Zenith XBS341 Series, Service Manual

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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 ) 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
0.7
V2/V MAX
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