Sega Saturn Sophia SH-2 171-6692D board reproduction project

Discussion in 'Sega Saturn Programming and Development' started by Shane Battye, Sep 29, 2018.

  1. Shane Battye

    Shane Battye Spirited Member

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    Hi All, I'm underway with reproducing the 171-6692D SH-2 boards that may be found in the following Sega Saturn development systems:

    Sophia Programming Box
    Sophia Graphics Box
    Sega Saturn Address Checker (the big one)
    Mars (possibly, uncertain as I've never actually seen inside one)


    I'm using a local PCB engineer with experience in board layout and assembly. The following are steps he's outlined which are intended to take place over the coming month or two (delayed due to production of the interface Hirose connectors - see below).
    1. Depopulate sample PCB and prep for re-assembly (note initially we are attempting to buzz it out just after removing the SH-2 chip and then re-test after replacing with a 'new' SH-2 chip).
    2. CAD
      • Set up mechanicals
      • Component data entry
      • SCH entry/check against sample PCB
      • PCB layout (layout for through hole connectors)/to SCH and check to sample PCB
      • Generate output docs
    3. Engineer design review
    4. Fabrication/assembly (I am supplying all components - see below). Initially intend on producing 10 boards as I'm unaware of the true demand of this part, personally I only need 3 and a fellow member has requested 2, which leaves 5 spares.
    COMPONENTS
    SH-2 chips
    I've gone ahead and purchased 20 pcs from China; these match the part numbers for the original SH-2 chips used in the Saturn (HD6417095 S F28, F28 designating 28mhz).

    These are at least form and fit equivalents but we will test functionality after replacing the original SH-2 chip on the donor board with one of these.


    80p connectors
    This was more troublesome to source. The original part (HIF7-80PD-1.27SV) was discontinued some while ago. Hirose still advertise a functional equivalent HIF7CA-80PA-1.27DSA(71), however this has a 4 month lead-time on production (it's a non-stocked part, engineering diagram attached to this post as PDF).

    Another issue being this is a through hole part where the original was surface mount, hence some redesign of the original board layout will be required (side by side shown in photo below, the new part is black).

    4p connector
    This is on the top-side of the board and connects to the power and ground supply in case of the Sophia. These are made by JAE and apparently still available.

    Remaining parts
    The extra top-side connector is not normally used in the Sophia and I have not attempted to source these yet, they may be added later. All residual components (resistors etc) are generally easily obtainable.

    So that's where I'm up to. Depopulating the donor board should commence in the next week or two and I'll keep updates.

    If you require an SH-2 board for one of your systems or just because you're curious then shoot me a DM.

    Oh and just to summarise the reason behind this project; the Sophia Programming Box will play any Saturn game if it contains 2x SH-2 boards. The problem is they shipped with only one (allowing the developer to either purchase a POD, EVA board or SH-2 board for the empty slot). Over time, some systems had their single SH-2 board taken to use in another box, leaving Sophia’s either with no SH-2s or possibly just the original one that it shipped with. These Sophia’s often act as expensive paperweights and so the aim is to bring them back to life; if they aren’t used for development, they can play some games and demos.

    Regards,
    Shane
     

    Attached Files:

    Last edited: Sep 29, 2018
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  2. Cat man

    Cat man Rising Member

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    Awesome project :).

    My Sophia doesn’t have any so I’ll take 2 :)
     
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  3. Shane Battye

    Shane Battye Spirited Member

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    Update; one of the ten boards has been requested by a fellow member. There are now four remaining unallocated boards from the original planned production of ten.
     
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  4. dcsw2k7

    dcsw2k7 Newly Registered

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    I am very happy to receive this news, my Sophie dumb just owed this part.
     
  5. Shane Battye

    Shane Battye Spirited Member

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    Last edited: Oct 10, 2018
    jollyroger and dcsw2k7 like this.

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