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Main => Monitor/Video Forum => Topic started by: Coadey on February 03, 2009, 10:46:38 am

Title: K7400 + JAMMA Games = Video Distortion(?)
Post by: Coadey on February 03, 2009, 10:46:38 am

Hi all,

I just purchased a new Wells Gardner K7400 (analog cga) arcade monitor for my JAMMA cabinet. This monitor works perfectly with a J-PAC+ArcadeVGA.

However on actual JAMMA games (Samurai Showdown, Smash TV, Time Killers, etc) I get wavy/diagonal lines running vertically through the screen that are similar from one board to another.  There is also a white horizontal line in the lower left, substantial curl at the top, and on the Smash TV board, the screen is very dark when centered and becomes more visible when H-POS moves it off-center (second video):

[youtube]http://www.youtube.com/watch?v=rFRs8gVmwi8[/youtube]

The Smash TV issue can be seen at:

http://www.whidbey.com/foxes/k7400.avi (http://www.whidbey.com/foxes/k7400.avi)

I've tried adjusting the v-hold/h-hold, eliminating cable interference, switching the composite sync to one of the two "+- H-SYNC/COMP" pins on the monitor, and trying a H/V sync split-pin from the JAMMA to both H-SYNC and V-SYNC, per some of the information at:

http://arcadecontrols.com/BBBB/sync.html (http://arcadecontrols.com/BBBB/sync.html)

(The K7400 accepts either H/V or a single Composite sync on H.  Both H/V pins are +-).

The picture doesn't roll, and otherwise seems stable and color accurate.  Any idea what might be causing this on game boards and not a J-PAC?   Could all of these boards have bad video (it's my first time testing them) or could the power supply be causing an issue (I tried powering it on while the J-PAC was connected and it didn't seem to change anything).  The monitor and power supply are both grounded to a common AC on an EMI-filtered surge protector, there is no isolation transformer, and this monitor auto-degausses on powerup.

Thanks!