DYNEX LC22HV40 – HOW TO ENTER SERVICE MODE TROUBLESHOOTING CIRCUIT DIAGRAM

DYNEX LC22HV40 – How to enter Service Mode _ Troubleshooting _ Circuit Diagram

How to enter Service Mode - DYNEX LC22HV40 – Back-light and SMPS schematics

SERVICE MODE [Factory Mode]

a. Press “INPUT”, “2”, “5”, ”8” and “0” one by one to enter level-one factory menu;
b. Press ▲ and ▼ to move the cursor to the adjustment page of the level-one factory menu then press “ENTER” or ►to enter;
c Press ▲ and ▼ to move the cursor up and down;
d. When the cursor move to a certain adjust item, press ◄ and ► to adjust value;
e. Press “MENU” to exit to the previous factory menu;
f. Press “EXIT” to exit the factory menu;
g. After exit the factory menu, press “SLEEP” to enter the factory menu again as long as power on.
h. “Power on mode” items of “Other setting” menu;

On= turn on

Off =standby

Memory = memory function of turn on

White balance adjustment:

  Enter the factory menu Color Temp, set Color Mode to Cool first, a 11-step gray scale picture will appear, fix Gain Green, adjust Gain Red, Gain Blue to let the color coordinate of the ninth level to be (285, 293); fix Offset Green, adjust Offset Red, Offset Blue to let the color coordinate of the third level to be (285, 293). Adjust Gain Red, Gain Blue, Offset Red and Offset Blue repeatedly until the value of the two levels gray scale are (285, 293) then press MENU to return to the previous menu or press Save to EEPROM to store the value.  Check if the color temperatures of Normal and Warm are up to the mustard, if not, adjust Gain Red, Gain Blue, Offset Red and Offset Blue till they are accord with the requirement.

DTV adjustment (same for HDMI)
  Select the 26 channel in AIR mode, enter the factory menu Color Temp, set Color Mode to Cool first, a 11-step gray scale picture will appear, fix Gain Green, adjust Gain Red, Gain Blue to let the color coordinate of the ninth level to be (285, 293); fix Offset Green, adjust Offset Red, Offset Blue to let the color coordinate of the third level to be (285, 293). then press MENU to return to the previous menu or press Save to EEPROM to store the value.  Check if the color temperatures of Normal and Warm are up to the mustard, if not, adjust Gain Red, Gain Blue, Offset Red and Offset Blue till they are accord with the requirement.

YPbPr adjustment
  DADC correction: Input 480i/60Hz signal of 75% color bar and gray scale to YPbPr (VG848 Timing 968, Pattern 918), enter the factory menu ADC Setting and perform ADC Auto.  White balance adjustment: input 1920x1080I/60Hz of 8-level gray scale signal to YPbPr from VG848 YPbPr channel, enter the factory menu Color Temp, set Color Mode to Cool first, fix Gain Green, adjust Gain Red, Gain Blue to let the color coordinate of the seventh level to be (285, 293); fix Offset Green, adjust Offset Red, Offset Blue to let the color coordinate of the second level to be (285, 293). Adjust Gain Red, Gain Blue, Offset Red and Offset Blue repeatedly until the value of the two levels gray scale are (285, 293) then press MENU to return to the previous menu or press Save
to EEPROM to store the value.  Check if the color temperatures of Normal and Warm are up to the mustard, if not, adjust Gain Red, Gain Blue, OffsVGA adjustment ADC correction: Input VESA 800x600/60Hz signal of chess to VGA (VG848 Timing 854, Pattern 914), enter the user menu ADVANCED and perform AUTO to display the whole picture, enter the factory menu ADC setting and perform ADC Auto to correct ADC.  White balance adjustment: input 800x600I/60Hz of 8-level gray scale signal to VGA from VG848 VGA channel, enter the factory menu Color Temp, set Color Mode to Cool first, fix Gain Green, adjust Gain Red, Gain Blue to let the color coordinate of the seventh level to be (285, 293); fix Offset Green, adjust Offset Red, Offset Blue to let the color coordinate of the second level to be (285, 293). Adjust Gain Red, Gain Blue, Offset Red and Offset Blue repeatedly until the value of the two levels gray scale are (285, 293) then press MENU to return to the previous menu or press Save to EEPROM to store the value.  Check if the color temperatures of Normal and Warm are up to the mustard, if not, adjust Gain Red, Gain Blue, Offset Red and Offset Blue till they are accord with the requirement Red and Offset Blue till they are accord with the requirement.

ATV adjustment (same for AV, S-VIDEO)
DVD AGC Gain correction

 Select the 21 channel in AIR mode, enter factory menu VD AGC Setting and select VD AGC Gain, press  ► till display “OK”, then press “MENU” to return to the previous menu presetting before ex-factory
Enter the factory menu and select Shipment, the unit will preset the data automatically. Perform the step after factory menu adjustment. SHIPMENT will perform the steps below:
1 Clear the program information of the channel
2 Clear VCHIP information
3 Default setting of user analog
4 Set Menu Language to English
5 Set AIR/CABLE to AIR
6 Power on mode is Off

AGC Description
  The AGC has two modes of operation. When the chip is powered up, the non-coherent IF AGC & RF AGC will function first. The non-coherent AGC loop will provide the control voltage necessary for proper gain control of the external gain amplifier and tuner in the RF section. The two AGC will extend the dynamic range of power amplifier. It automatically adjusts itself to any system with a matched filter. The automatic gain controller (AGC) takes the input data stream from either the ADC output or the DC remover output, and applies non-coherent detection of the gain level, and adjusts it to a pre-configured reference level.  The two AGC work exclusively in parallel; there is the AGC that feeds its output to the IF amplifier, and the AGC that outputs to the tuner amplifier. The AGC also support manual mode, where one is fixed to a pre-configured level, while the other performs normal AGC functions.

General Troubleshooting

Picture is out of focus or jumping

Bad status in signal receiving
Poor signal
Check if there are failures with the electrical connector or the antenna.
Check if the antenna is properly connected.

Fringe in picture

Check if the antenna is correctly oriented.
Maybe there is electric wave reflected from hilltop or building.

Picture is interfered by stripe shaped bright spots

Possibly due to interference from automobile, train, high voltage transmission line, neon lamp etc.
Maybe there is interference between antenna and power supply line. Please try to separate them in a longer distance.
Maybe the shielded-layer of signal wire is not connected properly to the connector.

There appear streaks or light color on the screen

Check if interfered by other equipment and if interfered possibly by the equipment like transmitting antenna, non-professional radio station and cellular phone.

Unable to switch the power on

Check to see if the power plug has been inserted properly into the socket.

If yes, check and replace damaged component/s at the main power regulator [SMPS] board.  If needy, replace this board as card basis.

No picture and sound.

Check to see if the power supply of liquid crystal TV has been switched on. (As can be indicated by the red LED at the front of the TV set)
See if it’s receiving the signal that is transmitted from other source than the station
Check if it’s connected to the wrong terminal or if the input mode is correct.
Check if the signal cable connection between video frequency source and the liquid crystal TV set is correct.

Deterioration of color phase or color tone

Check if all the picture setups have been corrected.

Screen position or size is not proper

Check is the screen position and size is correctly set up.

Picture is twisted and deformed

Check to see if the picture-frame ratio is properly set up.

Picture color changed or colorless

Check the “Component” or “RGB” settings of the liquid crystal TV set and make proper adjustment according to the signal types.

Picture too bright and there is distortion in the brightest area

Check if the contrast setting is too high.
Possibly the output quality of DVD broadcaster is set too high.
It maybe also due to improper terminal connection of the video frequency signal in a certain position of the system.

Picture is whitish or too bright in the darkest area of the picture

Check if the setting for the brightness is too high
Possibly the brightness grade of DVD player (broadcaster) is set too high

No picture or signal produced from the displayer if XXX in search” appears

Check if the cable is disconnected.
Check if it’s connected to the proper terminal or if the input mode is correct.

There appears an indication - outside the receivable scope

Check if the TV set can receive input signal. The signal is not correctly identified and VGA format is beyond the specified scope

Remote control cannot work properly

Check if the batteries are installed in the reverse order.
Check if the battery is effective.
Check the distance or angle from the monitor.
Check if there is any obstruct between the remote control and the TV set.
Check if the remote control signal- receiving window is exposed to strong fluorescence.

No picture and sound, but only hash

Check if the antenna cable is correctly connected, or if it has received the video signal correctly

Blur picture

Check if the antenna cable is correctly connected.
Of if it has received the right video signal.

No sound

Check if the “mute” audio frequency setting is selected.
Check if the sound volume is set to minimum.
Make sure the earphone is not connected.
Check if the cable connection is loose.

Check speaker/s.

Check and replace damaged component/s at the audio output section circuit.

When playing VHS picture search tape, there are lines at the top or bottom of the picture.

When being played or in pause VHS picture search tape sometimes can’t provide stable picture, which may lead to incorrect display of the liquid crystal TV, In this case press “auto” key on the remote control so as to enable the liquid crystal TV set to recheck the signal and then to display correct picture signal.

SMPS (Power Supply) & Back-light inverter schematics

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