ELECTRONIC STATION (cont)
If the output voltage exceeds the zener reference level, a
crowbar turn-on signal is produced.
The signal is amplified and applied to the crow-
The crowbar is turned on, shorting out the power supply output until the
ac input power is recycled.
AC CONTROL PANEL ASSEMBLY 1A5
(1) General.The ac control panel assembly 1A5 (FO-7) consists of five
15 ampere circuit breakers (CB1-CB5) and a terminal block (TB1).
Refer to FO-33 for
ac power distribution diagram.
(2) Circuit Description
(a) Facility power of 115 vac is applied to the ac control panel assembly on
three wires (neutral, ground, and hot).
The neutral wire is connected to TB1,
terminal 1 (terminals 1-4 are connected), and the ground wire is connected to TB1,
terminal 11 (terminals 11-16 are connected).
The hot wire is connected to TB1
(terminals 6-9) and then connects to the line side of circuit breakers CB1 thru CB5.
All of the output cables neutral and ground wires are connected together at their
respective terminals, while the hot wires are switched by circuit breaker CB1 thru
The circuit breakers function normally as on-off switches and if the delivered
current exceeds 15 amperes they disconnect the circuit.
To reset, the circuit breaker
handle must first be set to OFF, then to ON.
(b) Circuit breaker CB1 supplies power to electronic station plugmold 1J2,
CB2 supplies power to electronic station plugmold 1J1, CB3 supplies power to elec-
tronic station disc/tape drive assembly 1A1O and digital computer assembly 1A11, CB4
supplies power to test console test bench plugmold 2A2W2A2, and connector 2A2A4J3, and
CB5 supplies power to test console test bench plugmold 2A2W2A1.
PMT CONTROLLER 1A7
The PMT controller 1A7 (FO-8) provides power to maintain the
optical signal analyzer 2A1A1 PMT at a constant temperature.
When describing the
function of the PMT controller, the complete system is discussed.
(a) The PMT housing unit is cooled by two thermoelectric elements pumping
heat to a heat exchanger, where the heat is removed by a fan.
A thermistor (sensor)
mounted in the cold area of the housing monitors temperature.
(b) When the PMT controller is first turned on, it will pump current through
This cools the housing and lowers the temperature of the sensor. The
resistance of the sensor increases as the temperature decreases until the temperature
of the housing is equal to the temperature preset by the front panel temperature