Capstan Assembly Thrust; Takeup Torque; Fast Forward And Rewind Torque; Pi Nch Roller Pressure - Tascam 122 Service Manual

122
6-4. CAPSTAN ASSEMBLY THRUST
1) Turn the thrust adjusting screw so that thrust
of the capstan shaft is within 0.05 mm to
0.15 mm.
Thrust play
0 .05
mm to
0.'5
mrn
Flywheel
Fig. 6-5
6-5. TAKEUP TORQUE
Takeup torque adjustment is critical to stabilize
tape travel and reduce variations in tape speed.
1) Load a cassette torque meter (0 to 100 g-cm,
1.4 oz-inch) in the cassette holder. .
2) Measure the torque by running the tape of the
meter in the reproduce mode. The meter read­
ing should be 45 - 65 g-cm (0.6 - 0.9 oz-inch).
3) If the reading is outside this range, clean the
surf,ace of the idler pulley in the reel table as ­
sembly which comes into contact with the
tape using cleaning liquid. Also check the
operation of the moving parts of the reel table
assembly.
4)lf the reading is still unsatisfactory, replace
the reel table ass'y.
6-6. FAST FORWARD AND REWIND
TORQUE
1) Load a cassette torque meter (0 to 160 g-cm,
2.20z-inch).
2) With the deck in the fast forward and rewind
modes, read the meter. If the meter is provid ­
ed with tape, note the readings with the tape
fully wound on the reel taking up the tape in
each mode so that the measurement is not
influenced by the tape's inertia. The fast for ­
ward torque must be in the range 90 - 160
g-cm (1.3 - 2.2 oz-inch) and the rewind tor ­
que must be in the range 90 - 160 g-cm (1.3
- 2.2 oz-inch).
3) If the readings are outside these ranges, clean
the surface of the idler pulley with cleaning
liquid and check the operation of the moving
parts of the reel table ass'y.
44
6-7. PINCH HOLLER PRESSURE
Pinch roller pressure must also be adjusted to
the correct value to stabilize tape travel and
reduce variation in tape speed.
1) Remove the cassette door cover to install the
torque scale.
2) With the deck in the reproduce mode, attach
the scale near the shaft of the pinch roller,
being careful not to touch the pinch roller.
See Fig. 6-6.
3) Move the scale gradually in the direction of
the arrow until the capstan shaft and pinch
roller are completely separated.
4) Gradually return the pinch roller and note the
reading on the scale when the pinch roller
touches the capstan and starts rotating. The
reading should be between 390 and 490 g
(13.8 and 17.3 oz).
5) If the reading is outside this range, repalce
the pinch roller pressure spring or adjust the
pressure by bending the spring as shown in
Fig. 6-6.
Bend here
to adjuu
Fig.6~
,