888-2408-002 6-21
WARNING: Disconnect primary power prior to servicing.
Troubleshooting
• ISO_Az or ISO_Bz - These faults will most likely be preceded by PA and
PA_ISO faults which have imbalanced the Z-Plane outputs. PA currents, voltages
and temperatures and PA_ISO load temperatures should be checked as a likely
cause of this problem.
• ISO_AB - This fault will most likely be preceded by PA and PA_ISO faults
which have imbalanced the Z-Plane outputs. PA currents, voltages and tempera-
tures and PA_ISO load temperatures should be checked as a likely cause of this
problem.
Lastly, if the system is muted and the temperature continues to rise to 150°C, the
Master Controller will shut the transmitter off.
6.9.24 EXC#_FAULT, Fault
Indicates there is an exciter malfunction. This is a summary fault including VSWR,
Overtemp, etc.
6.9.25 EXC#_LOW, Fault
If forward power drops to 70% or less of normal exciter RF output an indication is
given.
6.9.26 EXC#_AFC Fault
This is the PLL unlock fault from the DIGIT Exciter or the SuperCiter. It causes no
direct transmitter action, but is merely displayed in the fault log and on the front
panel fault light. Action will not be taken until an exciter low power condition is
detected. The controller will delay 10 seconds to give the exciter time to recover,
then switch to another exciter (if available).
6.10 PA Signal Tracing
Tracing signals from the PA Controller to the PAs can be very confusing. The
problem lies in the fact that the PA Controller Boards and the Z-Planes are generic
except for the ID jumper settings which designate the board for a specific position.
Since the schematics for each of these boards must apply to any position, the
labeling is also generic.
For instance, the PA Controllers have the ability to control and monitor 8 amplifiers.
These lines to and from the amplfiers are labeled PA1-PA8 on the PA Controller
schematic. Since PAC#1 and PAC#2 control and monitor different amplifiers it
would not be possible to put the correct labels on the schematic with respect to
specific amplifier connections. As an example, the gate control voltage to amplifier
A4 comes from PA Controller#2. Tracing the signal from the A4 gate voltage input
back to PA Controller #1 would reveal that it is actually connected to the
PA7_GATE signal on the PA Controller schematic. PAC#1 also has a PA7_GATE
output, but it goes to amplifier B3.
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