Zenith XBV243 Service Manual page 51

GUIDE ROLLER HEIGHT ADJUSTMENT
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.
PRELIMINARY ADJUSTMENT
Test Equipment/ Fixture
Post Height Adjusting Driver
Adjustment Procedure
1) Confirm that the Tape runs along the Tape Guide Line of
the Lower Drum.
2) If the Tape runs at the bottom of the Guide Line, turn the
Guide Roller Height Adjustment screw clockwise.
3) If it runs at the top, turn it counterclockwise.
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.
PRECISE ADJUSTMENT
Test Equipment/Fixture
Oscilloscope
Alignment Tape
Post Height Adjusting
Driver
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 ) H e i g h t A d j u s t m e n t S c r e w : F l a t t e n t h e R F W a v e f o r m .
( F i g . C - 4 - 2 )
4 ) T urn(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.
NOTE
I f t h e a d j u s t m e n t i s e x c e s s i v e o r i n s u f f i c i e n t t h e t a p e
w i l l j a m o r f o l d .
VR168 - 923-03485
All manuals and user guides at all-guides.com
MECHANISM - VCR
Play or Review Mode
CH-1:PB RF Envelope
CH-2:NTSC: SW 30Hz
PAL: SW 25Hz
Head Switching Output
Point
RF Envelope Output
Point
4-15
Guide Roller Height Adjustment
screws on the Supply and Take-Up
Guide Rollers.
ADJUSTMENT DIAGRAM
Fig. C-4-1
Play an Alignment Tape
Waveform Diagrams
P2 POST
ADJUSTMENT
P3 POST
ADJUSTMENT
Fig. C-4-2
Tracking control at center
Fig. C-4-3
Connection Diagram
RF ENVELOPE OUTPUT TEST POINT
HEAD SWITCHING OUTPUT TEST
POINT
Adjustment Point
Guide Roller Height
Adjustment screw
Upper Flange
Guide Roller
Retaining Screw
Adjustment Point
Guide Roller Height
Adjustment Screws
Turn the Roller Guide Height
Adjustment Screw slightly
to flatten the waveform.
Turn(Move) the tracking
control to both directions
OSCILLOSCOPE
D35E COMBO - SERVICING