LG CF20 LG CF21 Service mode – option adjustment – circuit diagram – Troubleshooting table - Hotel Mode - CRT TV

Used ICs and FBT: TDA2006 – LA4282 – TDA8842 or TDA8841 – TDA8351 – STR-F6654 – TDA6107Q – TDA7429S – SAA5281 – MSP3410D – [FBT Part number 6174Z-8005E – FBT-FTSPN13-T8005E] - LG CF-20/21S42EH  LG CF-20/21S12EH

RF AGC (Automatic Gain Control) Adjustment

Test Point : AGC TP (J29)
Adjust : Remote Control

The RF AGC was aligned at the time of manufacture for optimum performance over a wide range conditions.  Readjustment of RF AGC should not be necessary unless unusual local conditions exist, such as:

1) Channel interference in a CATV system.

2) Picture bending and/or color beats, which are unusually due to excessive RF signal input when the receiver is too close to a transmitting tower or when the receiver is connected to an antenna distribution system where the RF signal has been amplified. In this case, the input signal should be attenuated (with pad or filter) to a satisfactory level.

3) Picture noise caused by "broadcast noise" or weak signal.  If the broadcast is "clean" and the RF signal is at least 1mV (60dBu), the picture will be noise free in any area.

Adjusting RF AGC to one end of rotation will usually cause a relatively poor signal to noise ratio;

Adjusting to the other end of rotation will usually cause a degradation of over load capabilities resulting in color beats or adjacent channel interference.

Adjustment
1. Connect RF signal (65dB!1dB) and turn on the TV.
2. Press OK buttons on TV set and Remote Controller at the same time to get into SVC (Service) mode.
3. Press Channel UP/DOWN button on the Remote Controller several times to find AGC.
4. Press Volume UP/DOWN button until the AGC Voltage is the same as the Table below.
5. Press OK button to memorize the data.

HOTEL TV Mode
NOTE: This mode is useful for HOTEL TV MODEL. Dealer or HOTEL manager can use this option.

AFTER SELECTING HOTEL MODE, CAN NOT CHANGE INITIAL SET UP CONDITION.
- CHANNEL PROGRAM(AUTO PROGRAM, MANUAL PROGRAM, EDIT FUNCTION) and OSD LANGUAGE set up condition is fixed so the HOTEL lodger cannot change and remove initial set up data condition at his pleasure.
This function prevents HOTEL lodger from needless changing channel memory data and OSD language condition.
It will be helpful for maintaining the best suitable condition of TV SET.

Limit MAX. VOLUME LEVEL.
- The HOTEL lodger can only use limited range of volume level because loud TV sound can disturb other lodger's private business.
The HOTEL manager select maximum volume level proper for HOTEL.

Only Audio without Video source available through A/V input
- When the Audio signal is fed to A/V input jack, the Audio is available without Video.
In the previously existing Model, sound is muted if there is no Video signal.

HOTEL mode operating guide
1) SET UP(CH.SEARCH AND EDIT) the Channel Program
2) SET UP Proper max volume level in SVC Mode.
3) SET UP HOTEL option in SVC Mode (OPTION-2)

OPTION Adjustment (SVC MODE:OPTION-1, OPTION-2)

NOTE: When the EEPROM has been replaced, the Option data should be restored as the function of individual system and specification.

1) Press OK buttons on both TV set and Remote Controller at the same time to get into SVC mode.

2) Press the Yellow button several times to find OPTION-1 or OPTION-2.

3) Input the correspond OPTION data referring to Table below with the numeric buttons 0~9

Option table

Circuit diagram (Schematic)

SMPS - split

Troubleshooting

White Balance Adjustment.(LINE SVC-0) and initial data W/B

NOTE : This adjustment should be performed after screen voltage adjustment.
1) Tune the TV set to receive 100% white pattern.
2) Press OK buttons on TV set and remote controller at the same time to get into SVC mode.
3) Press Channel UP/DOWN button for function adjustment.
4) Adjust VOL+ or VOL- button for GG031.
5) Adjust VOL+ or VOL-button in each status of "Rg--"/"Bg--" for X=281!8, Y=288!8 with color analyzer.
6) Press OK button to memorize the adjustment data.

Click on the pictures to magnify