ELECTRONIC STATION (cont)
Line voltage of 115 vac is supplied to the voltage transformer and
PMT housing fan through the POWER switch/indicator and power relay. From there it is
rectified and sent to the input of the power amplifier.
(a) A temperature reference point voltage is established by the temperature
This voltage is summed in a differential amplifier with the PMT housing
temperature sensor voltage through the temperature sensor amplifier. The differential
amplifier output is proportional to the difference between the actual temperature of
the cooled housing and the temperature point set by the temperature control. This
difference voltage is amplified by the driver (which drives the power amplifier) and
supplies current to the temperature elements in the PMT housing.
(b) The scope drive amplifier subtracts the temperature control reference
from the output of the differential amplifier and its output is used to
the temperature control voltage at the rear panel SCOPE DRIVE connector.
If a cooling system failure occurs, the overheat thermistor
(sensor) increases in temperature, thus decreasing its resistance. The decrease in
resistance causes the overheat sensor amplifier to energize the overload relay. When
the overload relay energizes, it causes the power relay to reenergize and turn off the
With the POWER switch/indicator turned on and the power supply
deactivated, the OVERLOAD indicator turns on.
After the PMT housing overheat
condition passes, the PMT controller can be reactivated by pressing the RESET switch.
h. EXTENDER ASSEMBLY 1A9
The extender assembly 1A9 (FO-9) consists of two HP-IB extenders
Extender 1A9A2 transmits and receives serial data from the HP-IB
connected to, and supplied with, the AN/USM-410 electronic equipment test
Extender 1A9A1 transmits and receives serial data from the HP-IB extender
the test console test bench.
Both extenders transmit and receive 16-bit
data from the digital computer assembly 1A1O or 1A11.
(a) A data frame arrives as a string of 22 bits at the receive coupler. As
passes through the receive coupler, it is synchronized with an internal
(b) From the receive coupler, the data frame is clocked into the decoder.
After decoding, it is clocked into the 16-bit data register where the four parity
bits, start bit, stop bit, and frame reject signal are checked. If correct, the 16
data bits are converted from serial data to parallel data and loaded into the parallel