Spy Hunter - horizontal lines every 2 inches

Bullwinkle

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Well, to add to the slew of recent Spy Hunter questions, mine was working fine with the occassional "block of color" racing past on the right side as the game played. This block of color was about the size of the weapons van but was not in the field of play ..it was off in the grassy area. It would happen maybe once per game and you would barely notice it (it certainly did not affect gameplay)

Fast forward to yesterday, I fire it up for a game and now there is a horizontal line across the screen every 2 inches from top to bottom (see pic).

photo.JPG

Although it doesn't affect gameplay..it is now annoying. I'm assuming this is a memory issue, but please let me know if there is something else I should check. I am also assuming this is not a monitor issue.

I am in the middle of making the cables from the Tron Cable Kit from bob roberts and will replace those. Any thing else I should look at or a specific ram location I should change?

Thanks in advance.

Tom
 
Hi Tom,

Spy Hunter has two boards that handle video--the 'Video' board handles the sprites, and has a number of socketed RAM chips. The 'Super CPU' board handles the background images, the palettes, sprite colors, etc.

I have seen similar issues before with bad RAMs on an MCR video board. One simple way to test RAM issues is to rearrange the RAMs on the video board one pair at a time (I think there are eight in total). If you do this, you may see a scenario where a problem on the screen changes. This would be because you have moved a 'bad' RAM to another location. This is also a nice way to reseat the RAMs, which can sometimes clear things up.

Although I have seen white horizontal lines from bad video board RAMs, that is not a guarantee that RAMs are causing your issue. You'll have to dive in to find out. There is also some RAM associated with video on the CPU board. One nice trick is that you can test an MCR boardset without the sound board attached. You will get a sound board error on bootup, but you can just ignore that and see what you are getting for video. It beats having to put the full stack back together every time you test it!

Also, before you do any fiddling with RAM chips, etc, I highly recommend finishing assembly of your new interconnects. There is no sense mucking with your chips if your interconnects are at fault, and believe, me, they can cause some *funky* problems!

Good luck!

-Jude
 
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Jude,

Thanks for the input. SH is new to me, have had it for about a month now and there are more boards in this one than my other MCR game. Where I have a demolition derby upright... I know I need to do the interconnects first so I'll complete that and move on from there - they are the original cables or the 'flat plastic with traces blue & white cables'..so they gotta go regardless!

thanks again

Tom
 
the block on the right hand side of the screen is a ram issue on the CPU pcb. Its generally caused by using a ram thats too fast. The only ram i've found that seems to do ok in that location would be either a 58725, or a 6116-4.
The lines through the screen are harder to diagnose, but could easily be related to the ram issue with the blocks.
Without pulling a pcb to look at the location, its the 24 pin ram thats on the top left hand side of the pcb, closest to the background roms.
 
the block on the right hand side of the screen is a ram issue on the CPU pcb. Its generally caused by using a ram thats too fast. The only ram i've found that seems to do ok in that location would be either a 58725, or a 6116-4.
The lines through the screen are harder to diagnose, but could easily be related to the ram issue with the blocks.
Without pulling a pcb to look at the location, its the 24 pin ram thats on the top left hand side of the pcb, closest to the background roms.

cool..I will take a peak at what's in there. Thanks!
 
OK, I finished the new interconnects, installed and no difference (though I feel better having the new cables in there).

I have a spare video board (the one that is not in the stack and resides on the side of the machine by itself) so I replaced that board and it made no difference.

I also shifted all rams on the video board in the stack one position each to see if the issue would change and it did not. Still got a few more things to check on but running out of ideas.
 
To eliminate the monitor being the issue try another one? I had a similar issue with a 25" monitor with red lines going across from left to right. It happen to be the red video transistor on the neck board.
 
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OK, I finished the new interconnects, installed and no difference (though I feel better having the new cables in there).

I have a spare video board (the one that is not in the stack and resides on the side of the machine by itself) so I replaced that board and it made no difference.

I also shifted all rams on the video board in the stack one position each to see if the issue would change and it did not. Still got a few more things to check on but running out of ideas.

What video board that isn't in the stack and resides on the side by itself? I don't think there is such a beast.
 
OK..here we go...
88mph said:
Hi Tom,

Spy Hunter has two boards that handle video--the 'Video' board handles the sprites, and has a number of socketed RAM chips. The 'Super CPU' board handles the background images, the palettes, sprite colors, etc.

I have seen similar issues before with bad RAMs on an MCR video board. One simple way to test RAM issues is to rearrange the RAMs on the video board one pair at a time (I think there are eight in total). If you do this, you may see a scenario where a problem on the screen changes. This would be because you have moved a 'bad' RAM to another location. This is also a nice way to reseat the RAMs, which can sometimes clear things up.
I moved all the rams one position on the video board and the problem stays the same.

88mph said:
One nice trick is that you can test an MCR boardset without the sound board attached. You will get a sound board error on bootup, but you can just ignore that and see what you are getting for video. It beats having to put the full stack back together every time you test it!
Yes it does! thanks for the tip :) Though after all my tests, this is what I get upon bootup:

screen.jpg

88mph said:
Also, before you do any fiddling with RAM chips, etc, I highly recommend finishing assembly of your new interconnects. There is no sense mucking with your chips if your interconnects are at fault, and believe, me, they can cause some *funky* problems!

Good luck!

-Jude
Completed the interconnects. No difference, but I'm happier with the newer cables in place

cdjump said:
the block on the right hand side of the screen is a ram issue on the CPU pcb. Its generally caused by using a ram thats too fast. The only ram i've found that seems to do ok in that location would be either a 58725, or a 6116-4. The lines through the screen are harder to diagnose, but could easily be related to the ram issue with the blocks. Without pulling a pcb to look at the location, its the 24 pin ram thats on the top left hand side of the pcb, closest to the background roms.

I swapped the two 6116-4 rams around and no difference. I also see a 58725 on the video board, I reseated that and no difference. I will say though, I sometimes get scrambled graphics when I mess with the 6116-4 or some of the roms, but rebooting the machine clears it up. I'm wondering if its a socket issue and not the ram. I also had 2 6116-4 ram chips on my demolition derby, swapped them out and get the same screen as the pic above..no difference yet

oppolo said:
To eliminate the monitor being the issue try another one? I had a similar issue with a 25" monitor with red lines going across from left to right. It happen to be the red video transistor on the neck board.

Good idea! I never even gave this a thought, though I threw in my spare G-07 and it gives the same lines

demogo said:
What video board that isn't in the stack and resides on the side by itself? I don't think there is such a beast.

yeah...that's just me being numb...can you say "super cheap squeak"

Thanks everyone for all the help so far. I'm leaning toward bad sockets, might try to reflow the ram sockets first... maybe I'll get lucky. If anyone else has any other ideas, please let me know.

Thanks again,

Tom
 
Still having issues with these horizontal lines, but I did notice something different. If you look at the pic I posted earlier, it shows them across the screen all the way to the bottom. When I remove the SSIO board, the image flips upside down and I only get the horizontal lines half way down the screen (or up the screen as it's now flipped).

I've reflowed solder on all the connectors and all the ram locations. Replaced the 58725 & 6116-4 rams but still not fixed. Anyone with any other ideas?

Thanks,

Tom
 
Still having issues with these horizontal lines, but I did notice something different. If you look at the pic I posted earlier, it shows them across the screen all the way to the bottom. When I remove the SSIO board, the image flips upside down and I only get the horizontal lines half way down the screen (or up the screen as it's now flipped).

I've reflowed solder on all the connectors and all the ram locations. Replaced the 58725 & 6116-4 rams but still not fixed. Anyone with any other ideas?

Thanks,

Tom

Hi Tom,

The image is flipping upside down in the absence of the SSIO board because the CPU board thinks the game is in 'cocktail' mode. (It cannot get the appropriate reading from the DIP switches on the missing SSIO board.)

Since you didn't see any changes with the RAM swapping, you may have an issue with a logic chip in the video area on either the video or CPU board. Do you have a logic probe? It can be tedious, but if you go through the schematics and look up the functionality of individual logic chips, you might be able to find a stuck pin somewhere.

Hopefully cdjump will chime in again--he has a wealth of knowledge about these boards.
 
88mph,

Thanks for the reply. I do indeed have a logic probe and can hopefully read the schematic to know what's doing what. I did swap in a switcher with the MCR switcher adapter to see if it was possibly power and it didn't change anything. So at least my power supply is good.

Thanks again... I appreciate the help.
 
88mph,

Thanks for the reply. I do indeed have a logic probe and can hopefully read the schematic to know what's doing what. I did swap in a switcher with the MCR switcher adapter to see if it was possibly power and it didn't change anything. So at least my power supply is good.

Thanks again... I appreciate the help.

> I did swap in a switcher with the MCR switcher adapter

Blech!
 
The switcher adapters are great for the test bench.

A good strategy to save some time at this point would be to borrow an error free boardset. That way you could swap boards and figure out which of your boards (video or CPU) is causing your problem. It is all about isolating the location of issues with such a big board set.
 
I hear ya... Don't know anyone local with a spy hunter but I do have a lead on a spare boardset, and I like having backups... Hopefully I can procure another set and then use it to troubleshoot.
 
Spy Hunter - horizontal lines every 2 inches - *possibly solved*

Update to this if anyone is following it.

I decided to mess with the Vid Gen III board a bit, shuffling the 93422 rams around a bit with no success (still had lines regardless of the location of each ram chip..at least for the few shuffles I did). Remembering a conversation I had with fellow KLOVer Dewman a few weeks back regarding piggy-backing and removing ram chips to test, I decided to pull them one at a time to see if I could eliminate the lines. Starting with D2, each one pulled individually created a new graphic issue when pulled... until I got to D8. I pulled that one and the horizontal lines went away! I moved D9 to D8 and lost some background colors, but the lines were still gone. I then inserted the original D8 into D9 and the lines came back. BAD RAM!

93422 cross references to a bunch of different SRAM chips (2101A, 9101 come to mind) so tonight I'll be popping new memory. Not sure if these can be mixed or if I need to have all the same brand / type ram installed, but I should be able to figure that out tonight.

Just thought I'd update anyone interested.

EDIT: I replaced all the RAM chips with the same AMD 93422s and it now works flawlessly! course, I did not identify the 2nd defective RAM of the ones I pulled, but I can do that later.

photo.JPG

The blur is from my crappy iphone cam ...not the monitor :)
 
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