TB 9-6625-1982-24
CAUTION
To avoid damage to the plug-in circuitry, power must be OFF
on the mainframe power module before connecting the TI.
b. With power OFF, connect TI to mainframe power module using extender.
c. Pull mainframe power module ON-OFF PWR switch to ON and allow at least 30
minutes (60 minutes if stored in high humidity environment) for equipment to warm-up
and stabilize.
d. Remove left or right side covers of TI as necessary to make connections or
adjustments. Replace cover(s) after completing adjustments.
30. Time Base
NOTE
Adjustment of the Time Base Oscillator is no longer performed
unless an out of tolerance value is determined while
performing the Time Base Performance Check.
a. Performance Check
(1) Connect time/frequency workstation 1 MHz OUTPUT using cable and 50
termination (if needed) to TI INPUT.
(2) Adjust TI TRIGGER LEVEL control for a stable display.
(3) Verify that the TI readout is within ±6 PPM (999.994 and 000.006) with display
OVERFLOW light on.
(4) If within tolerance disconnect connection made in a (1) and proceed to next
paragraph. If out of tolerance perform b below.
b.
Adjustments
(1) Adjust time base oscillator C2051 OSC ADJ (fig. 5) until the TI display reads
between 99.9998 and 00.0002 (OVERFLOW light on).
(2) Allow oscillator time to settle (at least 1 hour) after making adjustment and
verify it has not drifted. If needed repeat (3) above.
(3) Disconnect connections made in a (1) above.
(4) No further time base adjustments can be made.
