Space Invaders Monitor Issue

jgeiger

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I just picked up a really good condition Space Invaders cabinet. The game plays blind, sound works but there is an issue with the monitor. The image is just a single line up the middle of the screen. You can make out some differentiation where the characters and bases should be. Adjusting the H and V holds doesnt affect the image so much. Attached is a photo.

Any suggestions on how to fix this would be greatly appreciated. This is going to look great next to my SI Deluxe.

Thanks.
 

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Actually, one of the wires to the monitor was not connected. Connected that and got the picture back. After spending some time adjusting the V and H hold its still a little rolling and wavy. Those hold dials are super sensitive. Seems like it rolls from right to left. Some more pictures attached.

Thanks.
 

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Just ordered a cap kit from Bob Roberts and will put it in next week. I definitely saw at least on cap that was oozing on the chasis. Looking forward to getting this fixed so I can put it side by side with my Space Invaders Deluxe. The cabinets both look great and I love the black like diorama effect in SI.
 
Got my cap kit from Bob Roberts today and plan on taking care of this in the next couple days. Any suggestions or tips for working with the Space Invaders monitor mount? Its pretty tight in there. Based on the mounting it looks like Ill have to go in through the coin door to discharge it and also probably have to unbolt and move the chasis before removing the neckboard. Theres not a lot of clearance between the end of the neckboard and the chasis.

Let me know if anyone has any experience with this setup and if there are any tips to make it go smoothly.

Thanks again, looking forward to getting this one up and running.
 
Recapped the monitor and the roll is unfortunately still there. I tested out all the voltages and everything seemed to be in order. I reseated the chips on the main board and no change. I believe that SI boards work in Deluxe cabinets so going to test that out.

Found this long post about what sounds like the same problem. Looks like the guy replaced just about everything in the game with no success.

http://www.coinopspace.com/forum/topics/monitor-waviness-jumping
 
Recapped the monitor and the roll is unfortunately still there. I tested out all the voltages and everything seemed to be in order. I reseated the chips on the main board and no change. I believe that SI boards work in Deluxe cabinets so going to test that out.

Found this long post about what sounds like the same problem. Looks like the guy replaced just about everything in the game with no success.

http://www.coinopspace.com/forum/topics/monitor-waviness-jumping


I worked with Brian on that long post and before he got rid of the game we were not able to solved the case however he did make progress and narrow down the problem which seems to come down to a board issue. Its long been known that there have been problems like this between the mating connector of the mother and daughter board. Some people recomend resoldering all those header pins or replace the connector all together.
I actually have my board hardwired so i dont use a edge connection anymore but both boards are still mated and i havent had such a problem like this. This might even come down to a Rom problem because if the roms are removed you should get vertical lines through the monitor screen and they appear normal then this might prove to be a Rom issue specifically. This one of those trial and error kind of repairs. It might not even hurt to check the rams and replace those little capacitors on the motherboard near the mating connector.
 
The rolling problem is the filter cap, which is the big metal can looking thing. There's actually 3 caps inside it. If you do some searching for bw monitor cap you'll find some other posts on it. I think there's a place that can make you a can cap, OR you can just replace it with 3 seperate caps which is what most people end up doing. I think one person even managed to jam all 3 caps into the actual can.

Just as an FYI regarding the PCB, I really doubt the pcb would have any type of rolling video issue unless maybe its a bad ground somewhere, or somehow the sync signals are goofed up. (or a bad edge connector going to the wire harness). All the video is generated on the motherboard (the bigger half), and the monitor is connected directly to the motherboard through the edge connector (the one with the wire harness on it), so the daughterboard doesn't have much to do with it (other than some graphics processing, but again all the analog video is generated on the motherboard itself).

If the game loads and plays, then the roms and rams are good. Its possible to have a ram chip go flaky and put some random dots/pixels/lines on the screen, but again I dont think that has any thing to do with rolling video.

The lines you see on the screen when the roms are removed are just the video processing circuitry being idle and video ram having nothing in it :)
 
Thanks guys. I do still get the rolling when the ram chips are removed which is contrary to the other thread. I have a really good electronics store here near me so Ill see if he cant help me with put together a new filter cap. The other thread had the parts list for it as well.

Thanks again.
 
These guys will make one of those caps for you :

DH Distributors
Mailing address:
P.O. Box 48623
Wichita, Kansas 67201
Physical address:
651 South Yale Street
Wichita, Kansas 67218-2043
Phone or fax: (316) 684-0050
Toll Free: 1-888-684-0050

Call them and tell them the value .
 
I have a really good electronics store here near me so Ill see if he cant help me with put together a new filter cap. The other thread had the parts list for it as well.


Keep in mind, there's several different monitor manufacturers that made monitors for Midway. That "can" cap isn't the same value for different monitors. That parts lists might not match your can cap. The values of that can cap will be printed/stamped on its side.

Edward
 
Thats good to know Ed. Thanks for the info. I was planning on pulling the cap out and taking it to the electronics store with me to make sure we can match everything.

I did put the boards in to my SI Deluxe cab and they worked just fine. So, its definitely does not seem to be a board issue. One thing I did notice was those edge connectors are really sensitive. When I dropped my SID board back in just a little wiggle on that connector and the display got out of whack.

One other question. What is the thin, spirally, wire that is hanging off the monitor chasis? Looks like you could use it to hold your cigarette while working on the monitor but just a little movement of that thing and the display goes crazy.

Thanks.
 
Thats the dag wire/springy-thingy (technical term). Its the equivalent of the ground wire attached to the back of the picture tube on a normal monitor. Although it looks useless, it has to be there and touching the tube.
 
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