TM 11-5820-890-30-4
12-14. SELF-TEST. Continued
The RCU display is also tested in self-test. The RCU SIG display segments are lit in sequence until a full display is
achieved. C is displayed showing that the COMSEC module is installed, and then all of the dots in each digit of
the display are lit. The HUB LOW display is also lit.
There are secondary displays for each failed test. They are displayed when any keyboard button is pressed while
the FCTN switch is being set to TST. They are:
SECONDARY DISPLAY
FAILED TEST
9--01
Control module ROM-O
9--02
Control module ROM-1
9--03
Control module RAM
9--04
Two-wire interface
9--05
Main switching module
9--06
Bit sync switching module
9--07
Data rate adapter
9--08
COMSEC module
9--09
Not used
9--10
Not used
9--11
Asynchronous link
9--12
Fill routing module ROM
9--13
Fill routing module RAM
9--14
Fill detect
9--15
Fill I/O bus
9--16
Data rate select
9--17
Fill routing module DMA
9--18
Fill routing module timer
12-15. FILL OPERATION.
The COMSEC module requires fill data for CT operation. This data consists of COMSEC variables loaded through
the AUD/FILL connector by a fill device. This section discusses the loading of COMSEC variables using the
KYK-13 fill device. See figure FO-27.
The presence of the fill device is detected when it is attached to the AUD/FILL connector. The fill detect circuit in
the fill routing module places a positive bias on the FILL VA line. Fill devices operate at logic levels of 0 V dc and
-6.75 V dc. When the fill device is attached, it overrides the positive bias on the FILL l/A line. FILL SEL-N/R goes
to a logic 0 and FILL DETECT goes to a logic 1. FILL SEL-N/R is routed to the ICOM data I/O module where it
switches FILL INFO from the AT/FILL INFO line. It is also used in the fill routing module to switch the REQ-N line to
the PTT-N/REQ-N line.
FILL DETECT is routed to the control module. The control module monitors this line and issues a fill request to the
fill routing module (via the asynchronous link) if the FCTN switch is in LO and the LOAD/0 key is pressed. LOAD is
displayed when the fill request is issued.
12-21
