narc too much green WG k7000, possible short

retrogamez

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Fixed!!! - narc too much green WG k7000, possible short

I think I have a short in my green gun. The game has a green tint to everything. When pulling up the diagnostic screen and testing each indiviual color I get all three colors except they are off. At first I thought it might be a bad pot but putting a multimeter on the resister next to each pot. I get the same resistance betwee all three colors. And all three change equally when adjusting the pot positions. So I decided to start from scratch and unplugged the signal cable and adjust my screen, brightness and contrast. Well instead of getting white, then grey, then black when turning the screen all the way up and then backing it down. I get Bright green, dark green, then black. This is with all drives set in the middle and all cut offs turned all the way down. If I try to turn up the red and blue cut offs to try to turn the screen grey, I get no change just alot of green. So does my speculation sound correct? Like I said all colors work and are adjustable. If i turn up red and blue real high the picture looks almost correct except for the horrible bleed over. Any input is appricaiated. Hopefully I'll be puchasing a rejuvanator and cap kit soon. Unless someone local in the dfw area would like to try rejuvanating this tube for me.
 

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does it have the green tint to it with out a video signal.
if it does it is most likely your tube.

also test all 3 of the neck board transistors to see if the green is shorted.

Peace
Buffett
 
back when I first got into fixing monitors, I had a K7500 that had a constant red tint. I was encourage by my jedi master that the effective and easy way to diagnose this is to switch the transistor that's suspect (in your case, the green) with another that is seemingly fine. if your problem carries and your tube turns red or blue, then it's not the tube that's bad, it's the transistor you pulled out of the green.

if your tube is still heavily green, then yeah, you have a shorted green gun.

typically on WG monitors the transistors go in the same order as the adjustment pots. I can't really remember if a K7000 goes blue to red or red to blue, so I'm sure you can figure that out. at any rate, the green one will be in the middle anyway, so disregard what I just said anyway. :) (but remember it for future reference)
 
Thanks guys. I didn't think about I can probably test the tube with a multimeter to check for a short. Also I was thinking that since I had all my colors that it couldn't be the transistors. But I guess they are just a switch and could get stuck in the open position as well as the dead. To answer the question about the green tint with no signal. The pic below is with no signal cable plugged in. Solid green screen instead of white. After reading all the problems with this monitor I'm tempted to do a full over haul and replace all caps and transistors. What's funny is I used to play the crap out of this game on Nintendo and never know it was adult oriented on the actuall arcade. You can imagine my suprise when I got to the level with the hookers and adult book stores.
 
test the neck transistors or swap the green to red and see if it changes to all red as suggested.

a cap and flyback is highly recommended on this chassis.

but don't just replace a good working part just because only replace the bad ones.


Peace
Buffett
 
Hey I just wanted to post that I fixed my issues and let other people know what the issue was. So my screen was tinted green really bad as seen in the pics about. When I check the color test I had all my colors but they were shaded green. So I had a darker red, a bright green, and a dark blue. So this told me that my colors were all working I just had too much green. Normally you would just turn down the color. Well my cut offs were turned all the way down and if I turned my green all the way down. It made no difference. So I unplugged the video cable. From my understanding with no video plugged in and all cut off pots turned all the way down you should get a white screen. Mine was green as seen in my first pic. So naturally you should turn up the red and blue until the color turned white. This is of course with the screen turned up on the flyback. Well When I adjusted my red or blue, they did nothing. So I assumed my pots were probably bad. I pulled out the multimeter and tested the resistance on them and All of the show the same ohms when set to the same point. So now I belived I had a short. I know everyone says the transistors go out often on this board and can give you too much of one color. But from my understanding thats becuase another color is not working that has a bad transistor. So I assumed I had a short and decided that before I started desoldering and resoldering components that I purchase a rejuvenator and do a test for a short. Ordered one from ebay that didn't have much of a description and had only two adapters with it. Not knowing what they were I assumed I would have to make my own cr-23 adpater. To my suprise when I opened the box today one was a cr-23 and the other was a universal pinout with indivigual pins. I hooked it up and set my heater and g1. Then go to set cut off and I get nothing. Switched to high and still nothing. Went to test and got the short light. Cleared that and then did another test and it showed all my tube were bad. So I decided to do a rejuvenate. After that all tubes stilll shoed bad. I disconnected and plugged backup to the monitor and lord behold I have more normal looking colors. It still was not perfect though, too much green. Did a clean and balance on it again. Still showed bad on all three guages, but when I plugged it back in I had a solid white screen with no video cable plugged it. Plugged the video back in and there are all my colors. Had to spend about 1.5 hrs adjusting the pots to get the colors to look right. So all in all I'm very happy to have a working narc now and the cost of the rejuvenator paid for its self. I still need to do a cap kit though. I get horizontal and vertical lines on the screen when the brightness is turned up. Pics posted below are of right after fixing the colors but before the adjusting and fine tuning. I also want to say thank you to everyone on here. I've never seen a community where everyone is so helpful and there are no mean hateful comments. I just got into arcades right after christmas and thanks to everyone's posts. I have learned so much in a very small amount of time.
 

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looking good:)

keep up the good work and soon you will turn into pro:)

there is allot of info on this forum and it will take a good wile to absorb it all.

Peace
Buffett
 
often times a monitor will have what's called a "base color", which is the single color the monitor will show if you turn every bias pot down. the K7000 I think is actually green, which I discovered when dicking with my MK2's K7000 (needed serious white balancing, convergence, etc.)

there's another method you can use to try and clear up a stuck gun, over time metal can flake off inside the guns and will get stuck on the cathode, which will of course short it. if you pull the monitor out, grab like a cushy blanket, and set the monitor screen down on there and gently tap the glass neck with a screwdriver you might be able to dislodge the metal fragment(s) and when you put the monitor back in and run it, the heaters should blast it away and you might be good.

helpful for anyone that doesn't have a rejuvenator. I know of another method that sounds downright scary and I will probably never attempt it lol.

if you grab the K7000 manual off Wells-Gardner's site I think it has white balancing instructions in it. it's a pretty involved process that requires messing with both the drive/bias pots and the contrast. then when you're all done, turn your brightness down far enough that you seen no pixels in a black background, set your focus, and you're all set.

also verify you don't have an old white knob flyback. if you do, start tracking down a replacement.
 
frickin awesome. For a tube that tests weak, looks good now.

You had nothing to lose by trying, and good for you, it worked.

I dont make it a habit of zapping every tube i have with my rejuve, but when i have an issue like this, what the heck, nothing to lose.
 
Mecha thanks go the input. I'll have to try the white balance tonight. As for the fly back. It looks new and no white knobs. I'm guessing it was replaced recently. Also I should mention that the unit had no light in behind te marquee. But what it did have was two 110 electrical bare wires hanging down and touching the screen and shield. I was glad I looked it over and cleaned out the dirt before hooking it up. That could of been a disaster. As for my rejuvenator I have a feeling it needs to be rebuild because I didn't get any reading when setting the cutoff knobs. So I turned them all up just a little bit and hoped for the best. So far I'm 3 for 3 on buying a broken arcade and fixing it. To bad I've had no sleep for the last month. Lol
 
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