Mechanism Check Method - Toshiba W-707 Service Manual

1-4. Mechanism Check Method

If the abnormal condition is caused by the mechanism
itself, analyze the cause according to the following
procedures.
1-4-1. External Appearance Check
1. Check whether there are foreign matters or not inside
the VCR.
2. Check whether the cylinder and the guides for tape
transport system are contaminated.
1-4-2. Motor and Sensor System Check
Check whether some abnormalities are found in the
motor or the sensor system (including control circuits)
according to the flowchart.
1-4-3. Abnormality Analysis by Self-check Function
The unit has a self-check function. The self-check
function works as a system which stored some abnormal
condition. So, use this function to try to analyze the
cause(s).
For the data display method and the content of the data,
refer to self-check function in item 1-8.
After repairing, initialize the data by pressing the button
while displaying the abnormal mode.
Notes:
• Abnormal data is displayed only when the first
abnormal condition occurs, and is not displayed in
the second time and after. Accordingly, the claim
from customers and the actual data displayed may be
different.
• The data is stored only when the power turns off after
occurring the abnormality condition(s). The data is
not stored when the unit operation is recovered by
the microprocessor.
The typical examples in abnormal condition are shown
below.
A B C
Cylinder stops at playback position during
playback the tape.
Cylinder stops at FF/REW position during
rewind the tape.
T reel sensor is abnormal at playback position
during playback the tape.
S reel sensor is abnormal at review/playback
position during REVIEW/PLAYBACK the tape.
Cassette-in and out operation cannot be performed.
Mode shift cannot be performed during shifting to
REVIEW/PLAYBACK mode.
A: System control mode, B: Abnormality No., C: Mechanical position when an abnormality occurs.
Table 1-4-1
Abnormal condition
Does the
loading motor and the
worm wheel rotate without
a cassette after turning
the power ON?
YES
Does the
FL cam gear rotate
approximate 15 degrees
clockwise with the operation
above and return
immediately?
YES
Does the
capstan motor rotate
after loading a cassette
holder without
a cassette?
YES
Does the
T reel rotate with the
operation above?
YES
Does the
VCR stop at
the playback position
after detecting the tape remain
with the cassette with
a safety tab
inserted?
YES
Motor and sensor system
are normal.
Fig. 1-4-1
Check item
Check the cylinder motor.
Check if the cylinder and tape transport
guide are clogged.
Check the capstan motor.
Refer to the cases 2 and 3 described on
the table "Defective analyzing table 1-4-2".
Refer to the case 1 described on the
table "Defective analyzing table 1-4-2".
NO
Loading motor is
abnormal.
NO
Tape start sensor is
abnormal.
NO
Capstan motor is
abnormal.
NO
Reel belt and reel system
are abnormal.
Reel sensor system is
abnormal when the
cassette is ejected
without rewinding tape
NO
or stopped in the way
of unloading operation.
When the mechanical
operation is not
normal, the cam
switch is defective.