Image Map Image Map
Results 1 to 8 of 8

Thread: Macintosh SE FDHD logic board schematic?

  1. #1
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    2,317

    Default Macintosh SE FDHD logic board schematic?

    Is there a schematic for the Mac SE logic board out there somewhere? I think I've traced the system instability to some problems on the logic board, but the traces I'm examining disappear inside the board and I have no idea where they go.

  2. #2

    Default

    Hello, I have some poor GIF's of schematics for the Mac SE/30 I can Email you if you tell me where to send them. Zipped file is 1.63Mb.
    Thanks;
    Charles

  3. #3
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    2,317

    Default

    The SE/30 is a completely different design and won't help me.

  4. #4

  5. #5
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    2,317

    Default

    Those schematics are not complete and don't show the area of the logic board I'm working on.

  6. #6
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    2,317

    Default

    Well after a year working on the board on and off, I got it to boot reliably and the garbage on the screen went away. The problem? One of the caps was an incorrect value, unbelievable that a single incorrect cap value can cause so much trouble.

    But one step forward and two steps back, in the process of working on the board, the left two RAM slots stopped working. With a fully populated 4 x 1mb config, the machine only sees 2mb. If I remove the two memory modules in the right two slots, the mac will boot to a corrupted sad mac screen with the hex code:

    0 0 0 E
    0 0 F 0

    Which is very odd because normal codes on this machine are 32 bit values, not 16 bit values.

    If I replace the memory in the working right two RAM slots with 256k modules for 2.5MB of RAM, the mac will boot with alternating columns of corrupted and non corrupted graphics and throw a mostly illegible message about not enough RAM being installed, so it's not seeing the 2 x 1mb sticks at all. I can swap the right modules with the left modules and the behavior doesn't change, so I know the memory modules aren't bad. They also work in another SE so I know all four modules are good.

    Has anyone had problems with the memory slots on the Mac SE?

  7. #7
    Join Date
    Oct 2008
    Location
    Kamloops, BC, Canada
    Posts
    6,199
    Blog Entries
    44

    Default

    We talked about this a bit earlier but I just though: are you sure that half of your sad mac code is not hiding behind one of the vertical bars of corruption?
    [Need something to waste time on? Click here to visit my YouTube channel CelGenStudios]
    --------------------------------------------------------------------------------------------
    [No time for videos? Click here to visit my Twitter feed @CelGenStudios]

    = Excellent space heater

  8. #8
    Join Date
    Apr 2015
    Location
    Austin, Texas
    Posts
    2,317

    Default

    Found the problem, the PLCC socket the ASIC resides in had bad solder joints. I was going crazy tracing out the board since there's not really that much between the memory slots and the 68000, just a bunch of buffers and some passive components.

    Now my SE FDHD is fully working, just need to make a dongle for the video port on the TotalSystems upgrade board and get the RAM on it working.

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •