Table of Contents
Advertisement
i
n u - o i i o - i 3 / r r.
n r
a i : ^ L i v i , i \
MAINTENANCE
Table 4-35.
I/O Signal Activity Check
Test Point
Normal Signal
Key Components
Comments
U2-Q1 to Q7
Pulse train
1
msec PW
U7
Address Latch
U4-Y0,Y1
Pulse train
U4
Address Decoder
1
msec PW
Ul-20
1
5 MHz Clock
U5.Y1
7.
When the Asynchronous I/O has been repaired and is
operating satisfactorily, deenergize the receiver and
disconnect test equipment, if no further tests are to be
performed.
4.3.4.28
Serial I/O Buffer, A6A4, (794300) Testing and Troubleshooting
Serial I/O Buffer Testing and Troubleshooting includes a checkout
procedure and fault isolation information.
A Digital Voltmeter and a widaband
Oscilloscope (Table 4-1) are required to perform the tests outlined below.
The testing and troubleshooting information in this paragraph is keyed to
several fault isolation tables.
These tables are used to isolate the module fault to a
defective integrated circuit or functional group of integrated circuits.
Perform the
following procedure in the sequence given.
When a faulty signal is encountered,
replace the key components indicated in the table.
1.
Deenergize the receiver.
Remove the receiver top cover.
Place module A6A4 on an extender card.
Set the receiver to the following parameters:
a .
b.
c .
d.
e.
Tuned Frequency
Bandwidth
Gain Mode
Detection Mode
Tuning Rate
-
42.0000 MHz
50 kHz
AGC FAST
AM
Fast
Using the oscilloscope, verify the data signals using
Table 4-36.
Activity should be checked in conjunction
with rotating the tuning wheel slightly from side to
side.
4-53
Advertisement
Chapters
Table of Contents
