OPERATOR MAINTENANCE AND ADJUSTMENTS
5.5.5 LOS THRESHOLD ADJUSTMENT (Routine Adjustment)
a. Perform a Master Reset on the TM7000 (see Step 5.1.1).
b. Connect J3 Pin 11 (LOS) to an Oscilloscope, using J3 Pin 9 as the return.
Observe this signal to be at a true (Hi) level with no Code Input to rear panel
BNC connector J8.
c. Connect an adjustable amplitude IRIG B modulated Serial Time Code to an
oscilloscope and to J8, the Code Input of the TM7000.
d. Adjust the IRIG B Serial Time Code input for a level of 1 Volt peak-to-peak or
other desired level.
e. The loss of signal (LOS) threshold is adjustable with the “THOLD”
potentiometer (R132), located near the left rear corner of the STCG
Assembly. Starting with the potentiometer fully CCW, slowly adjust CW until
the signal at J3 Pin 11, LOS, goes true, then turn CCW until LOS goes false.
5.5.6 MULTI-ENCODER CODE OUTPUT ADJUSTMENTS (Routine Adjustments)
a. From the “Select VERSATILE DISPLAY Function” menu, select sequentially,
GENERATOR/SET-UP/OUTPUTS/RE/GEN.
b. Select “B” (or other desired code) by pressing the switch directly below it and
observe it to blink.
c. Connect the rear panel BNC connector J12, the Multi-Encoder Modulated Serial
Time Code Output, to an oscilloscope terminated with 50 Ohms and observe the
Modulated Serial Time Code.
d. Amplitude Adjustment: While observing the code output on an oscilloscope,
adjust R20, labeled “AMP”, for 3 volts peak-to-peak (or other desired amplitude)
into a 50 Ohm load.
e. Modulation Ratio Adjustment: While observing the code output, adjust R21,
labeled “RATIO” for the desired ratio of the “Mark” amplitude to the “Space”
amplitude.
Symmetricom, Inc. TM7000 TymMachine TCG/T (Rev D) 5-11
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