JVC AV-27BM3

AV-278M3
AV-27CM3
@ PURITY, CONVERGENCE AND WHITE BALANCE ADJUSTMENTS
* The locations of SERVICE SWITCH, SCREEN VR, CUT-OFF VR and DRIVE VR are described in the ALIGNMENT LOCATION of
SERVICE ADJUSTMENT or the SCHEMATIC DIAGRAM.
e@PICTURE TUBE
The picture tube is a precision in-line gun type. For this picture
tube, dynamic convergence is carried out by a precision deflection
yoke which eliminateé the use of convergence yoke and
convergence circuit. The adjustment of picture tube is therefore
mace easier as only the adjustment of static convergence by using
a magnetic is enough. The deflection yoke and purity/convergency
magnets assembly has been set at the factory and requires no field
adjustments. However, should the assembly be accidentally jarred
or tampered with, some or all adjustments may by necessary.
@COLOR PURITY & VERTICAL CENTER
Loosen yoke vetaining screw ( Fig. B-1 } . With a sharp knife cut
between tho picture tube and the wedge. Remove wedges
completely and clean off dried adhesive from the picture tube.
PAINT is uscd to lock the tabs of the purity/convergence magnet
assembly in place { Fig. B-1 ) . The paint must be removed with
the end of a screwdriver before any adjustments are attempted.
(As to models equipped with a magnet locking ring, beforehand
loosen it. )
4. Select no signal UHF channel. ( or Display a monochrome
pattern }
2. Let the purity tabs come in lino horizontally as is shown in Fig.
B-2. A long tab should be in the same direction as tho other
short tab.
3. Move tho yoke slowly backward.
4. Turn the GREEN CUT-OFF VR to maximum and the RED
and BLUE CUT-OFF VRs to minimum. Then adjust the
SCREEN VR so that the green band can be seen best. (Fig.
B3)
5. Rolate the two tabs in the opposite directions and with them
kept at an angle, together in either direction so that the green
band is centered on the picture tube.
6. Check the vertical center position by displaying a horizontal
fine. ( Select the CUT-OFF SERVICE SWITCH from N to S
and a HORIZONTAL LINE will appear. ) Unless correct,
bring it lo the nearest center by rotating the two tabs, kept at
an angie, together in either direction. ( Fig. B-4 )
7. Repeat steps 5 and 6 alternately until the green band and the
vertical center come to the center.
8. Move ihe yoke slowly towards the bell of the tube so that the
whole surface of the picture tube is filled with a green pure
raster.
9. Tuming RED or BLUE CUT-OFF VR to maximum and
GREEN CUT-OFF VR to minimum, make sure of a red or
blue pure raster.
40. Secure yoke retaining screw ( do not install wedges at this
time} .
(As to models equipped with a magnet locking ring, secure it and
keep six magnets from moving even if it is touched slightly.)
12 (No.50718)
(EXAMPLE) >
EF. YOKE
I-aaaners tecane-aing|
MAGNETS LOCKING RING
Four POL
CONVER'
badd. NMAcner®
ICE
Simark"a")
(goa SIX POLES|
CONVERGENCE
MAGNETS(mark"6")
YOKE RETAINNING
SCREW PURITY
MAGNETS(mark"P")
(REAR VIEW)
SHORT AND LONG
LONG AND SHORT PROTRUSIONS
PROTRUSIONS
(FRONT VIEW)
GREEN BAND.
CENTER
Bring the green band to the center.
Fig.B-3
(FRONT VIEW)
HORIZONTAL LINE
“S VERTICAL CENTER
(identified with a
white notch)
Bring the horizontal line nearest to the witte
aoiches shown in the dotted circles.
Fig B-4