ELECTRICAL ADJUSTMENTS
1. ADJUSTMENT PROCEDURE
Read and perform these adjustments when repairing the circuits or replacing electrical parts or PCB assemblies.
CAUTION
•Use an isolation transformer when performing any service on this chassis.
•Before removing the anode cap, discharge electricity because it contains high voltage.
•When removing a PCB or related component, after unfastening or changing a wire, be sure to put the wire back in its original position.
•When you exchange IC and Transistor for a heat sink, apply the silicon grease on the contact section of the heat sink. Before applying new silicon grease, remove all the old silicon grease. (Old grease may cause damages to the IC and Transistor).
Prepare the following measurement tools for electrical adjustments.
1.Oscilloscope
2.Digital Voltmeter
3.Pattern Generator
On-Screen Display Adjustment
1.In the condition of NO indication on the screen. Press the VOL. DOWN button on the set and the Channel button (9) on the remote control for more than 2 seconds to appear the adjustment mode on the screen as shown in Fig.
35 H POSI OSD | 117 |
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36 | V POSI OSD | 57 |
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37 | H POSI TEXT | 117 |
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38 | V POSI TEXT | 57 |
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39 | H POSI 60 | 45 |
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00 CUT OFF |
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| VCO Status - | |
| 9- EXT |
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| MMM | |
Fig.
2.Use the Channel button
3.shown in Fig.
Press the MENU button on the remote control to end the adjustments.
NO. | FUNCTION | NO. | FUNCTION |
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00 | CUT OFF | 20 | TINT |
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01 | RF AGC | 21 | SHARP |
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02 | AGC GAIN | 22 | CONTRAST CENT |
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03 | R DRIVE | 23 | CONTRAST MAX |
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04 | R CUTOFF | 24 | CONTRAST MIN |
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05 | G DRIVE | 25 | COLOR CENT |
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06 | G CUTOFF | 26 | COLOR MAX |
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07 | B DRIVE | 27 | COLOR MIN |
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08 | H POSI (50) | 28 | M R CUT OFF |
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09 | V POSI (50) | 29 | M G CUT OFF |
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10 | V POSI (60) | 30 | M B CUT OFF |
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11 | V SIZE (50) | 31 | CVBS OUT |
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12 | V SIZE (60) | 32 | APR THRESHOLD |
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13 | VCO COARSE | 33 | BELL FILTER |
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14 | VCO FINE | 34 | BANDPASS |
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15 | VCO COARSE L1 | 35 | H POSI OSD |
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16 | VCO FINE L1 | 36 | V POSI OSD |
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17 | BRIGHT CENT | 37 | H POSI TEXT |
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18 | BRIGHT MAX | 38 | V POSI TEXT | Fig. |
19 | BRIGHT MIN | 39 | H POSI (60) |
2. BASIC ADJUSTMENTS
2-1: CONSTANT VOLTAGE
1.Place the set with Aging Test for more than 5 minutes.
2.Connect the digital voltmeter to TP501.
3.Set condition is AV MODE without signal.
4.Adjust the VR501 until the DC voltage is 135 ± 0.5V.
2-2: VCO
1.Place the set with Aging Test for more than 10 minutes.
2.Connect the oscillator (38.9MHz) to TP001.
3.Activate the adjustment mode display of Fig.
4.Press the VOL. +/- button on the remote control until the "OK" appear on the screen. If the "OK" is not displayed, select the "+" side on the changed from "+" to
5.Press the Page UP button once to set to "VCO FINE" mode.
6.Press the VOL. +/- button on the remote control to select the 5 step down point from the upper limit on the "OK".
(Example: In case of the "OK" range 30~41, select 36.)
2-3: AGC VOLTAGE
1.Place the set with Aging Test for more than 15 minutes.
2.Receive the VHF HIGH (63dB).
3.Connect the digital voltmeter to pin 5 of CP101.
4.Activate the adjustment mode display of Fig.
5.Press the VOL. +/- button on the remote control until the digital voltmeter is 2.6 ± 0.05V.
2-4: CUT OFF
1.Set condition is AV MODE without signal.
2.Using the remote control, set the brightness and contrast to normal position.
3.Place the set with Aging Test for more than 15 minutes.
4.Activate the adjustment mode display of Fig.
5.Adjust the Screen Volume until a dim raster is obtained.
2-5: WHITE BALANCE
NOTE: Adjust after performing CUT OFF adjustment.
1.Place the set with Aging Test for more than 15 minutes.
2.Receive the gray scale pattern from the Pattern Generator.
3.Using the remote control, set the brightness and contrast to normal position.
4.Activate the adjustment mode display of Fig.
5.Press the Page UP/DOWN button on the remote control to select the "R DRIVE", "G DRIVE", "M R CUTOFF" or "M G CUTOFF".
6.Adjust the VOL. +/- button on the remote control to whiten the R DRIVE, G DRIVE, M R CUT OFF, and M G CUT OFF at each step tone sections equally.
7.Perform the above adjustments 5 and 6 until the white color is looked like a white.