3-10
888-2587-001
4/18/11
WARNING: Disconnect primary power prior to servicing.
FM HD Radio System
Section 3 Operation
The operator may refer to the transmitter technical manual, Section 3, for specific
details on how to view and clear the Foldback fault-related description in the Diagnostic
Display’s fault log. If more troubleshooting is necessary, a
technician
can refer to
Section 6 of that manual for detailed fault explanations.
3.6.3.3
INTERLOCK LED Illuminated
The Interlock LED will illuminate for following reasons:
•
Transmitter is
muted because the
Failsafe
loop is open
•
The transmitter is
turned off and will not be allowed to turn on because the Interlock
loop
is open. This could be a response to a fault signal from a reject load, VSWR or
thermal detector, RF switch, etc.
Navigate through the ZHD+ Diagnostic display to the Fault Log to determine which
loop is open and causing the LED indication. The operator may refer to the transmitter
technical manual, Section 3, for specific details on how to view and clear the fault
description in the Diagnostic Display’s fault log. If more troubleshooting is necessary,
qualified personnel
can refer to Section 6 of that manual for fault explanations.
3.6.4
ZX Emergency Response
3.6.4.1
ZX Basic Operating Principle
The ZX transmitter is designed to automatically stay on air at the maximum safe power
possible. It will operate at the power level determined by its internal automatic power
control circuit unless commanded to reduce power via any of the foldback conditions
indicated on the front panel (i.e. reverse power, PA current, PS current, over-
temperature).
There are two exceptions to this principle in ZX transmitters produced after June 2007:
1. A sudden reverse power overload (i.e. an arc due to VSWR) will cause the
transmitter to issue an internal power lower command and permanently
lower the output power. With each successive arc, the transmitter will
lower power further until the cycle of arcing is broken.
2. Certain overtemperture conditions will cause the transmitter to automati-
cally reduce its power by approximately 50% until a reset command is
issued by a front panel ON command. This is typically the case when one
or more PA modules are removed from service for extended periods of time
