Sunday, December 13, 2015

AKAI 21CTU93BC how to enter to service mode and adjustments


This TV uses memory IC. In the memory IC are memorized data for correctly operating the video and deflection circuits.
When replacing memory IC, be sure to use IC written with the initial value of data.
(1) Power off
Switch the power off and unplug the power cord from AC outlet.
(2) Replace IC
Be sure to use memory IC written with the initial data values.
(3) Power On
Plug the power cord into the AC outlet and switch the power On.
(4) Check and set SYSTEM default value:
3. Note: enter a factory mode method
1) Factory remote control: 
Press the factory remote control up [PRESET], press  again[TEST]key, appear on the television screen 'M'.
2) Customer remote control
3) Press [menu] key, appear the picture menu, press few character keys 6483, the screen appears M.
4) Press [standby] key, withdraw factory mode.
5) The “TEST” will be displayed on the screen.
6) Check the setting value of the SYSTEM default value. If the value is different, select items by [CH+]/[CH-] keys and set value by [VOL+]/[VOL-] keys.
7) Press “STANDBY” key again and return to the normal screen.
1. Receive normal colour bar signal.
2. Connect DC voltmeter to VD541- and isolated ground.
3. Adjust potentiometer in power unit to get the voltage as 110V ±1.0V for 21 inch hereinafter,
130 ±1.0V for 25 inch upwards. FOCUS ADJUSTMENT
1. Receive a crosshatch signal.
2. While watching the screen, adjust the FOCUS VR to make the vertical and horizontal lines as fine and sharp as possible.
To enter BUS control mode, Press “TEST” key on the Remote control unit of factory. (
Customer remote control press "MENU" key behind in a row press"6""4""8""3"
Choose a "SETUP SELECT" options in"M2" menu, one by one in order press the numerical key"6, 4, 8 and 3", press "MUTE" key again can depend on this get into "M3"~"M9" of design menu, general factory the 
production doesn't need to carry on M 3~ adjustments of M9.
In "M0"~under"M9" appearance press” CALL” the key can get into "M" appearance. At “M”under the appearance press “-/-“ the key can get into “BUS OPEN” appearance, at “BUS OPEN under, press “-/-“ the key recover factory appearance.
[M1] menu
MENU0 Geometrical adjustment
Receive PAL standard Complete pattern signal.
Adjustment steps

a) Adjust V. SLOPE, to the center horizontal line just appeare from half bottom shadow.
b) Adjust V. SIZE, to get 90% of vertical picture contents would be displayed on CRT.
c) Adjust V. SHIFT, the center horizontal line correspond to CRT vertical center.
d) Adjust H.SHIFT, to get the picture horizontal center correspond to CRT horizontal center.
Receive NTSC signal and repeat above [M0] and [M1] adjustment.
[M2] Menu
AGC Adjustment.
Receive 60dB╬╝(1mV)VH colour bar pattern signal
adjust AGC valuevoltage from high to low).to noise reduce gradually and just disappeared point.
Select “shipping”, push [V+] [V-]key to be shipped.
[M3] Menu
CRTcut off and white balance adjustment.
Receive white signal.
a) CRT cut off adjustment.
1. Select “SC”, then automatically vertical scan will be stopped.
2. Adjust SCREEN control on Flyback transformer to get the darkest single horizontal line (red, green, or blue, sometimes shows more yellow, more purple or more white).
b) White balance adjustment.
1. Select RD/BD menu.
2. Adjust RD/BD to get colour temperature as x=281, y=311
c) Sub-Brightness adjustment. (Use stair case signal)
1. Select SB menu.
2. Adjust SB to get the darkest step being cutoff.
1. Demagnetize CRT with the demagnetizer.
2. Loosen the retainer screw of the deflection yoke.
3. Remove the wedges.
4. Input a green raster signal from the signal generator, and turn the screen to green raster.
5. Move the deflection yoke backward.
6. Bring the long lug of the purity magnets on the short lug and position them horizontally.
7. Adjust the gap between two lugs so that the GREEN RASTER will come into the center of the screen.
8. Move the deflection yoke forward, and fix the position of the deflection yoke so that the whole screen will become green.
9. Insert the wedge to the top side of the deflection yoke so that it will not move.
10. Imput a crosshatch signal.
11. Verify that the screen is horizontal.
12. Input red and blue raster signals, and make sure that purity is properly adjusted.