User's Manual

APEX™ Exciter Incorporating FLO™ Technology
Exciter Maintenance Maintenance and Troubleshooting
2604s500.fm
03/08/07 888-2604-001 Page: 5-1
WARNING: Disconnect primary power prior to servicing.
5 Maintenance and Troubleshooting
This section is a maintenance and troubleshooting guide to the APEX exciter. It is divided
into the following three parts.
• Exciter Maintenance
• General Troubleshooting Notes
• System Troubleshooting
• Exciter Troubleshooting
Trouble shooting is to the board level only, if a board is defective it should be replaced.
5.1 Exciter Maintenance
All APEX circuit boards except the front panel board can be accessed while operating the
exciter. The APEX exciter is mounted in the transmitter on slides, permitting it to be pulled
forward out of the cabinet.
The top and bottom covers can be removed to provide access to the digital and analog
circuit boards. Figure 5-1 shows the top (analog) view and Figure 5-2 shows the bottom
(digital) view of the exciter with the covers removed. These drawings provide the names
and locations of the various circuit boards of the exciter.
The upper side of the chassis is the analog section, which consists of the up converter,
down converter, PLL (phase lock loop), RF output amplifier, power supply, UDC
(up/down converter) interface board, and the exciter cooling fan.
The bottom side of chassis houses the FPGA modulator, adaptive pre corrector, DAC
(digital to analog converter) converter, ADC (analog to digital converter), controller, and
the UHF external I/O (input/output) interface boards.
If the exciter is being bench tested and is inverted to access the bottom boards, the display
can also be inverted by accessing Display Invert function. The path to this function is Main
screen > Setup > Display.
The exciter wiring diagram is shown in Figure 5-3 (left side of drawing) and Figure 5-4
(right side of drawing). These two pages can be printed and fastened together to produce
one complete drawing.
5.1.1 Cleaning
Occasionally the circuit boards of the exciter will need cleaning. All precaution against
static should be observed. The technician should be grounded, either through conductive
shoes or through a static grounding strap.
The exciter should be powered down before the cleaning process is started. A vacuum
cleaner should be used to remove dust from the assemblies. A natural bristle brush with a
metal band and a wooden handle can be used to dislodge dust. A vacuum cleaner hose can
develop static due to the air rushing through the hose. The hose should have a metal nozzle,
which should be grounded.
Do not use compressed air to blow dirt from the exciter because the dirt will just settle back
down on something else. Also, the fast moving air could damage or dislodge delicate
circuit board components, and it could also accentuate static problems.