3-1
Electronic Test Equipment
ABBREVIATIONS
1. Servo Circuit
1) PG Adjustment
Purpose:
For the phase dividing of the Video A,B heads with
180° and the exact tracking of each track to meet
head switching point with VHS Spec.
Procedure:
a. Playback a PAL SP test tape.
(At this time, the “ART” is lighting, after pressing
the A. TR(+) or A. TR (-) and adjust the X-Value).
b. Connect CH-1 terminal of oscilloscope to W401 or
W402(H.SW) and CH-2 terminal to Video Out
Jack of the unit.
c. Trigger the complex Video signal of CH2 to CH-1
(H.SW), and adjust VR501 so that the distance
from A(B) head selection point of H.SW signal to
the starting point of Vertical synchronized signal is
416µsec
!
32µsec.
Reference:
1.
!
PG adjustment is practiced in the state of
maximum RF level and locked servo system.
2. The deviation between A/B Head Adjustment
location should be within
!
20µsec.
3. The deviation between the specification of
adjustment and the practical measurement value
should be within
!
20µsec.
4. Oscilloscope and VCR set should be connected
with GND.
WAVEFORM
Composite Video Signal
• MODE : Playback
• SPEC : 416µsec
!
32µsec
• M.P
: W401 OR W402 (H.SW)
Video Out Jack
• A.P
: VR501
Fig. 3-1
Fig. 3-2
• Oscilloscope
• Video Signal Generator
• Level Meter
• + Driver
• Test Tape (SP)
• Recording Tape
• Digital Multimeter
• Monitor Scope
• Power Supply
• SPEC : SPECIFICATION
• M.P : MEASUREMENT POINT
• A.P : Adjustment Point
Waveform
VIDEO OUTPUT SIGNAL
CH-1
CH-2
OSCILLOSCOPE
CTL
VR 501
IC 501
IC 301
V.OUT JACK
(JACK 301)
H/SW
RF
2) Connection Diagram
SECTION3 ELECTRICA
ELECTRICAL ADJUSTMENT PROCEDURES
(Solder side)
