Sharp 27DV-S100 Service Manual page 32

27DV-S100
27DV-CS10
CHECKING THE VIDEO SEARCH REWIND
BACK TENSION
• Remove the cassette housing control assembly.
• After short-circuiting R7057 and JUMPER:420
provided on the main PWB, plug in the power cord,
then turn on the power.
• Checking
1. After pressing the play button, press the rewind button,
and set the video search rewind mode.
2. Place the torque gauge on the take-up reel disk, and
turn it counterclockwise very slowly (one rotation every
2 to 3 seconds) and check that the torque is within the
set value 3.4 ± 1.5mN⋅m (35 ± 15gf⋅cm).
• Problems caused by maladjustments
1. Tapes may get scratched whether much or slightly
maladjusted
Torque gauge
CCW
Figure 1-12.
Note:
Set the torque gauge securely on the take-up reel disk. If
it is not secure, the measurement will be incorrect.
CHECKING THE PINCH ROLLER
PRESSURE
• Remove the cassette housing control assembly.
• After short-circuiting R7057 and JUMPER:420
provided on the main PWB, plug in the power cord,
then turn on the power.
• Checking
Press the play button to set the playback mode.
• Problems caused by maladjustments
1. Much maladjusted : The service life of the capstan
2. Slightly maladjusted : Images onscreen may get
distorted.
Take-up reel disk
and pinch roller may be shorter.
Pinch roller
Capstan shaft
Figure 1-13.
1. Detach the pinch roller from the capstan shaft.
Do not separate excessively. Or the pinch lever and
pinch double action lever may disengage.
2. Engage the tension gauge adapter with the pinch roller
shaft, and pull in the arrow direction.
3. Gradually return the pinch roller, and measure the
pulling force when the pinch roller contacts the capstan
shaft.
4. Make sure that the measured value is within setting 9.0
N to 11.8 N (900 to 1,200gf).
CHECKING AND ADJUSTMENT OF
TENSION POLE POSITION
• Remove the cassette housing control assembly.
• After short-circuiting R7057 and JUMPER:420
provided on the main PWB, plug in the power cord,
then turn off the power.
• Setting
1. Turn off the power switch.
2. Open the cassette tape (T-120), and fix with tape.
3. Set the cassette tape into the unit.
4. Put the weight (500g) on the cassette tape.
5. Turn on the power switch.
6. Make the adjustment with the beginning of a T-120
tape.
Weight to prevent
float (500g)
Figure 1-14.
• Checking
1. Set a cassette tape, push the REC button to place the
unit in the SP record mode. Now check the tension pole
position.
32
Tension gauge
900 - 1,200gf
Tension gauge adapter
(T-120)
500g