A few questions about replacing a screen on iMac G4

Discussion in 'PowerPC Macs' started by dustinschings, Jan 13, 2017.

  1. dustinschings, Jan 13, 2017
    Last edited: Jan 13, 2017

    dustinschings macrumors 6502


    Sep 3, 2015
    I have a base to a 1GHz G4 iMac. There were two, a 15" and 17". I am not sure if it was a 15" or a 17". The 15" had PC2700 and the GeForce 4 with 32MB VRAM. The 17" had PC2100 but Gefore 4 with 64MB VRAM.

    This dome has PC2700 RAM and the GeForce 4 64MB VRAM. This seems to contradict the information on everymac.com.

    I am wondering, should I order the 15" screen, or the 17" model? Are there any differences I should be aware of? The base is in good shape and if I can get a neck and screen for a good price I may spring for it. I have a maxed out 20" model, and honestly, I think a 15" would be cooler to have at this point than a 17". Would the video cables in the neck be the same pinouts?

    Thanks in advance!

  2. DeltaMac macrumors G3


    Jul 30, 2003
    The RAM is not a good indication, as it may have been replaced at some point (and a model that came with PC2100 would run fine with PC2700, or even PC3200 DDR RAM.
    The serial number would be on the bottom access cover. If you don't have the access cover, the serial number should be inside the optical drive door (press on one end of the door, and the other end will pop out far enough to grab :D )
    And, you can look up the serial number on the 'net. That will tell you exactly which screen size was original.
    The video connector on the logic board might not be the same, not sure (the logic board is different part number for each size, and each different processor speed), and the neck and display are not interchangeable. You will want to find a 15-inch display, and the neck for the 15-inch, too. You can't use a 17-inch display with a 15-inch neck, for example. The neck cables are different for each size display (15, 17, and 20), and the various pieces are different (LCD panel, bezel, back cover, and the inverter board).
    So, you will want the complete assembly, if you can find it - display assembly, including the neck. (first step is finding out by serial number, what was original configuration :D )
  3. zackkmac macrumors 6502a

    Jul 7, 2008
    I have heard that the weight of the dome also ties in with the display size - so putting a 17" LCD and neck on a dome that originally had a 15" display could cause balancing issues. But that could be wrong. I think I read it here a long time ago when I had a couple of G4s.
  4. d-oost macrumors 6502a

    Jan 10, 2016
    From personal experience, I did notice that the dead 17" iMac G4 I picked up (I tried reviving it, but since it won't budge, it'll be stuffed with modern parts like an Intel NUC) felt more heavy to hold than the 15" iMac G4 I already had.
  5. CooperBox macrumors 6502a


    Nov 28, 2010
    France - between Ricard & Absinthe
    From your info given, I am inclined to say that the base you have is from a 15" USB 2.0 iMac (PowerMac6.1).
    I agree with DeltaMac, when you have found the Serial No. look up your iMac's precise original specs (type into your browser, 'Apple Serial Number info / Decode your Mac's Serial Number'.
    It's always advisable to install parts made for a specific model in order to avoid heart-ache and frustration later down the line. However fwiw, there is some FrankenMac options available on the G4 Imac. Some time back I picked up a (fully serviceable) 20" model to serve as spares for my regular 20". It was only some time later that I noticed that the dome and base didn't match up in terms of connection identification.
    Here is a photo of a correct 20" iMac.


    And here's a photo of the 20" 'FrankenMac'. Note how the firewire 400 ports are indicated with the ethernet logo, and the USB ports with the firewire logo etc. (The dome appears to be that of a 17" USB2 iMac). I've checked the serial number online, and this iMac was in fact originally shipped as a 20".


    For comparison purposes the following photo shows a correct 17" USB 2 iMac (PowerMac6.1)


    I can only presume that a previous owner of the 'FrankenMac' damaged the original dome significantly, and needed a replacement, finding a 17" USB2 model.

    I agree with Daniel O, the 15" is indeed lighter than the 17" due to the larger screen, and (probably) a heavier duty spring inside the neck. The 20" is heavier still - an iMac which is a little unpleasant to carry from room to room.
    As I've stated in earlier threads the 20" 1.25MHz has a gorgeous screen, great for watching 720p videos with CorePlayer. But the 17" 1.25MHz USB2 model offers a superb compromise.
  6. dustinschings thread starter macrumors 6502


    Sep 3, 2015
    The serial number on the bottom panel and on the CDROM lid is qp3075vhnhx and that reports that it is a GeForce2 with 32MB VRAM. Also says it was a 17". (all this per appleserialnumberinfo.com) However when I boot it up it reports it is a GeForce4 with 64MB and confirms the SN. So it looks like a Feb 2003 iMac 17".

    Also about the RAM, I meant to say that it is RUNNING at PC7200 speed according to System Profiler, although everymac says it should only run at PC2100 speed. Question: does the speed indicated in System Profiler show the speed the system is running at currently, or just the speed of the stick?

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