LG KF-20P31, Service Manual

Page: 52 / 80

4-18
DECK MECHANISM ADJUSTMENT
4.Guide Roller Height Adjustment
Adjustment Procedure
1) Confirm if the Tape runs along the Tape Guide Line of the
Lower Drum.
2) If the Tape runs the Bottom of the Guide Line, turn the Guide
Roller Height Adjustment Screw to Clockwise direction.
3) If it runs the Top, turn to Counterclockwise direction.
4) Adjust the Height of the Guide Roller to be guided to the Guide
Line of the Lower Drum from the Starting and Ending Point of
the Drum.
Purpose: To regulate the Height of the Tape so that the Bottom of the Tape runs along the
Tape Guide Line on the Lower Drum.
Test Equipment/ Fixture
• Post Height Adjusting Driver
Test Conditions (Mechanism Condition)
• Play or Review Mode
Adjustment Point
• Guide Roller Height Adjustment
screws on the Supply and Take-Up
Guide Rollers.
Fig. C-4-1
Upper Flange
Guide Roller
Retaining Screw
Guide Roller Height
Adjustment screw
ADJUSTMENT DIAGRAM
Test Equipment/Fixture
• Oscilloscope
• Alignment Tape
• Post Height Adjusting
Driver
Test Equipment Connection Points
• CH-1:PB RF Envelope
• CH-2:NTSC: SW 30Hz
PAL: SW 25Hz
• Head Switching Output
Point
• RF Envelope Output
Point
Test Conditions VCR(VCP) State
• Play an Alignment Tape
Adjustment Point
• Guide Roller Height
Adjustment Screws
Fig. C-4-2
Fig. C-4-3
P3 POST
ADJUSTMENT
P2 POST
ADJUSTMENT
Turn the Roller Guide Height
Adjustment Screw slightly
to flatten the waveform.
Tracking control at center
RF ENVELOPE OUTPUT TEST POINT
OSCILLOSCOPE
HEAD SWITCHING OUTPUT TEST
POINT
Turn(Move) the tracking
control to both directions
4-1. Preliminary Adjustment
4-2. Precise Adjustment
Adjustment Procedure
1) Play an Alignment Tape after connecting the Probe of the
Oscilloscope to the RF Envelope Output Test Point and
Head Switching Output Test Point.
2) Tracking Control(in PB Mode) : Center Position(When
this Adjustment is performed after the Drum Assembly
has been replaced, set the Tracking Control so that the
RF Output is Maximum).
3) Height Adjustment Screw : Flatten the RF Waveform.
(Fig. C-4-2)
4) Turn(Move) the Tracking Control(in PB Mode)
Clockwise and Counterclockwise.(Fig. C-4-3)
5) Check that any Drop of RF Output is uniform at the
Start and End of the Waveform.
If the adjustment is excessive or insufficient the tape
will jam or fold.
NOTE
Waveform Diagrams
Connection Diagram