Screen Roll problem

MrHiu2

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Recently, my Rootbeer Tapper machine's monitor has had some issues. The screen rolls, which is making in unplayable at this point. I have tried using both the vertical and horizontal knobs, but with limited success. Sometimes after adjusting the monitor, the game plays fine for about 40 minutes or so. Then it starts to roll again.



Any suggestions on what else could be wrong?
 
Either a cold solder joint on the sync input header on the monitor chassis, or the monitor needs caps, or possibly even a bad hold pot in the monitor. What kind of monitor is this?

-Ian
 
Would it help if I tried to get some video footage of the problem?

Probably not. What would help the most is if we knew what monitor is in the game. If you don't know, then a picture of the chassis will do.

Also, look and see how the syncs are connected to the monitor. I assume that it used to work fine, and has gotten worse suddenly, or has the monitor ever worked in that game?

-Ian
 
Good ol' G07 :) Best monitor ever.

How is the video/sync connected? There are two connectors - a six pin connector and a three pin connector. For negative sync applications, both plugs are used. Try wiggling the sync connector (three pin one) and see if anything changes. These monitors are notorious for developing cold solder joints at the video input header and sync header. Pull the chassis out and look at the bottom of the board under the headers, and check for cracked solder joints.

Also, touchy sync can be an indication of failing capacitors - has this monitor ever been recapped?

-Ian
 
As for that last question, I have no idea whether or not It has ever been recapped. I will see if I can recap it, and I will get wiggling the sync connector.


I will see what I can do. Thank you for the help
 
Go ahead and recap/refly the chassis and touch up the solder on all the header pins and your problem should go away.

Well, yeah - that'll definitely fix it... But I'd start by checking solder joints, it might be something that simple. I've seen plenty of unrebuilt G07's that still hold up fine. Sure, a full rebuild is the best course of action for longevity, but it might be excessive...

-Ian
 
Don't forget to check to be sure these resistors are the correct value. Some chassis were sent out with 4.7 k resistors (incorrect value) installed in the sync circuits.

R314 390 ohm 1/4 watt

R317 390 ohm 1/4 watt

R303 390 ohm 1/4 watt

R306 390 ohm 1/4 watt

I have no idea why these things stayed in sync with the wrong resistors over all of these years but once one starts rolling, I head straight to these guys. they are located on the opposite corner of the board as the flyback...
 
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