How to enter Service Mode – adjustments LG CB20T20X and LG WP32A30
To enter Service mode, LG CB20T20X - 20 inch CTV press "OK" buttons on both TV set and the Remote control at the same time.
White Balance Adjustment. (LINE SVC-0)
This adjustment should be performed after screen voltage adjustment.
1)Tune the TV set to receive an 100% white pattern.
2) Press OK buttons on TV set and remote controller at the same time to get into SVC mode.
3) Press PSM (RED) button on remote controller. (Standard picture)
4) Press Channel UP/DOWN button for desirous function adjustment.
5) Adjust VOL+ or VOL- button for GG031.
6) Adjust VOL+ or VOL-button in each status of "Rg--"/"Bg--" for X=293 8, Y=295 8 with color analyzer.
7) Press OK button to memorize the adjustment data.
R-Drive => 28
G-Drive => 31
B-Drive => 25
Vertical S Correction Adjustment
Select SC and adjust until top-bottom side pincushion are equal.
Press OK button to memorize the data.
When the EEPROM has been replaced, the Option data should be restored as the function of individual system and specification.
1) Press OK buttons on both TV set and Remote Controller at the same time to get into SVC mode.
2) Press the Yellow button several times to find OPTION-1 or OPTION-2.
3) Input the OPTION data referring to Table below with the numeric buttons 0~9.
RF
AGC (Automatic Gain Control) Adjustment
Test
Point: AGC TP (J05)
Adjust : Remote Control
The
RF AGC was aligned at the time of manufacture for optimum performance over a
wide range conditions. Readjustment of RF AGC should not be necessary unless
unusual local conditions exist, such as ;Adjust : Remote Control
1) Channel interference in a CATV system.
2) Picture bending and/or color beats, which are unusually due to excessive RF signal input when the receiver is too close to a transmitting tower or when the receiver is connected to an antenna distribution system where the RF signal has been amplified. In this case, the input signal should be attenuated (with pad or filter) to a satisfactory level.
3) Picture noise caused by "broadcast noise" or weak signal. If the broadcast is "clean" and the RF signal is at least 1mV (60dBu), the picture will be noise free in any area. Adjusting RF AGC to one end of rotation will usually cause a relatively poor signal to noise ratio;
Adjusting to the other end of rotation will usually cause a degradation of over load capabilities resulting in color beats or adjacent channel interference.
2) Picture bending and/or color beats, which are unusually due to excessive RF signal input when the receiver is too close to a transmitting tower or when the receiver is connected to an antenna distribution system where the RF signal has been amplified. In this case, the input signal should be attenuated (with pad or filter) to a satisfactory level.
3) Picture noise caused by "broadcast noise" or weak signal. If the broadcast is "clean" and the RF signal is at least 1mV (60dBu), the picture will be noise free in any area. Adjusting RF AGC to one end of rotation will usually cause a relatively poor signal to noise ratio;
Adjusting to the other end of rotation will usually cause a degradation of over load capabilities resulting in color beats or adjacent channel interference.
Adjustment
1. Connect RF signal (65dB!0.2dB) and turn on the TV.
1. Connect RF signal (65dB!0.2dB) and turn on the TV.
[Standard
adjustment Channel]
- EU 05 Ch. (frf = 175.25MHz) : CK, CL, CB
- EU 41 Ch. (frf = 631.25MHz) : CI
2. Press OK buttons on TV set and Remote Controller at the same time to get into SVC-0 mode.
3. Press Channel UP/DOWN button on the Remote Controller several times to find AGC.
4. Press Volume UP/DOWN button until the AGC Voltage is the same as the Table below.
5. Press OK(Y) button to memorize the data.
- EU 05 Ch. (frf = 175.25MHz) : CK, CL, CB
- EU 41 Ch. (frf = 631.25MHz) : CI
2. Press OK buttons on TV set and Remote Controller at the same time to get into SVC-0 mode.
3. Press Channel UP/DOWN button on the Remote Controller several times to find AGC.
4. Press Volume UP/DOWN button until the AGC Voltage is the same as the Table below.
5. Press OK(Y) button to memorize the data.
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Click on the pictures to zoom in
LG WP32A30
Because this is a cold chassis, it is
not necessary to use an isolation transformer. However, operate it using
an isolation transformer between the power supply line and chassis
input will prevent electric shock and protect the test instrument/s.
PURITY & CONVERGENCE ADJUSTMENT
Convergence and Purity has been factory aligned. Do not attempt to
tamper with these alignments. However, the effects of adjacent receiver
components, or replacement of picture tube or deflection yoke may
require the need to readjust purity any convergence.
Purity Adjustment
This procedure DOES NOT apply to bonded yoke and picture tube assemblies.
The instrument should be at room temperature (60 degrees F or above)
for six (6) hours and be operating at low beam current (dark background)
for approximately 20 to 30 minutes before performing purity
adjustments.
Do not remove any trim magnets that may be attached to the bell of the picture tube.
1)
Remove the AC power and disconnect the internal degaussing coil.
2. Remove the yoke from the neck of the picture tube.
3. If the yoke has the tape version beam bender, remove it and replace it with a adjustable type beam bender
4. Replace the yoke on the picture tube neck, temporarily remove the three (3) rubber wedges from the bell of the picture tube and then slide the yoke completely forward.
2. Remove the yoke from the neck of the picture tube.
3. If the yoke has the tape version beam bender, remove it and replace it with a adjustable type beam bender
4. Replace the yoke on the picture tube neck, temporarily remove the three (3) rubber wedges from the bell of the picture tube and then slide the yoke completely forward.
5.
Reconnect the internal degaussing coil.
6. Position the beam bender locking rings at the 9 o'clock position and the other three pairs of tabs (2,4 and 6 pole magnets) at the 12 o'clock position.
6. Position the beam bender locking rings at the 9 o'clock position and the other three pairs of tabs (2,4 and 6 pole magnets) at the 12 o'clock position.
7.
Perform the following steps, in the order given, to prepare the receiver for
the purity adjustment procedure.
a. Face the receiver in the "magnetic north" direction.
b. Externally degauss the receiver screen with the television power turned off.
c. Turn the television on for approximately 10 seconds to perform internal degaussing and then turn the TV off.
d. Unplug the internal degaussing coil. This allows the thermistor to cool down while you are performing the purity adjustment. DO NOT MOVE THE RECEIVER FROM ITS "MAGNETIC NORTH" POSITION.
e. Turn the receiver on and obtain a red raster by increasing the red bias control (CW) and decreasing the bias controls for the remaining two colors (CCW)
a. Face the receiver in the "magnetic north" direction.
b. Externally degauss the receiver screen with the television power turned off.
c. Turn the television on for approximately 10 seconds to perform internal degaussing and then turn the TV off.
d. Unplug the internal degaussing coil. This allows the thermistor to cool down while you are performing the purity adjustment. DO NOT MOVE THE RECEIVER FROM ITS "MAGNETIC NORTH" POSITION.
e. Turn the receiver on and obtain a red raster by increasing the red bias control (CW) and decreasing the bias controls for the remaining two colors (CCW)
f.
Attach two round magnets on the picture tube screen at 3 o'clock and 9 o'clock
positions, approximately one (1) inch from the edge of the mask (use double-sided
tape)
8.
Referring to above, perform the following two steps:
a.
Adjust the yoke Z-axis to obtain equal blue circles.
b.
Adjust the appropriate beam bender tabs to obtain correct purity (four equal
circles).
9.
After correct purity is set, tighten the yoke clamp screw and remove the two
screen magnets.
10.
Remove the AC power and rotate the receiver 180 degrees (facing "magnetic
south").
11.
Reconnect the internal degaussing coil.
12.
Turn the receiver on for 10 seconds (make sure the receiver came on) to perform
internal degaussing, and then turn the receiver off.
13.
Unplug the internal degaussing coil.
14.
Turn on the receiver and check the purity by holding one (1) round magnet at
the 3 o'clock and a second round magnet at 9 o'clock position. If purity is not
satisfactory, repeat steps 8 through 14.
15. Turn off the receiver and reconnect the internal degaussing coil.
15. Turn off the receiver and reconnect the internal degaussing coil.
Convergence
Adjustment
Caution: This procedure DOES NOT apply to bonded yoke and picture tube assemblies. Do not use screen magnets during this adjustment procedure. Use of screen magnets will cause an incorrect display.
1. Remove AC power and disconnect the internal degaussing coil.
2. Apply AC Power and set the brightness to the Picture Reset condition. Set the Color control to minimum.
Caution: This procedure DOES NOT apply to bonded yoke and picture tube assemblies. Do not use screen magnets during this adjustment procedure. Use of screen magnets will cause an incorrect display.
1. Remove AC power and disconnect the internal degaussing coil.
2. Apply AC Power and set the brightness to the Picture Reset condition. Set the Color control to minimum.
3.
Apply 8V to the pin42 of IC501.
4. Adjust the Red, Green and Blue Bias controls to get a dim white line.
5. Rem6. Reconnect the internal degaussing coil and apply AC power.
7. Turn the receiver on for 10 seconds to perform internal degaussing and then turn the receiver off again.
8. Unplug the internal degaussing-coil.
9. Turn on the receiver, connect a signal generator to the VHF antenna terminal and apply a crosshatch signal.
Caution: During the convergence adjustment procedure, be very careful not to disturb the purity adjustment tabs are accidentally move, purity should be confirmed before proceeding with the convergence adjustments.
Note: Make sure the focus is set correctly on this instrument before proceeding with the following adjustment.ove the AC power and 8V from the pin42 of IC501.
4. Adjust the Red, Green and Blue Bias controls to get a dim white line.
5. Rem6. Reconnect the internal degaussing coil and apply AC power.
7. Turn the receiver on for 10 seconds to perform internal degaussing and then turn the receiver off again.
8. Unplug the internal degaussing-coil.
9. Turn on the receiver, connect a signal generator to the VHF antenna terminal and apply a crosshatch signal.
Caution: During the convergence adjustment procedure, be very careful not to disturb the purity adjustment tabs are accidentally move, purity should be confirmed before proceeding with the convergence adjustments.
Note: Make sure the focus is set correctly on this instrument before proceeding with the following adjustment.ove the AC power and 8V from the pin42 of IC501.
10.
Converge the red and blue vertical lines to the green vertical line at the
center of the screen by performing the following steps (below TABLE).
a. Carefully rotate both tabs of the 4-pole ring magnet simultaneously in opposite directions from the 12 o'clock position to converge the red and blue vertical lines.
b. Carefully rotate both tabs of the 6-pole ring magnet simultaneously in opposite directions form the 12 o'clock position to converge the red and blue (now purple) vertical lines with the green vertical line.
11. Converge the red and blue horizontal with the green line at the center of the screen by performing the following steps. (Below TABLE)
a. Carefully rotate both tabs of the 4-pole ring magnet simultaneously in the same direction (keep the spacing between the two tabs the same) to converge the red and blue horizontal lines.
b. Carefully rotate both tabs of the 6-pole ring magnet simultaneously in same direction (keep the spacing between the two tabs the same) to converge the red and blue (now purple) horizontal lines with the green horizontal line.
a. Carefully rotate both tabs of the 4-pole ring magnet simultaneously in opposite directions from the 12 o'clock position to converge the red and blue vertical lines.
b. Carefully rotate both tabs of the 6-pole ring magnet simultaneously in opposite directions form the 12 o'clock position to converge the red and blue (now purple) vertical lines with the green vertical line.
11. Converge the red and blue horizontal with the green line at the center of the screen by performing the following steps. (Below TABLE)
a. Carefully rotate both tabs of the 4-pole ring magnet simultaneously in the same direction (keep the spacing between the two tabs the same) to converge the red and blue horizontal lines.
b. Carefully rotate both tabs of the 6-pole ring magnet simultaneously in same direction (keep the spacing between the two tabs the same) to converge the red and blue (now purple) horizontal lines with the green horizontal line.
c.
Secure the tabs previously adjusted by locking them in place with the locking
tabs on the beam bender.
12.
While watching the 6 o'clock positions on the screen, rock the front of the
yoke in a vertical (up/down) direction to converge the red and blue vertical
lines. (Fig upper left)
13. Temporarily place a rubber wedge at the 12 o'clock position to hold the vertical position or the yoke.
14. Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue horizontal lines are converged. If the lines are not converged, slightly offset the vertical tilt of the yoke (move the rubber wedge if necessary) to equally balance the convergence error of the horizontal lines at 3 o'clock and 9 o'clock and the vertical lines at 6 o'clock and 12 o'clock.
15. Place a 1.5 inch piece of glass tape over the rubber foot at the rear of the 12 o'clock wedge.
16. While watching the 6 o'clock and 12 o'clock areas of the screen, rock the front of the yoke in the horizontal (left to right) motion to converge the red and blue horizontal lines. (Fig. upper right)
13. Temporarily place a rubber wedge at the 12 o'clock position to hold the vertical position or the yoke.
14. Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue horizontal lines are converged. If the lines are not converged, slightly offset the vertical tilt of the yoke (move the rubber wedge if necessary) to equally balance the convergence error of the horizontal lines at 3 o'clock and 9 o'clock and the vertical lines at 6 o'clock and 12 o'clock.
15. Place a 1.5 inch piece of glass tape over the rubber foot at the rear of the 12 o'clock wedge.
16. While watching the 6 o'clock and 12 o'clock areas of the screen, rock the front of the yoke in the horizontal (left to right) motion to converge the red and blue horizontal lines. (Fig. upper right)
17.
Temporarily place a rubber wedge at the 5 o'clock and 7 o'clock positions to
hold the horizontal position of the yoke.
18. Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue vertical lines are converged. If the lines are not converged, slightly offset the horizontal tilt of the yoke (move the temporary rubber wedges if necessary) to equally balance the convergence error of the horizontal lines at 6 o'clock and 12 o'clock and the vertical lines at 3 o'clock and 9 o'clock.
19. Using a round magnet confirm purity at the center, right and left sides and corners. See Purity Adjustment Procedure.
20. Reconfirm convergence and apply a 1.5 inch piece of glass tape over the rubber foot at the rear of the 5 o'clock and the 7 o'clock wedges.
18. Check the 3 o'clock and 9 o'clock areas to confirm that the red and blue vertical lines are converged. If the lines are not converged, slightly offset the horizontal tilt of the yoke (move the temporary rubber wedges if necessary) to equally balance the convergence error of the horizontal lines at 6 o'clock and 12 o'clock and the vertical lines at 3 o'clock and 9 o'clock.
19. Using a round magnet confirm purity at the center, right and left sides and corners. See Purity Adjustment Procedure.
20. Reconfirm convergence and apply a 1.5 inch piece of glass tape over the rubber foot at the rear of the 5 o'clock and the 7 o'clock wedges.
