Sony SVT-RA40 Service Manual page 53

4-3-4. Audio R/P Head (ACE Head) Height
Adjustment, Azimuth Adjustment and
Horizontal Position Adjustment
1. Hight/azimuth adjustment
1. Refer to Section 4-3-3, complete the GUIDE ROLLER
adjustment, and perform the AUDIO R/P HEAD
adjustment.
As the audio R/P head assembly (ACE HEAD) has
been temporarily adjusted before shipment, do not
rotate screws unnecessarily.
2. Mark screw A, screw B, and bracket with a water-
proof marker so that their original positions can be
known even after the screws are rotated.
Marking screws A and B in the same direction will
enable the adjustment mentioned later to be performed
easily.
3. Play the alignment tape (VHJ-0005), and observe the
audio output waveform using an oscilloscope.
Loosen screw B in the counterclockwise direction to
decrease the audio output level. Then tighten it in the
clockwise direction until the maximum level. Tighten
further in the clockwise direction to decrease the level,
and loosen in the counterclockwise direction until the
maximum level.
4. Rotate screw A in the same direction by the same
degree as screw B in step 1. (Check visually accord-
ing to the mark made. )
5. Play the alignment tape (VHJ-0006), rotate screw C,
and maximize the audio output waveform (temporary
azimuth adjustment).
6. Perform the adjustments in 3 to 5 again.
7. Perform fine adjustments using screw B.
Perform the same adjustments as 3, and if screw B
was adjusted by more than 30 degrees, perform the
adjustment in step 4 again, and then perform fine
adjustments.
8. Play the alignment tape (VHJ-0006), rotate screw C,
and maximize the audio output waveform (actual
azimuth adjustment)
Marking
C
A B
Fig. 4-3-5
SVT-RA40/RA168
Audio R/P head
assembly (ACE head)
2. Horizontal position adjustment
1. Play the alignment tape (VHJ-0006).
2. Press the tracking buttons (tracking + and tracking _)
simultaneously and set the tracking to the centre.
3. Using an oscilloscope, observe the waveform of the
video head output.
4. Loosen the two fixed screws on the audio R/P head
(ACE head) by between 20 d and 30 d anticlockwise. .
5. Using a slotted screwdriver, adjust the position of the
audio R/P head (ACE head). At the position where the
amplitude of the envelope waveform is at its maximum
at the tracking centre, tighten the fixed screw on the
audio R/P head (ACE head). When you do this, check
that the envelope waveform changes equally whether
the tracking is shifted by pressing the tracking button
in the plus or the minus direction.
6. Play the alignment tape (VSJ-1001) and check that the
amplitude of the envelope waveform is at its maximum
at the tracking centre. If not, repeat steps 1 to 6.
7. Refer to the electrical adjustments section of the
service manual, and adjust the switching position of
the servo circuit.
Note:
1. When you press the tracking buttons (tracking + and
tracking _) simultaneously, the tracking is reset to the
tracking centre. When the tracking is at the tracking
centre, the message "TR -: -" will appear in place of
the clock display on the front panel. If you keep
pressing the tracking _ button the messages "TR -: "
and "TR --: " will appear, while if you keep pressing
the tracking + button, the messages "TR : -" and "TR :
--" will appear. .
2. STEP 6) applies only the model with the model for
REAL TIME and the EP (LP) PLAYBACK function.
After resetting the tracking to
the tracking centre, set the en-
velope waveform to maximum.
Screw
Fig. 4-3-6
Slotted
screwdriver
Screw
Audio R/ Phead assembly
2-37