WG 19K7302 horizontal and vertical scrolling

JuanUp

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Scrolls horizontally and vertically without locking in either position. It doesn't normally snap into position then move off. It just rolls. Really weird. Any help would be great.

Thanks,
Juan
 
Last edited:
Thanks, Bill. Yes, it did work before I popped it in.

I pulled the CRT and board from the chassis and put it in the original Williams Robotron monitor chassis since they are mounted on the bottom rather than the front. I guess I broke it in the process.

Ken Layton troubleshooting guide suggests that it might be one of these:

Q402 Horiz output (2SC4769 or NTE 2353), Q405 (2SD2058 or NTE 377), I301 Horiz/vert/sync IC (LA7851 or NTE 7062), and I302 Vertical output IC (LA7833 or NTE 1773)

By the way, this information is located here:

http://home.comcast.net/~mtpacifico/_kenskorner/kenskorner.html

Gonna' probe around and compare it to another good one.

Juan
 
Progress! Turns out 4A on the CPU board was dead. We now have vertical sync... but still no H sync. :(

~62uS +H pulse
~16mS +V pulse

Juan
 
Last edited:
I'm pretty sure that monitor has a positive/negative sync button. Did you try pushing it?

Edward
 
Thanks. Yes. There's no difference in picture in either setting. The horizontal refuses to lock and drifts in either direction. The slightest adjustment on the horizontal osc pot will skew the image and roll very fast.

Thanks, Alpha-tron. :)

Juan
 
Last edited:
Have you tried the monitor with another game?.....or Robotron with another monitor?

Edward
 
Yes. It does the same thing.

Gonna' run through this list of things to check when I get a chance:

+H/S line at R334 - make sure signal is clean
Q402 - Ken Layton troubleshooting guide
Q405 - Ken Layton troubleshooting guide
Q305 - HORIZONTAL TEARING from WG troublshooting manual
C333 - HORIZONTAL TEARING from WG troublshooting manual
C380 - HORIZONTAL TEARING from WG troublshooting manual
C382 - HORIZONTAL TEARING from WG troublshooting manual
C383 - HORIZONTAL TEARING from WG troublshooting manual
C332 - HORIZONTAL TEARING from WG troublshooting manual
D402 - NO HORIZONTAL SCAN from WG troublshooting manual
D403 - NO HORIZONTAL SCAN from WG troublshooting manual
I301 - Ken Layton troubleshooting guide
I302 - Ken Layton troubleshooting guide

Thanks,
Juan
 
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