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Thread: Dead G4MDD single 1.25GHz - advice needed

  1. #1
    Join Date
    Mar 2005
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    Default Dead G4MDD single 1.25GHz - advice needed

    I have G4MDD single 1.25GHz, that was bought as defective from eBay with no HDíS, RAM or Graphic card inside. So hier are the symptoms:
    Normally I should hear a number of beeps, when I start the Mac without Video card, RAM and HD, but when i press the power button, it lights as long as I am pushing it, but when I let go, it immediately fades. However, the computer starts, the red LED on the mainboard lights up, no chime sound, and then, about 10-20 seconds later, the fans start to spin at full speed (wind tunnel mode)...
    I saw that others have the same problem but didnít found a proper explanation for this behavior.
    I tried everything that should be helpful in such a situation according to the opinions in different forums:

    -checked battery - 3.6V;
    -resetted the PMU;
    -Voodoo-trick from Greentree;
    -reseated de processor;
    -Checked the PSU according to the Service Manual for G4MDD (I donít get 12v when I check pin 12 and pin 24, with power cord pluged in but without turning on the computer Ė may be it is normal - anybody?!);

    So I assume that the processor or the motherboard is burned Ė but which one?! Does anybody knows how can I start give out more money for this machine Ö
    Or may be someone can suggest something else, that I didnít tried.

    Any help would be appreciated
    Last edited by smith; 03-01-2005 at 07:33 AM.

  2. #2
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    Aug 2001
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    Default

    The only thing I can think of is try a shop where they can run 2 tests:

    1: Test motherboard with known good RAM module and known good processor

    2: Test processor in known good MDD.


    Other than that I can think of absolutely nothing you can try without swapping in and out some parts.

    Rick
    molṑn labe'
    "I am a mortal enemy to arbitrary government and unlimited power. I am naturally very jealous for the rights and liberties of my country, and the least encroachment of those invaluable privileges is apt to make my blood boil."
--Ben Franklin

  3. #3
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    Default

    smith,

    Welcome to the MacGurus Forums. My MDD 1.25G DP FW400 died the same death, massive jet engine sound after 28sec., and I tried the same things you did except the PSU voltage check. Maybe even more but I have since, apparently deliberately, forgotten what other desperate steps I tried except that I tried removing RAM sticks one by one in case I had a stick that died, as well as trying with just one boot drive and then the other, one on the ATA/100 bus, one on the ATA/66 bus. Eventually, I took it into an Apple Store Genius Bar (have a 3yr AppleCare) after reinstalling the original CPU board, heat sink, and graphics card.

    I had two bootable drives, tried two different graphics cards, an extra PSU which I decided not to try, and the GigaBump. Nothing worked. So pretty much nailed it down to PSU or motherboard.

    At the Genius Bar, the Tech spent maybe 20-30 minutes running the same tests I had done, with suggestions from other Moderators. I watched him. He then pronounced the mobo dead. How he arrived at that conclusion I don't know for sure. I just figured he had insider Apple info on the most likely cause. So that afternoon, I left the MDD for repair.

    Imagine my surprise, the next morning I received a call that the MDD was ready for pickup. The receipt says that a Level 1 Tech installed a new mobo. Costs, none to me. Receipt says:
    Logic Board, 167MHz, v.3 $389.06, Hardware Repair-Level 1 $85.00, Total $474.06. k

  4. #4
    Join Date
    Mar 2005
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    9

    Default

    ricks, kaye, thanks a lot for your quick replies.
    so I will need to find some place where I can test the mobo and the CPU apart... But I'am already searching for a new mobo too
    There is just one thing that bothers me:
    the part# of my mobo is 820-1476-A, but I see that they are 167MHz MDD mobo's with different part numbers, such as 802-1308-A or other beginning with 661-....
    Should I look for exactly the same number or it can be just any 167MHz mobo?!

    thanks again, this is a great forum

  5. #5
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    Mar 2005
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    Default

    Actually I discovered that the same number (820-1476-A) is on the CPU daughter card too, so it can't be the part# of the mobo
    The part # for my MDD is 661-2812 (according to different web-sources, but not found anyware on the logic board self?!...)

  6. #6
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    Aug 2000
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    Default

    smith,

    I remember that the number on my old mobo was very confusing. My MDD was a custom build and therefore both the mobo and the CPU board had custom numbers to reflect that. Apparently Apple does that so you won't replace either without them knowing that. Maybe they all come that way to match with the original buy.

    Anyway, I just looked at the docs from the Apple repair and discovered another page that sez the mobo replacement part number is 661-2812. That should help you. k

  7. #7
    Join Date
    Sep 2004
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    212

    Default Mobo cost...

    Well, at least there's one positive angle to Ur dilemma... A replacement Mobo for the MDD seems a lot cheaper than for my Quicksilvers. Why that is, I have no idea. Just bought yet another working unit for a little less than what Apple charges for a replacement with only a 90 day warranty. Did find one place in Boston who are charging 'only' $ 500,- for a QS MB (from Apple) incl. installation. How they can do that, beats me.
    I've been hunting long enough for a new 'dual boot' DP MDD, with nothing but letdowns from less than 'lily white' vendors. Let alone 'sky-hi' prices from the likes of 'PowerMax'... With enough QS's to last me at least 5 years I will soon go for a DP from the GigaBumpers. Have been running a single 1.33MHz 'up' on one of the units for some 3 months now, with no trouble whatsoever. As stated elsewhere, I even removed the side panel Mac fan; no overheating. Air comes out +/- luke... (To be revisited during coming summer)

  8. #8
    Join Date
    Sep 2004
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    212

    Wink MoBo replace...

    Actually, U need to replace a 661-2812 with a like numbered board... The 661-1771 can be replaced with either. Price should be the same, more or less. Now, for an MDD still under warranty it's a different story.
    Goes without saying.

  9. #9
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    Mar 2005
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    Default

    And what if I replace my mobo (661-2812) with a 661-1771 mobo?! The only difference I see, is the second 2-pin fan connector on the other side of the AirPort connector. And what for is this connector?
    Or would be possible to use a 133Mhz logic board which system bus is changed to 167Mhz by taking out R676?
    Too many questions, I know, but if someone knows some answers and has experience with those MDD mobo's, please, share your knowledge

  10. #10
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    Mar 2005
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    Default

    No One Knows Anything

  11. #11
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    Default

    Some 133MHz Boards work, some don't check this link:
    http://forums.xlr8yourmac.com/cpureview.lasso

    enter Apple G4 Dual CPU DDR at Mac Model and Apple at Card Manufacturer.

    Regards

    Nicolas
    Custom Configurations! Rad Hacks and Mods!

  12. #12
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    Mar 2005
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    Default

    I bought an used MDD 167MHz mobo (661-2812) from ebay, with broken ethernet port, but working (according to the description of the seller), but still no joy - the computer acts like before - after 17s windtunnel-mode.
    So it should be the CPU that dead is, or.. I don't know.
    Anyway, thanks to everyone for the cooperation
    If I succeed to get my MDD to work, I will keep you posted...

    regards,
    smith

  13. #13
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    Nov 2004
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    Default I had this exact thing happen last Sunday...

    Same symptoms, same machine, exactly.
    And it turned out my processor's dead.
    I found one on eBay for $138. Went and got some thermal paste and achohol wipes yesterday, and am working up the courage to start working on it. I'm nervous because I want to make absolutely sure I've got the right amount of paste on it, and that I get it where it's supposed to be. If you replace your processor, be prepared to do the thermal paste; clean your heatsink off thoroughly and be diligent about cleaning the processor. For the paste, I recommend Arctic Silver.

  14. #14
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    Lightbulb

    check my Troubleshooting => MDD Upgrades => Service Manual.
    One 3mm dab of paste will do. Has full instructions on how to completely disassemble the MDD.

    Sweating is *not* allowed

    good time to sweep the dust bunnies and check things out.

    also, I didn't realize that the ATA cables on the two buses are different and one is rated for 66MHz and the other for 100MHz, and not to interchange. Odd.

    One of these days, when I have a new cpu probably, I'd like to tweak the jumpers and try pushing my 1.25/SP up to 1.5 for a week and see.

    Oh, and 10.4.x seems to have better thermal calibration scripts.

  15. #15
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    Nov 2004
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    Default new issue...

    ...after waking from sleep, I more often than not cannot dial the modem (I have Internet Connect in my toolbar); I have to repair permissions first, then connect.
    It did not do this before.

  16. #16
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    Default

    (Dial-up) Modems not working after deep sleep seems common enough. Repairing permissions, can't see how that would "fix" or be related. I would check MacIntouch. I would also look at adding the DNS IP addresses in the Network control panel.

  17. #17
    Join Date
    Mar 2005
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    Default

    So, echohaus, I assume that the replacement of the dead CPU with a working one resolved your problem, am I right

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