LG / GOLDSTAR CE29Q12IP
Manual de Servicio

ADJUSTMENT INSTRUCTIONS
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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. 2. Never disconnect leads while the TV receiver is on. 3. Don't short any portion of circuits while power is on. 4. The adjustment must be done by the correct appliances. 5. Unless otherwise noted, set the line voltage to 230Vac!10%, 50Hz.

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SECAM-L' Adjustment
NOTE : This adjustment should be performed after PIF adjustment. Test Point Adjust : TP1 : VR102

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

1) Turn on S1 and S3 and off S2. 2) Adjust VR102 so that the DC voltage may be indicated 2.5!0.1Vdc.

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RF AGC (Automatic Gain Control) Adjustment
Test Point Adjust : J209 or Observing Display : VR101

Main Board(Component side view)

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Multimeter or Oscilloscope 1

PowerSupply 5V

JP7 IC05 JP4 IC102 5V L107 S3 JP5 S2 100� 4.7k� VR102 Q106 16 TP1

IC101 TDA4474 24 7 JP1 11 JP2 0.01pF SignalGenerator 38.9MHz (B/G,D/K,I,L) 34.25MHz (SECAM-L')

The RF AGC control (VR101) was aligned at the time of manufacture for optimum performance over a wide range conditions. Readjustment of VR101 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

15 JP3

VR102

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 the VR101(RF AGC) control 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. For best results, adjust the VR101 control while performing on all over local channels, or the voltage at TP2 will be 2.3!0.1Vdc in RF level 65!1dBuV.

100� S1

Fig. 1 : Connection Diagram of Equipment for PIF Adjustment

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PIF (Picture Intermediate Frequency) Adjustment
Test Point Adjust : TP1 : L107

1) Connect the measuring equipment to the Main Board as shown in Fig.1. 2) Set RF frequency and output level of RF SIGNAL GENERATOR as shown Table 1. 3) Turn off S1 and S3 and on S2. 4) Adjust L107 so that the DC voltage may be 2.5!0.1Vdc. System B/G,D/K/I,SECAM-L SECAM-L' Frequency 38.9MHz 34.25MHz Modulation OFF OFF (Table 1) Output level 10mVp-p 10mVp-p Adjust L107 VR102

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