Neg Vs Pos sync hell, Almost there, one hang up left!

[Pipercub]

I have a Nintendo Playchoice10 board and two standard CGA arcade monitors w/8liner chassis. I am having no luck in getting the monitors to display. The original NECs were killed in a lightning storm and are gone beyond repair, the PC10 board was not in the cabinet at the time. By my understanding the PC10 is a positive sync and the 8/liner is negative sync only. Ok, so I built a sync converter using a regular HEX inverter (proven circuit used for other pos to neg sync, Qix is one I think). No joy, hooked it up and no picture. The colors need to be inverted as well but that would just cause a funny display color, not prevent it from working. All I get is a green screen no change when I switch from not inverting to inverting the signal. I am at a loss for what to do. Here is the stange thing, the cabinet had the NEC monitors in it and was hooked up to a shinobi board when I got it. They displayed fine, are the NECs capable of both Neg and Pos sync? How could they work with a Neg sync board? The colors had been inverted using the invert/non invert selector on the NEC monitor (Note, this only inverts colors not sync). If the NECs are Neg sync only as everything I can find indicates how the hell was that working, this leads me to doubt the PC10 board's being pos sync and maybe it is neg? But how could that be because the thing should display fine without the inverter? IN short, this standard arcade monitor will not work with the PC10 board no matter what sync I feed it and I can't figure out why.

[Ken Layton]

The Nintendo Sanyo (20-EZ series) monitors used composite negative sync with the color signal being inverted. Some (but not all) Nintendo Sanyo monitors had an small inverter board mounted on top of the flyback cage. It was mainly used for conversions as all you needed to do was move the output cable from the non-invert to the invert connector to flip your signal. These inverter boards show up on ebay all the time and usually sell in the $20 range (used). Maybe you should install an inverter board to use with the 8liners chassis? The board operates on 12 to 16 volts DC.

Remember that the 8liners chassis only accepts composite negative sync. There are three color adjustment trimpots next to the video input connector that adjust the strength of the incoming color signal (they might be already turned all the way down). The original Nintendo Sanyo and Nintendo Sharp monitors ran on 100 volts AC but the 8liners chassis has a switching power supply built in and can operate perfectly with 100 volts or 120 volts as it adjusts itself quite nicely.

Also remember that Nintendo's wire colors in the wiring harness did not follow normal wiring color codes for video standards so double check the schematics. Just because the wire color is green doesn't necessarily mean that there's a green video signal on it. Here is the typical Nintendo wire signal/wire color/pin number for the video connector on the main monitor board:

Video Green / Brown wire / pin 1
Video Red    / Red wire     / pin 2
Video Blue   / Orange wire / pin 3
Video ground / Yellow wire / pin 4
Video ground / Green wire / pin 5
Video sync   / Blue wire    / pin 6

[Pipercub]

Ok, the sync pos/neg being right clears up allot. Thank you for your assistance. I will nix the converter. I do have the color inverter boards from the original monitors and I believe they function. I did have the color scheme correct for wiring using the PC10 service manual so that is out of the loop. The only display I got with the sync at negative and the colors wired correctly was a  green screen with no picture. I will go home and verify the color input and contrast etc. (monitor 101 I know) and see where I am. But even without the color inverter in the loop I should get a picture just with skewed colors right? When I switched from not inverted to inverted with the shinobi board and the stock monitors I did get a picture just color skewed, so it should work in reverese? I ask because I would like to at least get a picture with just the monitor and board before introducing an unknown.

But I am reasonable to think that a standard arcade monitor will work fine in this game as long as I invert the colors?

Thanks again!

[Pipercub]

Ok, connected the sync and colors straight up and no picture, color inverted or otherwise. Then Connected the Nintendo color inverter inline, powered it up and still nothing. The only thing I get is a green screen.

[Ken Layton]

Since you say the original monitors took a lightning strike, could your game power supply be bad? Have you checked all the power output voltages from the supply? Does the game coin-up? Does the game play blind?

[Pipercub]

OK, major progress with one last real issue.

I connected the audio to an amplified speaker set and powered it up (voltages long ago verified) and I did get in the blind sound. I neutralized all the pots for color control, bright, positions etc. and started from that baseline. After getting a faint heavily distorted picture I reversed the neckboard leads and finally got a rightside up and not backwards picture. Lets just say that there was not a single adjustment that was right. After about two hours of working at it I have a sharp, centered, and proper picutre with one exception...

 The green is totally smeared. This throws the picture off and makes some colors invisible at places so the game looks perfect in some places and terrible in others. I can best describe the smear as a ghosting to the right, as if one shined a flashlight on a wall at an angle. No adjustment change seems to impact this problem. I would swear it looks like a monitor that needs a cap kit, but just for green!

I appreciate all the help thus far, I am getting there. Just FYI the tube appears to be new and the 8liner is new. But just for GP, can the 8Liner chassis be used with the Nintendo tube?

[Ken Layton]

Yes there is a version of the 8liners chassis that works with the Nintendo tube. It the 10 pin neckboard and high impedance vertical yoke model.

As to your green problem have you turned the green input trimpot next to the video input connector on the main monitor board? It sets the color level going into the chassis. There should also be a green control (or two) on the neckboard itself.

Does your playchoice gameboard also have video output adjustment trimpots on it?

[Pipercub]

I can bring up the green level  using any combination of the board adjustment, the inverter has a level adjustment too, and the level adjustments on the chassis and neckboard too. Bringing the level up or down will make the green stronger or weaker but the smear distortion is unchanged, it gets brighter or dimmer but is the same. I will try to get a picture tonight at home.

[Ken Layton]

Try turning the "Screen" control on the flyback down a little bit.

[Pipercub]

The flyback had two adjustments, one set everall brightness and I adjusted it for a good level with the bright pot on the PCB centered. The other one controlled sharpness and I adjusted it to get a very sharp picture other than the green issue. I could turn it in either direction to blur the image as a whole but when it is centered between the two limits it is very clear. All of this had no effect at all on the green smear.

[Ken Layton]

It's possible your picture tube may have a short to the green gun.

If that's the case you'll need to connect the tube to a picture tube restorer/analyzer to find out for sure.

[Kremmit]

I'm new, so I may be talking out of my bunghole, but:

Could this be a convergance issue?  Mabye the green gun is just out of alignment?  

Good luck!

-Kremmit