Electrohome roll

[ncflagg]

I have a Mame cab with an ATI 2400 and soft-15khz. I can adjust the monitor just so but the screen always wants to roll. Controls/pots are very touchy. Tried 640x480 and lower resolutions. Does something on this Electrohome need repaired?

http://www.youtube.com/v/C3xzIDvG9pE

[Kevin Mullins]

I can adjust the monitor just so but the screen always wants to roll. Controls/pots are very touchy.

I'm assuming you tried adjusting both the Vertical Hold AND the Vertical Linearity pots. (?)
How do you have your sync input connected?

[ncflagg]

I think I just twisted the sync wires together.

[Ken Layton]

Is the sync connected properly?

http://homearcade.org/BBBB/sync.html

[ncflagg]

You may be right there. I will try splitting up the sync. (and makie sure I'm not missing a pot somewhere)

[DarkSide]

I'm not sure if this is usefull, but i had the same problems with a Kortek Chassis, when connected to the PC, the picture wouldn't stop rolling, and the controls was very touchy, the solution was connecting a 5kohm resistor between video ground and horizontal/vertical sync wires.

[ncflagg]

Splitting the H and V sync was the answer. Oddly, after getting the sync corrected the color was washed out. After a lot of elimination I finally discovered that TWO of the VGA connector pins had fallen out! Namely, the blue and green pins.

Now I remember why I quit working on this project several months ago.... 

Thanks, all.

I'll try to remember the resistor trick for next time.