TM  11-5820-333-30 2-17.   SELF   TEST When its FUNCTION switch is set to TEST, the local control panel or the remote control unit tests itself and the interface to the control module. If good, the control module begins the rt self tests. The rt receive path and ECCM module are then checked. a. Control Panel or Control Unit Test (FAIL 7 and FAIL 8). The local control panel or remote control unit first requests a display update from the control module. If a response is made, the control interface is considered good. If not, “FAIL 7” is displayed. Then the control panel or control unit tests its RAM, ROM, and connections to the front panel switches. If a check fails,   “FAIL 8” is displayed. Pressing any key after FAIL 8 will display as follows: DISPLAY TEST 8-01 ROM 8-02 RAM 8-03 Switch   connections If neither FAIL 7 nor FAIL 8 occur, the control panel or control unit signals the control module to begin rt checks. b.  Display  Checks.  “E  -“  should be displayed when FUNCTION is set to TEST if the control test passes. The control module checks for the presences of the ECCM module. The ECCM module grounds the FH HERE-N line. See FO-8. If the ECCM module is absent, the letter” E” is replaced by a dash (-). The next display is “88888”. It checks the display segments. c.  Receive  Path  Test  (FAIL  1).  The  receive  path  is  tested  in  three  steps.  First,  the  control  module  performs  a memory check (RAM and ROM). Second, the TONE SQUELCH line is checked with no squelch tone present. (It should be at logic O). Third, the receive path is checked at eight frequencies in the SC mode and two frequencies in the FH mode. Squelch tone is included and the test passes if TONE SQUELCH line is at logic 1. The 150-Hz squelch tone modulates the 3.9 MHz oscillator located in the amplifier-oscillator. The harmonics from the  3.9  MHz  oscillator  serve  as  test  frequencies.  The  control  module  steps  the  synthesizer  through  the  test frequencies. Because the tuner/mixer and synthesizer have several bands, it is possible that only one or two frequencies will fail. There are secondary displays for each failed test. They will be displayed when a keyboard button is pressed as the FUNCTION switch is set to TEST. They are: DISPLAY FAILED TEST 1-01 Control  module  RAM 1-02 Control module ROM 1-03 Receive at 30.0 MHz, SC (no tone) 1-04 Receive at 78.0 MHz, SC (tone) 1-05 Receive at 66.3 MHz, SC (tone) 1-06 Receive at 58.5 MHz, SC (tone) 1-07 Receive at 50.7 MHz, SC (tone) 1-08 Receive at 46.8 MHz, SC (tone) 1-09 Receive at 39.0 MHz, SC (tone) 1-10 Receive at 35.1 MHz, SC (tone) 1-11 Receive at 31.2 MHz, SC (tone) 1-12 Receive at 35.1 MHz, FH (tone) 1-13 Receive at 78.0 MHz, FH (tone) The audio present during the “88888” display is a result of the receive tests. There will be 10 short bursts of unsquelched  rushing  noise.  However,  because  they  are  so  quick  and  close  together,  they  are  difficult  to  count. d. ECCM module (FAIL 3). The ECCM module also performs an independent self-test. It checks its RAM, ROM, interleave, linear sequence generator, and other circuits. If it does not pass, “FAIL 3” is displayed. The beep heard at the end of “88888” display indicates the presence of ECCM module. DISPLAY FAILED TEST 3-01 ECCM ROM #l 3-02 ECCM  RAM  #2 3-03 ECCM RAM 3-04 lnterleaver/Alarm 3-05 Linear  Sequence  Gen. 3-06 Non-Vol.  Memory  Protect 3-07 Sync Signal 3-08 interrupt  Signal 2-16