3M DELTA Series - Elec Rical Adjus Men S; General; Reproducer; Servo Motor Duty Cycle

SECTION V - ELECTRICAL ADJUSTMENTS
A. GENERAL
Before making any of the adjustments described
in this section, make certain that all mechanical
adjustments outlined in Section III have been prop 
erly made. Errors in mechanical adjustments cause
errors in electrical adjustments. This occurs due to
the interdependence of the two systems. It must
also be stressed that in order for the electrical adjust 
ments to be made properly, the sequence of adjust 
ments outlined in this section must be followed.
B. REPRODUCER
1 VOLT PER
DIVISION
1. Servo Motor Duty Cycle
a. Connect an oscilloscope probe to the motor
duty cycle test point. Pin 9 of P301 on the
motor control board.
b. Adjust R313 so that an approximate 70% duty
cycle is observed on the scope display. This
adjustment must be made with a tape cart 
ridge running in the transport. See Figure
5-1. Slight variations in the duty cycle will be
observed as the controller compensates for
rotational nonlinearities of the motor.
2. Program Playback Amplifier
a. Program level — The output level is factory
adjusted to 0 dBm while reproducing an NAB
1 kHz reference tone (160 nWm). R 109 is the
mono level control and left channel of stereo.
R 110 is used for right channel level control.
Figure 5-1
See PC card overlay — Section VI. If an out 
put level lower than -10 dBm is required, an
external pad should be added in order to
preserve the optimum signal-to-noise perform 
ance of the system. Whenever an output level
adjustment is made, a corresponding Pro 
gram Play meter calibration must be made,
as outlined later in the Record Amplifier
Meter calibration section.
b. High Frequency Equalization — High fre 
quency equalization controls R107 (left or
mono) and R108 (right channel) are used to
adjust 10 kHz so that it matches the 1 kHz
level established earlier on the test tape.
3. Cue Detect Sensitivity
Cue tone detection in Delta Series reproduc 
ers is performed by a digital detector. Cue tones
recorded in accordance with NAB standards for
frequency and level tolerance will operate the
Delta digital cue detector. No adjustments are
required.
C. RECORDER
1. Input Level Strapping
a. This "adjustment" involves only a strap posi 
tion change if required. The strap positions
accommodate a wide range of input refer 
ence levels to obtain optimum signal-to-noise
and front panel level control positioning.
b. Refer to the Record and Meter Amplifier card
drawing found in Section VI.
c. As shipped from ITC, the input strap is con 
nected for a 0 dBm input level range. The "0"
correspondence to a 0 VU meter reading
when the level control is at its approximate
mid-range position.
5-1