Zenith XBV243 Service Manual page 54

ADJUSTMENT AFTER REPLACING DRUM ASSEMBLY (VIDEO HEADS)
Purpose: To
Test Equipment/ Fixture
Oscilloscope
Alignment tapes
Blank Tape
Post Height Adjusting Driver
Screw Driver(+) Type 5mm
Checking/Adjustment Procedure
TAPE TRAVEL AFTER REASSEMBLING DECK ASSEMBLY
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.
CHECK 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 cassette.
VR168 - 923-03485
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MECHANISM - VCR
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
Specification
4-18
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 0.7
V1
V2/V MAX 0.8
RF ENVELOPE OUTPUT
Test Equipment
Connection Points
Connection Points
NOTES:
1) CUE is fast forward mode (FF)
2) REV is the rewind mode (REW)
3) Referenced to the Play mode
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 assem-
bly as indicated by proper audio reproduction and prop-
er tape counter performance.
Adjustment Points
Guide Roller Precise
Adjustment
Switching Point
Tracking Preset
X-Value
OSCILLOSCOPE
CH1 CH2
V V2
Fig. C-7
Test Conditions
(Mechanism Condition)
VCR(VCP) State
D35E COMBO - SERVICING