MCR Experts - Spy Hunter vertical jumpiness

DogP

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Hey,

My Spy Hunter has started having a minor glitch, where all the cars briefly jump vertically on the screen. The game plays perfectly, but the glitch happens seemingly randomly, sometimes many times in a game, and other times not at all.

I checked the voltage (5.1V at the chips), and I replaced the ribbon cables with the madrits cables. Any MCR experts have any ideas of what I should check for? I'm guessing something on the Video Generator board?

Here's a video showing the glitches several times:


Thanks,
DogP
 
Mine did the same and I was going to say replace the cables as that fixed mine, but you stated you already did that...so hopefully someone else will chime in with suggestions. Maybe a flakey header solder joint??
 
Could be a solder joint, or maybe a corroded contact on a pin or something... I'll see if I can get someone to watch the screen as I wiggle connectors. The MCR stacks are such a hassle to troubleshoot in a cabinet, I just figured I'd ask for suggestions before digging too deep.

Thanks,
DogP
 
I had something similar happening on mine. My culprit turned out to be dirty/corroded connectors from the linear power board to the MCR stack.

I re-pinned the power connector attaching to the MCR stack, sprayed the inside down with Deoxit, worked it on and off several times, let it dry, and then hooked it back up and it's been good ever since.

It'd be real interesting to see what voltage you're getting on the caps on the corners of the SSIO board when this glitch happened. Mine was drifting low when my car jumpiness happened.

Also, if you didn't spray down those connectors for the board interconnects with Deoxit before you replaced them, I'd do that and work them on and off.
 
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Thanks... that's interesting. I'll check them out. I was testing the voltage on the SSIO, which was 5.09V, with or without jumpiness (voltage never had any noticeable change).

I did spend some time working on it... it doesn't seem like it's the ribbon cables or their connectors. I sprayed them with deoxit and wiggled a bunch, but never had any sort of correlation between anything I did and the glitches.

I pulled the back plate off so I could handle the video board while playing... the only thing that I did notice is that of the 20 or so games I played... I never saw a glitch when I had the video board "floating", and never had a game without a glitch while electrically connected to the metal frame. So, I wonder if there's a ground loop or something between the boards causing these glitches.

I tried unfolding the board all the way, and also just holding it barely off the metal frame with the same results (trying to make sure it's not pressure on the cables from their position). I'm gonna try insulating the screws/mounts and reassemble to see if it really does make a difference.

DogP
 
If you have 5.09 on the SSIO, what do you have leaving the linear power board? It sounds like the voltage may be cranked up a little on the high side.
 
I didn't check the voltage at the linear, but obviously the voltage at the game board is the important part. It was 5.09V on the SSIO and 5.07 on the video board... which is right on target where I want it. I made sure the power connectors were clean, and sprayed them with Deoxit as well.

An update to my problem though... there definitely seemed to be a correlation between the video board touching the metal frame and the glitches. As a test, I screwed it all back together, and the glitches returned in full force. Then I used an alligator jumper wire to ground the PCB frame to the metal power chassis in the bottom of the cabinet (where the rest of the ground straps connect). I've played about 10 games with that jumper in place, and haven't seen a glitch yet. I'm somewhat hopeful that fixed my problem. It definitely did something, as my pot calibration changed slightly (I could no longer hit 1F on the pedal).

DogP
 
I didn't check the voltage at the linear, but obviously the voltage at the game board is the important part. It was 5.09V on the SSIO and 5.07 on the video board... which is right on target where I want it. I made sure the power connectors were clean, and sprayed them with Deoxit as well.

An update to my problem though... there definitely seemed to be a correlation between the video board touching the metal frame and the glitches. As a test, I screwed it all back together, and the glitches returned in full force. Then I used an alligator jumper wire to ground the PCB frame to the metal power chassis in the bottom of the cabinet (where the rest of the ground straps connect). I've played about 10 games with that jumper in place, and haven't seen a glitch yet. I'm somewhat hopeful that fixed my problem. It definitely did something, as my pot calibration changed slightly (I could no longer hit 1F on the pedal).

DogP

Yeah, just wanted to make sure that you weren't pumping 5.3v into the game to hit 5.09 on the SSIO. With so many boards and connectors it's real easy to see power drops.

You really should be hitting around 21 or 22 on the gas pedal user input screen or you probably need a new gas pedal pot.

I'm not sure what you mean when you say that the video board is touching the metal frame. All of the boards should be on a standoff or not touching the metal.
 
You really should be hitting around 21 or 22 on the gas pedal user input screen or you probably need a new gas pedal pot.
I'm pretty sure you're only supposed to have 00-1F... IIRC 20+ causes you to go ridiculously fast. At 1F, you get the flames shooting out of the tailpipes.

I'm not sure what you mean when you say that the video board is touching the metal frame. All of the boards should be on a standoff or not touching the metal.
All the boards are attached to a metal frame, like:
1281408936.jpg


But, it looks like I spoke too soon about the grounding... I'm seeing the jumpiness again. :/ I hate working on MCR games... nothing is conveniently accessible (frustration is mounting from this game, Tron, and Kickman :p ).

DogP
 
Sorry to hear about the grounding not fixing it.

Yeah, I know they're all attached to the metal frame but there should be standoffs on all of the boards so nothing is actually touching the metal.

You are actually supposed to go over 1F. 1F is just the beginning of turbo, and there are various degrees to it. If you put a new pot in the game you'd go up to 22 or 23h and then the game wouldn't register more. As the original pots aged, their range decreased on the top end so my original blue pot fell far short of turbo speeds before I replaced it.

And yeah, turbo is very fast but that's the whole point; the speed is another arrow in your quiver. You just die very quickly if you use it too much. :)

I think I'm ranked around 4th in the world so I'm pretty sure I'm correct.
 
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I'll have to check my Tapper boardset, but it certainly looks like all the boards are supposed to be grounded to the frame (there's an exposed pad and large plated through-hole on every board at every metal stud on the frame). They all should be at the same ground potential anyway... but having the video board isolated seemed to be the only difference between glitching and not. My Tron and Kickman boards are connected with nylon standoffs and no metal frame though.

I still have plenty of adjustment left in my pot... I've just always read that it should only go up to 1F, so that's where I have it adjusted to (like: https://forums.arcade-museum.com/showthread.php?t=41325 ). I played one that went >20 at a friends house once, and it seemed WAY too fast, then found all the posts saying 1F max, so we readjusted the pot. Maybe I'll try tweaking my pot to go >20, though I'm not sure I want to. :p

DogP
 
The Spy Hunter MCR boardset is grounded to the frame. All the standoffs are metal and the screws connect to the ground pad. Some may also have the yellow ground strap connected as well, probably based on date of manufacture (or maybe they all did and the strap got removed by ops along it's life..)
 
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I'll have to check my Tapper boardset, but it certainly looks like all the boards are supposed to be grounded to the frame (there's an exposed pad and large plated through-hole on every board at every metal stud on the frame). They all should be at the same ground potential anyway... but having the video board isolated seemed to be the only difference between glitching and not. My Tron and Kickman boards are connected with nylon standoffs and no metal frame though.

I still have plenty of adjustment left in my pot... I've just always read that it should only go up to 1F, so that's where I have it adjusted to (like: https://forums.arcade-museum.com/showthread.php?t=41325 ). I played one that went >20 at a friends house once, and it seemed WAY too fast, then found all the posts saying 1F max, so we readjusted the pot. Maybe I'll try tweaking my pot to go >20, though I'm not sure I want to. :p

DogP

Yes, the grounding that you describe makes sense through the posts. Nothing else component-wise should be touching the metal though; that's what I was trying to say.

That post you linked to was with the original blue pot. They get flaky with age, the return values gets "jumpy" and non-linear and their range decreases and often won't even make it to 1F. I can't tell you the number of posts I've read from people saying "isn't there supposed to be a turbo in this car?" because their original blue pot isn't returning values at the high end any longer.

Things get weird where the pot "wraps around". With a new pot you go back to the full range which seems to be around 22h or 23h. There should be various degrees of "turbo" before you hit the end of the range.

If you can go higher than 1F then you should adjust it that way. Just make sure that your low end remains at 0 because you don't want the car moving with your foot off the pedal.

Sometimes when people can't get the full range out of their pot any longer they "cheat" and adjust the range to the right so the higher values are accessible but the lowest you can go is 3 or 4 so the car will creep forward.
 
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Just a quick bump... still got the game pulled out and trying to track down this jumpy video problem. Any ideas?

Anyone know what chip(s) control foreground object placement? It looks like the background (road, trees, etc) scrolls as expected, but the foreground objects all jump, as if one of the position bits is toggles when it shouldn't.

Thanks,
DogP
 
I FINALLY got this glitch tracked down! It ended up being a bad 74LS157 at location 10F on the Video Gen III board. It had a weak 3Y driver, causing glitches on the ORWR signal.

It was a really weird bug to track down... when I had the boards unfolded, it would never glitch, but as soon as I screwed the boards back together, it'd start glitching. So I couldn't tell whether it was a grounding issue, or something else. I insulated all the metal and put it back together, and it still failed, ruling out the grounding issue. I figured it was probably either a hairline crack (flexing differently when screwed together), or a VERY slight thermal issue (board getting a bit warmer when screwed together). I tried flexing the board a bit and couldn't reproduce the issue, so I grabbed the hair dryer, and after getting the board really hot, it would glitch quite often (which was nice, because the hardest part was trying different things and waiting for the glitch to occur).

Once I determined there was a thermal problem, I grabbed my hot air tool, hoping I could pinpoint the single chip with the thermal failure (since the hair dryer warms the whole board)... but was never able to track down exactly which chip it was... just the general area of the board (I was moving from chip to chip too quickly I guess).

When I figured out the general area, I tried my logic comparator, but when I clipped it on most of the chips, it caused other graphical problems (pretty common to happen w/ the logic comparator), and I never saw any non-matching outputs.

So, instead I grabbed a contraption I made a while back to clip on each chip and pull the pins up or down by pressing a button. I found that when I clipped it on 10F and I had the button pressed to pull up, it never glitched, even when hot... and when I clicked it to pull down, it glitched more. I wasn't sure whether it was an input to 10F, or output from 10F that was being helped by the pullup... so I began pulling wires off my pullup clip until just pin 9 was remaining. Pin 9 was the critical pin, and being an output from the chip, I figured that had to be the problem... so I replaced the chip, and it's finally FIXED!

While I was in there, I adjusted the pot so I can get up to 22 on the gas pedal. And the one good thing that came from all the testing I had to do is that I'm finally much getting better at the game. I got my high score of just over 74K. :) Before this, I'd struggle to get 20K. :p

Anyway, thanks for the help!

DogP
 

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I FINALLY got this glitch tracked down! It ended up being a bad 74LS157 at location 10F on the Video Gen III board. It had a weak 3Y driver, causing glitches on the ORWR signal.

It was a really weird bug to track down... when I had the boards unfolded, it would never glitch, but as soon as I screwed the boards back together, it'd start glitching. So I couldn't tell whether it was a grounding issue, or something else. I insulated all the metal and put it back together, and it still failed, ruling out the grounding issue. I figured it was probably either a hairline crack (flexing differently when screwed together), or a VERY slight thermal issue (board getting a bit warmer when screwed together). I tried flexing the board a bit and couldn't reproduce the issue, so I grabbed the hair dryer, and after getting the board really hot, it would glitch quite often (which was nice, because the hardest part was trying different things and waiting for the glitch to occur).

Once I determined there was a thermal problem, I grabbed my hot air tool, hoping I could pinpoint the single chip with the thermal failure (since the hair dryer warms the whole board)... but was never able to track down exactly which chip it was... just the general area of the board (I was moving from chip to chip too quickly I guess).

When I figured out the general area, I tried my logic comparator, but when I clipped it on most of the chips, it caused other graphical problems (pretty common to happen w/ the logic comparator), and I never saw any non-matching outputs.

So, instead I grabbed a contraption I made a while back to clip on each chip and pull the pins up or down by pressing a button. I found that when I clipped it on 10F and I had the button pressed to pull up, it never glitched, even when hot... and when I clicked it to pull down, it glitched more. I wasn't sure whether it was an input to 10F, or output from 10F that was being helped by the pullup... so I began pulling wires off my pullup clip until just pin 9 was remaining. Pin 9 was the critical pin, and being an output from the chip, I figured that had to be the problem... so I replaced the chip, and it's finally FIXED!

While I was in there, I adjusted the pot so I can get up to 22 on the gas pedal. And the one good thing that came from all the testing I had to do is that I'm finally much getting better at the game. I got my high score of just over 74K. :) Before this, I'd struggle to get 20K. :p

Anyway, thanks for the help!

DogP

Marvelous! Great job!
 
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