Double Image On Centipede Upright

[cornishHen]

I have just switched out monitors on a recently aquired centipede machine and the new( used) monitor is displaying a double image of the game ( see attached photos ).  Any ideas why this would happen?  The game appears to play fine and sound working.  Just double vision and squished. 

Thanks!!

[SirPeale]

This is a dedicated game?  Because it almost looks like it's not in sync.

What kind of monitor is it?

[cornishHen]

Its an original centipede arcade pcb pushing the monitor.  Currently it is hooked up to a monitor that was working for a horizontal jamma game( Rastan ).  I hooked up the reg, green, blue, horiz, vert sync from the centipede pcb to the new monitor.  One thing to note is the monitor was using pos vertical and pos horiz sync for the previous jamma game.  I tried using positive sync with the centipede output but it just gave me green and red fuzzy distortion, so I tried to feed the vert/horz sync from the centipede pcb to the negative sync terminals and thats where I am now.  The screen is not flickering or rolling.  Is it possible i just need to adjust a sync pot? I am very new to troubleshooting monitor issues.  Thanks again!

[cornishHen]

Peale,
Thanks for the response.  The original centipede monitor was an electrohome G07.  I am now trying to wire the centipede pcb to a Rauland 19VMBP22 (atleast thats the tube) the chassis has a Midway electronics sticker. 

[SirPeale]

May we please see a picture of the chassis?

[modessitt]

Well, I've got to tell you, when I normally see this problem, it is usually because you are trying to display a Standard Res signal on a Medium Res monitor, or vice versa.

But Rastan was a Standard Res game, as is Centipede, so this shouldn't be a problem.  Unless the JAMMA configuration was different...

Centipede did use negative sync.  I've seen some monitors that don't like the sync sent to both pins, so try sending it to the negative horizontal pin only to see what happens.

This may also be one of those monitors that either have a switch to change between resolutions (in which case you should check to make sure it didn't get flipped when moving) or has an auto-sense circuit that automatically changes the resolution to match the signal input.  If it has an on-screen menu, try doing a factory reset of the settings.  I had one of the auto-sensing monitors do this until I reset the memory, then all was fine.

[cornishHen]

Here's some photos of the chassis...hope this helps.

[SirPeale]

Okay, you have a WGK4600 series.  Why is it still attached to a Williams monitor mounting board?

[cornishHen]

well, the monitor is actually still in the Rastan machine..   The centipede machine is next to the Rastan machine and I simply ran monitor control wires over to the Rastan machine monitor for a test as the centipede monitor appears to have some type of screen collapse ( single green vertical line ).    The Rastan monitor is still hooked up to the Rastan powersupply but has centipede RGB/sync going in.  Hope that makes sense.  I really wanted to make sure I could get the centipede machine working on that monitor before pulling it out of a working Rastan machine.  Is having it on a midway chassis a possible cause?

 

[modessitt]

Can you please post a close-up pic of the video signal connectors as they are attached to the left daughter card?

[cornishHen]

I have attached a picture of the monitor connector, but I think the centipede pinout I used in combination with the monitor pinout image should be more useful.. After looking at the monitor pinout again,  I was mistaken in reporting that I am using negative sync.  I am actually using positive sync for centipede where the Rastan machine was using negative.  I have included the url for the centipede P19 connector pinout I used.   I matched its red, green, blue, syncs to the label on the monitor..

 centipede pintout:
http://www.ggdb.com/kb.aspx?c=Coin-Op&s=Arcade&vid=503&kb=44

[cornishHen]

OK..I have an update... I aquired yet another non working centipede machine with a different monitor and power supply, and I receive the same double image( image below ).  It appears to be pcb related.  I have visually inspected the pcb and noticed nothing odd.  Any tips?  Should I move this thread to another forum as it doesnt appear to be a monitor issue. Thanks again! 

[SirPeale]

Nah, it's still a video issue as far as I'm concerned.  Unless you *want* it moved, of course.

[grantspain]

maybe a faulty video ram,its not 2 pics,its a half a pic x2

[RayB]

You're only getting half of each mushroom, so to me that looks like a board problem.

[cornishHen]

One thing to note...I tried running the self test and I get no beeps..Am I doing something wrong?  I even tried hitting the reset button on the pcb while in self test.  Also, anyone have suggestions of where to buy ram chips?  I found arcadechips.com..

[cw]

if you check the harness pinout (and its not in some of the manuals for whatever reason) the centipede pcb does output a neg and a pos sync. They are just on diff pins.