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  • SPACE STRANGER REPAIR

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    Hi Guys,

    I've been repairing a Space Stranger.

    Here's what I got on screen when I first powered it up.

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    I found an broken 08 so things were looking up.

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    After hours of checking the circuits everything seamed fine so I randomly swapped in a known working cpu.

    Then with the sound PCB removed I got this with a fresh set of EPROMS.

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    This was a great step forward.

    With the sound board attached all I got was flickering then a dark blank screen, repeating.

    But after flicking switch 5 I got Strangers!!!!!!!!

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    Unfortunately with the sound board the picture rolls really fast.

    After no success with the rolling screen decided to test the game. I had to repair the preamp replacing a 3900. It coined up and played. Cools sounds.

    I tried it on an arcade monitor and managed to dial it in with VHOLD, but the sync is not there. Switching off and on again the picture comes in still but not centered.


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    Unfortunately not fixed yet. I have a few ideas. Just thought it would be fun to post as I try and nut it out.

    Big thanks to [MENTION=2995]Kaizen[/MENTION] for posting the schematics in his post on Super Space Stranger. There's no way I could have got this far without them.

    Here's some things I observed. The Interrupt on the CPU is running a 50Hz. No doubt the routine to move the strangers in RAM during V retrace??. I would of expected this to be 60Hz?? Plus using my multi-meter I measured the Hz on the video out. It was 13.39Khz, not the expected 15khz H frequency??

    I had a thought... the game may be fixed. The table is not with me so I can't check right now. But I'm thinking the set up may work with only that monitor as the game essentially a hack of space invaders. Oddly there are two chrystals on board too. Using my cro I found it to have neg sync.

    I think the diag below is the Space Strangers equivalent of the video bit shifter??

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    Update: Actually that circuit is quiet during demo and is active only during actual game play. Pauses for a bit after a player dies.

    I checked a 74 in the clock section and it has outputs of 15.61khz, so I think the clock is good. MMM... has got me stumped. It may just need to be paired with the original monitor, but not sure....???

    Going to check out the video output section next...

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    May just be a bad ttl leading up to the sync output??
    Last edited by taito; 27th January 2019, 02:46 PM.

  • #2
    So looked at the sync signal closely and they both have the same appearance/frequency, with the I/0 board plugged in or not plugged in. The composite signal was nice without the I/O board plugged in. I could clearly see VSync. But with I/O board plugged in I couldn't get a picture on the cro...all messed up.

    So the picture isn't rolling at all. Something is rendering the game to a different part of the screen each pass, kind of like an animation does.

    And I don't think it's the output shifter section.. it is doing it's job. I feel the problem may lie with the timing of the output from RAM. So I'm going to look here next.

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    Can't work out why it will write perfectly without the I/O board, but not when it's attached.
    Last edited by taito; 27th January 2019, 05:40 PM.

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    • #3
      I had a stoke of luck. When examining the PCB upside down I put a bit of pressure on the board and the picture came good for a moment. It seamed torquing the connector made it better. I couldn't believe it!!!!

      Most probably a dirty connector I thought, so in my excitement I unplugged both boards and gave them a clean. But when I reconnected them all up again, I couldn't replicated it. Ah!! Tried and tried but no good!! I examined the connections between the boards and they all seam good.

      So it could be fixed, but the TV I'm using is a bit fickle. I seriously don't know.

      Update: I found that the Vsync signal was very weak. leading up to the video out section, barely 1 of a volt drop from 5 volts. I traced that to a suspect 04. Will change that out and see, but first, lunch.

      Update: Lunch is cooking so went to swap out the 04 but my de-soldering station died. Got out the old solder sucker, and I'd say it was parity time wise compared to the de-soldering iron. Just more effort. Swapped out the 04 but no good. I'm not a fan of clipping legs to check so that was the risk I took. So I swapped out the 20 upstream and I got a little pleasant surprise.
      Last edited by taito; 28th January 2019, 12:05 PM.

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      • #4
        Was greeted with, "LET US PLAY SPACE STRANGER". Yippie!!!

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        So here's that bad ttl signal I mentioned. Cro set to 5V per division.

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        Just need to fix a few audio issues and I'm done!

        Prologue: So the TV was fine after all. Having that moment where it all came good when I torqued the connector sent me in the wrong direction. I'm glad I decided to abandon that and get back to logic fault finding. Paid dividends.
        Last edited by taito; 28th January 2019, 01:12 PM.

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        • #5
          Its got to be really satisfying when you get to this stage, well done.

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          • #6
            Cheers [MENTION=1535]thegrunta666[/MENTION]

            I've been testing it out and it's a lot of fun.

            The game play is different to space invaders. You can catch up to UFO's, not possible with the original version. The UFO's appear, all the time it seams... Plus! they do U-turns, which is fun, because sometimes you're just about to get a shot then they piss off in the opposite direction!!

            The decent of invaders is a little slower I feel making the game a lot of fun. The extra speed of the base makes you a bit more maneuverable too, also making it a bit more easier. I really like it!!!!! One other feature I recently discovered is you can shoot the dropping bombs, which terminate with a little visual explosion, but the missile keeps on going on to hit a stranger. That's cool!

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            If anyone want to see the cabinet, here's a link to [MENTION=2995]Kaizen[/MENTION]s post, and it's where I got the manual scans too.

            https://www.aussiearcade.com/showthr...tranger+repair
            Last edited by taito; 30th January 2019, 12:08 PM.

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            • #7
              Just a matter of interest... how simple is this Chassis!!!

              9 transistors and one IC!!! :0

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              • #8
                Nice effort mate
                Regards

                Dez

                DSB Electrical
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                Another AA Visitor. Stay a while, stay FOREVER!

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