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1600-03 that won't play Sonic, but will play everything else

Discussion in 'General Sega Discussion' started by elvis, Oct 12, 2009.

  1. elvis

    elvis

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    I've had this question for many years now. I'm hoping someone far brighter than I can offer me an explanation.

    I have a Australian PAL MegaDrive, model 1600-03, which exactly matches the descriptions here:
    http://info.sonicretro.org/Sega_Mega_Drive..._New_Zealand.29
    http://en.wikipedia.org/wiki/Variations_of...and_New_Zealand

    It was purchased new back in 1992, and still to this day plays most MD titles flawlessly. The only titles it can't play are the Sonic the Hedgehog series (tested 1, 2, 3 and Sonic&Knuckles).

    Symptoms when running Sonic games include (and these happen totally at random points in the games - sometimes combined, and sometimes independent): game crashing (hard lock and/or black screen), graphic/sprite errors, sound errors ("crunchy" sound, or corrupt samples), no sound at all, and occasionally the total inability to boot the system at all while the Sonic cart is plugged in. Again, this is limited ONLY to Sonic games. I've tested a number of other titles over the last 17 years and they work fine. Similarly, I've bought other PAL MD units over the years (a 1601-03, and several MD2 units) and they play the Sonic games perfectly.

    At first I thought it was the Sonic cartridge I purchased in 1992. I had it replaced under warranty days after purchase, and the effect was the same. As mentioned, when Sonic 2 was released, it had the same effect. Ditto for the other Sonic games over the years. I've collected multiple Sonic cartridges over the years, and the results are always the same.

    I've asked a wide variety of (usually self-confessed) technical people why this might occur. The answers I've had range from dubious to plausible, but never with any backing of technical explanation. The dubious include people claiming the Sonic games "overclock" the MD unit to provide the speed the game needs (I know MDs can be overclocked, but AFAIK it requires a physical replacement of the oscillator onboard). The plausible explanations include people claiming Sonic "exploits" certain hardware functions of the CPU to leverage functions and features outside of conventional programming. This sort of thing is well known across other hardware and software in the console world, but again doesn't give any insight into actual specifics in this particular case.

    I also know that at least one other game is known to have problems with certain versions of MD hardware. Back in the day the PAL publishers of "Populous" issued a statement saying that the first release of their game had issues with certain MegaDrives, and that they would replace the cartridge for those that had issues. I've not had the chance to test a PAL version of Populous on my various MD units, however.

    So can anyone shed light on why the Sonic games don't like my 1600-03? Does anyone know specifically if there are low-level differences between the 1600-03 and other models that would specifically affect Sonic titles? And if so, what are they? Or is it just a simple case of my console being faulty? But if so, what ultra-specific fault would affect only Sonic titles, and not any other game? Does Sonic just push the MD harder than the "average" game, and the M68K on board is a bit flaky?

    Again, this is a question I've had for almost two decades now. If anyone could offer explanations, I'd appreciate it greatly.

    If I ever get the time (a luxury I'm very short on these days), I'm tempted to replace the M68K and oscillator of my 1600-03 with newer chips to see if the problem goes away. I much prefer my original MD1 for both audio and video quality (the MD2 units seem to use really nasty parts). But it would be interesting to see if that solves the issue.
     
  2. GerbilSoft

    GerbilSoft

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    Is your MD using an original Motorola MC68000, or is it a second-sourced chip? (Sigmatel, Hitachi, etc.)

    Also, the MD does have switchable clock frequencies for at least one component: the VDP. Specifically, it changes pixel clock depending on whether it's outputting 320x224 or 256x224. This doesn't affect the main CPU, though. The main CPU frequency is fixed.
     
  3. SegaLoco

    SegaLoco

    W)(at did you say? Banned
    Maybe your system doesn't support BLAST PROCESSING. Anyways... that is pretty funny, if only you could failblog that. Gosh, I dunno what could cause that though. Are you sure it hasn't been damaged over the years.
     
  4. Shadow Hog

    Shadow Hog

    "I'm a superdog!" Member
    Are you positive that it's the system and not the carts? I mean, did you do the usual "rubbing alcohol on a Q-Tip" method on the contacts to see if that caused the issue? I've managed to get many games working through that method - several NES titles that glitched up, a couple of N64 cartridges that wouldn't even boot, and God knows how many other cartridge games bought second-hand. disregard that I suck cocks (should've read the full post - yes, you HAD tried other carts)
     
  5. elvis

    elvis

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    I can't remember. I'll open the unit tonight and verify.

    I'm guessing the VDP speed would affect more than just Sonic titles though?

    Very sure. This has happened since very early in the unit's life. I bought my first Sonic game mere months after buying the console. Plus I'm one of those horribly anal people who's excessively cautious with their consoles.

    That doesn't rule out the possibility that the console was damaged at time of purchase, of course. But again, it's extremely strange that the negative effects are limited to Sonic titles only, and nothing else.

    So another question: what would people recommend as another title to test? I've got various Sega first-party titles like SoR 1, 2 and 3 which all run fine. Shooters like "Gaiares" and "Gynoug" (aka "Wings of Wor") all work fine too. I'm wondering if later-life titles like "Comix Zone" would be a good candidate to stress the console? Or what about another fast-moving platformer? I might try to get a hold of Bubsy or Sparkster and try them too.

    I do have a Tototek flash cart as well, which I might try (I've only used it in the MD2).
     
  6. nineko

    nineko

    I am the Holy Cat Tech Member
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    Try to flash a Sonic hack and see what happens, this might settle it.
     
  7. elvis

    elvis

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    Will do. Thanks for the suggestion.

    Will update when I try a few things out.
     
  8. TmEE

    TmEE

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    The VDP and/or other chips have come loose on the board partially (I've fixed one such MD, which had occasional flashing on screen... quick resoldering the chips did the trick). I know I had to resolder the ASIC in my MD2 after I placed my MD2 on one of the speakers of my HiFi setup. Vibration + surface mounted components = fun
     
  9. Sik

    Sik

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    being an asshole =P
    That still doesn't explain why it only affects Sonic games and nothing else.
     
  10. Rika Chou

    Rika Chou

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    Maybe it's a Nintendo made clone! :P
     
  11. TmEE

    TmEE

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    T-04YBSC-A !
    this must mean there's more :psyduck:



    A floating pin can cause a lot of weird things to happen, it is affected by all else that goes on and perhaps Sonic games just happen to trigger some unfortunate condition...... there's lot of possibilities. I would be resoldering all surface mount chips in that MD. I had trouble mostly with S&K when my MD2 had half died from metal and italo disco music vibration on my speakers, Alien3 worked perfectly and most other games I had. Tapping the chips caused funny effects, then I realized the problem and fixed it.
     
  12. elvis

    elvis

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    Checked it just now. Genuine Motorola.

    Image here, but it's 2MB so don't waste your bandwidth unless you're really curious.

    Next time I take some holidays (rare event for me, sadly) I'll open up the console, break out the magnifying glass and soldering iron, and do some tap-tests.

    A very quick look tonight under poor light didn't reveal anything obvious. But my eyesight gets worse every year, so I'll save judgement until I get a better look.

    If it is a bad solder, I'm curious as to why it only affects Sonic. I'll try and do some tests with the Tototek flash cart and some hacked bin files on the weekend.

    Thank you all for your feedback.
     
  13. Lostgame

    Lostgame

    producer/turnablist. homebrew dev. cosplayer. Oldbie
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    Bahahaha, I lol'd.