- 14 -
Press the “Maintenance” key nine times to enter the ninth menu, which gives the following
display:
Remarks:
* AV1: set value 1
*AV2: set value 1 (0 for one channel of AV input)
*AV3: set value 0
*SVHS: set value 1 (0 for 21” and 14”)
*UI MODE: set value 2
*MESH MODE: set value 0
*IF: set value 1
*REVERSE SEARCH: set value 0
Press the “Maintenance” key ten times to enter the tenth menu, which gives the following
display:
Remarks: all being set value 0
Note:
1.
Those with “*” are factory set values and must not be altered.
2.
You can exit from the factory status by pressing the “TV” key on the remote
controller in any level of factory menu.
III. Repair for common faults
1. Fault principle and analysis for video amplification section
①
Characteristics and principle of automatic white balance adjustment of
8838/8842 series TV set
The primary colors R, G and B from the decoding circuit, after passing three independent
video amplifiers, are applied to the cathodes of three independent electron guns, to control
three independent electron beams, which are converged to hit the respective fluorescent
materials. They should show white when mixed, but the luminous efficiency of the
fluorescent materials cannot be the same due to the characteristics of elements in the three
amplifiers and the electron emitting ability of the electron gun cathodes. Therefore balance
adjustment must be performed to display a white color, hence it is referred to as white balance
adjustment. In an ordinary color TV set, white balance is adjusted by adjusting the bias
resistance of the video amplification, i.e., the static bias of video amplification pole and signal
amplitude amplification ability, to control the balance of the three current beams. Despite
careful adjustment before leaving the factory, after long-time service, any change in any
parameter of the three independent channels will break the white balance, resulting in “color
cast”. It can be restored to normal only after re-adjustment by specialized personnel. The
OPTION2
AV1 1
AV2 1
AV3 0
SVHS 1
UI MODE 2
MESH MODE 0
IF 1
REVERSE SEARCH 0
OPTION3
AV SOUND
AV1 0
AV2 0
AV3 0
SVHS 0
Summary of Contents for CTM6845
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