Sharp 37VT-26H Service Manual page 12

37VT-26H(GY)
Ë Ë Ë Ë Ë PURITY ADJUSTMENT
1. PURITY ADJUSTMENT
1. First of all, let a beam current of over 400µA flow
in the set to warm it up for 30 minutes or longer.
2. Keep the purity magnet in the zero magnetic field
in advance. Roughly adjust the static conver-
gence.
3. Receive the green-only colour signal. Adjust the
beam current to about 500 µA.
4. Degauss the cathode ray tube enough with the
degaussing coil.
ADJUSTMENT
Eastward magnetic field specified
1) Observe the beam landings "a" and "b", as
shown in Fig. A , through a microscope. Ad-
just the landings as specified. ( Fig. B , Fig. C )
2) If the right and left landings are equally out-
ward, move the deflection yoke forward.
3) If the right or left landing is shifted to the right
or to the left, adjust the opening angle of the
purity magnet.
4) Make sure the right and left beam landings are
just as specified about the screen center. Now
check the cathode ray tube corners.
Be sure that all the landings are at rank "B".
5) If any other colour appears on the screen,
move the deflection yoke back and forth.
LANDING ERROR
» Outward: Move the deflection yoke forward.
» Inward: Move the deflection yoke backward.
6) Receive the monoscope pattern signal.
RASTER ROTATION
7) Adjust the raster rotation to "0" eastward.
» Adjustment error : 0 ±2 mm
8) Tighten up the deflection coil screws.
» Tightening torque : 11±2 kg
Note : Each time the single-colour key is pressed,
the screen colour changes as follows.
Green-only
screen
Blue-only
Red-only
screen
screen
Single-colour
screen cleared
A
A
12
a b
Fig. A
A=B
B
Fig. B
A=B
B
Fig. C