CHAPTER FIVE
5.5.7 PLL (CARRIER FILTER) ADJUSTMENTS (See Caution Note below)
To adjust the PLL circuitry located on the STCG, proceed as follows:
*** CAUTION ***
This adjustment is performed in the factory and should only be required following
replacement of parts in the immediate circuit. Incorrect adjustment will render the
TymMachine translator unreliable or inoperable
.
a.
From the “Select VERSATILE DISPLAY Function” menu, select sequentially,
TRANSLATOR/YES/NEXT/IRIG/B.
b.
While the “Translating” screen is shown, select “IN” under “FILTER” by
pressing a switch under “IN” and observe the “FILTER” screen to appear.
c.
Under “CARRIER FILTER” Select “in” by pressing a switch below it and
observe it now to be capitalized, indicating the Carrier Filter is IN.
d.
Press the “NEXT” switch and observe the “PLAY/SEARCH SPEED RATIO”
screen to appear.
e.
The “PLAY SPEED RATIO” must be set to “1:1”. If it is not set to “1:1”, it may
be set to “1:1” by pressing a switch under “slower” or “faster” until “1:1” is
shown.
f.
Connect an IRIG B 1:1 Modulated Serial Time Code input to rear panel BNC
connector J8, the Code Input BNC.
g.
The adjustment potentiometers R96, R97, and R88 are located near U40.
Adjust R96, labeled “RANGE 1” fully Clockwise.
h.
Connect J3 Pin 5 to the Universal Counter using J3 Pin 9 as the return and set up
the Universal Counter to read Frequency. The Counter shall display a frequency
of 1KHz +2Hz.
i.
Temporarily ground Pin 9 of IC U37 and adjust Potentiometer R97, labeled
“FREQB” for an output frequency at J3 Pin 9 of 960Hz +5Hz as read on the
Universal Counter.
j.
Remove the ground from Pin 9 of IC U37 and temporarily connect Pin 9 of IC
U37 to +5 Volts and adjust Potentiometer R96, labeled “RANGE1” for a
frequency of 5Hz as read on the Universal Counter.
5-12
TM7000 TymMachine TCG/T (Rev D)
Symmetricom, Inc.