Motorola R-20018 Manual page 52

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Module
A7
Processor 110
A9
Processor
A12
Front Panel
Interface
Table 5-7, Test Point Identification (Cont)
Test Point No.
Signal Name
4 Synth. D/ A Output
5 Ground
6 Composite Modulation Audio
7 Composite External Mod, Audio
8 Synthesizer Clock 104, 857.6 Hz
9
1 kHz Modulation Source
1
AID Input
2 Unfiltered 10.245 MHz T.V.
3
DVM/Freq. Counter Select
4
Frequency Counter Input
5
Not Used
1
Ground
2 Dot Clock
3
Character Row Clock
4 Character Clock
5 Enable
6 Character Line Clock
7 R/W Select
8 Char. Gen/Processor Select
1
Attenuator Buffer Output
5-46
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Test Paragraph
5-139
5-141
5-141
S-142
S-143
S-143
S-143
Table 5-6. System Troubleshooting (Cont)
Fault
SINAD meter inoperative
No generate output
No Frequency Modulation
Internal wattmeter in error
No monitor function
Monitor frequency error display
is missing
Monitor frequency error is in
error
S-43
Troubleshooting Procedure.
2. If sync pulse and the syn present lines are
okay replace the Scope Amplifier module
(A2).
1. If the DVM mode checks okay replace the
Scope/DVM Control module (A3).
2. If the DVM mode does not check okay go to
the troubleshooting list for DVM AC
inoperative.
1. Remove the RF cable between the RF Syn-
thesizer (AS) and the RF Input module (A11 ).
Check for a nominal -10 dBm level at the
Synthesizer output. If no output replace the
RF Synthesizer.
2. If the Synthesizer output is okay replace the
RF input module.
1. Check for modulation signal at pin 56 of the
RF Synthesizer (AS). If the signal is okay
replace the RF Synthesizer.
2. If the modulation signal is not present pro-
ceed to the troubleshooting list under "no
DPL (modulation) signal on CRT".
1. Replace RF input module (A11).
1. Apply a 10.7 MHz modulated carrier to the RF
input. Check for normal receiver operation
except reduced sensitivity. If receiver is not
working replace the Receiver module (A4).
2. If the receiver checks okay and the generate
function is okay. replace the RF Input module
(A11).
1. Go to the troubleshooting list under "fre-
quency counter inoperative".
1. Check for presence of IF signal at pin 91 of the
Scope/DVM Control module (A3). If not
present replace the Receiver module (A4).
2. If the IF signal is present replace the Scope/
DVM Control module.