Operating instructions

6.1.9.2 Preliminary Center Position and Gain Adjustments
Before performing these adjustments, the Swing Arm Travel adjustments
should be performed as described in § 6.1.3. This method of adjustment
requires a digital voltmeter but needs no tape on the machine. Remove any
tape and/or reels.
1. Turn off the machine and extend the REEL CONTROL PCB Assembly.
Using the digital voltmeter, monitor voltage at TP1 (Take-up) or TP6
(Supply) and a ground test point on this PCB Assembly.
2. Hold the Take-up swing arm at its center position and adjust VR1 for
Take-up to 0.0 Volt. Perform the same operation on Supply swing arm
adjusting at VR5.
3. Next, test and adjust the voltage when the swing arm roller is manually
held at the ends of the swing channel. Determine which end of the
channel has the smaller absolute voltage reading.
4. Hold the swing arm at the end position where the smaller absolute value
is measured.
5. Determine the reel size to be used. Refer to Table 6-1. Adjust the
appropriate trimmer so that the corresponding voltage on the table is
measured at the swing arm position held at Step 4.
6. Move the swing arm to the other end position. Confirm that the voltage
measured there is within the range of ±0.7 V from the adjusted voltage in
Step 5.
Reel Size T.P. Voltage Trimmer
Less than 10.5" *± 2.0 (1.0) V VR4 (T.up Gain-S)
T.UP 10.5" TP1 ± 3.5 (3.0) V VR3 (T.up Gain-M)
14" ± 6.0 (4.0) V VR2 (T.up Gain-L)
Less than 10.5" *± 2.0 (1.0) V VR8 (Sup Gain-S)
SUP 10.5" TP6 ± 3.5 (3.0) V VR7 (Sup Gain-M)
14" ± 6.0 (4.0) V VR6 (Sup Gain-L)
* When using plastic reels smaller than 10.5", these voltages must be set down to 1.4 V.
Voltage values in parenthesis are for 1" machines.
NOTE: It is not recommended to use unbalanced reel sizes. When using
unbalanced reel sizes, set Reel Size Dip switch(es) for the small reel side on
the REEL SIZE DETECTION PCB Assembly to "7".
6.1.9.3 Tape Tension Check
1. Load a 10.5 inch reel of tape onto the transport and wind until the tape is
evenly distributed between the Take-up and Supply reels.
2. While in Stop mode, use a Tentelometer or another tension gauge to
check the tension on the portion of the tape between each swing arm
and its adjacent reel. The tension should be between 260 and 300
grams (170-200 grams for 1").
3. If the deviation from the above specification is within ± 20 grams, use
the POS trimmers on the REEL CONTROL PCB Assembly to correct the
tension.
4. If the tension is more than 20 grams out of specification, do no adjust
the POS trimmers. Instead, the swing arm spring (under the transport
deck cover) must be readjusted. (Refer to § 6.1.5.)
Table 6-1
Gain Adjustment Trimmer
MTR-90III Operation and Maintenance Manual
October 1990
Section 6 Alignment
6 - 13