Monitor adjustment time

Posted by magnus.jansson on June 14, 2023

So I got the game up and running and the sound was fixed so I'ts working fine now and plays well. Actually much easier than the red ROM version (my boards are 1:st gen and houses the green ROM version of the game.

The next thing I noticed was that the image was a bit rotated, the height and width is off, out of focus, the colors were hidous and it was pulsating. I need to fix the monitor.

Here is one of the test patterns from the board. As you can see the image is rotated and that the height and width is off

But since this is an old monitor and it does not seem to be renovated at all so I first need to clean it and do a recap.

The next thing to do after cleanup and recapping, was to adjust the b+ voltage that was way to low. The b+ voltage on my Electrohome G07 should be 120V but was as low as 114V.

Next step is to adjust the rotation and puriness so I rotated the yoke a bit to make the image parallell to the screen. I also changed the focus a little bit, while at it.

I adjusted the height a bit but I dont have any tool to adjust the width. Dont use a metallic object to adjust the widht since the width coil is sensitive.

When checking the colors I was surprised that they were so off. I tried to degauss the screen but that did not help much. A little bit better but not much

Here is the colors before degaussing:

Red screen:

Green screen:

Blue screen:

As you can see the colors are bright and strong.. but not very uniform at all. What to do?

I was thinking that this seems like a purity issue and how well the colors line up on eachother.

That will also explain why it feels like the screen is pulsating when the screen switches between the different colors on the title board but not during gameplay.

What I did next was to adjust the purity rings. I started with the puriness on a red screen, and adjusted the first ring on the yoke. After that I turned on both blue and red color from my test image generator and adjusted the blue colour, and finally the green.

The screen turned up pretty good and now it is time to play the heck out of this game.