Sega Saturn PCB revisions

Discussion in 'Sega Saturn Programming and Development' started by protivakid, May 2, 2013.

  1. protivakid

    protivakid Spirited Member

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    Is there a list out there of the various Saturn PCB revisions (say "VA0") and which type of console you can find them in (say "Model 1 J-NTSC)?

    I know for the genesis there is an extensive list comparing the graphics and sound of each board, but even a basic list for the Saturn would be cool.
     
  2. Shane McRetro

    Shane McRetro Blast Processed Since 199X

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    Druid should have something written up somewhere by now :friendly_wink: and I'm sure he'll chime in shortly.
    In the mean time there's this site over here.You'll need a translator, but it at least breaks them down a little.

    Edit: Of course a serial tells a thousand words, and all the information is in the serial most of the time!
     
    Last edited: May 2, 2013
  3. Druidic teacher

    Druidic teacher Officer at Arms

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  4. Shane McRetro

    Shane McRetro Blast Processed Since 199X

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    Haha, it was just to keep him busy for a few hours until the real Saturn whiz showed up! :friendly_wink:
     
  5. protivakid

    protivakid Spirited Member

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    The site is cool, for some reason I can't enlarge the images but maybe that's just how it is. At least I know how to determine the revision. Is there a list that details differences such as power supply, boards but with real VA(x) numbers?
     
  6. Druidic teacher

    Druidic teacher Officer at Arms

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  7. protivakid

    protivakid Spirited Member

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    For the pictures on the site linked by the seconds poster (the one with fake version nubmers), for some reason I can not enlarge any of them. Only shows thumbnails of the different components.

    There is nothing specific I am looking for, I mostly just love the saturn and want to know as much as I can about it. I have read through the genesis PCB revision guide multiple times and would love to see something similar for the saturn. It's also helpful to know which systems I can swap repair parts in / out of now that the saturn is older.
     
  8. Shane McRetro

    Shane McRetro Blast Processed Since 199X

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    Second poster? :p That's me!
    If you want some high resolution photos head over to here.
    Just search Saturn and your dreams will be realised. Such fantastic looking hardware! :smile-new:
     
  9. retro

    retro Resigned from mod duty 15 March 2018

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    It's listed in the service manuals.
     
  10. protivakid

    protivakid Spirited Member

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    Love the pics! One thing I noticed, for the model one saturn, does that black glossy plastic piece that covers the access / power lights pop out? In the below pic it looks like only pressure tabs are holding it in.

    https://picasaweb.google.com/101985...el1050054493?noredirect=1#5781268822502155410
     
  11. protivakid

    protivakid Spirited Member

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    Love the pics! Question though, on the model 1 saturn does that glossy black piece that covers the power & access lights pop out? It looks like its only held in with pressure clips.
     
    Last edited: May 3, 2013
  12. Druidic teacher

    Druidic teacher Officer at Arms

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  13. retro

    retro Resigned from mod duty 15 March 2018

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    Ummm, can't remember... and they've gone missing! Quite possibly, though - I had all the PAL ones, I believe.
     
  14. Druidic teacher

    Druidic teacher Officer at Arms

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  15. retro

    retro Resigned from mod duty 15 March 2018

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    Err, no. A lot of them had several things in common, anyway - certainly they'd list it in a comparative manner.
     
  16. Druidic teacher

    Druidic teacher Officer at Arms

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  17. retro

    retro Resigned from mod duty 15 March 2018

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    There was a chart right at the front of the manuals. It tells you whether you can swap parts, essentially. And besides, covering multiple revisions is commonplace in service manuals.
     
  18. link83

    link83 Enthusiastic Member

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    Sorry to slightly bump this thread, but this subject also interests me, as I am currently looking to acquire a Saturn which has the best picture/audio quality possible. I was hoping there would be a guide like "Ace's Mega Drive PCB Revisions Guide" but I haven't been able to find anything similar for the Saturn, so I just I had a few questions...

    1) Do all Saturns use the CXA1645, or were different video encoders chips also used, and if so which one has the best RGB output?

    2) Has anyone attempted swapping the CXA1645 video encoder for a CXA2075? According to the CXA2075 chip designer here:-
    "There's ONE little catch, however. In order to attain the ultra-high
    performance, we had to burn more power. This is not normally a problem (and I
    don't know about most of the playstations) but the Sega that used the 1645
    didn't have quite enough power budget (they used a fusable wire to supply
    current to a few circuits) and our 2075 was over the power limit they had set.
    I left Sony about that time after providing some suggestions for reducing
    power for them so I don't know what they did with it at that point."

    Sega ended up using the CXA1645 in the Saturn, but I thought it would be interesting if it could handle the extra power requirements of the CXA2075?

    3) Is there any benefit to replacing any/all capacitors on the motherboard? (Unlike the Mega Drive and Dreamcast the Saturn's decoupling capacitors for RGB are located on the motherboard, not externally in the SCART cable)

    4) Are there any technical differences between NTSC and PAL Saturn motherboards besides a few jumper locations, a different crystal oscillator, and C-Sync being replaced by +9V on the AV port? (Trying to dertemine if its worth importing an NTSC model)

    5) Which version/manufacturers CD drive/laser is the most reliable?

    6) I have read here that some later PAL models (VA7+) have interference present in the video signal, supposedly caused by the CD drive when reading a disk. Is there a known cause/fix for this?

    7) I have also read that some versions of the Saturn have compatability problems when used with an XRGB-Mini, does anyone have more info? Specifically I believe some PAL models have problems with the sync signal when switched between 50Hz and 60Hz?

    Thanks in advance for any advice :)
     
    Last edited: May 21, 2013
  19. Druidic teacher

    Druidic teacher Officer at Arms

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  20. link83

    link83 Enthusiastic Member

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    Thanks very much for you detailed reply Druid II :D

    I have been doing some more research since you posted your message and your name pops up alot regarding the Saturn! It would be great if you could write a revision guide sometime with all your findings. I just have a few follow up questions if you dont mind! (I have numbered them below)

    1) Hmm, thats interesting. Might the the 'BF' encoder actually be a BH7236F? (ROHM manufactured video encoder) Also do you know which VA revisions it was used on? and was it only used on Saturns manufactured in a specific country? (China, Indonesia etc)

    2) I'm not really into s/pdif mods, so would be curious to know if one d/a converter is considered better than the other?

    Thanks, this is exactly the sort of detail I love to know! :)

    You probably already know this, but the Dreamcasts custom video encoder 'SEGA 315-6258' is actually made by ROHM and the real part number is BU1426KS (No datasheet since its a custom part, but the pinout is on the released Dreamcast VA0 schematics)

    3) Do you know if Sega used high quality/good brand capacitors in the Saturn, or just whatever was cheapest? I know many Mega Drives and Game Gears are affected by cheap/poor quality capacitors so wasn't sure if the Saturn was affected too. I realise replacing aging capacitors in general can help, but I would be more inclined to replace them if they were of poor quality to begin with - if that makes sense.

    4) Are all three pins controlled by one jumper location, or would they all need to be seperately switched (Including the crystal) if I wanted to switch between 'proper' NTSC and PAL modes?

    Thats good to know, in my experience I tend to find the Samsung lasers fails more often in the Dreamcast than the Yamaha ones. This is just anecdotel evidence though, especially since the Samsung drives seem to be much more common than the Yamaha's.

    5) Hmm, so given that retro said there were three Saturn PSU revisions based on the Sega service manuals:-
    It sounds like the A and B PAL PSU revisions are fine, but the C revision may be causing some ripples in the picture?
    Alternatively perhaps the rippling is due to the extra +9-12V power line for SCART switching present on PAL PSU's?

    6) I found this info on the XRGB wiki, which refers to Mega Drive's, but I believe the same issue applies to the PAL Saturn as well:-
    http://junkerhq.net/xrgb/index.php/Sega_Genesis
    I previously found posts on the shmups.system11.org forums mentioning this issue, but I cant find them now :/
    Perhaps its been fixed with an XRGB firmware update, but if not I just wanted to be sure I wasnt at a disadvantage by buying a PAL Saturn?

    ----------------------------------------------

    7) I personally prefer the look of the Model 2 Saturn slightly more than the Model 1, so if there isnt any major quality differences between them, then I think I would be best to look for a PAL Model 2 VA5 "SD" - any thoughts?

    Thanks again Druid II :)
     
    Last edited: May 24, 2013

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