MC II sprite issues - Spy Hunter

Sid723

Member
Joined
Jan 16, 2011
Messages
92
Reaction score
2
Location
Mokena, Illinois
Hey all, You all may have seen this one before, but here it goes.

I have a Spy Hunter upright. All works great except for the car sprite is kinda blocky and not exactly right. I replaced some of the socketed RAM chips. Not sure if they are for the video or not. That didn't change anything.

Any help will be very appreciated. Thanks in advance.
 
yep. most likely a 93422 on the video board, or bad interconnects or bad sockets or all of the above.
 
MCIII Sprite issues

yep. most likely a 93422 on the video board, or bad interconnects or bad sockets or all of the above.

Yes, those are the chips I replaced. There are 8 on the video board at 2D, 3D and 5D through 10D. I got the same results. I guess it could be a bad socket, but I will have to check that out. As for a picture, I have the boards out and I can't get it back together until the weekend. I will have a picture by then. Other than the chips or sockets, any other ideas of what components I could check?
 
Spy Hunter Sprite Issues

I am sorry for not checking in for almost a year folks. Work and life got in the way.
Anyways, I am back. I left the sprite issue on the shelf since then, but I would like to get
back to it and get it resolved.

I see on this forum that another person had the same sprite issues and was able to
resolve the issue by changing some connectors and cleaning up some chip connections.

I replaced the ribbon cables way back then and that didn't help. I still have to check
the connections on the video ram chips that we talked about before, so that is where
I will start.

Thanks for hangin in there.
 
I found a bad socket for one of the RAM chips, but it is an usual size. Does anyone know where I can get some of these sockets?

I have various sizes, but none of them are right for the job.

Appreciate the help.
 
Did you verify it was a bad socket? If not, try switching out the VidGen ROMs. I have a TRON board w/ bad sprites and it was the ROMs. I also had a board w/ a bad 93422. It put weird colored sprites on the screen, but did not actually alter the character sprites.
 
All the 93422s were replaced. I even switched a few around with no change. I verified all the ROMs with a set I found on a MAME site. All of this checked out.

The bad RAM socket I found has several pins that show no continuity from some of the RAM pins to the trace on the other side of the board.



Update: I found a site where I ordered the RAM 22 pin sockets. I ordered all 10 just in case I found some more bad sockets.

Now I am just waiting for the sockets.
 
I replaced the suspect socket in the RAM section, but the sprites are still the same. I am beginning to suspect the sockets are ok.

Next step:
I verified the ROM chips with the MAME online and they are good. I think I will check the ROM sockets next. It now looks like more sprites are affected with lines (van, spy car, cars, motorcycle, helicopter). The problem could also be the support logic in that section. Does anyone know which ROMs affect which sprites?

Any more suggestions?

Thanks.
 

Attachments

  • 0203121238a.jpg
    0203121238a.jpg
    98.2 KB · Views: 69
I had a very similar issue on my board set. I mistakenly put in a rom backwards while reseating chips, and fried the rom. I flipped it and put it back together again to see if it was still good, and it wasn't. Well, I forgot to note which it was and took me a while to track it down.

So, I eventually pulled chips and ran the board to see what the effect was until I changed the redish lines caused by the burned up eprom (similar to yours but red and thinner). I noticed that the video chips on the video board 3fg, 2fg, and 1fg, affected the sprites with lines like that. I pulled 3fg and had exactly the same image of white lines as you show. I honestly believe one of those eproms is bad or not doing anything, which I believe is to fill in those lines with sprite graphics.

As I said, my screen looked exactly like yours when I pulled 3fg and fired it up without the chip in the board. I think one of those eproms is completely dead.

See here: http://youtu.be/zgtRhf15s2I
 
Last edited:
If that was the case here you should make CERTAIN all rom chips are getting vcc and ground (+5,0), epically the one mentioned here.

I had a very similar issue on my board set. I mistakenly put in a rom backwards while reseating chips, and fried the rom. I flipped it and put it back together again to see if it was still good, and it wasn't. Well, I forgot to note which it was and took me a while to track it down.

So, I eventually pulled chips and ran the board to see what the effect was until I changed the redish lines caused by the burned up eprom (similar to yours but red and thinner). I noticed that the video chips on the video board 3fg, 2fg, and 1fg, affected the sprites with lines like that. I pulled 3fg and had exactly the same image of white lines as you show. I honestly believe one of those eproms is bad or not doing anything, which I believe is to fill in those lines with sprite graphics.

As I said, my screen looked exactly like yours when I pulled 3fg and fired it up without the chip in the board. I think one of those eproms is completely dead.

See here: http://youtu.be/zgtRhf15s2I
 
OK, removed the video ROMs again and verified with MAME and all are good.
I did a continuity check on all ROM pins (5volt, gnd, Address, Data, etc.) all are getting continuity from one ROM to the next. In other words, those that have the same address lines in common (such as 8A & 7A, 6A & 5A, 4A & 3A, and 2A & 1A) and those that share data lines, I just checked continuity from one chip to the next.

I then did the same for the RAM chips and all looks like they are wired correctly with no opens or shorts. I then powered it up and measured 5 volts on all power pins for the ROMs.

All that is left is the support logic, which has me baffled. I guess the next step is to take a scope to it and see if anything looks out of the ordinary (whatever that is).

Any more ideas are appreciated at this point.
 
OK, I have some good news and bad news.

The good news is I did find a source that describes how the video circuits operate on the game. It is called the "MCR II system - General Information and Troubleshooting Procedures for Microprocessor Video Games" and it was published by Bally/Midway.

The bad news is that I am having a hard time understanding how the descriptions in the book relate to the actual chips and parts in the diagram. But, I am getting there slowly but surely.

The other bad news is that I did some scoping out of the signals around the RAM chips (2D, 3D, 5D, 6D, 7D, 8D, 9D, 10D) and I see that there is no signals coming out of the D3 and Phase 3 outputs (pins 13 and 14 respectively). I also get no output on pin 13 of J7 (VID02). What does this mean? VID02 never changes at all. If they wanted a signal called VID02, I would think that it should change.

I believe I am onto something but I am not sure. The only thiing in common to the RAM outputs that don't change is a 74273 (2G on the board). I will try to replace it, but I have no local sources, so it's order time on the net.

I can't ask anyone to do this, but if any Spy Hunter owner out there that has an opportunity, can you check these signals and let me know if they are right?

Any more suggestions greatly appreciated.
 
OK, the 273 did not make a difference. I did read on in the MCR II book and am beginning to understand what is happening in the video and CPU boards. For instance, the CPU board is responsible for generating the background video (road, sides, fork in the road, etc). The manual calls the background (the part that moves to give the illusion that you are moving) the background information. All the objects that move around the screen (Spy hunter, bad guys, motorcycles, good cars, truck, etc) the foreground information.

The Video Generator board is only responsible for creating the "foreground" information. Which is the source of my greif. After poking around with a logic probe and scope probes, I found something illogical. The chip at 5C is a NAND gate. One of it's inputs is almost always low, while the other input has a changing signal on it most of the time. This means to me that the output should mostly be hanging around high and only occassionally showing a signal. This is not the case. The output is showing a signal all of the time, and occassionally, it will show a longer pulse than normal. When I put my logic probe on the output, the logic probe is seeing the output as mostly low and sometimes it will show a signal. This is also wrong. A NAND gate that has a low on it's input should show a high most of the time.

It was a 7400, but after changing it, the signal problem was still the same. This could only mean that something was loading down the output. The NAND output was used to reset some ring counters that received data from the video ROM. As it turns out, two of the ring counters' outputs do not change at all. So, the next thing I will do is change the two suspect ring counters (74LS194s). I also traced the signals from these two ring counters to the video staging RAM and it turns out the same bits that do not change in the RAM are the same ones coming from the two suspect ring counters.

So, I ordered a lot of chips that I don't usually have in stock along with sufficient quantities of the ring counter chip. Waiting for the parts to come at which time I will install and see what happens.

If any of you would like to read the MCR II system manual, here is the link:

http://arcarc.xmission.com/PDF_Misc/MCR2.pdf


Till next time.......
 
Last edited:
So, the next thing I will do is change the two suspect ring counters (74LS194s). I also traced the signals from these two ring counters to the video staging RAM and it turns out the same bits that do not change in the RAM are the same ones coming from the two suspect ring counters.

I replaced the two suspect ring counters yesterday. After that, I now have signals coming from these two ring counters outputs. I also have the NAND gate giving out the correct signals too (not loaded down like before). Also the 4 video signals (VID0 - VID03) are all now showing signals.

Problem is: The picture is still the same. :-(

Each ring counter has two outputs (rotate right, and rotate left). I did still have two ring counters each with 1 output that does not change, so these may also be bad. I will replace them next.

This is frustrating! You'd think after fixing the logic and getting the correct signals would show some kind of change in the picture, but it doesn't.

Well, till next time.
 
FINALLY!!!

It works!!

I changed the last two ring counters (1B and 8B). each of these ring counters had 1 of the outputs that didn't change. I was not sure if this was because it didn't need to change (per the program) or that it wouldn't change. After replacing them, I finally have good looking sprites on all the characters (spy car, bad guys, helicopter and truck).

Whew!! This project is finally done. I hope none of you have to go through this.

Thanks to all that helped.

Next project: Getting my newly attained Ms.Pac working. (I currently have a thread started on this one)
 
Back
Top Bottom