Figure 3-32.--Cyro alarm circuits--signal flow.

The gyro alarm failure alarm circuit can be disabled

A simplified signal flow diagram of the gyro alarm

by pushing the gyro alarm OFF push button. This

circuits is shown in figure 3-32. The switches are shown

supplies +15 volts dc to one side of the error relay and

in the normal mode of operation; namely, internal gyro

effectively disconnects the gyro failure alarm circuits.

operation with the failure alarm armed The gyro alarm

In addition an interlock circuit prevents unwanted plat-

circuit is only tied to the system in this mode by the

form oscillation when the alarm circuit is not actuated.

system supplies and the error relay. In operation, the ship

gyro signal is converted to a dc signal in the linear

Gyro Demodulator Board

synchro to dc converter (F110/F111). This signal goes

through the ship gyro stab-lock switch, is amplified in

the F106 card and is summed with a scaled voltage from

The gyro demodulator board contains a synchro to

dc converter and a gyro error detector circuit. The F110

the platform LVDTs and an offset voltage that makes up

and F111 are identical cards: one is used in the pitch

for alignment differences between the ship gyro and the

channel and the other in roll. The synchro to dc converter

platform base. This summed signal (error voltage) is

is a sealed module not repairable by shipboard person-

applied to the F110/F111 card, full-wave rectified,

nel.

faltered and compared against a preset threshold. If

the error voltage exceeds the preset threshold, the

Gyro Error Detector Circuit

comparator trips and removes the +15 volts from the

error relay. This turns off the SGSI cell and gives a not

ready indication at the remote panel. The comparators

The gyro error detector circuit consists of a pre-

on the F110/F111 cards are electrically latching relays.

cision N-wave rectifier, a filter, a voltage comparator,

If the error is removed, these relays can be reset by

a transistor, and a relay. The input signal to this card is

pushing the gyro alarm reset button to remove latching

the summation of the ship's gyro and the platform

LVDTs.

voltage.

Figure 3-32.--Cyro alarm circuits--signal flow.

3-24