Crt Yoke; Positioning; Linearity; Cleaning Procedures - Zenith ZVM-1240 Service Manual

CRT YOKE
NOTES:
1.
2.
3.
These adjustments may interact with the focus
adjustment.
Do not overtighten the yoke clamp.
Make sure the yoke is positioned as far forward
on the CRT as possible. If necessary, unclamp
the yoke; then slide it forward, and reclamp.
Positioning
1.
2.
Loosen the clamp screw and rotate the deflec-
tion yoke until the edges of the display are
parallel with the edges of the screen; then
tighten the clamp screw.
Adjust the centering rings so that the display
is centered on the screen.
Linearity
1.
2.
3.
Remove the ferrite foam magnets that may be
installed on the yoke.
Select the most nonlinear of the four displayed
edges and install a ferrite magnet on the yoke
post nearest the greatest distortion.
Repeat step 2 as necessary, around the yoke,
until a uniform rectangular shape is displayed.
NOTE: If only a small change in linearity is needed,
reduce the size of the ferrite magnets by cutting off
a small portion with diagonal cutters.
Page 12
Cleaning Procedures
WARNING: Be sure that the monitor's power cable
is unplugged before you clean the monitor.
•
Clean the cabinet with a lint-free cloth, mildly
dampened with a nondetergent cleaning solu-
tion; do not spray liquids directly on the monitor
or use a wet, saturated cloth.
• Clean dust from the monitor's screen with a lint-
free cloth.
•
•
Clean heavy dirt from the monitor's screen with
a swab soaked with isopropyl alcohol.
Be sure the monitor is completely dry before
applying electrical power.
Servicing Diagrams
Component location drawings, waveform photographs,
and schematic diagrams are provided along with Table
3, B
+
Supply Transistor Voltages.
The circuit location of each waveform is indicated on
both the schematic and the component location draw-
ing. A Z -160 PC Series computer with color bar output
was used to supply signals for generating the
waveforms. Refer to "Waveform Photograph Explana-
tions" at the back of the manual.
Servicing