Figure 1-6. HSS and helicoptar interconnect diagram

TM 9-1270-212-14&P

Figure 1-6. HSS and helicoptar interconnect diagram

b. Reticle Power. Power to light the pilot and gunner

sheet 1). The 28-volt output is comected across gated

reticles in the helmet sights is provided by T3. The outputs

diode Q1 and zener diode CR4. The gated diode does not

of T3-1 and T3-4 provide 8 volts ac, which is attenuated to

break down unless it is triggered at the gate input, and,

5 volts ac by R5 and R6 on TB1 when the reticles are

once triggered, it trips to a near short-circuit condition and

connected. There will be no drop across R5 and R6 in a

does not automatically reset. The gated diode can only be

no-load condition. R5 provides power for the pilot reticle

reset by turning off power momentarily. Zener diode CR4

through J1-d, and R6 provides power for the gunner reticle

does not conduct unless the supply voltage exceeds 36

through J1-e. J1-d is connected to the reticle brightness

volts. If the voltage exceeds 36 volts, CR4 cortducts and the

control on the pilot armament control panel in the

voltage dropped across R1 is sufficient to triger Q1. PS1 is

helicopter. The 0- to 5-volt ac output of the brightness

not damaged if the crowbar circuit shorts the output,

control is connected to the interface control unit (IFCU) in

because it contains automatic current limiting protection.

the helicopter. The IFCU applies the ac power to pins 1 and

3 of pilot helmet sight plug A1P1, lighting the three helmet

115-volt, 400-Hz ac input power is

(3) The

sight lamps in parallel (refer to fig. l-11). J1-e is connected

distributed as listed for ECP5 on foldout FO-4 or FO-5. T1

to the brightness control on the gunner armament control

provides a pair of 10-volt and a pair of 20-volt inputs to

power supply card A12 through T1 pins 3 and 4,9 and 10,

panel, to the IFCU, and to pins 1 and 3 of gunner helmet

5 and 6, and 7 and 8. Refer to foldout FO-9. These inputs

sight plug AlP1; the gunner reticle is lighted in the same

energize four full-wave bridge rectifiers, the outputs of

manner as the pilot reticle. For specific helicopter wiring

which are connected to solid-state regulators AR1 through

information and IFCU location, refer to: TM 55-1520-

AR5. The regulators are current limited and thermally

234-23 for the AH-1S(Mod) helicopter, and TM 55-1520-

protected against overload. The remaining circuitry is used

236/239-23 for the AH-1S helicopter.

during a BIT and is discussed in paragraph 1-22c(2)(i).