Extra Monitor On Top Of The Machine?

zenomorp

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Ok, back in the day, when the arcade game was very popular, they used to put a second monitor on top of the cabinet so people could spectate easily. My question is, how did they interface it? Did they simply splice into the Jamma harness's video wires and run them to each monitor, or did they have a splitter of some kind?

The reason I am asking is because I wanted to re-create this type of setup on my MK1 and snap some pictures for the 20th anniversary of MK. I have extra monitors and building a box and replicating the look is the easy part, but I'm not sure how to go about hooking both monitors up at the same time. Don't want to damage anything.

Thanks for the input!
 
I know that Bally/Midway sold the top monitors that were made for their machines. There was an ad for them floating around the forums a while back .
 
I know that Bally/Midway sold the top monitors that were made for their machines. There was an ad for them floating around the forums a while back .

Did the ad describe how they were interfaced? That's the info I need. I figured simply splicing the CGA wires and running them to each monitor would work, but the PCBs are really meant to supply that much output. I don't know what it would do to the board.
 
BallyMonf.jpg


Sorry bout image quality I don't know where this originated from, but i'm sure this is the concept your looking for. No real knowledge on my end on if it would cause any damage or not.
 
Yes. That is what I'm looking to do, but I need to build a box to house the monitor and figure out how to interface it. If I can't get a hold of the exact procedure, I'll try and use an amplified VGA splitter, hack some VGA cables and go that route.
 
Judging from the number of Dual Cyberball and Dual Vs Nintendo. cabinets I have seen with 4 player boards installed I am going to assume that the average JAMMA video signal can survive being split just fine.

No need to even build a box, just grab an appropriate sized television set case and install the monitor in there.
 
Yeah, you should be able to just split the signal... even if it makes it slightly dimmer, I assume you're gonna leave it like that, so just bump up the brightness a little bit. If you're gonna be constantly switching it out, you might want to build an amp so you don't have to keep adjusting the monitors.

DogP
 
Judging from the number of Dual Cyberball and Dual Vs Nintendo. cabinets I have seen with 4 player boards installed I am going to assume that the average JAMMA video signal can survive being split just fine.

No need to even build a box, just grab an appropriate sized television set case and install the monitor in there.

cyberball has seperate video for each monitor with 2 connectors on the board. Run and gun and xmen 6 player I think use jamma for 1 screen and a connector on the board for the 2nd monitor.

last month I crushed a topper I think for mk1 style cab. I think it had something like y connectors for monitor power and video.
 
Hmm...I'm also interested in this because I remember an Aracde I passed by when Dragon's Lair was popular that was doing this. I'm not exactly sure how but my guess is in the case of that old laser game that coulda just hooked something to the player.

Honestly I just like to do video capture off arcades instead of trying to rig a camera to it...
 
I just picked up a wood grain case MGA TV with a tube that should tube swap with a G07 chassis. Looking into the TV i was thinking that it might be cool to almost completely convert it to RGB by thowing a G07 chassis and flyback in the TV casing. I may just keep the old tube in the case just to see if I can build it into a monitor box this way.
 
All right. I'll try splicing the wires off the Jamma harness first and see what happens. I'll report back with a video and or pics. Thanks a lot guys. Looking forward to finishing this project.
 
Yeah, you should be able to just split the signal... even if it makes it slightly dimmer, I assume you're gonna leave it like that, so just bump up the brightness a little bit. If you're gonna be constantly switching it out, you might want to build an amp so you don't have to keep adjusting the monitors.

DogP
Why would it make it dimmer? The signals activate transistors. It's not like the juice from the signal wire is what powers the electron gun. I'm just a noob so help me learn.
 
Why would it make it dimmer? The signals activate transistors. It's not like the juice from the signal wire is what powers the electron gun. I'm just a noob so help me learn.

The monitor has a termination impedance, so when you hook two in parallel (with equal impedance), you get half the total impedance on the video pins (two resistors in parallel, which doubles the current). This causes a larger voltage drop across the output impedance of the video signals on the board.

If the board has a DAC with low output impedance, this would cause no change, but most boards have a high output impedance... many have just digital outputs with resistors (switched resistors or resistor ladder) to select the voltage levels.

DogP
 
My guess is that a pair of 0-1V RGB input monitors would handle the split just fine.

But a 5v monitor would not be able to handle the drops. It isn't like you could just turn up the brightness either. There would be enough juice when not much color is used, (particularly dark screens). But when more juice is required (like lots of white), it will dim out.

I am pretty sure that most back to back single panel Japanese cabs use an amplifier.

That's just my opinion, i might be wrong.

Hmm...I'm also interested in this because I remember an Aracde I passed by when Dragon's Lair was popular that was doing this. I'm not exactly sure how but my guess is in the case of that old laser game that coulda just hooked something to the player.

Honestly I just like to do video capture off arcades instead of trying to rig a camera to it...
 
I was talking about TMNT, NBA Jam and other single screen 4 player titles installed in old Cyberball and Dual Vs. cabs, not games that were supposed to be twin monitor in the first place.

cyberball has seperate video for each monitor with 2 connectors on the board. Run and gun and xmen 6 player I think use jamma for 1 screen and a connector on the board for the 2nd monitor.

last month I crushed a topper I think for mk1 style cab. I think it had something like y connectors for monitor power and video.
 
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