MCR Troubleshooting.

cdjump

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Why won't my MCR game boot?

I get this question alot, and i'm tired of typing the same thing over and over.

For an MCR game to boot, you need several things.

+5v. This should be measured at one of the caps on the corner of the ssio.

Vbatt- this should be +5v as well when the game is powered on. If not the game will not boot. Powered off, it should read the backup battery voltage minus around .5v. If vbatt is low or missing the pcb will not boot as it provides 5v to the cpu ram.

/Reset- this must start out logic low (.4v or less) and stay low for until the +5v is stable, and then go high (logic level of 2.7v or higher. On MCR games it will often be well over 5v). A lot of arcade games have the reset generator circuitry onboard the pcb. MCR games do not. /Reset is produced on the 90412 power supply. This is critical, as a perfectly good pcb will not boot if the 90412 is bad.

Other things needed for the game to fully work -
12v. 90412 have 2 sets of 12v on them. One is regulated and goes to the pcb, the other unregulated and goes to the sound amp. If either is missing, the game will not have sound.



So how do i test all of this stuff?
ssiocaps.jpg
+5v - measure at one of the caps on the corners of the ssio. Red Square+, Black Square-

/Reset - Pin 26 of the z80 at A12 Purple Line+, Black Square-. Unless you power cycle, this should be around +5v. If it is logic low, you have a reset problem on the power supply. Also check that dipswitch 10 at b3 is off.

12v - any of the 3 tantalum caps circled in red. + is the tapered side. Or Yellow line+, Black Line- of the lm3900 at D3. (D3 pin 7-, pin 14+)

VBatt. This is harder to test. Black Square -, or black line on cpu image-. Blue line on cpu image +. You may need to unplug everything but the J1 power connector, and snip a few zip ties to get the pcb pulled out enough to be able to test this. (J1 pin 6 or 7-,pin 16+).
mcr cpu.jpg
 
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Other issues -
Corrosion - the 90412 is notorious for corrosion from the onboard battery. They leaked, then ran onto the traces, corroded the traces, and then keep going. Sometimes all the way into the harness. All 4 of the connectors on the 90412 pcb are subject to this corrosion. If you shine a light into them, and they look dull, or green, chances are, they're corroded and need to be replaced. Having said that, replacing the ones on the power supply, and then not repinning the harness side and replacing any corroded wire is just a bandaid, as the corrosion is going to keep traveling both further up into the harness and back into your new connectors on the power supply (whether its a 90412, or switcher/adapter). People wonder why the adapter works for a while and then quits, its because the corrosion from the harness/pins has worked its way back into the new connectors on the power supply.

IDC connectors-
While they often still look nice and shiny, they're usually wore out. The wipers inside them are losing tension and not contacting the header pins firmly any more. These cause all manner of issues, from controls not working to lamps not working to the game not booting, and even burning the connectors and headers on the pcb up. The correct solution is to remove them, and replace them with molex kk100 or kk156 headers with crimp pins. Then, if the do wear out down the road, they can be repinned. Its time consuming, but necessary if you want your game to be reliable.
Burnt IDC.jpg


Blown tantalum capacitors, no sound, no 12v on the ssio.
There are 3 10uF tantalum capacitors on the 12v rail of the ssio that tend to short out. If its an mcr or mcr 2 game, when this happens they will blow the choke on the 12v rail on the cpu pcb and you'll lose 12v to the ssio, and then no sound. Replace them or with 10uF 25v caps, or lift one leg to test. Replace the blown choke with a jumper. The caps are circled in red on the ssio image.

Stuck at the grid screen.
This is almost always the z80ctc is bad.

Game shows raster, but is frozen.
This is a problem with the reset circuit or bad connection. If you see the screen jump about 2 or 3 times per second, chances are the reset circuit is ok. Also make sure dipswitch 10 at B2 is off.
 
There are 5 mcr cpus, 3 of them are considered mcr3, but they aren't interchangeable.

Not trying to be all inclusive, and only referencing cpus -

MCR1(ish)- Kick, Kickman, and Solar Fox. <- Only these three are romswaps with each other
MCR2 - Tron, Satan's Hollow, Domino Man, Kozmik Kroozr, Wacko, and Two Tigers (conversion) - These are romswaps with each other.
MCR3(a) - Spy Hunter, and Crater Raider - These 2 are romswaps with each other.
MCR3(b) - Tapper,RB Tapper, Timber, Discs of Tron, Timber, NFL Football and Demolition Derby - These 7 are all romswaps with each other.
MCR3(c) - Journey. No rom swaps. Not compatible with any other MCR roms, or CPU.

There are 3 main versions of video pcbs.
MCR2 - Identifiable by only having 4 eproms. Compatible with MCR and MCR2 cpus.
MCR3 - Same size as the cpus (small). Compatible with some mcr 3 games- Spy Hunter and Crater Raider for sure. Originally shipped only with these 2 games.
MCR3 large - there are at least 4 revisions (-G,-H, -J, and -L) Compatible with All mcr 3 games (although it doesn't line up properly with the Spy Hunter plates.) Edit- G and H revisions can be used with any mcr3 game, but require modding for 27128 roms (often done from the factory).



There are 3 sound pcbs -
Sound Interface Board- originally shipped with kick and possible Solar Fox. Similar to panning ssio, without the extra panning circuitry installed. J3 only has 9 pins. No J6 connector
Super Sound Interface Board - By far the most common. Shipped with most mcr2 and mcr3 pcbs. Exceptions below.
Super Sound Interface Board with Panning - Required for Environmental Discs of Tron, and Spy Hunter cockpits. J3 has 10 pins. No J6 connector. Also shipped with some tappers, normally with J3 pin 10 cut.


In general, Sound boards are interchangeable, but if you use a standard ssio in a game with 4 speakers, you'll lose the rear speakers (and panning effect). Using a panning ssio in a regular cab makes no difference.
If J6 is used, you must use a regular ssio (as the others don't have J6). Needing J6 is common with cocktails.
 
AFAIK, Sarge is a monoboard, not MCR.
I am a little vague on what the definition of monoboard is that you are using. are you referring to it as a single board setup similar to what an asteriods would be that runs the entire game or is it a special board that is part of a 3 board stack that also connects to a separate power supply and separate sound card.

just looked it up, its an mcr3
 
Midway changed from the 3 board stack to a single video/cpu pcb and separate sound board at some point. Demo Derby was available in both monoboard, and MCR 3 pcb stack options. There were multiple versions of the monoboards. For the purpose of thread, monoboards are not relevant.
 
You mention the MCR needs the /Reset which is produced by the 90412 power supply board. So does this mean you can't use a switching power supply (bypassing the 90412) to test an MCR boardstack?
 
You mention the MCR needs the /Reset which is produced by the 90412 power supply board. So does this mean you can't use a switching power supply (bypassing the 90412) to test an MCR boardstack?

You need this:

 
I always thought the original ribbon cables were a main point of failure.
Replacements are available from various arcade online sources.

2017-04-12_14.50.53__67157.1501851936.1280.1280.jpg
 
You need this:


I did buy one of those for my workbench, I hadn't gotten around to actually testing my setup. I built a harness that plugs into that adapter board, and to the header pins on an MCR stack. But I'm glad I ran across this post or I would have been looking around for a while until I figured out the /reset signal.
 
I always thought the original ribbon cables were a main point of failure.
Replacements are available from various arcade online sources.
Yes, some are a lot better than others. I'd go with Madrit's remaining stock (which I think he sold off to 1-2 others).
 
I did buy one of those for my workbench, I hadn't gotten around to actually testing my setup. I built a harness that plugs into that adapter board, and to the header pins on an MCR stack. But I'm glad I ran across this post or I would have been looking around for a while until I figured out the /reset signal.
The adapter has the reset generator on it. You just need to populate it on your harness, and VBatt, too.

You can pretty much elliminate the adapter on the test bench by hooking vbatt directly to 5v. You'll lose setting when turned off, but oh well.
I use these on some of my test benches for /reset -

They work fine, and are just hook to 5v and ground and /reset.
 
I always thought the original ribbon cables were a main point of failure.
Replacements are available from various arcade online sources.

That's somewhat of a misnomer. It came from the original MCR FAQ, which has as much wrong as it does right. What the faq was referencing was not the blue and white interconnects that came on tron and later pcbs, but the brown paper ones that came on kick and kickman.
They break off right where they plug into the connector on the pcb, and make troubleshooting the pcb stack impossible. Those get replaced with 90 degree header pins and later style interconnects on every kick i work on.
I do replace the blue and white ones, too, because they tend to get crimped during shipping, and then work harden and break on the return journey.
As far as new interconnects go, i think mine are the best, but i'm biased. I don't sell them outside of with a repair though. Arcadeshop's offering is barely usuable. The top tends to fall off of them. The ones that Madrits made are the best available for purchase, imo.
 
I have a question related to MCR. I am currently working on a Kick, whenever I power the game up the sound board starts smoking. Game works with the sound board unplugged. Any idea what could be the cause? Also, I cannot apply credits or put it in service mode. Is this because the sound board is disconnected? I would think probably no but you never know. Thanks for any info
 
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