Previous 1 2 Next 19 Replies Latest reply: Nov 10, 2009 3:38 PM by WZZZ
WZZZ Level 6 Level 6 (12,775 points)
Over the last several months I've sometimes had to press the power switch maybe three or four times before the computer starts up. And sometimes, less frequently, it takes a few presses to get the computer to sleep. When it sleeps, it sleeps fine. It might boot up directly with one press for several days.

After it boots up, it boots up fine and stays booted until shutdown at end of day. No green or dimmed or funny looking power light; absolutely no problems. So, can't rule it out, but don't think these are symptoms of the PAV board.

Worst case scenario: early warning of dreaded failing PAV board? Or is this simply a mechanical malfunction in the switch, possibly some dirt or even corrosion in the contacts which could be cleaned with contact cleaner? A failing relay? I thought it might even be the angle at which I apply pressure to the switch.

What's involved in getting to that switch, including replacing?

Also, if this is a mechanical problem with the switch, could it be bypassed using a different keyboard with a power switch key? And, if so, which keyboard would I have to find?

Anyone ever see this one before? (Just did a search and don't see anything more recent than 10/01/09 for Spudnuty, the iMac G3 master. Hope he's still around.)

Message was edited by: WZZZ

iMac G3/400 OSX 10.4.11 "It takes a licking and keeps on ticking", iMac G5/1.6 OSX 10.5.7
  • rccharles Level 5 Level 5 (6,655 points)
    Sometimes i have to press the poweron button twice and on occasion thrice. I tend to hold down the button until I hear the electric sound.

    The battery is dead on my machine. I have the time set from an atomic clock on the net.

    How is your battery?

    Robert
  • WZZZ Level 6 Level 6 (12,775 points)
    That's rather interesting information about your startup. You think it's your battery? I put a new one in March of '08. Should still be good and it keeps the time even if off wall power.
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)
    If it's the switch itself, using the power button on the keyboard should work without the problem.

    The original iMac (smaller size) USB keyboard has a power button. The first larger size USB keyboard from Apple ("Pro" keyboard) did not have a power button. The original iMac keyboard should be readily available on eBay.

    The Macally iKey, which is a full-size keyboard that is similar in feel to the old Apple Extended Keyboard II (ADB)

    http://www.macally.com/EN/product/ArticleShow.asp?ArticleID=149

    has a power button. I'm surprised they still sell it. It may be available for less from a reseller. I have an old blue one.

    You can also try this procedure to reset the PMU

    http://mrjcd.com/junk/PMU.jpg

    As stated, be sure to only press the button ONE TIME between startup attempts.
  • WZZZ Level 6 Level 6 (12,775 points)
    Thanks Kenichi for the helpful information. Good to know I could power on with a different KB. I must have the Apple Pro; no power key. That Macally keyboard doesn't look bad for $30.

    About the PMU reset. That can be responsible for this erratic power on behavior? Could that switch be reached through the top door, maybe with a long thin stick like a chopstick or dowel? I hate to open this thing. Chance of more old, brittle plastic tabs breaking. Broke one the last time.
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)
    The picture shows it being visible next to the RAM slots, so you should be able to reach it through that opening. I'm more familiar with the older tray-loaders, where you have to pull out the internal chassis to reach the "cuda" button (as it is called on that model). Often, the PMU button press resolves the problem where the iMac G3 will not start up at all (no sign of power). In your case, since it does start up sometimes, pressing the PMU button may not help, but it wouldn't hurt to try (as long as you press it just one time between startup attempts).
  • spudnuty Level 5 Level 5 (7,045 points)
    Hey W,
    Yup haven't been around much. Had a lot going on.
    Here's a pic of the power button on the front bezel of a G3 iMac:
    http://s291.photobucket.com/albums/ll306/spudnuty/?action=view&current=iMacpower button.jpg
    The gray plastic that these are made of can crack and seems to be prone to that over the years. However you see this more in the upper part of the front bezel which is subject to more heat.
    If you take the bottom off the machine you can check out the action of the inner actuator (the part you see in the pic).
    The "actuator" part is pressing on a tactile swich which is on a small sub board that is mounted on the frame. It's a little hard to harvest but I do have a lot of non working G3s if that turns out to be the source of your problem.
    Also sometimes the outer part of the power button will get sticky.
    As to the keyboard button I've got a iMac G3 350 (OS 9.2.2) a 400 (10.4.11) and a 600 (10.4.11) and can't get the original Bondi or a Strawberry keyboard to work with them. I don't have a later keyboard however and all the later ones don't have that power button.
    The repair manual says it will work on the 400 and SE but I do seem to remember about this never being enabled.

    Over the last several months I've sometimes had to press the power switch maybe three or four times before the computer starts up. And sometimes, less frequently, it takes a few presses to get the computer to sleep. When it sleeps, it sleeps fine. It might boot up directly with one press for several days.


    After it boots up, it boots up fine and stays booted until shutdown at end of day. No green or dimmed or funny looking power light; absolutely no problems. So, can't rule it out, but don't think these are symptoms of the PAV board.
    Doesn't seem like the PAV board but you can never rule that out w/ these machines.
    Check out the part in the pic and post back.
    Richard
  • WZZZ Level 6 Level 6 (12,775 points)
    Hi Richard,

    Thanks for all the information. I don't think it's the outer part of the switch being sticky; it seems to move freely enough. From that photo, it looks like the "actuator" is rather small and located on one side of the button. Perhaps that would mean that applying pressure on one side or another--one of my theories-- might make a difference. If that piece has broken off completely, I'd imagine I wouldn't be able to start up at all.

    Sounds like the actual switch on the sub-board isn't very accessible. Not any easy place to spray contact cleaner, I suppose. What do you think?

    For the keyboard question.

    The repair manual says it will work on the 400 and SE but I do seem to remember about this never being enabled.


    Is there any way I could know for sure before purchasing another KB? There is only a remote chance I might be able to borrow one to try.

    I think I'll probably wait until this gets somewhat worse. Right now, it's a little troublesome, but not, by any means, impossible. My main concern right now was to rule out the PAV board as a prime suspect. Although, I do understand, from what you say, that could still be possible.

    (I'm kind of overwhelmed right now with an iMac G5 problem. Incredibly bad luck with Apple replacement parts: New, but defective logic board from Apple--this has been replaced--and now, very likely, a new, but defective Apple power supply, which will also need replacing. Might post over in the iMac G5 area at some point.)
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)
    According to LowEndMac's profile page, if your iMac G3 400 MHz is +Summer 2000+ (or later), it shipped with the Pro keyboard

    http://www.lowendmac.com/imacs/400-mhz-imac-dv-g3-2000.html

    Other Internet references say the Pro Keyboard was introduced in 2000, so that makes sense.

    Therefore, the earlier slot-loaders from 1999 came with the smaller iMac keyboard with a power button, so it should work on that model. If your iMac is the darker shade Indigo or Ruby color, it is from the 2000 line, so I suppose it is possible that power button will not work since they shipped with keyboards that no longer had the power button.
  • WZZZ Level 6 Level 6 (12,775 points)
    Doesn't look good then. This is a slot / 400, early 2001 and shipped with Apple Pro, no power button on keyboard. I guess, therefore, it makes sense that it wasn't equipped to turn on from the KB. I suppose I have to borrow one, if I can, to know for sure. Thanks for staying with this.
  • spudnuty Level 5 Level 5 (7,045 points)
    Hey W,
    From that photo, it looks like the "actuator" is rather small and located on one side of the button. Perhaps that would mean that applying pressure on one side or another--one of my theories-- might make a difference. If that piece has broken off completely, I'd imagine I wouldn't be able to start up at all.

    What might have happened is that the actuator part is cracked or broken. In my experience that part is quite brittle. The one you see is the only intact one I was able to remove out of 3. All the rest cracked.
    Not any easy place to spray contact cleaner

    And it wouldn't help anyway since that tactile switch is sealed al la:
    http://tinyurl.com/yl2ozfj
    I'd take the bottom off (4 screws) and check the state of the inner switch.

    Incredibly bad luck with Apple replacement parts: New, but defective logic board from Apple--this has been replaced--and now, very likely, a new, but defective Apple power supply, which will also need replacing.

    Yes all those parts are from the original production run and contain the same defective capacitors that were in thousands of computers made at that time: Dells, Sonys, HPs etc. We had about 20 Dell P-4s go bad with that cap problem at the school. My current fix is either Jim Warholic caps or a hacked Flex Micro ATX and auto adapter replacement.
    Richard
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)
    I didn't say it would not work on later G3 iMacs. Just pointing out which ones shipped with the older small keyboard.

    Note: Even on current Macs, if you use a keyboard with a power button and press it when the Mac is powered on, you get the dialog box with +Restart, Sleep, Cancel, Shutdown+ (but the button is not recognized if the Mac is powered off).
  • WZZZ Level 6 Level 6 (12,775 points)
    SPUDNUTY: Yes all those parts are from the original production run and contain the same defective capacitors that were in thousands of computers made at that time.


    That's exactly what I was afraid of. That thought had crossed my mind already. Are you certain that's what they're using for current repairs?

    Opened it up today again and while the board has been replaced--the caps look good now--I noticed they looked awfully similar to the ones on the original board that went bad. The originals were Michicon. Didn't bother to check the name of the ones on the new board, but seems they could be just the same.

    So, they could go through ten more power supplies before finding a good one, and neither the boards nor the power supplies, if they are from that original stock, are going to last very long, for that matter, either. And I've heard replacing the caps in the PS doesn't always help since there's often collateral damage to other parts inside. I guess this belongs in the iMac G5 forum, which I've just started visiting since acquiring this G5. It looks like so many of the posts there are around this issue, that that forum could be renamed the "iMac G5 Logic Board and Power Supply Forum." Actually, I've heard the iSights are not plagued by this problem, just the early generation.

    About the G3 power button issue: can just the outer part with the actuator be replaced. Eventually, if that little tab breaks off--assuming that it's cracked--no power up? Really hope the keyboard with a power button works.

    And thanks, Kenichi, for pointing out that a G3 supplied with the Apple Pro Keyboard might still work with the right keyboard.
  • Kenichi Watanabe Level 7 Level 7 (30,460 points)
    Came across this device, and the description (if it is accurate) indicates that "iMac DV Summer 2000 or later" cannot start up from a power button on a USB device.

    http://www.welovemacs.com/usb-key-bt.html

    So I guess it won't help to find a keyboard with a power button.
  • WZZZ Level 6 Level 6 (12,775 points)
    indicates that "iMac DV Summer 2000 or later" cannot start up from a power button on a USB device.

    Ouch!
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