Adjustment After Replacing Drum Assembly (Video Heads); Check The Tape Travel After Reassembling Deck Assembly; Deck Mechanism; Checking Audio And Rf Locking Time During Playback After Cue Or Rev - LG TL-AT130M Service Manual

DECK MECHANISM ADJUSTMENT

7. Adjustment after Replacing Drum Assembly (Video Heads)

Purpose: To correct for shift in the Roller Guide and X value after replacing the Drum.
Test Equipment/ Fixture
• Oscilloscope
• Alignment Tapes
• Blank Tape
• Post Height Adjusting Driver
• Screw Driver(+) Type 5mm
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".

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
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.

8-2. Checking for tape curling or jamming

Test Equipment/ Fixture
• T-160 Tape
• T-120 Tape
Checking Procedure
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.
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
Specification
• RF Locking Time: Less than 5
sec.
• Audio Locking Time:Less than
10sec
Specification
• Be sure there is no tape jamming or curling at
the begining, middle or end of the tape.
Test Conditions
(Mechanism Condition)
• Play the Blank Tape
• Play an Alignment Tape
Connection Diagram
RF ENVELOPE OUTPUT TEST POINT
HEAD SWITCHING OUTPUT TEST
POINT
Waveform
V1/V MAX E E 0.7
V2/V MAX E E 0.8
RF ENVELOPE OUTPUT
Test Equipment
Connection Points
Connection Points
• CH-1: PB RF Envelope
• CH-2: Audio Output
• RF Envelope Output Point
• Audio Output Jack
NOTES:
1) CUE is the forward search mode
2) REV is the backward search mode
3) Refer to the Play mede
Test Conditions (Mechanism Condition)
• Run the CUE, REV, Play mode at the
beginning and the end 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.
4-18
Adjustment Points
• Guide Roller Precise
Adjustment
• Switching Point
• Tracking Preset
• X-Value
OSCILLOSCOPE
CH1 CH2
V1 V V2
Fig. C-7
Test Conditions
(Mechanism Condition)
• Play an Alignment Tape
(with 6H 3kHz Color Bar
Signal)
VCR(VCP) State