Ps Interface Pcb - Harris ZX2500 Technical Manual

ZX Series
Q17 provides a ground to this amplifier chassis and all chassis connected to the
SYSTEM INTERFACE bus when a "Exciter Ready" mute is being called for by the
FlexStar exciter while switching modes.
J3 and J4 provide an interface point for an optional Web Remote daughter board. T1,
CR3, and J10 provide the necessary connection interface between the Web Remote
Ethernet output and a CAT5 cable from the outside world.
4.8 8X PS Interface PCB
Consult drawing 801-0203-531 page 1
The PS interface board serves as an interface between the plug-in power supply
modules and the transmitter chassis. It also serves as an interface point for the cooling
fan power and logic connections.
AC mains is input via a series of faston connectors and passed directly to the E and F
blades of connectors J1 through J8.
AC sample circuit T1-CR12 produces a sample of the incoming line voltage of one
input. This circuit signals an AC fault via comparator U1A and inhibits PS module via
Q1 when the incoming AC mains voltage falls below approximately 190V. It is
necessary to artificially restrict the AC input range of the PS modules to 190V to
prevent excessive current surges during brownout conditions down to 90V, the nominal
low voltage cutout point of the PS modules as supplied from their manufacturer. The
other two AC inputs have similar circuits as driven by transformers T2 and T3 on
subsequent pages of the schematic.
The D1 pin of each PS module is driven by the V_PROG DC voltage passed from the
front panel controller via buffer amp U3D (page 4). This voltage can adjust the PS
module output voltage over an approximately 43V - 53V range.
Comparator U1B compares the PA8 current sample against a reference from voltage
divider R18-R50 and pulls PS control pin D3 low via steering diode CR1A when the
PA8 current sample exceeds 3V. This corresponds to a +3.5V fault condition
originating in the PA backplane boards, as described previously. The PS module can
also be shut down by a low condition originating in CR1B-Q1 due to an AC fault or in
CR1B-CR1G-U4A (page 4) when a off condition is received from the front panel
controller. Comparator U4A will hold its output low whenever the ON_OFF_RESET
(J9-3) line from the controller falls below the +0.8V reference from voltage divider
R55-R54.
12/20/11
WARNING: Disconnect primary power prior to servicing.
Section 4 Theory of Operation
888-2595-001 4-9