Main Board Adjustments; Rgb Cutoff And G2 Adjustments; Rgb Drive Adjustments; Vertical Height And Vertical Center Adjustments - Zenith ZVM-133-TC Service Manual

MAIN BOARD ADJUSTMENTS
r--~----2M (JUMPER)-----........., ......
lj
o
~HORIZONTAL
I
MAIN BOARD
I
~
[) ~
CENTER , -
UI
~
5M (JUMPER)
~ [~L,,::- H<>ROZO~"
0
'V
OSCILLAT6~ ~OSCILLATOR
ADJUST TEST POINT
+95 VOLT
~~
ADJUSTMENT ~ I
~
VERTICAL
l.[9
CENTER
01
GREEN RED
BLUE DRIVE DRIVE
VERTICAL
HEIGHT
DRIVE
~
o
~ ~
(@J
MED
F~~~~f ' U 1 - ! ~ : , , : .
' I
iJ II
i
~ ;~"""'
o
~
GREEN
tI!l
RED _
I
C~~~~FCUTOFF
CUTOFF
I
~--------------------------~,
Figure 4-3
Main Board Adjustments
RGB Cutoff and G2 Adjustments
These adjustments should be made in a darkened
room.
1. Turn each control (R2506-REO, R2516-GREEN,
and R2527-BLUE) fully counterclockwise.
2. Adjust G2 on the sweep board (see Figure 4-4)
until the raster just appears.
3. Adjust each cutoff control until a gray raster ap-
pears.
4. Readjust G2 until the raster just disappears.
Servicing
RGB Drive Adjustments
Apply a white field on the entire CRT. This can be
done with a video source or, with a Z-100 or Z-100
PC computer, by using the Z-BASIC or GW-BASIC
command:
PAINT(O,O),,7
Observe the screen closely and see if any red, green,
or blue tints are present. Adjust the appropriate drive
(R2506-REO, R2517-GREEN, R2528-BLUE) until the
tint disappears.
Vertical Height and Vertical Center
Adjustments
These controls (R3418-height and R2125-vertical cen-
tering) should be adjusted under low-light conditions.
1. Turn the G2 control clockwise until a raster ap-
pears.
2. Adjust these two controls so that the top and bot-
tom of the raster are 1/2-inch from the edges of
the CRT.
3. Turn the G2 control counterclockwise until the ras-
ter just disappears.
Horizontal Width and Horizontal Center
Adjustments
Horizontal centering control R3441 (located on the
main board) and horizontal width LX3261 (located on
the sweep board) should be adjusted under low-light
conditions (see Figure 4-3).
NOTE: Width selection must be made before attempt-
ing these adjustments.
1 . Turn the G2 control (located on the sweep board)
clockwise until a raster appears.
Page 4-7