Status.

c. Status.

(1) A total of 18 status signals and 2 spares are supplied from LRU-1

to the BTS to monitor the status of LRU-1. The signals are

monitored by indicator lights. The status signal, negative logic

is connected from LRU-1 Jack J7 through Cable W1 to Jack J1 on the

status panel.

(2) LAMP DRIVER ASSY 1A2A3 (U1, U2, U3, U4, U5) receives the status

signals from J1. The status signals are connected to five

identical integrated circuit chips. Each chip contains four lamp

driver circuits. Each driver consists of a two-input nand gate and

output power driver.

(3) Power Supply PS1 supplies +12 Volts to one terminal of al 1 status

panel lamps.

(4) Whenever the inverting output power driver receives a positive

logic 1 signal, that particular status panel lamp illuminates. The

following is a simplified circuit of the U1 lamp driver and status

lamp DS1.

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