WG k7000 Vertical rolling

8-Bit

Member
Joined
Sep 25, 2008
Messages
189
Reaction score
2
Location
WOOSTER, Ohio
Problem has been resolved: Faulty V-Sync wire

I have a WG k7191 25'' monitor that I'm using for MAME (vga card with using Soft-15KHz). Everything is fine the exception that there is a vertical rolling problem happening which I'm having trouble with. I've done a cap job and replaced the vertical hold pot (it was cracked).

The Vertical Hold pot is HYPER sensitive. If I get the image so that it's stable after a couple minutes of very very slight adjustments, it seems dramatic change in the picture (opening a menu for example) will cause it start rolling again. Once it starts rolling it is consistent and changing back to an image where it used to be stable (closing that menu for example) doesn't not affect the roll.

The monitor IS grounded. Any help would be appreciated.
 
Last edited:
I replaced the pot with one with the same value I pulled off (200 K). The only difference the new pot made is that before the adjust would hit spots where it would become wildly erratic, now it's smooth all the time. The sensitivity or roll have not been affected.
 
Is the sync hooked up correctly? Does the video card put out a strong enough sync signal?

Most people use the "ArcadeVGA" card since it amplifies the signal for arcade monitors.
 
I have it wired up on the -sync pins (far right in the attached diagram). I could try switching them to the +sync ones instead. Also, how would I test for amplitude of the sync signal? What is an acceptable rating?
 

Attachments

  • Pins.JPG
    Pins.JPG
    25.8 KB · Views: 58
Problem has been resolved. V sync wire was damaged.
Continuity tested fine when unhooked, but when I tested it with it hooked up to the monitor pins it wasn't consistent just because of the way it would bend.

Replacing the Vertical Sync wire resolved the problem.
 
Back
Top Bottom