Colors drop out, and then come back... any ideas?

[Frankiebonez]

I just purchased my first arcade machine.  Its an Ultimate Mortal Kombat 3 machine converted from a Golden Tee golf game, with a 33" monitor.  I believe the monitor is the original from the Golden Tee game, albeit I dont know the brand (if anyone can point me to a picture of the chassis board I'm sure I could identify it).

I was adjusting the size of the picture on the screen, and had touched most of the knobs being h-pos, v-pos, v-hold, h-hold, v-size, and h-size.  At this time I had not touched the contrast or brightness.  The problem is that after a few minutes, a color will drop out.  First time the greens dropped out, then they would come back, and drop out again, etc.  Its not isolated to one color though, the blue dropped out a few times, then came back.  As of right now the green has dropped out again.  I havent really touched any of the cut off or drive pots, I dont think thats a problem at all.  It will sometimes come back too if I turn the machine off and then back on, but not always.  I'm wondering if I damaged something when playing with the screen size .  The monitor has a relatively new cap kit, 3 months old I was told from the person I purchased it from.

Any ideas as to what it could be?  I have tried adjusting the picture size back to how it was originally, and have turned down the contrast and brightness incase that was causing an issue for some reason, but it doesnt seem to have helped. 

Thanks tons guys!  You'll be seeing more from me now that I have finally ventured into the arcade hobby

[modessitt]

Could be a lot of things... but assuming that there is a fairly new cap kit on the chassis.....

Have you seen this work perfectly after the conversion?  GT's sometimes came with Medium Resolution monitors and had a dip switch setting on the CPU to choose between Med-Res or Standard-Res, depending on what monitor was installed.  UMK3 only uses Standard-Res.  Standard-Res signals will not display properly on a Med-Res monitor, and vice-versa.  Since I haven't seen a GT in person that uses a 33" monitor (usually has a 27"), I'm not sure the monitor is original.  Read the 1st sticky on this thread.  The second message has links to monitor ID pages with pictures for you to identify the monitor type.   If it's a D9200 or similar, you probably need to go into the factory menu and reset the memory.

If it looked fine at some point, I would then check the video input connector to the monitor.  This is where your Red, Green, & Blue signals come from your CPU.  Try gently tugging on the wires while it's connected to see if your colors pop in and out.  This would mean there probably is a loose or dirty pin causing intermittent contact.  Your cable from your remote board could be causing this cable to move when you're moving the remote board with your hands (if it's not tied down anymore).

I would also check to make sure the connector on your MK board is also making good contact.  It's common in converted cabintes to have some continuity problems, especially right after moving a game from one location to another.

You might also check to see if your neck board is seated firmly as a faulty connection there can cause some of the guns not to fire.

If the picture was fine until you started messing with the remote monitor control board, check to make sure that the cable to that board is seated firmly in your little board, as well as your chassis.  Sometimes a loose connection here will cause screen issues.

Being that it's a converted cab, check to make sure that the video input signal wires aren't too close to the flyback or yoke, as in rare cases there can be magnetic interference with the signal, causing strange problems.

Some of this info is probably not going to help.  Also, it may be a problem not listed here.  Try what you can and let us know what you find out.

[Frankiebonez]

Sorry I should have been a bit more specific, that the game was a custom cabinet and originally was a golden tee game.    Its not a dedicated factory built golden tee cabinet.

The monitor isnt a WG, I'm sure.  The neck board isnt the same as I have seen on any WG monitor.  The neck board is definetly seated well, I have taken that off and put it back on recently when checking the pots on the neck board. 

The remote board is in the back of the machine hanging up.  It hasnt moved much at all, and all the connections at the chassis should be ok.  I'm EXTREMELY concerned with getting shocked when I play with the connections, is there anything to worry about with the R/G/B signal cables?  Also, the remote control board... any risk with getting shocked badly there? 

I havent even touched the actual MK board.  I dont think that is the problem.

AN INTERESTING NOTE:  I was just downstairs and my father had gotten his friend to lend him his de-gauser (sp).  I had de-gaused the screen, which actually helped with a tiny bit of color bleeding on the bottom of the screen.  After this, the green color still wasnt visible.  I then went into the back of the cabinet and turned up the contrast and the green color came on.  At this point I adjusted the contrast and brightness accordingly.  Lowered the brightness a tad and kept the contrast at basically the same setting as when the color came on.   Does this help at all with what might be possibly going on?  I'm thinking its something loose possibly on the little board for the color adjustments, or maybe the adjustment itself if that is possible.

[Frankiebonez]

I think I found the model number, not 100% sure cant find anything related on google or anything:

Sharp Image Electronics
Model: SI-233

[modessitt]

Try using the monitor ID sites to find out the exact type of monitor you have first.  This is very important info we need to accurately help you.

Fear of electrocution is a good fear to have when working with monitors.  You need not fear a shock from the remote board unless it's still tied to the monitor bracket, then be careful not to touch anything BUT the remote.

You should be able to find the RGB wiring coming up to the chassis.  You can gently tug on these without fear as long as you grab them several inches away from the chassis, usually well away from the monitor where they hang down.

If you're going to try to reseat any connector (including the neck board) on the chassis, you should turn your game off and discharge your monitor first, even on "self-discharging" monitors.  You can never be too safe.  There is info elsewhere on this forum on how to properly discharge a monitor.  Try a search.

If your colors are staying good with the contrast up, then that could definately be your problem, although it usually affects all colors at once.  If they're working now, you can try just letting them run that way and hope that was it.

[Frankiebonez]

IS the only method for discharging monitors, the screw driver and wire with aligator clips?  Or is there something I could buy that is relatively cheap and effective?  The method I have seen with the screw driver just seems a little iffy hehe. 

[SirPeale]

The method I have seen with the screw driver just seems a little iffy hehe. 

It's a fine method.  If you don't have gator clips you could take two screwdrivers.  Slip one under the cap, and take the other and cross the shaft, touching the frame.

[grantspain]

two screwdrivers is the method i use even when i'm 15ft up on a ladder changing an overhead scorer

[Frankiebonez]

Alright well here is something interesting I have found that is working, at least so far.

I keep the contrast a bit high seems to keep the colors in check, but when one color drops out, I go to the diagnostic menus.  I pick the option to see a full screen color, and find the color that is not available (in my case, green).  The screen appears black, I turn up the contrast really high and the color green pops on.  I then turn it back down and it stays, at least for a little while.

I also noticed that each time the color has gone out, it is when there is a bright white flash of light on the screen.  Does that tell you anything?

And the monitor has to be a Sharp monitor.  I cant find any specs for it on any of the websites to help determine the chassis.  Nor on Sharp's website.  Model is SI-233.  I dont see any other markings on the chassis in the cabinet, so I'm gonna have to say thats the one.

[Frankiebonez]

ALRIGHT!  I made some more progress... I found the monitor chassis.

This is the one I own. Model 33" SHARP 15K KTM-F33:


So with this information, can anyone give me any more ideas?  Thankfully this website sells the monitor chassis for relatively cheap, I guess I could just buy a new setup if need be... but we dont wanna do that!  LETS FIX IT! 

[modessitt]

Getting little flashes of light right before your color drops out.....

Sounds like you need to have your guns cleaned and balanced, or rejuvenated.  If you don't have a rejuvenator/cleaner, you could always buy one, or try to find someone near you who has one and is willing to help you out.  There is probably an internal short that needs to be removed before the failures go away.

[Frankiebonez]

By balanced, can that be done with the potentiometers on the neck board?  Or is that something that needs to be done with the rejuvenator?  Where can I get a rejuvinator?  There is a local TV repair shop near my home, I place like that would have those tools and be able to perform this service I woudl think right? 

Thanks tons Modessitt.  If your in NY ever I'll buy ya a cold one! 

[modessitt]

Don't thank me yet.  Might not fix it.     But the cold one sounds great! 

Yes, the rejuvenator does the clean?balance also.

Dunno if a local TV shop would have one or not, depends on if they specialize in new TV's or not.  Best advice would be to call them, or a local arcade repair guy to see if they got one.  Cheaper if you pull the monitor and take it to them to be done then to have them come out.

At least you'll have a rejuv'd tube.  A lot of colors brighten up considerably after this has been done, especially on older tubes.

Good luck!