Cube G4 Logic Board Help

Discussion in 'PowerPC Macs' started by CooperBox, Jan 12, 2018.

  1. CooperBox macrumors 6502a

    CooperBox

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    #1
    Hoping the likes of Bunnspecial, Hrududu or anyone else familar with complete strip of the G4 Cube can assist me here.
    I'm currently disassembling a G4 Cube and am trying to remove the logic board. For ref as a guide I'm using the Apple Service Source doc dated 2002 - found after internet search.
    Ref pages 65 thro 72. Have removed all the obvious screws detailed P65-67, and yet to prise up between the heat spreader & heatsink, so not suprisingly the board doesn't yet budge.
    What's puzzling me is, there is no mention of removing the 2 corner pillar bolts (shown below) which surely is a requisite before the board can be removed. Or am I missing something all to obvious?

    Cube120118a.jpg

    Cube120118b.jpg

    I'm no newcomer to messing with Cubes, having changed optical drives, HD's etc, but never dug as deep as the logic board, which I wish to remove, inspect, & repaste the processor.
    I find it hard to believe that Apple would have overlooked a disassembly step in their procedure, or is it me simply not seeing the wood for the trees?

    Also an aside, I suspect I may have a problem with the DC to DC board. Is this known to be a common cause of failure on the Cube?
     
  2. eyoungren macrumors Core

    eyoungren

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    #2
  3. CooperBox thread starter macrumors 6502a

    CooperBox

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    #3
    Thks for reply but no, this disassembly falls short and doesn't detail removal of the logic board itself. I'd already found that iFixit procedure and was surprised that only the basic components were indicated in the teardown.
     
  4. bunnspecial macrumors 603

    bunnspecial

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    #4
    I'm working a bit on memory, but I did just pull one out to look at it.

    The four corner screws SHOULD release the board.

    With that said, the three spring loaded screws hold the lobo/CPU card/heat sink together. The heat spreader is heavy and can get pretty solidly "glued" to the core and make removing the LoBo difficult.

    I will often loosen or remove the screws(I don't remember whether or not they're captive). From there, you can either work the CPU loose from the heatsink or work the card loose from the lobo. I recommend the former-just be sure you have paste on hand.

    Start lifting at the top and go slowly-and of course stop if something feels wrong. You should feel it come free, and then it sort of "hinges" out from the bottom.
     
  5. CooperBox thread starter macrumors 6502a

    CooperBox

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    #5
    Thanks Buns. It's late here, so will try tomorrow. But do I understand that the two corner pillar screws I indicated (and not mentioned or illustrated in the Apple guide) must be removed? If so the added difficulty is that one doesn't have easy directly-above access to either.
     
  6. bunnspecial macrumors 603

    bunnspecial

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    #6
    Yes, those hold the LoBo to the core. You MIGHT be able to get away with just loosening them as I think the hole on the board is open-ended so the board will slide out of them. Still, you need to do something with them.
     
  7. CooperBox, Jan 13, 2018
    Last edited: Jan 13, 2018

    CooperBox thread starter macrumors 6502a

    CooperBox

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    #7
    You are absolutely right, and I sussed this early this morning prior to reading your post.
    The following notes may assist anyone else planning the same task:

    I removed the single retainer screw on each side of the body:

    130120018a.jpg 130120018b.jpg

    This allowed pulling the Cube end cover slightly rearwards, gaining easier access to the following two corner pillar stud bolts which, when slackened together with a tug on the logic board, releases the board from location grooves on the stud bolts.

    130120018c.jpg 130120018d.jpg

    Obviously this is why in the Apple service notes they don't instruct removal or even slackening off these bolts. But in fact with a Cube which has run for many years & hundreds of hours, with associated heat build-up, this particular location gets very tight indeed. So imho it's advisable to slacken these, but not remove.

    From here it was plain sailing. The processor card and heat spreader board was detached from the heatsink (photo below), and then removed from the logic board.

    130120018e.jpg 13012018f.jpg

    (Below): Processor card cleaned, ready for re-pasting and re-fitment.

    13012018g.jpg

    Again, thanks to both contributors.

    Regarding the DC to DC board. Were these known to be particularly troublesome on the Cube?
    I ask this, because this Cube functioned well for several years. Then when powered on a few days ago, nothing appreared on screen, suddenly powered itself off, and I immediately detected a slight burning smell. That prompted me to teardown the unit. So far visually, no obvious fault or evidence of burning.
    Any thoughts you can share will be welcome.
     
  8. bunnspecial macrumors 603

    bunnspecial

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    #8
    The short answer is yes.

    This is part of the reason why many of us recommend installing a base fan on every Cube-it helps keep temps low on on the VRM. Some GPU upgrades require moving the VRM, and when this is done it's generally moved to where it will get more airflow from a base fan.

    The VRM is one of the main reasons why-when installing a CPU upgrade-one MUST be sure it was intended for the Cube.

    I think you can still buy "uprated" VRMs from Japan, although they aren't cheap. The guys who do over the top Cube builds love them.
     
  9. LightBulbFun macrumors 68000

    LightBulbFun

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    #9
    Nice die shot :)

    your CPU was made 25th week 2000 :)
     
  10. CooperBox thread starter macrumors 6502a

    CooperBox

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    #10
    Actually whilst taking that shot I was thinking, ' There's someone on the forum who would die for a good die shot.' I'd forgotten it was you. Enjoy! :)
     
  11. CooperBox, Jan 18, 2018
    Last edited: Jan 18, 2018

    CooperBox thread starter macrumors 6502a

    CooperBox

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    #11
    Although I didn't pinpoint the reason for the anomaly on the above G4 Cube, the excercise did encourage me to teardown another Cube which has always performed well since purchase a few years ago.
    In fact the ad I'd seen at the time mentioned that it had been used as a server, and photos showed a pile of books on top (partially covering the cooling vents) so how this poor thing survived overheating is one of life's mysteries. So I thought at least it should benefit from a complete internal clean and chip repaste.
    Some of the photos which follow may be of interest to those unfamilar with these amazing PowerPC's, especially as there is limited info/pictures readily available since the demise of Cubeowners.com

    Cube2-18Jan18.jpg Cube2a-18Jan18.jpg

    Cube2b-18Jan18.jpg Cube2c-18Jan18.jpg

    Logic Board & Heat spreader:-
    Cube2d-18Jan18.jpg Cube2e-18Jan18.jpg

    Another die shot close up. Just to keep LightBulbFun smiling & whistling for the rest of the day......;)

    Cube2f-18Jan18.jpg
    Cube2g-18Jan18.jpg Cube2h-18Jan18.jpg

    All buttoned-up, a light touch on the power button, and BINGO!

    Cube2i-18Jan18.jpg
    I thought I would try OS Panther for a change, and populate that with apps and other info found in the recent Panther thread. And I'm glad I did. It's now running very sweetly indeed. :)
     
  12. LightBulbFun macrumors 68000

    LightBulbFun

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    #12
    Nice shots :)

    this ones CPU was made 32nd week 2000 :)

    its worth noting that both of the 7400s you posted are of the slightly mysterious Die shrunk variety (notice the more rectangular die compared to the square cut out in the plastic gasket which is designed for an original 7400)

    I have been meaning to try and compare one of these Rectangular 7400 to a 7410 to see if there is any die size differences...

    im guessing both of these G4 Cubes say "PowerPC G4 (2.9)" in OS Xs System Profiler?
     
  13. CooperBox thread starter macrumors 6502a

    CooperBox

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    #13
    Affirmative, 2.9 is indicated in system Profiler for the latest Cube I worked on. For the first, I won't know until I've determined/fixed the problem and able to re-boot.

    Had to smile. Many folks get a high from studying in detail unusual perforations on a postage stamp, minting errors on a coin, or erroneous banknotes in their personal collections. We now know what keeps you awake until the early hours. ;) I'm familiar with the term philateilist, numismatist & notaphilist. But what do you call yourself.......?

    On a side note, did you make any meaningful progress on my donated Clamshell hardware? Looking forward to an update if you did.
     
  14. LightBulbFun macrumors 68000

    LightBulbFun

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    Nov 17, 2013
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    London UK
    #14
    im a processist? LOL

    I still need to do the G4 clamshell, its a very involved processes so it takes a lot of setup hence why I have not done it yet (and keep putting it off :oops: ) not helped by how difficult it is to remove the logic-board from a clamshell. I have done a few dry runs tearing down and putting the clamshell back together tho as practice, like upgrading the HDD to a 40GB one so i have space for Leopard as well as testing out and frying the diode on the DC in board for @AphoticD :D

    I did play with the other dodgy clamshell motherboard that beeps 3 times Tho, removing the onboard RAM does not change anything sadly, so either something is damaged upstream from RAM or it does not have any way of detecting changes of on board RAM so it thinks there is still RAM onboard and beeps 3 times when it tries to run memory that no longer exists LOL at some point I might try putting some known good ram chips back on the board and seeing if that changes anything

    in regards to the first Cube, try sniffing each board and see if you can locate where the burning smell comes from, I have seen G4 Cube logic-boards have components go out in quite a blaze of glory before... (components catching fire is one of those things thats easy to miss but then painfully obvious once you spot them :D )
     
  15. AphoticD macrumors 68000

    AphoticD

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    Australia
    #15
    Nice work @CooperBox beautiful photos as always. What camera /lens are you shooting the close ups with?

    Loving the sexy, mature age pin-up chips. :) :apple:
     
  16. CooperBox thread starter macrumors 6502a

    CooperBox

    Joined:
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    #16
    Camera is nothing too sophisticated. A now somewhat aged compact: Panasonic Lumix DMC-TZ5. Lens though is a pretty decent Leica 28-280mm, F3.3-4.9
    I class myself as a casual shooter, but really enjoy documenting my Apple teardowns with many photos, mainly to assist re-assembly. On a number of occasions these have helped me understand a difficult cable run or connector configuration otherwise not effectively illustrated in iFixit.
     

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