19 Jan 2020

OutRun - Sega 1986

My favourite arcade game ever!
Previous owner said it was working with graphic problems. Err... It was faaaaaaaaaar from that.

Anyway, main CPU ROMs were all missing (4 * 27C512) so i reinstalled them and powered the board. As often with "working boards with graphic glitches" it appeared to be completely dead.
Looking at the top board closer I was horrified to see so many fujitsu TTL chips. And by probing few of them randowmly my fear was just confirmed: an other case of fujitsu plague. I pulled them all (61 on the top baod and weirdly enough none on the bottom board) and out of curiosity tested them: "only" 32 were declared bad by my programmer. I fitted new parts and game booted, which was a good start, but graphics weren't at their best. Also music was completely missing but samples worked.


Regarding the missing music, with the use of my audio probe I could hear the digital (distorted) signal entering the YM3012 but nothing came out. It was of course faulty and a new one fixed sound completely.
For the graphic issue, probing around the RAMs on the top board, I found most address lines were floating on the road RAMs. This lead me to four LS367s (IC23/25/41/43): inputs were toggling so as the gate/enable signals but most outputs were silent. I pulled the four of them and they all failed the IC test on my programmer. On a side note they were from SGS and I've noticed recently a lot of them were starting to fail at an alarming rate (will we face a SGS plague in a close future?).


Ok that's definitely better but were are the sprites? My thinking was that, for them to be completely missing it should be something quite upstream or vital in the sprite generation. Probing the 315-5228 PLD (CK2605) revealed one of its outputs was dead. Having reversed many of those Sega PLDs recently I blessed myself for having done so! I burnt a replacement in a GAL16V8 and sprites were back. Many of the jed files (including the ones I've reversed) are available from jammarcade.net, definitely worth checking there.


Game fixed.


Yeah, 38 faulty chips...

4 comments:


  1. Re: Samurai Shodown RPG

    Dear Apocalypse,

    I apologize for ghosting you in the middle of this endeavour, it was a real dick move on my part.

    I couldn't make the time to work on the project and I didn't really understand how to use the software editor and then I got embarrassed to come back empty handed. I got embarrassed to log back here as well.

    And then life happened but this shit has been eating me for a while now. I've felt bad about disappointing you and the forum.

    I don't know what happened between you and the other members in this but I know what I did;

    So again I sincerely apologize

    I would like to pick up where we left off, if that is ok with you ?

    I'll take the reigns if you give me the knowledge and we can finally get this done for everyone.

    Regards

    -Aria

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  2. Please check the pending comments for your SamSho RPG post. One of your team mates is trying to reach out to you

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  3. 38 chips! Is that some kind of record on a Sega Super Scaler board?

    Great write up as usual, Apocalypse! Thanks.

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    Replies
    1. 38 were faulty but I replaced them all (61) since it's the only reliable way with those chips.
      And unfortunately not a record, sometimes both top and bottom boards are heavily fuckjitsu populated, braking the 100 mark of chips to be replaced.

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