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067-1011-00 DSG
e)
If asterisks appear on screen in either of the above
checks then the cursor control has been turned the
wrong way, rolling the words the wrong way through
the windbw displayed on the scope for the data
position trigger mode that has been selected.
Check
also that the record function has been reset each
time any change has been made.
Step
6.
Crystal Oven Temperature Check
After the unit has had at least 20 minutes to warm up,
check for 14.3V,
+/-
o.2v, at the oven test point J675
on the back of A3 Digital Sweep Generator board.
ADJUSTMENT PROCEDURE
Step 1.
Preparation
Connect the Digital Sweep Generator to a host TM500
Power Module via the optional.accessory flexible
extender cable.
Allow 20 minutes warm up.
Step
2.
Oscillator Frequency Adjustment
Use a precision frequency counter such as a Tektronix
DC503A, Option 1.
a)
Connect a X1 probe to Pin 12 or 25 of the DIGITAL
DATA OUTPUT connector.
Set CLOCK to INT.
b)
Adjust C793 on the A3 board (see Fig. 4-1) for
14.31818,
+
or • 100 Hz, on the counter.
c)
If necessary, select C788 (see Fig. 4-1) to center
C793 in its range.
If the plates of C793 are
meshed less than approximately 10%, reduce the value
of C788.
If they are meshed more than about 90%,
increase C788.
4-11
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