How do you wire up a color monitor in place of a B/W one?

Vectorman

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How do you wire up a color monitor in place of a B/W one?

I've got a Space Zap mini with the elusive Electrohome 13" B/W monitor. The monitor is dead and I'm having trouble fixing it.

Someone implied that I could just put in a 13" color monitor and it should work if hooked up correctly.

What is correctly for this scenario? Is it just tieing R,G, and B together? Do B/W monitors have a sync wire? I'm confused.

Help?

John
 
B&W monitors DON'T have (explicit) sync... they use composite video w/ the video and sync together on one line...

You could use a astrocade RGB board to split off the sync from the composite externally, then run the green out to all 3 colors, but all you really need is the sync separator part of the board...

The SI link is utterly useless, since space zap puts out composite straight from the astrocade custom chip, rather than assembling a composite signal from separate video and sync at the output, like SI does...
 
If the monitor will tolerate a video signal with sync information embedded in it, you could use an LM1881 sync seperator chip to generate the composite sync the monitor needs. Dunno how well it would work though.

Or, instead of using a color monitor, you could use an old monochrome or color composite computer monitor, or even a TV set. It's also not hard to modify a black and white TV to take composite video.

-Ian
 
I've got a Space Zap mini with the elusive Electrohome 13" B/W monitor. The monitor is dead and I'm having trouble fixing it.

Someone implied that I could just put in a 13" color monitor and it should work if hooked up correctly.

What is correctly for this scenario? Is it just tieing R,G, and B together? Do B/W monitors have a sync wire? I'm confused.

Help?

John

The manual states that the mini actually had a 15" monitor in it.

B&W monitors DON'T have (explicit) sync... they use composite video w/ the video and sync together on one line...

You could use a astrocade RGB board to split off the sync from the composite externally, then run the green out to all 3 colors, but all you really need is the sync separator part of the board...

The SI link is utterly useless, since space zap puts out composite straight from the astrocade custom chip, rather than assembling a composite signal from separate video and sync at the output, like SI does...

The Space Zap Mini is different that the upright and cocktail. The mini should have a Monitor Interface Board that splits out the horizontal and vertical sync. Of course the schematics show it as "sink". :) If he has that board (did they use the astrocade board for that?) then he can wire it up as suggested right?

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Thanks for all the guidance guys. After reading all of the above (and realizing that this is a 15" monitor, not a 13") I decided to just pull the thing out and go over it one more time.

I resoldered every single connection on the board and checked all of the wiring, then put it back and tried again. Things got better. Now I at least get raster when I turn up the brightness. But nothing else.

I had assumed that the boards were working right because they do coin up and sound like they're playing. But now I'm thinking the next step is to try hooking the signal up to the composite on another black and white monitor I've got to see if the problem is in the monitor or on the boards.

I've also got another working Space Zap in the warehouse...I'll try digging the boards out of it and seeing if putting them in makes a difference.

Is it possible (or likely) that the boards would sound like they're working but not be giving out the video signal?

Thanks again for the help...we're getting closer!

John
 
Thanks for all the guidance guys. After reading all of the above (and realizing that this is a 15" monitor, not a 13") I decided to just pull the thing out and go over it one more time.

I resoldered every single connection on the board and checked all of the wiring, then put it back and tried again. Things got better. Now I at least get raster when I turn up the brightness. But nothing else.

I had assumed that the boards were working right because they do coin up and sound like they're playing. But now I'm thinking the next step is to try hooking the signal up to the composite on another black and white monitor I've got to see if the problem is in the monitor or on the boards.

I've also got another working Space Zap in the warehouse...I'll try digging the boards out of it and seeing if putting them in makes a difference.

Is it possible (or likely) that the boards would sound like they're working but not be giving out the video signal?

Thanks again for the help...we're getting closer!

John

The boards might not be putting out the signal, but if you can hear it playing I would look at the Monitor Interface Board. Since it sits between the board and the monitor, that is double the number of connections that could be messed up, unplugged or whatever. :)

You could test the game board as Mark suggested by hooking it up to a composite in on a TV. Just use that signal and signal ground and wire up a RCA connector.
 
VJ, you were right. It was a cold solder joint on the monitor interface board. I hadn't even noticed that board in the cabinet until you pointed it out.

Now the picture is perfect - bright and sharp. Thanks for the guidance!

Another one done!
John
 
VJ, you were right. It was a cold solder joint on the monitor interface board. I hadn't even noticed that board in the cabinet until you pointed it out.

Now the picture is perfect - bright and sharp. Thanks for the guidance!

Another one done!
John

Excellent! One day I hope to have a space zap. I just have a boardset now. Played it back in the day on a mini. ;) Congratulations! Play a few games for me.

-VJ
 
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