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WJ-8718A/MFP
MAINTENANCE
4.1.4.6.1
I/O
Interface Troubleshooting Procedure
1.
Reference the following manual data to support Tables' 4-17 and
4-18.
a.
Circuit descriptions in paragraph 3.3.1.
b.
Location of Components Diagram Figure 5-12.
c.
Schematic Diagram, Figure 6-7.
d.
Modular troubleshooting ·concept, described in
paragraph 4.1.4.1.
2.
Recommended test equipment for troubleshooting
I/O
Interface
components are an oscilloscope, digital voltmeter, and ohmeter
(reference the equipment list in the WJ-8718 Series HF Receiver
Instruction Manual), and the general purpose digital troubleshooting
equipment, described in paragraph 4.1.3.1 of this supplement.
4.1.5
SWITCH
AND
LED
TROUBLESHOOTING
The operation of front panel switches, LED indicators, and LED displays can be
diagnosed by execution of the BITE program. Troubleshooting the front panel is indicated if a
problem arises during the execution of the program which cannot be isolated to a module in the
microprocessor structure (excluding MFP-Al modules), discussed in paragraph 4.1.4.1.
The front panel section of the MFP Option consists of the Tuning Encoder
Assembly and the Front Panel Switch/Encode Assembly, mounted directly behind the front
panel.
The latter assembly contains two subassemblies:
the Front Panel Encode Board
(MFP-A1Al) and the Front Panel Switchboard (MFP-A1A2).
In
addition, the assembly contains·
the track to interconnect the subass.emblies and .2-channel audio amplifiers. The front panel
boards are interconnected in a manner which facilitates troubleshooting.
Plug-in connections
allow extender cards to be mounted in the MFP-Al board. The encode board can be plugged
into the extender cards, allowing all points on the front panel to be probed with the unit in
operation.
.
The Front Panel Encode Board contains the logic circuits which interface the front
panel switches and LEDs with the microprocessor.
The board design reflects the modular
concept described in paragraph 4.1.4.1.
Troubleshooting the board on a modular level is
described in paragraph 4.1.4.4.1.
The following troubleshooting information is based on an
evaluation of BITE program results and involves both the Front Panel Encode and the Front
Panel Switchboards. The switchboard contains two switch matrixes, associated LED indicators,
and 7-segment LED displays. The switches and LEDs are divided into two groups: Group 1 is
associated with the right side of the front panel, and Group 2 is associat..ed with the left side.
4.1.5.1
BITE
Program
Evaluation
1.
Access and execute the BITE program, as described in para-
graph 4.1.1.1.
If a problem occurs, proceed to troubleshoot,
while referencing the following manual data.
4-25
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