DETAILED FUNCTIONAL CIRCUIT DISCUSSION

T.O. 31W2-2GSC24-2

TM 11-5805-688-14-1

NAVELEX 0967-LP-545-3010

5-588. When the output from AND gate U22 is high (no-

applied to one input of an exclusive OR gate. The

error condition), AND gate U36 is enabled. The low

diagnostic error signals applied to the display card are

output from AND gate U36 is applied as an enable signal

high-level in- puts in the no-error condition and be- come

to the lamp display decoder logic that causes signal RBI-

low-level inputs in the error condition. Self-test signal

to be generated and applied to the front pan- el. In a no-

ST2- is applied to the other inputs on the exclusive OR

error condition, signal RBI- causes the FAULT

gates. In normal operation, signal ST2- applied to the

LOCATION display on the front panel to show 00. The

display card is a high- level input. In the self-test mode

lamp display logic decoder also generates an indicator

of operation, signal ST2- becomes a low- level input.

enable signal to the front panel that causes all the

Each exclusive OR gate produces a low-level output

indicators to light in a no-error condition.

signal when both inputs are the same: both inputs either

high or low. The OR gate produces a high-level output

5-589. When one or more of the applied error signals

signal when the two inputs are different: one high and the

from the functional cards indicate a fault during the self-

other low. In the following discussion, the circuits on the

test mode, the self-test logic function that is performed is

display card are described in their normal operating

basically the same as described in the preceding

mode.

paragraphs; with two exceptions. The primary diagnostic

circuits cancel the 00 display function and the FAULT

5-593. Multiplexer positive stuff acknowledge signal

LOCATION display shows a defective card number

MPSA- from the OEG card conveys the diagnostic error

between 1 and 21. Also, the appropriate MULTI-

status for one multiplexer channel card during word 24.

PLEXER CARD or DEMULTIPLEXER CARD indicator

In a no-error condition, signal MPSA- is high and

on the front panel goes out.

becomes low in an error condition. Flip-flop U17-6 in the

multiplexer channel card error detector circuit produces a

5-590. When all the functional cards are in a no-error

clock pulse to counter U8 when low-level signal MPSA-

condition and an error condition is detected in the

and word 24 end-of-scan signal M24EPS2 from the OEG

diagnostic circuits on the display card, the output from

card are applied at the same time. At the time that

the card address self-test OR function circuit goes high.

counter U8 receives a clock pulse, the channel over-

Therefore, the output from AND gate U22 goes low. The

head address count signals (MOHO through MOH3) for

low-level signal enables the count 22 override circuit so

the card being sampled is parallel loaded into U8. The

that the FAULT LO- CATION display on the front panel

overhead address loaded into U8 is applied to the 12

shows 22. Also, the low-level input to the lamp display

inputs of multiplexers U3 through U6 in the card address

decoder logic generates signal LMCRD that causes the

encoder circuit. The low output from U17-7 is applied as

MULTIPLEXER CARD indicator on the front panel to go

an error signal to system priority encoder U7. If there are

out.

no other error inputs with a higher priority being applied

to encoder U7, the encoder produces the 010 address

select signals that are applied to multiplexers U2 through

5-591. DETAILED

FUNCTIONAL

CIRCUIT

U6.This address enables the T2 input of each

DISCUSSION.

multiplexer so that the dynamic and hard-wired card

address at the 12 inputs of multiplexers U3 through U5 is

5-592. Each card diagnostic error signal applied to the

applied to binary-to-BCD converter U12.

display card, except the out-of-tolerance inputs, is

5-160