I know this might sound like a ridiculous idea, but put the PSU in a plastic bag and put it in the refrigerator for about 5 minutes (NOT the freezer). Take it out and try and power up the unit. If it will power up every time it's cool, then you've likely found at least one of your problems if not THE problem.

I wouldn't go out and buy another supply yet without checking it out with one that's known to work well. I'd try to find someone you could borrow one from. If you have a local Apple/Mac users group, there may be someone there willing to help you out, or if you know someone in your area with the same type of unit.

Make sure the PSU really is intended for your unit. Some of these "after market" units are actually factory rejects that have been repackaged and sold to unwitting distributors. Most of the time they're OK with minor cosmetic defects, but some times they're flat out rejects that have no business being sold. They're typically acquired from auction sites.

I doubt this is it, but the battery might need replacement. It should be reading between 2.6 and 3.0 V. Also, make sure you haven't pressed on the unit's internal SMC reset button more than once sequentially because that can damage the SMC chip. If you have the unit open with the back of it closest to you, the SMC reset is on the far left side a little more than half way up the logic board. You don't need to reset the SMC because you're doing that anyway each time you pull the power out of the unit.

I'm mostly concerned with the logic board. If that ribbon was broken by you, accidentally, it's no big deal, but if it was deliberately done because the unit was doing exactly what it's doing now, it might have been cut to "silence" it from warning a user that there's something wrong with the unit. If it is the logic board, it's likely a bad trace or solder joint in the logic board. Sometimes people unfamiliar with working on these units will attempt to upgrade the RAM and then crack some of the traces. Unless you're really lucky these are almost impossible to isolate without special equipment. It would cost far more to isolate the problem on the board than it would to replace it.

Based on what you've written, I think the most likely culprit is the supply.

Hope this helps.

macwise · Jun 16, 2012

Thanks for the helpful response, as for the ribbon I'm not sure if the unit had sound or not when purchased, I myself may have accidentally cut the ribbon, can't say for sure. The PSU was purchased on Amazon and as far as I know is OEM and it says so on it. I will try to put it in a plastic bag in the fridge to cool it down as you suggested, if indeed that is the culprit then I will have to replace the PSU unless there is a work around the problem as far as the battery it reads 3.1 so it's not likely that. I was wondering what are the prospects of repairing the audio cable?
Thanks again

macwise · Jun 17, 2012

It seems that the lithium battery may have been bad since I had to keep resetting the date and time, I just replaced it and I have the Mini on and I'm waiting to see what happens, after talking to my wife we don't believe it had sound when we bought it, we bought it on ebay and at the time the issue was that it would not boot, we reinstalled the system on an external HDD and the problem was solved, bit it turns out the HDD interface controller is weak where the HDD connects we at first thought it was the drive at first and replaced it only to find the problem was not solved, so while that was an issue we don't know if it was connected with the audio ribbon I seem to remember finding the ribbon disconnected when I first opened it up and I tried to place it back in and the end sheared, so who knows really.
I just found a guide Installing Mac mini Model A1176 Audio Board - iFixit on IFIXIT that guides you in changing the audio card, I guess that's the only way to change the cable, now finding a audio card will be tricky since it's OEM unless I find a parts mini on ebay I don't think I will be able to replace it.

macwise · Jun 17, 2012

Here's an interesting development, I didn't realize that the PMU was set for the mini to go to sleep in about 45 mins. As I mentioned earlier I swapped the lithium battery and suddenly I come back to see if it shutdown and instead of shutting down it went to sleep. Here's what I suspect the battery was bad and it was affecting the PMU, this is the first time as far as I can remember that it went to sleep on it's own! Also I forgot to mention before replacing the battery, whenever I plugged in the PSU the light would come on and it would start without even plugging in the power button, is that normal?

macwise · Jun 17, 2012

It just shut down, rebooted itself with no problem, temp on SMC Fan showed around 70 C, right now running at 80 C 2500 RPM, could it have overheated and shut itself down or is their something else going on?
Thanks

BSD Meister · Jun 17, 2012

It's not normal at all for the unit to come on all by itself just by plugging in the PMU, in fact that shouldn't happen at all. That would make me think the power switch itself is flakey.

"It just shut down, rebooted itself with no problem, temp on SMC Fan showed around 70 C, right now running at 80 C 2500 RPM, could it have overheated and shut itself down or is their something else going on?"

I don't understand what you mean. Do you mean it rebooted all by itself and started up OK, or did you reboot it and it started OK?

The temperature sensors aren't really all that meaningful. They're connected to the top of the heat sinks, but if the heat sinks aren't seated properly on top of the chips they sit on, they can still show a normal looking temperature even thought the CPU is overheating. Temperatures being reported are only for the mini itself, not the PMU. The power supply I described earlier was OEM too, so they're not exempt from being defective (what is?)

One thing you might want to do is check the system log files. This can be done as follows:

1. Click on the Apple Icon in the extreme upper left corner of the display.
2. When the menu drops down, select "About This Mac"
3. When the dialog appears, click on the "More Info…" button. This brings up the System Profiler.
4. When the System Profiler appears, go down to the "Software" section. If it isn't expanded, click on the little triangle so a list appears under it.
5. From the list that appears, click on the "Logs" entry.

Assuming it's rebooting on its own, look at the "last modified" column in the list of log files as it will tell you which log files can be ignored. The most revealing log files will be "system.log" and "kernel.log," but some of the others such as "DiagnosticMessages" may be useful as well. "system.log" likes to turn itself over about every day or so and start a new file and compress it's predecessor. If you're not familiar with modifying these, which is generally command line stuff, you might not be able to read them easily.

In any case, assuming you can look at "system.log" and/or "kernel.log", click on them, then do a case insensitive search for words like "shutdown", "wake", "sleep", "reboot" etc. What you want to look for are some lines that indicate what triggered the events. Pay attention only to those that occurred when the system shutdown or rebooted. BSD Unix kernels typically have lines like "throttling CPU due to overheating" (or something like that, I don't remember the exact words). OS X's kernel MIGHT have similar descriptive text since a good deal of the OS is from BSD based systems. Some of the text in the logs will seem archaic but you might be able to make sense of them. Please don't paste all the log file contents on here.

The hard drive problem you described makes me think the previous owner was likely inside the unit. Some guys try to put a Core 2 Duo into either a Core Solo or Core Duo system to make their systems true 64 bit systems. Unfortunately, a lot of these guys aren't used to working on these systems and end up pulling out or damaging connectors and cables. NEVER pull on a cable on any of these systems.

The way to remove a connector from the logic board is as follows using jewelers screwdrivers:

1. Gently release the release tabs, if the connector has them.

2. Take a VERY SMALL screwdriver and insert it between the base of the connector attached to the logic board and the connector itself, and then rotate it in such a manner that it's pushing down against the logic board connector and up against the connector to be removed. This might need to be done in several different places to break the connector loose. Heat and oxidation make them bind.

3. Once the connector starts moving, use a slightly bigger screwdriver and repeat the process until the connector is loose enough to actually remove. You may need to cycle through several screwdrivers that are larger and larger.

The process isn't that hard or slow once you get used to it. I don't know how many units I've seen where people didn't have experience with these systems and wanted to do something like an HD upgrade and then end up tearing logic board connectors right off the logic board. They aren't villains, they just lack the experience.

Finally, about the CPU upgrade, I'm not saying someone did or didn't try that, but if the unit is overheating, it might mean the previous owner didn't apply the right heat sink compound or seat the heat sink properly. Look at the log files first if problems are still persisting because they will probably give an indication telling you what made the unit think it needed to reboot.

Time for bed now, Later, and best wishes!;D

macwise · Jun 17, 2012

Here's the latest, last night, I set the PMU to shutdown at 1 am and wake at 5 am. Well it did shutdown when supposed to as I watched it do it, but when I went back this afternoon to check it, since I forgot all about it, it was shut down. I tried to start it again and the white LED came on and then nothing, I unplugged the PSU and checked the voltage, it was practically null, I unplugged it from the AC and waited a few mins. checked again and it was 19, I plugged the PSU back in and it started up and booted with no problem, this leads me to believe the culprits were the battery, which is now replaced and the PSU which was most likely failing and it just getting worse, at any rate I think it's time to replace the PSU. I am on it now, so I"m going to post before it shuts down again, I am looking very closely at the logs and trying to figure out why it shut down, I will post what I find as I find it.

I think the best way to respond to all of your tips is in quote form so here goes.

BSD Meister said:
It's not normal at all for the unit to come on all by itself just by plugging in the PMU, in fact that shouldn't happen at all. That would make me think the power switch itself is flakey.

Power switch did you mean in the PSU or PMU? Since I changed batteries, it doesn't do that anymore.

"It just shut down, rebooted itself with no problem, temp on SMC Fan showed around 70 C, right now running at 80 C 2500 RPM, could it have overheated and shut itself down or is their something else going on?"

I don't understand what you mean. Do you mean it rebooted all by itself and started up OK, or did you reboot it and it started OK?

Yes it rebooted all by itself

The temperature sensors aren't really all that meaningful. They're connected to the top of the heat sinks, but if the heat sinks aren't seated properly on top of the chips they sit on, they can still show a normal looking temperature even thought the CPU is overheating. Temperatures being reported are only for the mini itself, not the PMU. The power supply I described earlier was OEM too, so they're not exempt from being defective (what is?)

True

One thing you might want to do is check the system log files. This can be done as follows:

1. Click on the Apple Icon in the extreme upper left corner of the display.
2. When the menu drops down, select "About This Mac"
3. When the dialog appears, click on the "More Info…" button. This brings up the System Profiler.
4. When the System Profiler appears, go down to the "Software" section. If it isn't expanded, click on the little triangle so a list appears under it.
5. From the list that appears, click on the "Logs" entry.

Assuming it's rebooting on its own, look at the "last modified" column in the list of log files as it will tell you which log files can be ignored. The most revealing log files will be "system.log" and "kernel.log," but some of the others such as "DiagnosticMessages" may be useful as well. "system.log" likes to turn itself over about every day or so and start a new file and compress it's predecessor. If you're not familiar with modifying these, which is generally command line stuff, you might not be able to read them easily.

In any case, assuming you can look at "system.log" and/or "kernel.log", click on them, then do a case insensitive search for words like "shutdown", "wake", "sleep", "reboot" etc. What you want to look for are some lines that indicate what triggered the events. Pay attention only to those that occurred when the system shutdown or rebooted. BSD Unix kernels typically have lines like "throttling CPU due to overheating" (or something like that, I don't remember the exact words). OS X's kernel MIGHT have similar descriptive text since a good deal of the OS is from BSD based systems. Some of the text in the logs will seem archaic but you might be able to make sense of them. Please don't paste all the log file contents on here.

Ok this is what I found in the logs. more coming as I find it.

Kernel Log
Jun 17 12:49:55 localhost kernel[0]: systemShutdown false
What does that mean?

Jun 17 12:50:09 localhost kernel[0]: Previous Shutdown Cause: 0

Jun 17 05:00:00 Mac-2 kernel[0]: RTC: alarm 2012/6/17 11:00:00, sleep 2012/6/17 07:10:31

As you can see it did wake as instructed.

System Log
Jun 17 12:49:54 localhost DirectoryService[13]: Improper shutdown detected"

there it is again and this code 13 according to my original post is known as a
"Uninstalled Interrupt" any clue what that means?

Unfortunately the log file did indeed turnover and yesterday is now compressed, if you could tell me the commands to pull it up I'm pretty good with the command line I'm sure I could figure it out.

The hard drive problem you described makes me think the previous owner was likely inside the unit. Some guys try to put a Core 2 Duo into either a Core Solo or Core Duo system to make their systems true 64 bit systems. Unfortunately, a lot of these guys aren't used to working on these systems and end up pulling out or damaging connectors and cables. NEVER pull on a cable on any of these systems.

Good point, as far as I know according to about this Mac, the CPU is Core Duo and has not been upgraded.

The way to remove a connector from the logic board is as follows using jewelers screwdrivers:

1. Gently release the release tabs, if the connector has them.

2. Take a VERY SMALL screwdriver and insert it between the base of the connector attached to the logic board and the connector itself, and then rotate it in such a manner that it's pushing down against the logic board connector and up against the connector to be removed. This might need to be done in several different places to break the connector loose. Heat and oxidation make them bind.

3. Once the connector starts moving, use a slightly bigger screwdriver and repeat the process until the connector is loose enough to actually remove. You may need to cycle through several screwdrivers that are larger and larger.

The process isn't that hard or slow once you get used to it. I don't know how many units I've seen where people didn't have experience with these systems and wanted to do something like an HD upgrade and then end up tearing logic board connectors right off the logic board. They aren't villains, they just lack the experience.

Finally, about the CPU upgrade, I'm not saying someone did or didn't try that, but if the unit is overheating, it might mean the previous owner didn't apply the right heat sink compound or seat the heat sink properly. Look at the log files first if problems are still persisting because they will probably give an indication telling you what made the unit think it needed to reboot.

Time for bed now, Later, and best wishes!;D

Thanks so much for all the help and suggestions.

dtravis7 · Jun 17, 2012

If you checked your Power Supply with a digital meter and it was nil when the machine would not boot, I think you found your issue.

macwise · Jun 17, 2012

I think your right, now my question is, is there any kind of trick, known or unknown to refurbish this power supply? The reason I ask this is because yesterday on ebay I saw a seller refurbished unit.
Thanks

macwise · Jun 17, 2012

One more thought, when I tested the volts earlier, I may shorted one of the pins and that's why it was nil. Anyhow it just shut down and I checked the volts and it said 19.4 or so, I plugged back in and it didn't want to start the PSU didn't seem hot but a little warm to the touch. I put the PSU in a plastic bag in the fridge for a few mins like suggested, checked the volts again still around the same, plugged in started right up and I'm on it now. I really want to believe it's the PSU but what about this thing with the volts, if the output is supposed to around 18.5 and it's 19 or so does that mean it's overheating? Anyhow I think I"m just going to go ahead and get a replacement PSU unless I can find someone who will lend me one to test with, still haven't tapped the Mac User Group around here, by the way I'm about an half hour east of Albuquerque.

macwise · Jun 17, 2012

It just rebooted itself again and once again Kernel log reports Jun 17 14:59:20 localhost kernel[0]: systemShutdown false
Jun 17 14:59:36 localhost kernel[0]: Previous Shutdown Cause: 0" while typing this it rebooted itself again, I googled the 0 code but don't understand what it means, as for System log nothing was reported.

I'm stumped, but I do believe there is another issue here other than the PSU, could be software related?
Thanks

macwise · Jun 17, 2012

Not too long after last post, it shutdown and now waiting for PSU to cool down again and check system log, bet I find that code 13 again. It seems to me there may be two separate or same issues going on, based in the logs, what do you think? Well I'm on it again and sure enough it didn't come up once but 5 times, what's up with that?

Jun 17 12:49:54 localhost DirectoryService[13]: Improper shutdown detected
Jun 17 14:11:47 localhost DirectoryService[13]: Improper shutdown detected
Jun 17 14:54:54 localhost DirectoryService[13]: Improper shutdown detected
Jun 17 14:59:19 localhost DirectoryService[13]: Improper shutdown detected
Jun 17 15:59:08 localhost DirectoryService[13]: Improper shutdown detected

BSD Meister · Jun 17, 2012

The code 13 is coming from DirectoryService, a background process used by the OS, probably because it's being told to shutdown improperly. The one that I think is most useful is:

Jun 17 12:50:09 localhost kernel[0]: Previous Shutdown Cause: 0

That code occurs when someone pulls the plug on the unit, or in your case most likely, the PSU just decided to shut itself off.

I would try the refrigerator trick a few more times, and if starts up properly every time then your PSU is simply triggering thermal shutdown prematurely. The power supply that I worked on that was going down when the room temp hit 78 def F was not overheating. The problem was a fault in the thermal detection circuitry itself.

I'd refer you back to my suggestion to try and borrow a PSU from someone just to be sure the PSU is the real (and only) problem. The power supply is seen as a "throw away" device and there are no instructions in any of Apple's docs telling how to service it. That doesn't mean it can't be done, you would just be completely on your own and probably have to map out and troubleshoot the entire circuitry yourself. I was also under the impression the supply is embedded in potting compound (that's not a fact, I thought I heard that at one time though).

Good Luck!

[EDIT]

Also, remember that an erratic connection between the logic board and it's connector to the supply could be bad too. Probably not likely but I thought I'd throw it in.

[END EDIT]

macwise · Jun 17, 2012

I just placed the PSU in the freezer in the bag for a little bit I checked the voltage and it was about 19.1 and then let it come up to room temp in this case would be around 80 F and plugged it in no problem with startup. I'm inclined to think it's the thermal shutdown, what would happen if the PSU were placed in a box with a cooling fan like a typical PC power supply. I have a feeling that the hotter the room temp the quicker the thermal shutdown is triggered. I hope your wrong about the connection on the logic board since that's no small issue and would require replacing the board. One last thought, as I recall back when the Pentium chips came out they were overheating and causing fires and the only way to keep them cool was with cooling fans, could the same apply to these power supply bricks, are they susceptible to overheating and that's why they have to be replaced so much? I would just assume take it apart if I can't use it, but not till I secure one that works. I am going to try the ABQ Mac Users Group and see if I can get one to try out.
Thanks again.

BSD Meister · Jun 18, 2012

The reason the bricks go bad more than other components is that they're typically on the floor. They get kicked, bumped, etc. etc. The failure rates for them aren't really that high.

As for cooling it off with something like a fan, it might work, but it might not either. You can't hurt anything by trying it. I mentioned the power connector to the logic board because it has to be considered a possibility, I doubt that's the issue. My comment about the supply being encased in potting compound was incorrect. I don't know how accurate this article is, but clearly this guy was able to open a supply up:

Rainy Day Magazine: RainyDayGarage - Apple Mac mini AC Power Adapter Disassembly and Cable Removal

I didn't read the whole article but it looks like he's trying to retrofit it for car use.

Here's another interesting one (read the comments the guy says about opening it up):

Mac Mini Power supply upgrades

I'd stick with the "borrow one" plan if possible, then consider surgery.

Good Luck.

pendlewitch · Jun 19, 2012

macwise said:
I think your right, now my question is, is there any kind of trick, known or unknown to refurbish this power supply? The reason I ask this is because yesterday on ebay I saw a seller refurbished unit.
Thanks

Hi,

Just my two-penneth

I can see huge effort and determination here to make this work but if your unit was being used in a commercial workspace I would have condemned it and removed it as a significant risk to fire and electric shock by now.

Your correct course of action here would be to purchase a proprietary Apple product if you can find one, and even then there may be related damage to the internals and hard drive of you mini.

macwise · Jun 22, 2012

Sorry I didn't see page 2 I thought my post was the last, here's what I did, I placed two chill packs in plastic bags on both sides of the PSU, that made a HUGE difference and it stayed on for hours but once the packs warmed up it shut down again. So I found a refurbished unit on ebay with 30 days return policy and it just arrived today, I plugged it in and what do you know it started right up, it's on now and so far it's working great, however I noticed that's it's warmer to the touch then the one I replaced, perhaps because it's working right? I am going to leave the mini on over night and schedule shutdown and wake up and see what happens tomorrow but my vibe is there will be no more unexpected shut downs. now as far as reboots that could be software related so I will just have to wait and see. I did apply to join the local MUG but haven't heard back . I have the brick on the table so other than my cat bumping into it I don't think it will get bumped around too much, heck I would put it in a strong box if I knew that would keep it from getting damaged lol. If there is a way to refurbish the old unit I will try it, just to have it as a back up, yes I have read online about how they retrofit these bricks for 12 volt vehicle use but never thought much about it, wow only way to open it up is with a table saw! Even if I could get it open I wouldn't know what to refurbish is the circuit board or the temp sensor? Anyhow now I will pay more attention to that topic since I'm intrigued by the info in that article, oh and I'm not too worried about it being a fire hazard since I unplug the PSU or shutdown the power strip most of the time any way.
Thanks

pendlewitch · Jun 23, 2012

macwise said:
Sorry I didn't see page 2 I thought my post was the last, here's what I did, I placed two chill packs in plastic bags on both sides of the PSU, that made a HUGE difference and it stayed on for hours but once the packs warmed up it shut down again..... Even if I could get it open I wouldn't know what to refurbish is the circuit board or the temp sensor? Anyhow now I will pay more attention to that topic since I'm intrigued by the info in that article, oh and I'm not too worried about it being a fire hazard since I unplug the PSU or shutdown the power strip most of the time any way.
Thanks

No worries... just trying to put an old fogey slant on things.

Just a question, do you understand what the implications could be if you placed liquids close to a PSU connected to mains voltage and they inadvertently leaked ? Clenched teeth and hands, hair standing on end and cardiac arrest, that sort of thing...

...or...short circuit, mains circuit protection devices operating, power outage in the building.

What appears to be happening is that the thermal switch inside the PSU is opening up and thus disconnecting the unit because it is overloaded or rather seeing excess current (maybe a short circuit). This phenomenon usually creates excessive heat and an associated risk of fire and equipment damage.

macwise · Jun 23, 2012

Well I'm happy to says that, it's now almost noon and the mini woke up with no problem and the PSU is working great, so that said I think it's safe to say the problem was the PSU I guess it's the old occam's razor, the most likely cause like I figured. Just for the record I never place liquids close to anything that has volts and that's why I used a non leaking chill pack and placed them in baggies with the open side to the opposite side of the PSU connection, and monitored it closely for any liquid. I don't recommend this practice, it was merely an experiment to see if it would alleviate the problem. I understand about the thermal switch inside, what I don't understand is why the unit I replaced was cooler to the touch than the one I have now?
Thanks