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WARNING: Disconnect and lockout AC primary power prior to servicing
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5.5.1.20 DC Distribution
The last sheet of the drawing shows the DC distribution and the voltage present LEDs.
There is a three terminal regulator for the 3.3 volt sense. and a LM4040 is used as a
4.096 volt reference. This reference is used by the analog to digital metering circuitry
and the voltage can be checked at the test point.
5.6 The Slave Controller Description
5.6.1 Slave Controller
The Slave Controller in the Platinum TV transmitter series is the local controller for
each PA cabinet. All of the slave controllers communicate with the Monitor in the
control cabinet via a communications bus, which loops from the Monitor through all the
Slave controllers and is terminated at the last controller on the bus.
The slave controller has a unique address code, set by means of a DIP switch, S1, on the
slave controller board. This allows the Monitor to send commands to, and receive data
from each slave controller.
The address latching and bus interface logic for the slave controller are shown on Sheet
1 of the drawing.
5.6.1.1 Sheet 1
A slave controller address, received by bus transceivers U1 - U4, is stored in the
Cabinet Address, Latch U6, and is then compared with the cabinet address selected on
S1 by U7. If the address numbers do not match, the slave ignores the following data. If
a match is seen, DS1 (ADR Select) lights briefly and the same signal operates the Read
Strobe encoder U8, generating a read strobe on one of 8 output lines based on the low 3
bits of data from the cabinet address latch. The read strobe is then used to select a block
of 8 status conditions (sheets 3 and 4) to be fed back along the bus to the monitor as
data.
If an analog reading is being called, the ADR Select line, along with low on the C/D*
and WR* lines, clocks the MUX ADR LATCH U9, storing the 6 low data bits and
routing them as address to the analog multiplexers shown on Sheet 6.
The Control Bus Receiver U5 receives the C/D*, WR* and RD* lines from separate Bus
conductors and uses them to provide drives to the latches and transceivers on Sheet 1.
The Power Up Reset circuit, U13, switches from a low to a high output as the 5-volt
power supply rises at turn-on. This signal is used to reset the TX ON/OFF Latch (sheet
2), and the delay latches on sheet 7 when power comes on.
A Cabinet Interlock input is provided (Sheet 4) for use with some versions of the
transmitter as inputs for reject load interlock contacts. It is isolated by U36 and then
read as a status, and also routed to U10 (sheet 1), where the external interlock light DS7