Apple Macintosh Performa 577 - Manual (Page 157)

Adjustments Yoke - 36
±
Warning:
Because you
must make yoke adjustments
from the rear of the
computer, use a mirror to
view the computer screen.
Do not reach around the
computer to adjust collars
and rings.
Note:
If you replace the
CRT, you will probably need
to adjust the yoke.
1 Using an insulated
Philips screwdriver,
loosen the yoke clamp
screw two or three
turns.
Yoke Clamp
Screw