MCR Demolition Derby steering problems

tec9

tec9

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Hey all-
I've got a 4 player Demolition Derby that is giving me problems. I am having issues with the cars steering. All of the cars intermittently steer just a little by themselves. They just change their angle just a bit here and there. It seems to happen alot more when you have 3-4 players. When I go into test mode, the wheels appear to function correctly. However when in test mode, if you press the start buttons quickly, the value/position of a random car might flash for a second to a different value, but go right back to the orignal number. Anybody have a working 4 player Demolition Derby that can check this in their test mode?
Here is what I have done-
-Swapped out the main PCB stack
-Swapped out the power supply (tried different voltages on the +5V and +12V)
-Swapped out the steering opto PCB's ( I have 2 spares I tried putting in all different locations)
-Swapped out the main transformer assembly
-Swapped out IC's on the SSIO for the inputs- 74LS244 and 74LS273
-Checked out all the wiring on the cabinet. I actually checked continuity from the components on one PCB to another PCB (eliminating the chance of putting pressure on a failing connector and getting a false reading) I even jiggled the harness on every pin.

After all that....the problem still exists. Can ANYBODY offer any help or suggestions?
-Mark
 
Update....Still working on this.....I can add the following to the list of things I tried:
-recapped the sterring opto boards
-tried powering the opto boards with a separate power supply than the machines
-repinned the two connectors that go into the SSIO PCB (J4 &J5)
-jumped the grounds on the opto PCB's to other ground spots.

If anybody has ANY suggestions....I'd appreciate it!
-Mark
 
sounds like your all over it,

is the power cord new? is the house power solid and not dipping? at that box and grounded? open up the box and make sure its all tight and right.

B.
 
I checked the machine in another outlet...and it did the same thing. Thanks for the suggestion though....I'm open to any ideas at this point!
-Mark
 
Do you have access to an O-Scope? I'd start checking your opto signal lines or your power supply for high-frequency noise riding on the DC.

Edit:

Per the MCR FAQ (http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=info&page=MCRfaq.txt) the opto's are read through J4/J6 as parallel data.

Which is weird, since the schematic seems to point out J4 and J5. J6 is over on the video board? I've admittedly never seen one of these, I'm purely going off the schematic.

http://arcarc.xmission.com/PDF_Arca...ition_Derby_2_Player_UR_(0A59-00300-0000).pdf

Ok, I'm looking at the MCRII SSIO schematics and wow, this thing is a beast.

Looks like B2, F2 and E2 on the SSIO Boards handle that. You already replaced those? You may want to check the resistor pullup blocks RM3-45. Should be 2.7k. If you've got hosed decoupling caps (C120-127, 112-119, 104-111) you could also see pulses at random (cap discharge).

Also, funky crap on your parallel output resistors can cause noise or atleast signal delay.
 
Last edited:
WindDrake said:
Do you have access to an O-Scope? I'd start checking your opto signal lines or your power supply for high-frequency noise riding on the DC.

Right now I don't have a scope....can I check for the noise with my meter?

Edit:

Per the MCR FAQ (http://www.mikesarcade.com/cgi-bin/spies.cgi?action=url&type=info&page=MCRfaq.txt) the opto's are read through J4/J6 as parallel data.

Which is weird, since the schematic seems to point out J4 and J5. J6 is over on the video board? I've admittedly never seen one of these, I'm purely going off the schematic.

http://arcarc.xmission.com/PDF_Arca...ition_Derby_2_Player_UR_(0A59-00300-0000).pdf

Ok, I'm looking at the MCRII SSIO schematics and wow, this thing is a beast.

Looks like B2, F2 and E2 on the SSIO Boards handle that. You already replaced those? You may want to check the resistor pullup blocks RM3-45. Should be 2.7k. If you've got hosed decoupling caps (C120-127, 112-119, 104-111) you could also see pulses at random (cap discharge).

Also, funky crap on your parallel output resistors can cause noise or atleast signal delay.
Click to expand...


I've swapped in another 4 player boardset, and even a two player boardset...and they both gave me the same results. I have all of the IC's above in sockets, and have changed them out, but still have issues. Is it likely that all three PCB's could have this issue? I did check the caps to see if any were shorted...and none were. I also checked the resistor networks, and they gave good readings. Maybe I should replace the caps??
-Mark
 
I have tried another rebuilt/ working power supply, in this machine and got the same results. I even tried using the MCR switcher adapter with a switching power supply and got the same results. I have also tried swappping out the large transformer assembly from my Tapper machine- and it still acted up. However these transformers have the original caps in them. They work fine in my Tapper, but both give me the same issue with steering in the Demolition Derby. I was going to replace the large caps in the transformer next, and repin all the connectors on the steering boards and the ones that connect the control panel to thee machine. (they used crappy IDC connectors on the steering boards)
-Mark
 
PM TonyH. Pretty sure he has a 2 player in good working order. At a minimum he can tell you how his acts.
 
mjenison said:
Fluttering optos is a common problem with pinball games. Did you try cleaning the optos with q-tips and windex?
Click to expand...

I have cleaned the optos....with a qtip and blew on them. (did not use windex though) The optos are rock solid in test mode. My concern is that in test mode they don't always come up as the same value. For example when you power up the machine, and go into test mode, (without touching the wheels) Some players may be a value of "0" and some may be "63" I also noticed that when you bang the start buttons very quickly in test mode the values change for second, but return to the original value. BUT if you out them all on "0" they don't flash when you push the start buttons.
 
A little more reading over the schematic makes me think that there could be a harness problem or EMI/RFI coupling onto your wires. After you re-pin them, try a snap-on ferrite choke.
 
Hi-
Does it matter where I put the ferrite bead? Should I put them at the steering boards, or at the connector of the main PCB?
Thanks!
Mark L.
 
Okay I still have the steering issues- here is a update on what I have checked/replaced:
3-Main Logic PCB's
3-Power supplies (2 of them rebuilt)
Main Transformer assembly has been rebuilt- Big Blue caps replaced
All the steering boards have been swapped around, (have four spares) and have new caps on them.
EVERY connector that is asscociated with the steeering has been repinned and replaced.
Checked ground from power cord to all earth ground straps.
Tried disconnecting things- (sound board, amp, coin door switches, lamps, etc)
Tried jumping the grounds and voltage on the steering boards to each other, and right to the power supply.
Tried another outlet in the house.

Can somebody please tell me what I am missing?? I am going to try the ferrite beads, but wondering where I should place them....at the main PCB connector, or at the steering PCB?
Thanks!
Mark L.
 
I just put on two chokes, on the harnesses J4 and J5 that lead into the main PCB, and it didn't cure the problem. These are what I bought:
http://www.radioshack.com/product/index.jsp?productId=2103222#showFullReviews

They are pretty tight around the harness....not sure how they are suppossed to fit. Should these go on any other connectors??? All of the steering data lines are through the J4 and J5 connectors. The steeering boards get their power from the power supply, and the are wired directly to it. (+5V and +12V).
Thanks for any all and suggestions!! I've never had a machine give me such a odd problem, I'm curious as to what this is. Not sure if I mentioned this, but the machine did work fine in my gameroom for a few years without this issue.

I also just picked up a 2 player demolition derby....I figured I can use it to help me figure out this issue. Gotta fix the monitor in it first though!
-Mark
 
Demolition Derby steeering issues- youtube vid link

Hey guys....still having this issue with this machine, and one other member here says his machine does the same thing...I'm thinking this could be a hardware glitch, but I can't find anybody else that has a four player that can help me out! Anyways I made a video of what is happening:
http://www.youtube.com/watch?v=JMynNLpnDW0

-Mark
 
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