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SPACE STRANGER REPAIR


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pcb.jpg

 

 

Hi Guys,

 

I've been repairing a Space Stranger.

 

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

 

start.jpg

 

I found an broken 08 so things were looking up.

 

08.jpg

 

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.

 

first picture on screen.jpg

 

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!!!!!!!!

 

strangers.jpg

 

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.

 

 

title screen.jpg

 

strangers on the move.jpg

 

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 @Kaizen 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??

 

output latch.jpg

 

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...

 

video output.jpeg

 

May just be a bad ttl leading up to the sync output??

Edited by taito
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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.

 

mem.jpeg

 

Can't work out why it will write perfectly without the I/O board, but not when it's attached. :(

Edited by taito
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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.

Edited by taito
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Was greeted with, "LET US PLAY SPACE STRANGER". Yippie!!!

 

let us play space stranger.jpg

 

coin up.jpg

 

game on.jpg

 

 

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

 

BadVsync.jpg

 

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. :)

Edited by taito
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Cheers @thegrunta666

 

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!

 

Let Us Play Space Stranger.jpg

 

Testing.jpg

 

If anyone want to see the cabinet, here's a link to @Kaizens post, and it's where I got the manual scans too.

 

https://www.aussiearcade.com/showthread.php/96312-Super-Space-Stranger-Cocktail-Repair-Log?highlight=space+stranger+repair

Edited by taito
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  • 1 month later...

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