Operating instructions

6.1.5 Swing Arm Adjustment
When the power is on and the swing arm solenoids have been activated, the
swing arm tension is solenoid controlled only in Fast Forward and Rewind
modes. The tension of the coil springs on each swing arm should be
checked periodically and adjusted as required to maintain accurate
functioning. Repeat the following procedure for the Supply and Take-up
sides of the transport. Refer to Figure 6-3.
1. Turn off the power to the machine.
2. Attach a spring scale to the swing arm post using a loop of string or
twine.
3. Pull the scale toward the rear of the deck plate until the swing arm is in
the middle position as shown in Figure 6-3. The mark on the swing arm
and the mark on the deck plate will be in line and parallel to the front of
the machine. If the spring scale indicates a reading of 460 ± 10 grams
(300 ± 10 grams for 1" tapes), no adjustment is necessary.
4. Loosen the double nut by holding the portion closest to the support
bracket stationary and unscrewing the other half. Then adjust the nut as
required to obtain 460 ± 10 grams (300 ± 10 grams for 1") tension. For
smoother operation, it is good practice to obtain the same measurement
for both the Supply and Take-up swing arms ± 10 grams.
5. Tighten the double nut to lock it in place.
6. After completion of this adjustment, make sure that there is some
tension on the spring even in the lower position.
NOTE: When this adjustment is correct, the tape tension measured between
the swing arm and the reel should be between 260 and 300 grams (170-200
grams for 1") as measured with a Tentelometer.
6.1.6 Tape Lifter Mechanism
The two tape lifters are linked together and are adjusted at the same time.
There are three different tape lifter adjustments, all of which require tape to
be threaded on the transport. It makes no difference whether the deck cover
plate is removed for these adjustments. Access to the lifter mechanism is
obtained by opening the VU meter panel. Refer to Figure 6-5.
1. Thread a reel of tape on the transport, activate the solenoids and place
the transport in Stop mode. There should be between 2 mm and 3 mm
clearance between the tape and the closest lifter. If this clearance is
correct, go to Step 3.
2. Locate the lifter solenoid beneath the deck plate. The resting position of
the tape lifters can be reset by loosening the 2 hex head screws that
secure the L-bracket to the flat metal linkage and sliding the L-bracket
forward or back along this linkage.
CAUTION: Use great care to avoid electrical shock. Avoid touching any
electrical component while adjusting mechanical components.
3. Place the transport in Fast Forward or Rewind mode. The lifters should
push the tape about 2-3 mm away from the reproduce head. If this
clearance is correct, go to Step 5.
Section 6 Alignment
6 - 8
October 1990
MTR-90III Operation and Maintenance Manual