I have an old 20" sony CRT with which I'd like to "experiment" as it was only $424 in 1998 so even if it got messed up, it wouldn't be a huge deal.
Is it possible to have proper color using just the red, green, and blue filters, Avia1 and using these items in the service menu?

GAMP 18 0-31 Green Amp.
BAMP 14 0-31 Blue Amp.
GDRV 18 0-31 Green Driver
BDRV 14 0-31 Blue Driver
RCUT 15 Red Cutoff - (lower level)
GCUT 4 0-15 Green Cutoff - (lower level)
BCUT 1 0-15 Blue Cutoff - (lower level)
RDRV 21 Red Amp. - (upper level)
GDRV 18 Green Amp. - (upper level)
BDRV 14 Blue Amp. - (upper level)
R-YR 15 0-15 Sets the amount of RED
R-YB 15 0-15 Sets the amount of RED
G-YG 11 0-15 Sets the amount of GREEN
G-YB 9 0-15 Sets the amount of GREEN
AXIS 0 0-15 Cleans up the red & oranginess in yellow



Do you have to fiddle with all these setting or just a few to fix the colors?

You want to read this thread: http://www.avsforum.com/avs-vb/showthread.php?t=852536




(Short answer: no)

You could successfully set the Color Decoder (if it behaves) using these:
R-YR 15 0-15 Sets the amount of RED
R-YB 15 0-15 Sets the amount of RED
G-YG 11 0-15 Sets the amount of GREEN
G-YB 9 0-15 Sets the amount of GREEN
AXIS 0 0-15 Cleans up the red & oranginess in yellow

however, you're out of luck setting Grayscale w/o, at a minimum, an optical comparator of some type (see Cinemaquest for Alan's offerings) or an inexpensive probe and software suite. Since you are attempting to adjust a CRT, phosphor-based display, an inexpensive meter is likely targeting those phosphors with it's own filters and you'll probably have a real good result.
If your aspirations are to acquire a skillset to further yourself in the calibration world, careful selection of an analyzer is recommended.
However, mess around and have fun!

Good luck!

R-YR 15 0-15 Sets the amount of RED
R-YB 15 0-15 Sets the amount of RED
G-YG 11 0-15 Sets the amount of GREEN
G-YB 9 0-15 Sets the amount of GREENJust to be clear, RYR is a red gain control and RYB is a red tint control, primarily affecting the hue of magenta. GYG is a green gain control and GYB is a green tint control primarily affecting the hue of yellow. You can use the red and green filters with both along with the proper test patterns. However, direct measurement is always better.