LG / GOLDSTAR MC994A CHASSIS
Service Manual

ADJUSTMENT
Y Safety Precautions
1. It is safe to adjust after using insulating transformer between the power supply line and chassis input to prevent the risk of electric shock and protect the instrument. Never disconnect leads while the TV receiver is on. Don't short any portion of circuits while power is on. The adjustment must be done by the correct appliances. But this is changeable in view of productivity. Unless otherwise noted, set the line voltage to 230Vac!10%, 50Hz. TUNER AGC Voltage Default AGC Data 6700VPV002A(LG C&D) 2.5 ! 0.1V 24 6700VPV002B(LG C&D) 3.0 ! 0.1V 24

2. 3. 4. 5.

: Screen Voltage Adjustment
Test Point Adjust : RK (Red Cathode of CPT Board) : Screen Control of FBT

Y Test Equipment required
1. 2. 3. 4. 5. RF signal generator (with pattern generator) DC Power Supply Multimeter (volt meter) Oscilloscope Color analyzer

1) Input the Color Bar Pattern into Antenna jack. 2) Select CutOff of SVC-3 mode. 3) Turn the screen control clockwise until the Horizontal line is visible and turn it counterclockwise until the Horizontal line is faintly visible.

: RF AGC (Automatic Gain Control) Adjustment
Test Point Adjust : AGC TP (J17) : Remote Control NOTE: This adjustment should be performed after warming up for 10 minutes. 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. Test Point Adjust : Observing Display : Focus control of FBT

: Focus Adjustment

1) Input the Color Bar Pattern into Antenna jack. 2) Adjust the Focus control of FBT for best overall focus.

: VCO Adjustment
1) Input Digital Pattern into Antenna jack. 2) Select A-PIF of SVC-4 mode. 3) Press VOLF/G button and A-PIF will be changed 0 to 1 while the number of PIF-C is rolling. 4) When PIF-C stops rolling, A-PIF will be changed 1 to 0 and VCO adjustment is finished. Caution : Do not press the Volume button again in A-PIF mode after adjustment is finished. 1. To get into SVC mode 1) Press OK buttons on both TV set and Remote Control at the same time. 2) Press Yellow button to select OPTION-1, OPTION-2, OPTION-3 or OPTION-4. 3) Press PR E/D button to select an adjustment. 4) Press VOL F/G button to change the data. 2. To memorize the adjusted data into EEPROM Press OK button. 3. To get out from SVC mode Press TV/AV or Power button.

Adjustment
1. Connect RF signal (65dB!0.5dB) and turn on the TV. 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 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(Y) button to memorize the data.

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