Sharp LC20 – LCD TV – Public mode – Lamp error detection - Back Light Inverter Circuit diagram

Lamp error detection
Functional description
This LCD colour television has a function (lamp error detection) to be turned off automatically for safety 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.)
Check when turning off the lamp error detection
When television is turned off by the lamp error detection mentioned above, it enters the adjustment process with the power LED red. Entering the adjustment process turns off the error detection and turns on TV.  This enables the operation check to detect errors in the lamp or lamp circuit.
Check whether "ERROR NO RESET" on line 4, page 1 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" on line 4, page 1 of the adjustment process and set the number to 0 using the volume button.

Afterwards, perform the operation check to confirm that the lamp error detection does not function.

B-L Inverter Schematic

How to enter into PUBLIC MODE
1. Turn off TV by pressing MAIN POWER switch.
2. While pressing "MENU" key and "VOL(+)" key at the same time, press MAIN POWER switch for more than 2 seconds.
TV will turn on, and you will see the screen display setting pass word of PUBLIC MODE.

3. Press "0", "2", "7" key of Remote control, you wilt see the screen display a setting of PUBLIC MODE.

1. You can select each item of functions by pressing cursor UP/DOWN keys or CH Up/Dn Keys on the remote control or CH Up/Dn keys on the LCD TV. The letter of selected item turns to yellow colour when you selected it.

2. The setting position of each item of functions are made by pressing cursor RIGHT/LEFT keys on the remote control or VOL (+)/(–)keys on the LCD TV.

3. Select ENTER position after you set all functions, and press cursor RIGHT/LEFT keys on the remote control or VOL(+)/(–)keys on the LCD TV for confirmation.

Unless otherwise you make ENTER confirmation, the settings will not be memorized.

6-functions of Public Mode settings expand for public application

1. MAXIMUM VOLUME (1—————60)

You can set the maximum volume at your desire level.

2. VOLUME FIXED (VARIABLE / FIXED)

You can fix the sound volume at your desire level.

When you set to "FIXED", the sound volume which you just set is fixed.

3. REMOTE CONTROL (RESPOND / LIMITED)

If you set "LIMITED", remote control keys of POWER, CH Up/Dn, VOL(–)/(+) and BRIGHT keys are responded, but other keys are not responded.

This is a position that you can not make MENU adjustments.

4. USER CONTROL (RESPOND / NO RESPOND)

"NO RESPOND" means that the TV does not respond when you press a user control buttons except main power button on the main unit.

5. MENU BUTTON (RESPOND / NO RESPOND)
With "NO RESPOND" selected, the remote controller and the set's MENU key are disabled.
6. ON SCREEN DISPLAY (YES / NO)
If you set "NO" position, OSD will not appear.
7. START MODE (NORMAL↔AV1↔COMPONENT↔CH1↔CH2...↔CH98↔CH99↔CH0)
When any other item than "NORMAL" has been selected, the set gets started in the selected input mode or channel at the next switch-on.
8. INPUT MODE FIXED (NORMAL↔FIXED)
(* This item cannot be selected if the start mode is "NORMAL".)
If "FIXED" has been selected, any channels and input modes other than those selected in the start mode cannot be picked up.
9. SOUND ONLY MODE (NO↔YES)
(* This item cannot be selected if "NO" appears on the on-screen display.)
Let's suppose that this item has been selected and the BRIGHT key on the remote control has been pressed.
The item "BRIGHTNESS [OFF]" can now be selected next to the item "BRIGHTNESS [DARK]".

Five seconds later, the screen shuts off and the sound alone is heard.

Once in this mode, no picture but the OSD appears. But the channels and sound volume can still be changed.
To quit this mode, press the BRIGHT key on the remote control again and select any item other than "BRIGHTNESS [OFF]".
10. RESET
You can cancel all Public Mode settings. (It returns to the factory setting.)
11. ENTER You make sure after you have specified all functions, then press the enter key. Unless otherwise you press the enter key, all positions that you have selected will not be set.