Space zap monitor and graphics issue

thebman80

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So I worked all evening on this and 4 black and white monitor chassis later I finally found one that partially works. The screen comes up in a band in the middle. I have not recapped this chassis yet so that could be an issue. But I would like to mention that I had a different chassis that did the SAME thing before it died on me. I'm thinking this might be a yoke/tube issue? I do have a spare tube and can confirm that tomorrow.

I also have a problem where the image is upside down and backwards the tube was originally from a space invaders. So I'm guessing maybe its the yoke wiring? Since space Invaders is reflected in a mirror.

Then there are graphical issues I believe the RAM cards I have in there are good. I did find 3 bad 2114's on the CPU PCB but it made no difference. My next guess is bad Eproms or sockets.

I also have no sound.

Here is a picture of the yoke if anyone with a space zap could confirm the red, yellow, black, and green wires that would be a great help. All I did was match them up with the color dots on the yoke assuming that was correct.

HpVi2iU.jpg


FzzLrFx.jpg


If you look at the image in the mirror above the screen it looks correct.

L0GGeps.jpg
 
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I also have a problem where the image is upside down and backwards the tube was originally from a space invaders. So I'm guessing maybe its the yoke wiring?

Here is a picture of the yoke if anyone with a space zap could confirm the red, yellow, black, and green wires that would be a great help. All I did was match them up with the color dots on the yoke assuming that was correct.

follow those wires down onto the chassis, there should be 2 connectors, or one big connector with the 4 wires going into it. one can OHM the yoke too to find which is the horizontal etc but you don't really need to know all that if you already have a starting (out of) position which you do have a working monitor albeit bass ackwards.
one set of wires are the verticle and the other 2 wires are the horizontal circuit. do not cross the wires or you will instantly fry the yoke. verify which two color wires are the horizontal circuit and which are the verticle. I used to know that but since I turned 50, I've forgotton many things and that seems to be one of them. go to the schematic and that should tell you which are which. on some of these chassis you can not cross the wires but some you can. depends on the connector.

you should be able to flip the connector 180 degrees to switch the image how you want it. if theres no connector onto the chassis, you will need to un-solder the wires from yoke and resolder them onto it

BEWARE ! you don't want to criss cross the outputs to the yoke

hopefully someone with a better memory can tell you if the blue wire goes with that wire for the verticle/horizontal circuit etc good luck
 
That is also another possibility I worked on this thing from like 6pm until 11pm went from nothing to what I have now. I have other pattern boards I can swap just didn't have a chance got to late and could barely stay awake.
 
Ok the problem with the mirrored image is now fixed. I swapped the yellow and green wires. Now I'm still unable to get the picture to expand in size at all. Plus the image is moved over to the right. I untightened the yoke and moved it slightly to straighten the picture out but this is where I'm at.

elkgePX.jpg


QmQYKvM.jpg
 
The sound. What's the condition of the sound board? When I had no sound, it was because the transistor was stupidly mounted to the coin box, which blew the transistor. After replacing it, I had sound
 
Noticed this thread and it's timely as I'm working on my Space Zap as well.

Anyone know how to repair/replace that filter cap on the chassis (big silver cap off to the side)? I've seen some info on multiple caps to replace it, but apparently it's not an easy like for like change out.
 
Have you tried adjusting the pots on the yolk.
Those tow metal rings on the yolk both turn and should help center the picture.
 

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Yeah I have moved them (the rings) the picture is more centered but I still cant get the thing to expand.

I have successfully done the can caps on another chassis before it went and died on me.

These monitors have to be the most temperamental things I have ever worked on.


I'm thinking about shot gunning all the transistors and diodes in the thing.
 
OK, the problem was solved just by chance this was a tube/yoke problem. I swapped in my spare space invaders tube to see if it worked and this is what I get.

YraJVC5.jpg


Now the picture isn't right so I loosened the yoke and spun it around and now I'm at this point.

i00IFWT.jpg


So the issue was a bad tube or most likely some fried the yoke on the other tube.

Now I can finally get the front of the game back together and it's on to PCB repair.

YCJiMbd.jpg
 
Go figure I figured it out I started testing other boards that I have and got to the Spare Space Zap CPU that I have. It wasn't booting so I figured well guess I will start testing the chips one at a time until I find the issue. So I pulled the U3 custom (First chip I pulled) and put it in the game and guess what? Now the game is working 100% it was a bad custom. I still have lots of other boards to test now and even more to repair.

I really hope someone tackles the customs one day I have a stack of CPUs that need some. I would probably be down for 10 to 20 of each custom lol

Here is the before:

MtbTRtB.jpg


Here is the after

BaMfKj8.jpg


And here is my spare CPU I labeled the custom semi-working.

dmM4X3g.jpg



SO, I just had one of those days were dumb luck prevailed.
 
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