SHARP LC-20S4E SERVICE MODE AND POWER SUPPLY CIRCUIT

SHARP LC-20S4E SERVICE MODE AND POWER SUPPLY CIRCUIT

SHARP LC-20S4E 

SERVICE MODE AND POWER SUPPLY CIRCUIT 

Adjusting procedure
Complete Set > Power ON > Enter Adjustment Process Mode (By Remote Control) > RF AGC adjustment > DCXO adjustment > Common Bias adjustment > White Balance adjustment
Entering the adjustment process mode
# After power on, press the adjustment process mode key on the service remote control.
# Switching on the TV set, holding pushed the "Input" and "Volume (–)" key at once, the TV set enters in the "K" mode.
In this condition, pushing "Volume (–)" and "P (DOWN)" key, the adjust mode appears.
Key operation in the adjustment process mode
# Use the "UP" or "DOWN" cursor key to select the adjustment mode item.
# Use the "LEFT" or "RIGHT" cursor key to change the data.
Initialization
When the EEPROM (IC101) has been replaced or when the EEPROM has been initialized, readjust the each adjust the each adjustments.
When the EEPROM has been replaced:
1) Plug in the AC cord to an AC power outlet and turn on the power.
2) When the setting is finished, the LED turns from red to green. In about 15 seconds, the initialization is completed.
When initializing the EEPROM data and making readjustments:
1) Enter the Adjustment Process mode.
2) Select the INIT TV item and press the "RIGHT" cursor key to enable the item.
3) Unplug the AC cord and plug it again in the AC power outlet. Turn on the power.
4) When the setting is finished, the LED turns from red to green. In about 5 seconds, the initialization is completed.
<Note>
When the INIT TV item has been enabled in the adjustment process, be sure to unplug the AC cord and plug it in again. Then start adjustments. Otherwise the readjusted data cannot be put in memory. Setting the screen size (inches)
1) Enter the Adjustment Process mode.
2) Check the model number.
3) Hold down the "LEFT" or "RIGHT" cursor key longer than 2 seconds, and select a screen size (20)

Adjustment
RF AGC adjustment
1) Feed in the colour bar signal (Field strength: 52dBµ V)
2) In Adjustment Mode, select RF AGC AUTO ("OFF") and press the "RIGHT" cursor key to start the adjustment.
3) Automatic adjustment complete, when it displayed "OK".
4) RF AGC data will be in the range of 0-63. If "NOK" is displayed, adjustment failed.
5) Check that the value is 30±10.

DCXO adjustment
1) Feed in the B/G NICAM signal. (Field strength: more than 70dBµ V.)
2) In Adjustment Mode, select the DCXO AUTO ("OFF") and press "RIGHT" cursor key to start the adjustment.
3) Automatic adjustment complete when "OK" is displayed. If "NOK" is displayed, adjustment failed.
4) Check that the value is 58±25.

Common bias adjustment
1) In adjustment mode, select the COM BIAS.
2) Select the internal signal "flicker pattern".
* Remote control direct key: No. 19 (13 Hex).
3) Adjust the flicker to become smallest.
4) After adjustment, exit from the "flicker pattern" display.
* Remote control direct key: No. 19 (13 Hex).

White balance adjustment
[A] White balance pre-adjustment
1) Feed the 0%/100% white signal.
2) In Adjustment Mode, select AWBSD ("OFF") and press "RIGHT" cursor key to start the adjustment.
3) Automatic adjustment complete when "OK" is displayed.
[B] White balance adjustment
For 40% white signal adjust RGB CUTOFF2 and for 80% white signal adjust RGB-GAIN.
1) Composite Signal
[Input signal] Composite video signal with picture of 80% white(Left) and 40% white(Right).
[Adjustment] Adjust the RGB CUTOFF2 and RGB-GAIN

Lamp error detection
Functional description
This LCD colour television has a function (lamp error detection) to be turned OFF automatically for safet when the lamp or lamp circuit is abnormal.
If the lamp or lamp circuit is abnormal, or some other errors happen, and the lamp error detection is executed, the followings occur.
1 The main unit of television is turned OFF 5 seconds after it is turned ON. (The power LED on the front side of TV turns from green to red.)
2 If the situation 1 happens 5 times sequentially, television cannot be turned ON. (The power LED remains red.) Countermeasures 

Check when turning OFF the lamp error detection
If the power has been turned off 5 times because of lamp error, hold down the unit’s "INPUT" and "Volume (–)" key simultaneously and turn on the unit’s power switch. The TV set gets back on power in the "K" mode.
In this state, press the unit’s "Volume (–)" and "P (DOWN)" key simultaneously. The Adjustment Process mode shows up.
This enables the operation check to detect errors in the lamp or lamp circuit.
Check whether "ERROR NO RESET" of the adjustment process is 1 or more. If it is 1 or more, it indicates the lamp error detection was executed.
Resetting of the lamp error count
After confirming that the lamp or lamp circuit is normal, reset the lamp error count. Select "ERROR NO RESET" of the adjustment process and set the number to 0 using the "LEFT" or "RIGHT" cursor key.

Hotel mode
How to enter the Hotel mode.
1) Turn on the power and enter the Adjustment Process mode.
2) Using the "up" or "down" cursor key on the remote controller, select the Hotel mode.
3) Using the "right" cursor key on the remote controller, change the setting from "0" to "1". Now the Hotel mode shows up.

4) Using "up" or "down" cursor key on the remote controller, select each item .
Make the setting with "left" or "right" cursor key .
5) Finally quit the Adjustment Process mode and turn off power. The TV set comes on in the Hotel mode after the next switch-on.

POWER SUPPLY CIRCUIT 

CLICK ON THE IMAGE TO ZOOM IN