TM 11-5820-890-30-4
2-16. SELF-TEST. Continued
The next display checks the display elements.
All the dots in each digit of the display are lit. The SIG display
segments are lit in sequence.
The HUB LOW display is also lit.
b. Receive Path Test (FAIL1). The receive path is tested in four steps. First, the control module performs a
memory check (RAM and ROM). Second, the control module checks the TONE SQUELCH line. It should be at
logic 0 since there is no received signal. Third, the receive path is checked at eight frequencies in the SC mode.
See figure FO-8. The 150-Hz tone is sent from the switching module (FM MOD) to the exciter/power amplifier.
The exciter/power amplifier uses the 150-Hz tone to modulate its 3.9-MHz output. The harmonics from the 3.9
MHz are used as the test frequencies. The tuner/mixer and synthesizer are stepped through eight frequencies,
The 150-Hz squelch tone presence is checked at each frequency.
Because the tuner/mixer and synthesizer
have several bands, it is possible that only one or two frequencies will fail. The last step repeats the receive path
checks for two frequencies in the FH mode.
There are secondary displays for each failed test. They will be displayed when any keyboard button is pressed
while the FCTN switch is being set to TST. They are:
SECONDARY DISPLAY
FAlLED TEST
1--01
Control module RAM
1--02
Control module ROM #1
1--03
Control module ROM #2
1--04
150-Hz detect line struck at logic 1
1--05
Receive at 78.0 MHz, SC
1--06
Receive at 66.3 MHz, SC
1--07
Receive at 58.5 MHz, SC
1--08
Receive at 50.7 MHz, SC
1--09
Receive at 46.8 MHz, SC
1--10
Receive at 39.0 MHz, SC
1--11
Receive at 35.1 MHz, SC
1--12
Receive at 31.2 MHz, SC
1--13
Receive at 78.0 MHz, FH
1--14
Receive at 35.1 MHz, FH
As a result of the receive tests, there are 10 short bursts of unsquelched rushing noise which can be heard in the
handset. However, because they are so quick and close together, they are difficult to count. At the end of a
successful self-test, a beep can be heard in the handset.
c. Data Rate Adapter Test (FAIL2). The data rate adapter section of the ICOM control module will perform
a self-test when the TEST line is set to logic 1. If the data rate adapter section passes self-test, then the DATA
MODE STATUS line is set to logic 1.
If it does not, the line stays at logic 0 and "FAIL2" will be displayed,
d. ECCM Module Test (FAIL3). The ECCM module also performs an independent self-test. It checks the
ECCM module’s RAM, ROM, interleaver, linear sequence generator, and other circuits. If it does not pass
self-test, “FAIL3” will be displayed.
e. Remote Operation Test (FAIL4). The remote operation test checks the remote l/O module and the
two-wire interface. It is performed separate from the above tests. The test is initiated when the FCTN switch
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