Operating instructions

6.1.9.4 Reel Motor Tracking with Capstan
The potentiometers for adjusting the motor tracking torques are located on
the TRANSPORT CONTROL PCB Assembly.
1. Turn off the power to the machine, and extend the TRANSPORT
CONTROL PCB Assembly with the EXTENSION PCB Assembly.
2. Turn on the power and thread 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. Disconnect the capstan motor by unplugging the
UNIVERSAL MATE-N-LOCK connector located to the left of the capstan
motor beneath the deck plate.
3. Place the machine into Rewind mode. Using your hand, spin the
capstan roller counterclockwise. Adjust potentiometer VR1 on the
TRANSPORT CONTROL PCB Assembly so tape moves onto the Supply
reel (about 20-30 ips). Refer to Figure 6-10.
4. Monitor the Capstan Tach output with a frequency counter at TP102 or
TP202 on the TACH SENSOR AMP PCB Assembly mounted under the
Capstan Motor (refer to Figure 6-11) and adjust VR1 for 600-650 Hz.
The frequency may drop after a few seconds, this condition is normal if
tape does not stop.
5. Place the machine into Fast Forward mode and turn the capstan
clockwise. Adjust potentiometer VR2 on the TRANSPORT CONTROL
PCB Assembly so tape moves onto the Take-up reel. It is important to
balance the two adjustments as closely as possible. Continued rotation
of the capstan roller by hand for more than 15 seconds at a time will
cause invalid results.
NOTE: This is not an overly critical adjustment, but it will increase Tach and
Capstan Roller slippage and affect the performance level of the CB-148 Auto
Locator if grossly misadjusted.
6. Press the STOP button, turn off the power to the machine, reconnect the
capstan motor and reinstall the TRANSPORT CONTROL PCB Assembly
to its proper position in the card cage.
Figure 6-10
TRANSPORT CONTROL PCB Assembly
R91
R92
R24R23
VR1
VR2
CP3
CP2
CP4
CP1
SW2
ON OFF
ON
SW1
JS1
JS2
Section 6 Alignment
6 - 14
October 1990
MTR-90III Operation and Maintenance Manual