Sony SVT-RA168, Service Manual

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2-34
SVT-RA40/RA168
4-2. Adjusting the BT Lever Assembly
Position and Checking the Back
Tension Torque in Play Mode
4-2-1. BT Lever Pole Position Adjustment
1. Without loading a cassette tape, put the mechanism
into PLAY mode (turn the power switch OFF).
2. Adjust point
A
on the band brake assembly by
rotating it so that the tip of the BT lever assembly is
aligned with the line on the right side of the mecha-
nism chassis. The mechanism should be in EJECT
mode when adjusting the BT Lever assembly position.
3. Refer to Section 4-2-2 and check that the back tension
torque is between 25 and 50g
.
cm.
Fig. 4-2-1
4-2-2. Checking the Back Tension Torque
Play Mode
1. Mount the cassette torque meter (VHJ-0016) and
switch to PLAY mode.
2. Check that the back tension torque is between 25 and
50g . cm.
4-3. Tape Path Adjustment
In normal circumstances, the tape path system does not
need to be adjusted. However, after removing or replacing
one of the parts shown in Fig. 4-3-1, you should check and
adjust the tape path. The adjustment of the tape path is
carried out while monitoring the envelope waveform of the
video head output, using an oscilloscope. To make sure
that the tape drawn off the reel runs freely and without
excessive tension along all the tape guides and cylinders
(drums), it is also important to check each tape guide by
eye.
Fig. 4-3-1
Poin t
A
Align the end of the BT lever assembly
with this line.
BT lever assembly
Tension
pole
0 tape
guide
Pinch roller
Capstan shaft
T guide roller
Full erase
head
BT post
T reel
Cylinder
(Drum)
S tape
guide
S guide roller
S reel
loading guide
T reel
Cylinder
(Drum)
S reel
Audio R/P head assembly
(ACE head)
T tape
guide