Playchoice 10 - monitor color issues (no green)

87 t-66

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The top monitor on my PC10 is missing the green colors. I have adjusted the green gain switch on board behind the monitor. Is there anything else I can try? Here are a few pictures of my monitor. Thanks

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swap the video wires from the bottom monitor to the top monitor and see if you still do not have green then it is something on the monitor.

but if you do have green then the you have a board or wiring problem.

if your monitors have not have had a cap kit and re-flow done to them now is a good as any time to get it done.

that is where i would start.

just so you are aware of what monitors you have they are the less common sharp XM-1801N monitors.

Peace
Buffett
 
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I swapped the wires and there is still no green. I was told by the previous owner that they were re-capped but can not verify for sure. It's not a big enough deal to tear it all apart but if it is something fairly easy I would like to fix it.
 
check the neck transistors for cold/broken solder joints.

measure all three of them they should all read about the same.

you can swap say the red and green transistors to see if the problem follows.

if it does the transistor is most likely the problem.

check for broken pads and traces and ohm out all wires that are associated in the green circuit.

Peace
Buffett
 
Sorry for my noob-ness...are you taking about the transistors that are soldered on the small board that sits right behind the monitor tube or something else? How should I measure them? Just the resistance between the 3 pins?
 
Buffett is referring to the neck board, the small board that plugs into the tube. On the neck board there are 3 transistors. Each transistor handles a different color. You can map out which transistor handles each color by finding the adjustment knob for a color, and following the traces on the back side of the neckboard until you find which adjustment pot connects to which transistor. Once you've zeroed in on which transistor handles green, inspect the area. Look for cold/broken solder joints. If you're unsure of what you're looking for, try this pic for reference:

fboxcrackjoint1.jpg


Those are broken/cold solder joints.

If everything looks OK, you can try desoldering the green drive transistor and swapping it with one of the other color transistors. If swapping the transistor with another color makes the other color go away and green comes back, than you can be assured that you have a problem with that particular transistor.
 
thanks. it will probably be a little while before i take that board apart as it doesnt affect game play at all. i am confident in my soldering/desoldering skills but want to play the game a little more before i tear it apart (i just got it last week).
 
i am going to go ahead and order new flybacks and cap kits for both monitors. is it a good idea to replace the transistors on the board too? is there a list of them somewhere so i dont have to tear it apart before i can order them? i would like to have all of the pieces on hand before i start taking it apart.
 
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