Service Adjustments and Calibrations |
AUDIO OUTPUP LEVEL VERIFICATION
REQUIRED EQUIPMENTS / CONNECTIONS:
JIG Filter: | TP18. |
RF signal generator: | RF antenna input. |
RMS Voltmeter: | Between JIG Filter and GND. |
| TP18 |
PROCEDURE:
1.Apply the next signals on the antenna input: Video: 100 IRE Flat Field, 30% modulation. Audio: 300Hz, 100% modulation, mono
(70±5dB, 75Ω open, P/S 10dB)
2.Check the Audio level to the
RMS Voltmeter show 150 +60_30 mVrms.
MTS CIRCUIT ADJUSTMENT
The MTS Circuit adjust of BR2L chasis, is doing through four steps:
1.VCO Stereo adjustment.
2.Filter adjustment.
3.Input level adjustment.
4.Stereo separation adjustment.
Note: The adjustment must be done in the sequence showed before. VIF, TP12 (Level Detector) must be adjusted before MTS adjustment.
STEP 1 – VCO STEREO ADJUSTMENT
REQUIRED EQUIPMENTS / CONNECTIONS:
1KΩ resistive jumper: Connect between the TP14 and GND.
22µF 16V capacitive jumper: Connect between the TP18 (MPX in). and GND.
Frequency Counter: Connect between the TP22
PROCEDURE:
1.Remove the antenna.
2.On the service mode, select “DAC: M1”
3.Adjust MTS STEREO PLL VCO “DAC: M1” until the frequency counter show 15.734KHz±50Hz. (15.684~15784KHz).
Note: The TV must be turn ON minimum 15 minutes before adjustment.
STEP 2 – FILTER ADJUSTMENT
REQUIRED EQUIPMENTS / CONNECTIONS: RF Generator: Antenna input (RF) Oscilloscope: Between TP21
Note: The GND of oscilloscope must be next of
PROCEDURE:
1.Apply the next signal to antenna input ( RF): Video: 100 IRE Flat Field, Modulation 30%. Audio: 15.734KHz sinusoidal wave.
(70±5dB, 75Ω open, P/S 10dB).
2.Adjust the output level signal generator for that a 15.734KHz wave form be 100 ±5mVrms on TP18.
3.On service mode, adjust “DAC: M2”.
4.Adjust MTS filter (DAC:M2) until the wave form amplitude, on oscilloscope screen be minimum.
STEP 3 – INPUT LEVEL ADJUSTMENT
REQUIRED EQUIPMENTS / CONNECTIONS: JIG Filter: Connect to TP22.
RF generator: Connect to RF input antenna terminal.
RMS meter: Between JIG Filter and GND.
TP22
PROCEDURE:
1.Apply the next signal on antenna input ( RF): Video: 100 IRE Flat Field, Modulation 30%. Audio: 300 Hz, modulation 100%, mono. (70±5dB, 75Ω open, P/S 10dB).
2.On service mode, adjust “DAC: M0”
3.Adjust the input level MTS (DAC: M0) until the Voltmeter show 212 ± 10.5mVrms.
STEP 4 – STEREO SEPARATION ADJUSTMENT
REQUIRED EQUIPMENTS / CONNECTIONS: RF generator: Antenna input (RF). Oscilloscope: Between TP22
PROCEDURE:
1.On audio MENU set STEREO.
2.Apply the next signal on antenna input ( RF): Video: 100 IRE Flat Field, Modulation 30%.
Audio: 300 Hz, modulation 100%, stereo (L channel) (70±5dB, 75Ω open, P/S 10dB).
3.Adjust the low level separation (DAC: M3) until the wave form amplitude on the oscilloscope screen, be minimum.
4.Adjust the audio of RF generator to 3KHz.
5.Adjust the high level separation (DAC: M4) until the wave form amplitude on the oscilloscope screen, be minimum.
6.Repeat steps 2 to 4.
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