broken Monaco GP videos

GaryMcT

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Figured I'd post these here in case anyone has had similar problems and has suggestions as to what the problem might be.

Thanks!
Gary



 
first place i would look at are the roms/proms and their sockets.

i recently did some reading up on monaco gp (whilst researching sega turbo stuff for my restoration) and i got interested in maybe running monaco gp in my turbo cab as well as turbo.

iirc the roadway and roadsides are sprites in the roms ?

a good place to start anyway. try reseating the roms, and all of the inter pcb cables.
 
Like stated above, That looks like there is just some bad connections to the eproms/proms. Just a bit of house cleaning should get you back up and running. Cleaning the roms, proms, and edge connector should work for you. Be careful with the legs, they bend very easily.

Clean the roms/proms/edge connector and re test. Post the results.
 
thats a good question, get to that in a minute.
in the video, the bridge (skinny section, the screen looks perfect, and the night driving section looks pretty close to perfect, but the other roadway and skid section (?) look like a black section rolling top to bottom, and the rest looks like dark green sectons with vertical striations in the colouring of the roadway.

does the roadway look perfect to you in game play ?
and do the black sections rolling top to bottom appear to you or is that the camera ? if it does appear to you then that could be rom/prom issues, so if you have a rom burner, maybe you could dump them and compare them to the proms avail online ? that will tell you if the proms are ok and to maybe look to the sockets next.

collision detection. hmm. i reviewed the first video again and i see what you mean. and the second. no skidding on the verges, and no collisions.
do you get the car engine acceleration sound ? i couldnt specifically hear it, but i did hear the "other car sound" but also no emergency vehicle sound. does the monaco gp do the skidding like turbo ? (car "rotating" a few degrees back and forth).
 
does the score display properly register each car as it is passed ? if it does then it would at least be recognising that your car vertical position relative to the car you pass is comparing properly and that the problem may be with the horizontal position comparison.
 
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the 74ls85 ics located at positions 3f, 4f, 5f, 6f, 3h, 4h, 5h, 6h are likely candidates for failure to detect a collision as they represent the only "comparitor" components that i can see in schematic mon16z.gif.

there are some other associated parts, 13h, 12f that may be associated as well. they are also a probable good place to look.

use a logic probe to check for stuck bits (high or low) or lack of activity on the 4 bit input lines on the comparitos, and check if the output of 12f does change at all or not

thats all i can glean from the schematics at the moment.

anyone else fixed one of these critters ?
 
Seems like the "road" signal might get messed up somewhere. Seems like "road" is never true. I think that would affect collision possibly, and also affects scoring, which isn't happening. I think you only core when you are in the road. I'll do some probing and see what I can find when j get a chance.
 
Mine did the same thing one day when I turned it on, but when I turned if off and back on again it was fine.

That being said I would start with checking supply voltages first, since mine wasn't a hard failure it could have just been low at that time (I haven't checked my voltages yet as mine is all apart getting restored).

I am not sure if the capacitors could be an issue on the boards as well, got to remember that they are getting fairly old by now. I replaced them on my boards just to be safe while they are out.
 
and collissions dont occur whle you are not on the road ! of course. an alternate possbility.

I believe that's the case.

I think a friend and I figured out where collision happens in the schematic.

I need to put it back together and probe "road" and see if it's messed up. I think the rasterizer never thinks that it is rendering road, so all sorts of other side effects occur, like no scoring, no scene change, no collision.

I'm not sure about the car sound question. I'll have to fire it up and check.
 
cool! as i worked my way back through the schematics i realised that i hadnt downloaded the schematics for the 2 main pcbs, and did so a few minutes ago. i'll try and catch up! edit: therefore my prev comments about the comparators are prob irrelevant
 
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Cool. Thanks. Will do.

I just started making a C-code/pixel-level simulator for the rendering part of the hardware so I can understand it better. I may try to get that going before I work in the game more.
 
My logic going from the videos you posted:

The bridge scene looks correct, so IC5 is working.
The night scene is almost working except for the objects in the 'headlights'.

Because the above is working that is indicating that IC2 is "probably" ok.

Everything else is an issue, which all feeds IC20 (the 'headlight' signal is also processed via IC20). Make sure the select signal at pin 1 is behaving properly (should be low unless you are in extended play if I am reading that right).

I would suspect the graphics would look 'more correct' once you enter 'extended play' mode.
 
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