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numerals 12345678. These numerals should appear as 12.345678 on the frequency
LCD. If this display is correct, then a confidence factor of 99% can be assumed
regarding the total reliability of the A6A2 Assembly and a confidence factor of 60%
for the A9 Assembly.
6. Ensure that the Receiver is under LOCAL control. If MAN is not displayec in LCD.
momentarily depress the MAN pushbutton on the front panel to achieve Manual IF
gain control. Once MAN is visible on the LCD, ensure that SHORT, MED, or LONG
are
not present in the display. If any of these three indications are. present,
mom~ntarily
depress the corresPQnding SHORT, MED, or LONG pushbutton,on the front panel
to remove .the indication from the display.
.
When set up correctly, only the MAN display should be present in the LCD. Also. ensure
that the meter indication is set for
RF
level. Once this condition has been attained, slowly rotate
the IF GAIN potentiometer on the front panel from the full clockwise to full counter-clockwise
positions and back again while observing the RF level meter display in the LCD. The RF level display
should range from zero (no indication) to full'scale and back again to zero. If this range· is not at-
. tainable, then either the A4 Main IF Assembly (60% probability) or the A9 Front Panel Assembiy
(40% probability) is at fault and should be replaced.
'
NOTE
Failure to attain the desired range defmitely indicates that
proceeding with the BITE checks is useless until the problem is
corrected. On the other hand, full range indication demonstrates
that the A4 Main
IF
meaSurement system used by BITE is
f~nctional
and BITE checks will yield useful results.
Since steps I through 6 are prerequisite to successful BITE testing, BITE' may now be effectively
applied.
5.4.2
BITE Check
I.
Ensure that the initial Check Procedures (Paragraph 5.4.1) have been successfully
accomplished.
2. Momentarily depress the LOCK and AM pushbuttons on the front panel. The
Receiver will enter its BITE check mode as indicated by
(1)
the appearance of
REMOTE in the LCD display; (2) the rapidly changing frequencies, modes, and.
LCD displays on the front panel, and (3) the presence of rapidly changing AF
tones and sounds (if AF is being monitored). BITE performs checkout procedures
on the following assemblies:
A2 - First Mixer
A3 - Second Mixer
A4 - Main IF/AF
AS (if installed) - ISB
A6A2 (memory portion) - Microcomputer
A 7 - First and Third LO Synthesizers
A8 - Second LO 'Syn thesizer
IF Bandwidth Filters
NOTE
By observing the frequency display LCD, it is possible to isolate a
fault to the board level by noting BITE error code(s) which appear
in that display.
5-6
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