Commodore 1080 Monitor: What do the "HDK" and "SCREEN" adjustment dials do?

[spaceman88]

Inside my monitor, I noticed two adjustment knobs labeled "SDK" and "Screen".  Does anybody know what they are for?  Thanks.

Is the "Screen" on the flyback transformer? If so it will basically adjust brightness, although if you go too high you will get retrace lines and your picture will look like crap. On most flybacks there is also a "focus" control. Now I haven't taken apart a 1080 in 15 years so your mileage may vary :-). Not sure about SDK.

[spaceman88]

After the picture tube ages, you can often improve your picture by adjusting the screen and focus controls.

[spaceman88]

In addition the the "screen" and "HDK" controls there are also a series of other adjustment knobs on the board such as "sub tint", "sub bright", "comp sub bright", etc.  Has anybody here ever had to adjust these knobs before.

These (like the Focus and screen) are factory set and are generally only adjusted to compensate for a fading picture tube. There should also be Red, Green and Blue controls (most often on the small CRT board). If you turn down the colour adjustment on the front so that you have a B&W picture (on some monitors you need to input a composite video signal not RGB), and your screen has a green or red or blue tint you adjust the other controls to get back to a grey image,