Yiannis

Q: Power Mac G4 MDD strange startup problem

Hello ,

 

I have an old G4 MDD dual 1Ghz which is been used by my 6 years old son  for gaming and watching movies.

I had Tiger 10.4.11 on a IBM deskstar HDD and Leo 10.5.8 on a seagate HD.

Everything was fine until some days ago, when my mac didn't boot from the first try…..black screen.

After a second attempt , booting was just fine.

 

I have now two system disks (IBM deskstar HDD) with 10.5.8 installed.

Mac is not booting always from first attempt….it takes two more  with or without the option key pressed to choose a startup disk.

 

I have done all the usual…….reset PMU-PRAM…replacing battery,replacing cables,cable select the drives and now forced one to master and second to slave.

 

I have run Service Diagnostics 2.1.5………..ALL TESTS PASSED.

 

Still not booting normally….

 

Any suggestions please??

 

Thank you all!

 

PS:It is also loosing very often internet connection via ethernet……..I think it's not a router problem as all my other macs are working normally.

PowerMac, Mac OS X (10.5.8), 2g Ram-1GHZ MDD

Posted on Oct 6, 2014 10:27 AM

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Q: Power Mac G4 MDD strange startup problem

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  • by BDAqua,Helpful

    BDAqua BDAqua Oct 26, 2014 11:29 AM in response to Yiannis
    Level 10 (123,670 points)
    Oct 26, 2014 11:29 AM in response to Yiannis

    I think the power button must be pressed...

     

    If after the completion of step 3, pressing the power button has no effect, and the PSU fans do not move, the PSU is likely bad.

     

    4. Connect the black lead to pin 12 of the power supply connector;

    connect the red lead to pin 24.

    The volt meter should measure approximately +12V.

     

    If you do not get a reading of +12V, recheck connections and measure again. If voltage is still not present, replace the PSU.

  • by Yiannis,

    Yiannis Yiannis Oct 26, 2014 11:40 AM in response to BDAqua
    Level 1 (95 points)
    Oct 26, 2014 11:40 AM in response to BDAqua

    I have read that several times but I didn't clear understand it.

     

    Thanks for clarify this!

     

     

  • by BDAqua,

    BDAqua BDAqua Oct 26, 2014 11:55 AM in response to Yiannis
    Level 10 (123,670 points)
    Oct 26, 2014 11:55 AM in response to Yiannis

    Me too!

  • by Yiannis,

    Yiannis Yiannis Oct 27, 2014 12:55 AM in response to BDAqua
    Level 1 (95 points)
    Oct 27, 2014 12:55 AM in response to BDAqua

    Is there a chance to find G4 MDD PSU schematics?

  • by BDAqua,Helpful

    BDAqua BDAqua Oct 27, 2014 9:33 AM in response to Yiannis
    Level 10 (123,670 points)
    Oct 27, 2014 9:33 AM in response to Yiannis

    I've not seen them available ever, there were a couple of places that repaired them, but of course they wouldn't release that info.

  • by BDAqua,

    BDAqua BDAqua Oct 27, 2014 10:02 AM in response to Yiannis
    Level 10 (123,670 points)
    Oct 27, 2014 10:02 AM in response to Yiannis

    Can you find a cheap PC ATX PSU?

     

    You can convert an ATX PSU for use on a G4...

     

    http://atxg4.com/mdd.html

  • by Yiannis,

    Yiannis Yiannis Oct 27, 2014 12:33 PM in response to BDAqua
    Level 1 (95 points)
    Oct 27, 2014 12:33 PM in response to BDAqua

    For the moment we will replace all the capacitors in the PSU.

     

    If that does not work I will look on Ebay for a used one….

  • by BDAqua,

    BDAqua BDAqua Oct 27, 2014 1:52 PM in response to Yiannis
    Level 10 (123,670 points)
    Oct 27, 2014 1:52 PM in response to Yiannis

    It is most likely a Capacitor, good luck.

  • by Yiannis,

    Yiannis Yiannis Oct 28, 2014 1:19 PM in response to BDAqua
    Level 1 (95 points)
    Oct 28, 2014 1:19 PM in response to BDAqua

    Thank you,I will report back with the results….

  • by Kimo B. Yap,

    Kimo B. Yap Kimo B. Yap Oct 30, 2014 9:16 AM in response to Yiannis
    Level 1 (15 points)
    Oct 30, 2014 9:16 AM in response to Yiannis

    Don't know how cheap you are looking for. I just replaced the power supplly  on my roommate's MDD machine. The usual symptom is you push the button on the front and it glows while it's pressed in but no fans, no chime, and it stops glowing when you let go. I think it was intermittent and slowly got worse until it failed completely. There are articles on the network about replacing the capacitors, but I decided it was too much trouble to go find all the right ones (and make sure they were better ones). The one I got is supposed to be refurb'd, but I'm still waiting to find exactly what's done (hoping it's all the capacitors and not just what appeared to have failed). Any of the three (I think) supplies for the MDD should work; lowest price I found was around $64 (plus S/H, tax, etc.), but I was in a hurry at this point and didn't want to wait around. The power supply board itself is pretty densely packed. Of the three supplies, the AC/Bel 360W seems to be the most common and the one Apple finally went with for most of the run. The AC/Bel 400W which is the one I wound up with was nicknamed the "wind tunnel" one because it has kind of noisy fans. The third one is a Samsung (which is what was originally/last put into my roommate's machine), but (although this wasn't the case for me), it seems that when they fail, they fail much more catastrophically.

     

    After you get it fixed in whatever way, one theory I read on why they seem to be so problematic is that the 24V line for the ADC connector is always live, even when the machine (and in particular the PSU fans) is turned off, so if you shut the machine down or maybe even put it to sleep but leave it plugged in to live power, the power supply eventually bakes itself to death. Don't know for sure, but thought I should mention it.

  • by BDAqua,

    BDAqua BDAqua Oct 30, 2014 11:30 AM in response to Kimo B. Yap
    Level 10 (123,670 points)
    Oct 30, 2014 11:30 AM in response to Kimo B. Yap

    Neat info, that heat/24VDC theory may very well be correct, MDDs were the absolute worst as far as heat, thanks.

  • by Yiannis,

    Yiannis Yiannis Nov 30, 2014 4:19 AM in response to BDAqua
    Level 1 (95 points)
    Nov 30, 2014 4:19 AM in response to BDAqua

    One month later time for an update……..

     

    PSU is fixed after all capacitors got replaced.

     

    BUT…….

     

    G4 still has the same behavior………..it starts normally with the chime sound but most of the time I get that black screen again.It takes some reboots to make it start up normally.

     

    So….

     

    Things that are NOT causing problems or helped  are:

    1) PSU (fixed)

    2) Graphics card  ( swapped from another G4)

    3) Memory (swapped from another G4)

    4) Cables

    5) Hard disks

    6) PMU reset

     

    I don't know what else to do or to look for…..maybe it is  the logic board???

     

  • by BDAqua,

    BDAqua BDAqua Nov 30, 2014 11:41 AM in response to Yiannis
    Level 10 (123,670 points)
    Nov 30, 2014 11:41 AM in response to Yiannis

    Geesh, that's about all that is left, & they did have their share of logic board problems... I think there's at least 3 different MDD logic boards.

  • by Kimo B. Yap,

    Kimo B. Yap Kimo B. Yap Nov 30, 2014 1:24 PM in response to Yiannis
    Level 1 (15 points)
    Nov 30, 2014 1:24 PM in response to Yiannis

    While the logic board sounds likely, I'd like to be sure I understand the current state. It seems like you are just back to the original issue, but after reading through the whole post, it seems things have changed over time and I'd just like to be sure the current state of things.

     

    So…

    First, I think you mentioned the power button (on the computer) doesn't work. Does that mean it doesn't light (even when you do eventually get the machine up) and it just doesn't work to power the machine? If the machine is actually booted and running, does pushing the button cause the machine to go to sleep (takes a few minutes) or provoke other response (sleep is the default although it cna be changed). Since you are starting from the monitor anyway because it isn't powering on the machine (I'm basing this on an earlier post and trying the verify it's still true and what I understand), then you might want to disconnect it completely from the logic board just in case it is stuck in some weird state and causing the logic board in turn to behave oddly.

     

    Moving on you say you get the chime but no screen. Do the disks spin up properly now? If they do do you hear chatter as if the machine was booting but just that there was no video? If not, have you tried removing all of the disks (or disconnecting the IDE cable at the logic board) and seeing if you at least get video and blinking question mark/folder? Can you boot into open firmware consistently and get a video signal (cmd-opt-O-F)? What about target disk mode?

     

    Sorry if this seems kind of repetitive, but, as I said, it seems different things have come and maybe gone over the course of this post and I think it is useful to get back to basics and being sure I understand the current state of the problem independent of history correctly.-kby

  • by Yiannis,

    Yiannis Yiannis Dec 1, 2014 3:38 AM in response to Kimo B. Yap
    Level 1 (95 points)
    Dec 1, 2014 3:38 AM in response to Kimo B. Yap

    First, I think you mentioned the power button (on the computer) doesn't work. Does that mean it doesn't light (even when you do eventually get the machine up) and it just doesn't work to power the machine?

    It lights but it has a broken button so I can't power on the G4 with it.

     

     

    If the machine is actually booted and running, does pushing the button cause the machine to go to sleep (takes a few minutes) or provoke other response (sleep is the default although it cna be changed).

    Using the button from the Apple ADC display it goes to sleep normally,and wakes up on mouse move .

     

     

    Since you are starting from the monitor anyway because it isn't powering on the machine (I'm basing this on an earlier post and trying the verify it's still true and what I understand), then you might want to disconnect it completely from the logic board just in case it is stuck in some weird state and causing the logic board in turn to behave oddly.

     

    I have disconnect it from the logic board but I still get the same issue.I have also replaced the switch ,from my other G4,but I get the same behavior.

     

    Moving on you say you get the chime but no screen. Do the disks spin up properly now?

    I hear every time the chime but not always the disk spinning.If after the chime sound I hear a "click" sound from the speaker then I know that the machine will boot up normally.Most of the time it fails.

     

    It will boot up after several attempts.

     

    If not, have you tried removing all of the disks (or disconnecting the IDE cable at the logic board) and seeing if you at least get video and blinking question mark/folder? Can you boot into open firmware consistently and get a video signal (cmd-opt-O-F)? What about target disk mode?

    I have to try all these and report back

     

    Here is  what I have done since yesterday:

     

    1) Left is without battery overnight to reset the logic board.

    Result=NEGATIVE

     

    2) Remove all the disks and left it with system only HD.

    Result=NEGATIVE

     

    3) Connect the HD to the 66mhz buss.

    Result=NEGATIVE

     

    4) Connect the disk to the DVD buss(33mhz?)

    Result=NEGATIVE

     

    5) Put the disk in master mode…just in case.

    Result=NEGATIVE

     

    Here is a strange observation…When I hit the startup button and I don't hear the HD to spin ,I remove the ribbon cable from the disk right after the chime and put it quickly back.Then the HD is spinning and the G4 booting up normally.

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