Educate me please?

theyangman

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So I've long been in the dark about monitors and I want to learn exactly what each of the pots are for.

I'm not talking about the pots on the remote board, those are labeled pretty plain and easy to understand but rather the pots on the neckboard.

Red Bias, Green Bias, Red drive, Green Drive and Blue Drive. I also do not see a blue bias anywhere on my monitor chassis, is that normal? The monitor in this instance is in my NFL Blitz cab.

What do these mean and what exactly will each pot do?

Sorry if this is basic for some but I just want some clarification?
 
Since no one has chimed in yet, I'll see if I can help you out. To start off, I am far from a monitor expert, but the best thing to do to get a good understanding is to check out the stickies in the monitor tech help section. Lots of good stuff from RetroHacker, KenLayton, Cadillacman and others.

Check out Buffet's YouTube channel for a lot of good tech info on monitors:

https://www.youtube.com/user/buffett1978

By the time you go through the stickies in the monitor section and watch a bunch of Buffet's (and other users' channels), all your questions about monitors will be answered. For the most part anyway.... :)
 
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The drive pots adjust the amount of gain applied to the voltage sent to the gun for that color, inside the tube. Since more voltage means more electrons shooting out of that gun, the practical effect is that they control the brightness of an individual color. When adjusted too low, the color will be absent or dim, and when too high, the color will smear off the right edge of wherever it's drawn.

Cutoff pots are somewhat harder to explain. They determine the lower threshold of the voltage applied to the gun. When the cutoff is too low, the gun turns on when it shouldn't, producing a "wash" effect -- blacks will have a tint of color to them.

You need all these to produce correct white balance. White is produced by mixing all three colors together, so if one is driven more strongly relative to the other two, you get a tint instead of pure white. Cutoff is used to balance the black/dark gray tones; again, if one is maladjusted, your dark tones will have a tint instead of being pure gray/black.

Older monitors didn't have all six pots, presumably as a cost saving measure. Whatever control is missing is set to a fixed value, and you have to adjust the others around it and/or compensate with the overall brightness / contrast controls.

The manual for your monitor should have a procedure for adjusting these controls. It's probably worth reading, just to understand, even if you don't go through the whole thing.
 
So the red looks good so does the blue. The green is really dark, regardless of the photo showing it nice and bright. And the white screen isn't as bad as it shows, it just has a slight purple tint.
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assuming the green gun in the tube is healthy, added Green Drive should improve the vibrance of the green. I'm going to guess the green gun is in the very least dirty, as that's what blocks the emissions and makes it look muddy.

the red is too strong, you can see it smearing into the blue and the overall red tint visible in the white. this is where you would turn the red cutoff down just enough to make the smear go away. it's hard to capture the levels in a picture like this, but you will probably find that the weak green may affect overall white balance (you'll have a more purple tint then). you can try dialing it up until before it smears and see where that gets you.

you'll probably wind up needing to rejuvenate the tube.
 
assuming the green gun in the tube is healthy, added Green Drive should improve the vibrance of the green. I'm going to guess the green gun is in the very least dirty, as that's what blocks the emissions and makes it look muddy.

the red is too strong, you can see it smearing into the blue and the overall red tint visible in the white. this is where you would turn the red cutoff down just enough to make the smear go away. it's hard to capture the levels in a picture like this, but you will probably find that the weak green may affect overall white balance (you'll have a more purple tint then). you can try dialing it up until before it smears and see where that gets you.

you'll probably wind up needing to rejuvenate the tube.

So when the green gun is dirty the rejuvenator will burn off the crap and could make it good again (at least for a little while right?) I hear stories that this method can also potentially kill your monitor too?

I've tried turning up the green drive but the green doesn't really change. It stays that emerald / forest green sort of color.

I can try turning down the red to remove the smear, but in your educated experience, is the green gun on his way out?
 
So when the green gun is dirty the rejuvenator will burn off the crap and could make it good again (at least for a little while right?) I hear stories that this method can also potentially kill your monitor too?

I've tried turning up the green drive but the green doesn't really change. It stays that emerald / forest green sort of color.

I can try turning down the red to remove the smear, but in your educated experience, is the green gun on his way out?

when you rejuv a monitor you want to only use the lowest setting needed and only do the guns that truly need it and that way you rarely ever have a problem nor kill the monitor. what tester do you have?
 
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