Sony Wega model kv-32fs120. Color is all reds and blues, no greens or yellows. We have tried adjusting the hue as per the owner's manual and also the re-set but nothing changes.

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/

Only yellow color denotes the absence of Blue color. Check it. Check its video output card for any loose solder terminals at the blue color output section circuits.

since every display color monitors are only work with 3 primary color which are red, blue and yellow. You could also search it that by mixing these colors, you could get any color your want. Thats how color monitors work. Now in case of green color, it creates by mixing blue and yellow. When you are turning the screen adjustment screw, the red color plug will become lose, makes it appear green.
I hope your got the reason.

is it on aux video or in the tuner setting?

THERE ARE ADJUSTMENTS TO THE VIDEO DRIVE THAT CAN CORRECT THIS PROBLEM/THEY ARE IN THE SERVICE MENU. WITH THE POWER OFF, PRESS MENU-5-VOL+ POWER THE SET WILL COME ON IN THE SERVICE MODE. STEP THREW THE MENU ITEMS UNTIL YOU GET TO RED/GREEN/BLUE DRIVE THEN ADJ. TO BALANCE THE COLORS WHEN DONE PRESS MUTE TO STORE THEN POWER OFF ON THE FRONT OF THE SET OR IT WONT SAVE.

Know to solders?Resolder ur video board socket holes that connected to( CRT tv Tube).Resolders the Yoke cable red, green,yellow connected to the main board also.Should get colors back,if the colors IC on the video in not dead,and capacitors help the IC on the video board.

Nowadays CRT's do not have good quality shadow masks anymore. After heating up a little they can give a so called "blooming" effect giving a blue an yellow leaf effect large over the screen. Reason nonparallelity in deformation of the shadow mask.

is that a negative picture?if not try to degause your tv fix your color.buy using degauser device.

That generally means that the CRT is weak and is putting out low emmisions. This is confirmed by the fact that the color quality is not that great when you can see a picture IE: not enough red, green or blue. This is very common when these CRT's age.

Probable bad picture tube = replace set.....T.