LG tw-863ax Service Manual adjust

- 5 -

1. IMPORT ANT

(1) Check Power-source voltage.
(2) Set the function switch to band being aligned.
(3) Turn volume control to minimum unless otherwise noted.
(4) Connect low side of signal source and output indicator to chassis ground unless otherwise specified.
(5) Keep the signal input as low as possible to avoid AGC and AC action.

2. TUNER ADJUSTMENT

(1) Test & Adjustment Points

3. ADJUSTMENTS

L7

L2

L50
L70

TC51

L51

L1

L3
TC71

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(2) AM(MW) IF Adjustment

(3) AM(MW) RF (Coverage & Tracking) Adjustment

(4) FM RF (Coverage & Tracking) Adjustment

IF Adjust for Adjustment

455kHz Maximum L7 (See figure 2)

Figure 1. AM(MW) IF Adjustment Connection Diagram

Figure 3. AM(MW )RF Adjustment Connection Diagram

Figure 4. FM RF Adjustment Connection Diagram

Figure 2. AM(MW) IF Curve

NO ITem SG Output Adjust for Adjustment

1 515kHz Maximum L3
2 1,650kHz or 1,710kHz(U.S.A) Maximum VC1-3
3 Repeat steps 1 and 2 several times.
4 600kHz Maximum L4
5 1,400kHz Maximum VC1-4
6 Repeat steps 4 and 5 several times.

Tracking

Coverage

NO ITem SG Output Adjust for Adjustment

1 87.35MHz(AX Band: 64MHz) Maximum L2
2 108.25MHz(AX Band: 109MHz) Maximum VC1-2
3 Repeat steps 1 and 2 several times.
4 90MHz(AX Band: 68MHz) Maximum L1
5 106kHz Maximum VC1-1
6 Repeat steps 4 and 5 several times.

Tracking

Coverage

IC 101 (Pin ⑬, ⑭)

IC 101 (Pin ⑬, ⑭)

IC 101 (Pin ⑬, ⑭)

L4

455kHz

Unit

AM Signal Generator

AM Signal Generator

Test Loop
Antednna

Test Loop
Antenna

AM Antenna

8Ω

8Ω

GND

GND

PN1

Dummy

GND

Electrionic
Voltmeter

60mm

IN OUT

SSVM

Osacilloscope

Unit

- 7 -

(5) SW1 RF(Coverage & Tracking) Adjustment

NO ITem SG Output Adjust for Adjustment

1 2.2MHz Maximum L51
2 7.3MHz Maximum TC51
3 Repeat steps 1 and 2 several times.
4 2.2MHz Maximum L50
5 7.3MHz Maximum Confirm
6 Repeat steps 4 and 5 several times.

Tracking

Coverage

(6) SW2 RF(Coverage & Tracking) Adjustment

NO ITem SG Output Adjust for Adjustment

1 6.8MHz Maximum L7
2 22.5MHz Maximum TC71
3 Repeat steps 1 and 2 several times.
4 6.8MHz Maximum L70
5 22.5MHz Maximum Confirm
6 Repeat steps 4 and 5 several times.

Tracking

Coverage

Figure 5.SW1 RF Adjustment Connection Diagram

Figure 6. SW2 RF Adjustment Connection Diagram

SW Signal Generaotr

SET

Rod Ant

SP out

GND

SSVM

Oscilloscope

8Ω

Ioad

10P

330Ω

SW Signal Generaotr

SET

SSVM

Oscilloscope

8Ω

Ioad

10P

330Ω

Rod Ant

SP out

GND

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(2) Moter Speed Adjustment

(3) Record Bias Adjustment

Figure 7. Azimuth Adjustment Connection Diagram

Figure 8. Motor Speed Adjustment Connection Diagram

Figure 9. Record Bias Adjustment Connection Diagram

3. T APE DECK ADJUSTMENT

(1) Azimuth Adjustment

Deck Mode Test Tape Test Point Adjust for Adjustment

Playback MTT-114 L/R Output R/L Maximum Azimuth adjusting screw

Deck Mode Test Tape Test Point Adjust for Adjustment

Rec/Pause MTT-5511 Q201 EMITTER 70kHz±500kHz L201

Deck Mode Test Tape Test Point Adjust for Adjustment

NORMAL MTT-111N L/R Output 3kHz±90kHz VR250

HI-DUBB MTT-111N L/R Output 5.4kHz~6.2kHz CONFIRM

Unit

Unit

Unit

Test Tape

MTT-114

Test Tape

MTT-111N

Test Tape

MTT-5511

L ch

L/R Output

L/R Output

Frequency Counter

Frequency Counter

Playback Mode

Playback Mode

Electronic

Voltmeter

Dual-trace

synchorscope

L out

CH1

CH2

GND

GND

GND

PN102(Bias)

Record/playback
and Pause Mode

R out

Record/playback
head

R ch

Head