Deck mechanism adjustment – LG TL-AT130M User Manual

Page 55

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4-18

DECK MECHANISM ADJUSTMENT

Purpose: To correct for shift in the Roller Guide and X value after replacing the Drum.

8-2. Checking for tape curling or jamming

Test Equipment/ Fixture

• T-160 Tape
• T-120 Tape

Specification

• Be sure there is no tape jamming or curling at

the begining, middle or end of the tape.

VCR(VCP) State

• Run the CUE, REV, Play mode at the

beginning and the end of the tape.

Test Conditions (Mechanism Condition)

1) Confirm that the tape runs smoothly around the roller

guides, Drum and A/C Head Assemblies while abruptly
changing operating modes from Play to CUE or REV.
This is to be checked at the begining, middle and end
sections of the tape.

2) Confirm that the tape passes over the A/C Head

Assembly as indicated by proper audio reproduction and
proper tape counter performance.

Checking Procedure

7. Adjustment after Replacing Drum Assembly (Video Heads)

Test Equipment/ Fixture

• Oscilloscope
• Alignment Tapes
• Blank Tape
• Post Height Adjusting Driver
• Screw Driver(+) Type 5mm

Connection Point

• CH-1: PB RF Envelope
• CH-2: NTSC: SW 30Hz

PAL: SW 25Hz

• Head Switching Output

Test Point

• RF Envelope Output Test Point

Test Conditions

(Mechanism Condition)

• Play the Blank Tape
• Play an Alignment Tape

Adjustment Points

• Guide Roller Precise

Adjustment

• Switching Point
• Tracking Preset
• X-Value

Checking/Adjustment Procedure

Play a blank tape and check for tape curling or creasing around
the Roller Guide. If there is a problem then follow the procedure
4. "Guide Roller Height" and 5. "Audio Control(A/C) Head
Adjustment".

RF ENVELOPE OUTPUT TEST POINT

OSCILLOSCOPE

HEAD SWITCHING OUTPUT TEST
POINT

Connection Diagram

Waveform

V1/V MAX

E

E 0.7

V2/V MAX E

E 0.8

RF ENVELOPE OUTPUT

Fig. C-7

8. Check the Tape Travel after Reassembling Deck Assembly.

8-1. Checking Audio and RF Locking Time during playback and after CUE or REV (FF/REW)

Test Equipment/ Fixture

• Oscilloscope
• Alignment Tapes(with 6H

3KHz Color Bar Signal)

• Stop Watch

Specification

• RF Locking Time: Less than 5

sec.

• Audio Locking Time:Less than

10sec

Test Equipment

Connection Points

• CH-1: PB RF Envelope
• CH-2: Audio Output
• RF Envelope Output Point
• Audio Output Jack

Test Conditions

(Mechanism Condition)

• Play an Alignment Tape

(with 6H 3kHz Color Bar
Signal)

Checking Procedure

Play an Alignment Tape then change the operating mode to
CUE or REV and confirm if the unit meets the above listed
specifications.

NOTES:

1) CUE is the forward search mode
2) REV is the backward search mode
3) Refer to the Play mede

V1

V

V2

CH1 CH2

Connection Points

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