SECTION VI
TROUBLESHOOTING
6.1
Introduction
This section contains procedures for troubleshooting problems in a
Platinum Series
transmitter system.
The transmitter architecture is modular, consisting of several
subsystems. The basic approach to troubleshooting a problem in
the transmitter is to isolate the faulty subsystem.
Many transmitter problems can be identified by the fault and
status indicators on the front panel of the control cabinet. Infor-
mation given by the display can also assist in localizing the
source of the problem.
If a module failure is suspected, the easiest way to confirm or
disprove the possibility is by swapping the suspected faulty
module with a properly operating module from another slot. If
the fault follows the module, the problem is probably internal to
the module. If the fault remains at the same slot after substituting
modules, then the search for the problem should focus on the rest
of the transmitter system.
It is suggested that a chart be kept, showing a diagram of the
transmitter cabinet slots and the serial number of the module in
each slot. Also, keep a log of maintenance and repair performed
on both the modules and the transmitter system. This information
can be useful in isolating recurring problems.
6.2
50 Volt Power Supply Troubleshooting
Troubleshooting the 50 volt power supply may be done by a process
of elimination. First, a visual inspection of the power supply should
be performed to identify any overheated components.
When a power supply exhibits a fault condition, swap the control
board with one from another power supply or a different control
board if a spare board exists. If the problem follows the control
board, replace the control board.
NOTE
There is always a small risk in substituting boards; that a circuit
defect can result in board damage.
If the problem stays with the power supply, disconnect all power
to the cabinet containing the power supply, remove the power
supply from the cabinet and remove the lid. The next step is to
check for failed SCRs.
Removing the control card will allow access to the SCRs and
CR1. Using an ohmmeter, check each SCR and CR1 for a shorted
condition. A normal SCR will measure very high resistance with
the ohmmeter test leads configured in both directions. CR1
should measure a low resistance with test leads configured in one
direction and a very high resistance with test leads configured in
the other direction.
6.3
Cabinet Complete Power Down
It may be desirable in some cases to perform maintenance on one
visual PA while operating at reduced power using the remaining
cabinet.
When no power is available to a cabinet slave controller, it may
load down the data bus in early versions of the slave controller
and cause errors in the analog values displayed for the remaining
cabinet in use. Slave controller boards beginning with Revision
F contain a relay, K1, which automatically disconnects the slave
controller analog lines from the data bus when power is removed
from the board.
Disconnect the slave monitor ribbon cable at J1 on the slave
controller during service to lift it from the data bus and allow
normal readings for the cabinets still in use.
6.4
Monitor System RESET
S2 on the monitor board may be used to restart the system in the
event of lock up due to noise or transient from some external
source. User programming should remain intact.
6.5
Monitor System ABORT
S1 on the monitor board will restart the processor. Any user
programming must be reentered. The power set points will
default to the NORMAL values determined by the switch set-
tings. All alarms in the alarms queue will be cleared and will start
a new sequence of numbering the faults. The bargraph page and
D/A Edit selections will return to the default parameters.
6.6
Contents of Raw Data Screens
Here is an explanation of the data contained on the Monitor Raw
Data screens. There are three major types of data presented on
these screens:
a. Analog converted to Digital (A/D)
b. Bit wise Status Information
c. Monitor Microprocessor Exception status.
The A/D data is a decimal number in the range of 0 to 4095,
representing an analog voltage from 0 to 5 volts (4.99877..volts).
This can also be interpreted as 819 counts per volt.
The Status information is presented on the MAIN Screen as ON
or OFF while on the SLAVE Screen the information is presented
as 1 or 0. In general 1 corresponds to ON and 0 corresponds to
OFF.
The Microprocessor Exception status is displayed as Hexadeci-
mal digits. The status appears when a processing exception is
888-2365-001
6-1
WARNING: Disconnect primary power prior to servicing.
Summary of Contents for Platinum Series
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