Clarification on SMU reset

Hi there - looking for a quick clarification on the SMU reset procedure.
does the unit need to be completely unplugged from the mains or not while pushing the button?
i have seen a few different references that could go both ways, but not sure I have seen a definitive answer.
thanks,
adam
PowerMac g5 Mac OS X (10.4.8)

Hmm... Definitive Answer. Well - this Apple Official
http://docs.info.apple.com/article.html?artnum=300341
is often linked-to as the PMU/SMU reset instructions. It doesn't mention the mains in the button bit.
Leaving the mains connected makes taking static precautions simpler, in that one hand can remain on the [earthed/grounded] G5 casing while poking about inside.
Would the PMU/SMU reset with mains [trickle current] disconnected and a flat internal back-up battery.

Similar Messages

No firewire after turning of mains power - SMU reset needed to fix

Everytime I turn the mains power off on my 20" G5 imac when I reboot I've lost all my firewire connections. If I do a SMU reset they both come back.
It's a new logic board having been replaced on Apple Care for the overheating and fan problems.
Unfortunately my Apple care has now run out.
I've so far:
1. Replaced the Logic Board battery,
2. Wiped the drive and reinstalled the OS,
3. Zapped the PRAM
4. Reset the NVRAM
5. Reset-all the Open Firmware
6. Swapped the Ram out
I know a lot of people have had similar problems, but none of the fixes work.
Any ideas on what might be causing this problem?
Thanks.

Hi airsine,
The "standard" fix for firewire problems is actually to remove all power to both the computer and the connected FW devices, disconnect the FW devices, wait 15 minutes (sometimes far less is all that is needed) and then fire it all up again. The FW ports have a self resetting fuse that can be reset using the above process. The SMU reset process can "mimic" this process, because it also involves removing power to the computer, though the SMU in theory itself should have no real effect on your FW ports.
I find myself wondering whether the problem is actually occurring not when you turn your system off at the mains, but when you turn it on again. Usually FW problems of this kind turn out to be related to either a problematic device, or combination of devices, dragging too much power, or a bad cable.
Have you tried adding the devices one by one, to see if the problem is related to any particular one of them? You might also want to try using a powered FW hub, as this can overcome problems associated with too much load on the FW port when devices are "daisy chained". What do you actually have connected?
Cheers
Rod

Frequent need for smu reset and restart

What could be causing this? A little background: Everything had been fine for some time, than just recently have had problems with this iMac. I had 2 gigs of crucial ram that appeared to go bad in the last two weeks, evidenced by kernel panics. Replaced that with the old chip (512 megs) that I was able to get to work. Now from time to time, the computer will freeze and the fan noise will get very loud. This is solved by a restart. Frequently, especially after the computer has been shut down overnite, I need to do an smu reset (unplug the power cord for 10 seconds, plug it back in with the power button held down, then restart.)

I opened up the back of the computer. There are no obviously burnt or exploded capacitors, there is maybe one that is a little bulging on top. I then took apart the power supply and visually inspected the capacitors. There were no obviously burnt or exploded capacitors, there were two where the top was a little bit bulging.
I examined the LEDs on the motherboard. They seem fine.
I am still getting the odd kernel panic. I booted up from the install disk and attempted to do a disk repair and got an error saying "invalid key for thread record".
So I am really perplexed. This computer is nearly 5 years old, and while I would love to get it working reliably, I wonder if I am at the point of diminishing returns, in other words don't throw good money after bad. I have read that DiskWarrior might be useful, but that is $100. Power supply might be bad, hard drive might be going, and I'm not even sure if that is the entire extent of the problem!!!

Clarification on ESS reset password

I am in need of small clarification regarding the reset of password in ESS.
When the password of the user has been reset with any new password by the BASIS team say 'INITPASS' and when the employee login with that password the system automatically leads to the change password screen.
How does the system identify that the password has been reset and which field/table is this information stored ?
USR02 has the login details. But which specific change takes place so that the system identifies to prompt for change in password.
Can anybody help me regarding the same.
Thanks in advance.
Regards,
Gowri Shankar.R.J

Anybody answer it plz

Beyond G5 SMU reset - how to fix?

Hi all,
I have a late 2005 G5 dual core 2.0Ghz. It had an unexpected power down on wake, which was fixed by unplugging the power cord for 2 mins.
A month later, it happened again. Then next week, again. I then opened it up and reset the SMU using the button.
A few successful wakes later, it happened again. Pressing the SMU button was the only solution that time.
Next wake did not succeed. An SMU reset was needed.
Now, even an SMU reset will not do the trick.
Question: what can be done to fix this? What could be swapped out? I hope and pray this is not a motherboard issue.
Thanks in advance
Tim
This posting brought to you by my trusty 400Mhz G4 Sawtooth.

Click off coming out of sleep usually means that either the SMU or the PSU (more likely) has detected either an overcurrent or out of specification voltage and has brought the system voltages down as protection. That is a little harder to isolate, so the usual solution is to replace the power supply.
One thing that can contribute to that sort of problem is a buildup of dust and other foreign matter in the power supply, which can create a voltage path that confuses the protective circuitry. This thread from April links to some interesting photos of a G5 supply that became a hutch for a family of dust bunnies. The best way to deal with this is to remove the power supply from the enclosure (see ifixit.com, maybe for instructions, or other places) and then take it outside and direct compressed air into the rear (non-fan) end and then into the fan end. If this hasn't been done before, expect an image similar to some early scenes in The Grapes of Wrath.
Power supply information can be found at the DVWarehouse site so you can at least discover which power supply is the one for your G5.

Late 2005; SMU Reset silenced the machine!

Wow, effective to say the least.
I suffered from a various Fan noise problems, it was like nearly all the fans were not running in heir noise optimum state/rpm's
I pressed the SMU reset button and voila, almost ALL noises are gone now. I actually started hearing beep noise of high pitch just to discover it was my ADSL modem.
The machine is nearly whisper silent now, the problems i used to have were Whirring noise from somewhere, Pulsating fan noise (clearly audiable), Ringing noise from HD Bay fan, SLOT intake fan was generally scratchy and other odd sounds that were clearly audiable.
The only thing i can hear is the default idle noise of a G5, i am certain. I really recommend this procedure to anyone with a Late 2005 G5 and suffering from any fan noise problems.

Its near the memory modules, behind the intake fans, 5cm right from the battery.
Remember to press it only once!

SMU Reset Issue

I have a 20" non-amb. light sensor iMac G5. Six months ago I replaced the power supply. About two weeks ago the logic board failed and was replaced by Apple. Yesterday the iMac would not power up. I went through the troubleshooting and eventually reset the SMU. After that, the internal power button would power up the machine. I replaced the back, stood it up, and successfully powered-up with the regular power button. I left it to sleep overnight, and this morning it would not wake up. I touched the power button, the light came on, then went out. Now it's back to not powering up.
Any ideas?

Did you happen to notice whether any of the capacitors were bulging or leaking while you were in there?
A problem like the one you describe really only has two points of trouble. Either the power supply or the logic board (or a power button making improper contact / stuck).
I guess I would try turning it on. Then if it fails, open it. Then try turning it on again using the power button.
If it still doesn't startup, then you could try resetting the SMU again. See what happens.
If it requires a SMU reset frequently, then you have something wrong somewhere.
While the cover is off, look at the various capacitors and see if they are leaking or bulging.
You could also examine the lights on the logic board, and see what they tell you. You can get their meaning at:
http://docs.info.apple.com/article.html?artnum=86815
Hope this helps some.
My immediate thought is that you likely have either a bad power supply or a bad logic board. Since everything is so tightly integrated, those are your two main candidates.

Powermac G5 quad - where ist the SMU-Reset Button?

my G5 quad is very fast, but too loud. The Main Logic Board Backside Fan increases speed after maximal 5 Minutes up to 3000 rpm, even if the quad really does nothing. I tried to reset the SMU by removing the power cord, but no difference.
An Apple instructor sent me this:
"To reset the SMU on a Power Mac G5 (Late 2005) computer, either use the steps listed above for the Power Mac G5 (Late 2004) or:
Turn off the computer by selecting Shut Down from the Apple menu or by holding the power button until the computer turns off.
Open and remove both the metallic outer door and the inner plastic air deflector.
Remove the fan assembly immediately to the left of the processor module.
Press the SMU reset button on the logic board.
Replace the fan assembly, air deflector, and outer door.
Turn on the computer."
…but I can't find the SMU reset button. Can anybody help me?
Powermac G5 quad Mac OS X (10.4.3) 2,5 GB RAM

Hello
Choose "turn off" in the Apple menu, unplug the power cord, open the side door, unplug the lower fan, put your hands on the Quad Tower Case before you touch the SMU Button, then push the button only one time.
Here is a Picture from a Dual-Core 2.0, should be on the same place:
http://img470.imageshack.us/img470/7594/quadsmubutton8gq.png
Apples Knowledgebase Article says it works also like for older Late 2004 G5's. A little confusing for me.
http://docs.info.apple.com/article.html?artnum=300341
Power Mac G5 2.0 Dual-Core | Firmware 5.2.7f1 | 512MB Ram | Mac OS X (10.4.3) | GeForce 6600 LE PCIe 128 MB | Pioneer DVR-110D

IMac G5 keeps freezing/crashing. SMU reset resulted in a loud fan noise.

I have a refubished iMac G5 OS X 10.6.8 desktop that was purchased in Aug, 2006. Recently it has been either freezing, shutting down completely, or the display will just shut off multiple times per day 20+ times/day. I am not interested in purchasing the $49 help from Apple. Is it time for a new computer?
I've been attempting some troubleshooting:
I have plenty of RAM- we installed more memory about 8 months ago.
Temperature running at 40 degrees C
I reset the SMU but now am hearing a loud fan sound and there is air blowing out of the horizontal vent in back of the desktop- which does not typically happen. The computer has not crashed since I reset the SMU 20 minutes ago. I'm worried about the noise.
Also, it has been really hot where I live, with a heat index of 110 today and I don't have air conditioning. Current indoor air temp is about 86 degrees F.
Also, I have been seeing thin horizontal stripes across my screen for the past few months, related or unrelated issue?
Thanks for the help!

Not that this will cure it but it may help:
As old as your iMac is, have you cleaned out the dust? Dust buildup can lead to over heating issues. Remove any and all things plugged into it including the power cord, Remove the RAM access grille. Vacuum all openings starting with the RAM access area (air intake). Vacuum all ports and plugs, DVD slot and the opening across the top of the rear of the body. Blow compressed air through all your openings and vacuum again to remove any dust you loosend. Reinstall the RAM grille. Plug in the keyboard and mouse if not blue tooth. Insert power cord...
You are now in a perfect position to do a
SMC RESET
http://support.apple.com/kb/HT3964
Shut down the computer.
Unplug the computer's power cord and ALL peripherals.
Wait 15 seconds.
Attach the computers power cable.
Wait another 5 seconds and press the power button to turn on the computer.
It is the 5 second timing that initiates the reset.
Here is a link to a Widget to monitor your temps and other operations:
http://islayer.com/apps/istatpro/

SMU reset offers temporary fix for lost firewires

So my folks have a 17inch G5 iMac (running Tiger), and they have been experiencing several problems that seemed to originate as a problem with the SMU: failure to go to sleep, failure to wake up, slow start ups, slow shutdowns, faster running of the fan, and finally the loss of data (not power) to the firewires. The final one is the major deal breaker because and for almost two years now my family has been using iChat as our major form of communication.
So I'm home for Thanksgiving and yesterday I reset the SMU, and EVERYTHING was fixed, firewires were back, it was going to sleep, I was hailed as a hero lol... etc...
Tonight when my mom tried to put it to sleep it wouldn't, so I went and checked in the system profiler, and the firewires are gone again.
Should I just reset the SMU again and hope for the best? and if this IS a temporary fix, what's the real problem and how do I fix it?
Any and all help is greatly appreciated.

Here some more stuff you can try:
1. Downloading and installing the combo updater of the system software update you've just applied via "Software Update...".
2. Another trick is to restart each by zapping the parameter RAM:
Zapping the P-RAM:
After the startup tone, hold down <commandd><option><r> until 3 additional startup tones are heard, then release the 4 keys.
3. A 3rd tip would be to do Open Firmware reset:
After the startup tone, hold down <command><option><o><f> until the text screen is visible. When text can be entered, type the following commands, followed by the <return> key (there are no space characters in each command):
reset-nvram
set-defaults
reset-all (the Mac will boot up after this command is entered)
Let us know if you regain your heroic status,

G5 won't power up - SMU resets

My G5 imac (ambient light sensor model) started shutting itself off recently and now won't start up. I've ruled out the the pos=wer supply (indicator LEDs) but want to confirm if it's the logic board or not. If it's not, I might repair it, but if it is I'll have to upgrade I guess.
I found this great apple post that takes me through an internal diagnostic (http://support.apple.com/kb/HT2173). However the step by step process suggests I should 'take it for further investigation if it fails to start up after SMU is reset and internal power button is pressed. I have got this to work (temporarily) a couple of times, but all recent attempts have failed to start the thing up.
I want to understand how to reset the SMU properly, and if this could be part of the problem AND if anyone knows what else it could be. Is it definitiely the logic board? How do I check the battery power?
Help much appreciated.

No replies but an update: I took a gamble and bought a replacement power supply. Luckily, it worked. I figured if it didn't work I could return it (costing me 20% handling + postage) and buy a new Mac as it would almost certainly point to the logic board.

G5 WON'T START AFTER SMU RESET

Hi!
my G5 won't start... tried a lot of stuff to make it run - i.e. swop feed cable (a big trouble to get one like it); rest SMU; connect it to another mac via firewire -, but nothing. only the start_up light is on.
any ideas?
thanks,
strawb

Unless your G5 is one of the dual cores you have a PMU not an SMU. To reset follow the directions here:
http://www.felipecruz.com/reset-pmu-and-non-volatile-ram-g5.php

I just reset the SMU on an ISIGHT G5 and a beep was emitted

I followed the instructions here
http://docs.info.apple.com/article.html?artnum=301733
Is that normal to get a "tone" or a beep while holding down the power button in the process of resetting the SMU?
I'm only asking, becasue I thought that a single beep was a RAM Issue, and no where does it say on the Apple document for SMU resetting, that there supposed to be a BEEP.
Anyone?

hey...how goes it?
I reset the SMU becasue I was tiold it might help with some noise issues. I don't necessary have any blaring fan issues, but I thought it wouldn't hurt to reset it for other noise that I am having with my imac.
Anyway, it didn't. But, the tone or beep I was describing was a solid "BLOOP" or "BOOOP." Very abrupt and forceful, to say the least. If that helps to describe the sound. It was nothing like the usual start up sound.
Anyhoo...
I think I'll take it in soon for a check up.
thanks again

Resetting the SMU. Silly machine.

I have a problem on startup, where by the power light comes on, but sticks with a black screen and no startup noise.
After following the troubleshooting guides on the site, I attempted to reset my SMU to see if that would help.
With the back panel off, LED1 came on, followed by LED2 once I pushed the button which of the two is nearest the top of the screen. Now - when pushing the other button (to reset the SMU), the guide said it should reset the computer. However, the button merely powered the computer down...I have no idea if the SMU reset actually happened or not. Is there any way to tell? Powering up the iMac again results in the same problem.
I'm out of warranty and don't have AppleCare. The service provider in my town charges £45 just to see the machine, then £90 an hour labour + parts if any are required. I'm a student! Need to try everything I can before resorting to forking out for the repair. Got food to buy and stuff...
Anyone got any suggestions? Please..?!

As you have one of the "first generation" iMac G5's you are a candidate for the free "repair extension program", Adam. It sounds like a classic case of this problem - see http://www.apple.com/uk/support/imac/repairextensionprogram/ and check your serial number.
Cheers
Rod

HT3964 smu macbook pro 13 late 2010 refuses to reset

smu macbook pro 13 late 2010 refuses to reset have tried smu reset pram without hardrive the unit runs until after the file logo shows up.
smu reset works with hardrive in but fan takes off then it shuts down.

I'd suggest you look at the manufacturer info on the 8 gig modules, then check their website to see if it's compatible with the 13".

Clarification on SMU reset

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