K4900 problems, not solved by cap kit.

bsdpinball

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Me and my frien are working on this monitor, I just did a cap kit for him and still have the same problem as I did before. I have lines that go horizontally through the monitor and also diagonal lines. It is kind of hard to explain, and even harder to get on video. I tried anyway.

http://www.youtube.com/watch?v=8XQ4mHfYQY4

at first I thought these may be re-trace lines but do not seem to match what I saw pics of on the net of retrace lines. Can anyone suggest where to look ?
 
Attach a ground wire from your frame to a cabinet ground strap and see if that helps.

Make sure you don't have a refrigerator, neon light, electric fan, etc plugged in nearby...
 
Grounding did not help, trying horzontal frequency pot. That is the horizontal hold pot ? If its not scrolling wouldnt that mean that pot is adjusted fine ?
 
Grounding did not help, trying horzontal frequency pot. That is the horizontal hold pot ? If its not scrolling wouldnt that mean that pot is adjusted fine ?

You sure the frame wasn't already grounded in the first place? I had a similar looking issue with a K7000 in a Victory Road, and it was the ground wire from the monitor frame that was causing it. Bob Roberts gave me the idea to disconnect it, and it fixed the problem completely. Here is a quote from his reply when I asked him about it (which contains some other suggestions you might try as well):

Bob Roberts said:
I would have thought it to be too high of a screen voltage or black level,
but you seem to have ruled that out, so I will go with my second guess of PS
interference. If you have an earth ground wire to your monitor frame
disconnect it to see if that cures your problem. If you do not have an earth
ground to your monitor already, then add one to see if that cures it.

No results... try adding or subtracting earth ground to your PS.... if a
switcher, use the FG terminal.

A final step if unresolved would be to try another PS.
 
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ok i was told to throw a jumper in between 31 and 601 and the monitor got worse. this is what we have now.

 
Based on your original post looks like there are multiple grounds (instead of just ONE ground) causing a ground loop.

You could try a different isolation transformer. Another thing to check is the main power supply (may need to be recapped as well).
 
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I believe he did. I did his cap kit and the problem was still there. And so far nothing has had any effect on it except turning down the birghtness so it is less visible
 
I believe he did. I did his cap kit and the problem was still there. And so far nothing has had any effect on it except turning down the birghtness so it is less visible

If that is the case, then something got toasted on the monitor. I would need a circuit diagram for this monitor to help further.

For future reference - never jumper anything out unless you really know what you are doing - and that then that is ONLY really used for troubleshooting.

The original problem is a ground loop issue and you are getting 60 hertz hum in the picture - now if this means a bad capacitor or something 'shorted' providing an extra ground path creating a ground loop hard to say at this moment in time. Usually it is one of the filtering capacitors (possibly a fault with the isolation transformer). But now you will have to fix the problem with the collapsed screen. :(
 
The manual states to jumper these two test points to adjust the horizontal frequency. I was not there when he did it so cant say for sure what happened.
 
here is the problem. i have another monitor that i tried swapping in and i am getting relatively the same issues. now keep in mind this a grruss cab that has the board hacked for power and ground due to the konami harness being cut(as i was told is comon on these older pieces).
 
here is the problem. i have another monitor that i tried swapping in and i am getting relatively the same issues. now keep in mind this a grruss cab that has the board hacked for power and ground due to the konami harness being cut(as i was told is comon on these older pieces).

This is saying the problem is not with the monitor.

Ok assuming you are now back to the original problem: first thing I will say - this is NOT an adjustment, turning knobs will not make this problem go away - it is interference. This has nothing to do with the horizontal (or vertical) sweep circuits - you are getting a 60 hertz hum which is 99.9999% of the time caused by a ground loop - meaning there is an extra ground wire where it shouldn't be or (most likely) a bad filtering cap.

As I mentioned try another isolation transformer, if the problem is still there you will have to look at replacing the filter caps on the power supply or possibly the main board that generates the video. A really simple fix is to plug the entire game unit into an isolation transformer...but most people don't have those laying around home unless you use to fix tv's. ;)

One thing I can tell you with the 'other' monitor is that something happened in the vertical drive circuit when the picture collasped as shown in the pictured posted. ;)
 
so is it save to say the monitor which had the jumper put in is screwed(chasssis needs work now) i am going to see if i could get another konami board and see if the issue still exist with a different game board. like i mentioned the konami harness is cut and boards are solder directly to spots on the board.
 
Probably. I can fix it for $50 + parts + shipping. If I get it and it works, then you only have to pay return shipping, and you'll know it's a game issue...
 
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