Gyro alarm circuits
Gyro signal card
Source light failure detector
Power distribution circuits
The gyro demodulator is a nonrepairable item. The
gyro demodulator receives 115-volts ac, 400-Hz
reference signals from stator leads S1 and S3 of the pitch
the ac synchro signals to dc with the in-phase ac signal
positive and the out-of-phase signal being negative. This
type of demodulator is called a phase-sensitive rectifier.
For an in-phase signal, the device behaves as a bridge
rectifier with a capacitor falter to remove ripple.
Figure 3-27.--Inverting amplifier diagram.
The internal gyro synchros that feed the demod-
ulator are excited with 26 volts ac, 400 Hz and have a
maximum output between S1 and S3 of 11.8 volts ac at
its input resistor and the feedback resistor with the inputs
±90° rotation. When the signals are demodulated by the
No voltage greater than 15 volts should be applied
rotation from horizontal.
to any pin of an op-amp or damage will result. The
op-amps output is short-circuit protected; thus, shorting
Linear Voltage Differential Transformer
the op-amps outputs will not damage them. Op-amps
exhibit three common types of failures: no output,
The LVDT is an ac electromechanical transducer
saturated positive, and saturated negative. A saturated
that converts physical motion into an output voltage
voltage is one that is maximum for a particular op-amp
whose amplitude and phase are proportional to position.
usually greater than 11 volts. Any op-amp whose output
In operation, an ac excited primary winding is
is greater than 11 volts and does not change with varying
coupled to two secondary windings by a moveable core
inputs may be defective. Check for large inputs and open
placed between them (fig. 3-28). Displacement of the
feedback resistors before replacing the op-amp.
The GSI system electronics is divided into 13
fictional areas as follows:
LVDT demodulator card
Figure 3-28.--LVDT aimplified schematic