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M860-00-Preliminary
T867 Fault Finding
C5.15
Copyright TEL
30/06/98
5.7.5
Audio Processor
N
IC240 pin 6
at 9V?
Key exciter &
lock synthesiser.
Connect 1kHz audio
to external CTCSS input.
Does exciter
modulate?
Audio output at
IC260 pin 8?
N
Y
Check audio path to
VCO control line.
Check alignment
of modulators.
Y
N
Audio output at
IC260 pin 1?
Y
Check buffer IC260
pins 8, 9 & 10.
N
Audio output at
IC260 pin 7?
Check low pass
filter stage IC260
pins 1, 2 & 3.
Y
Check stage IC260
pins 5, 6 & 7.
N
Demodulated audio
frequency response
flat between 50 & 300Hz?
Y
Check low
pass filter
stage IC260
pins 1, 2 & 3.
N
N
Y
Audio frequency
response IC260
pin 1 flat 300Hz
to 2kHz?
Audio frequency
response IC210
pin 8 6dB/octave
slope?
Check integrator
IC210 pins 8, 9, & 10.
N
Y
Audio superimposed
on 200kHz signal
IC720 pins 9 & 3 (synth)?
Check audio path
between integrator
& phase modulator.
N
Y
200kHz clipped
triangle wave at
IC720 pins 8 & 4?
Check IC720, Q710, Q720,
Q730, Q740, D710, D720,
C727, C729, C724 & C725
N
Y
Check loop filter
(IC750, pins 5, 6 & 7)
& associated
components.
Select standard
audio configuration.
Check pre-emphasis
network IC230 pins 12,
13 & 14 &/or low pass
filter IC260 pins 1, 2 & 3.
N
Y
Connect audio
to line input;
key exciter.
Does exciter
modulate?
Y
N
Demodulated
audio frequency
response as per
Section 4.5?
Audio processor
OK.
Audio signal at
IC210 pin 14?
Y
N
Audio signal at
IC230 pin 1?
N
Audio signal at
IC230 pin 14?
Y
N
Audio signal at
IC240 pin 4?
Y
N
Y
Check Q260 is not faulty or
being turned on inadvertently.
Y
Check audio path between
limiter IC210 pin 14 &
summing amp. IC260 pin 7.
Check IC210
pins 12, 13 & 14.
Check IC230 pins 1, 2 & 3 or
audio path between pre-
emphasis network & limiter.
Check IC230 pins 12, 13 & 14
or audio path between multiplexer
& pre-emphasis network.
Check IC240 or audio
path between line trans-
former & multiplexer.
Summary of Contents for T860 Series II
Page 6: ...AII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 12: ...A2 4 Mechanical M860 00 Preliminary 30 06 98 Copyright TEL...
Page 18: ...BII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 20: ...B1 2 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 30: ...B1 12 T865 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 32: ...B2 2 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 42: ...B2 12 T865 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 56: ...B3 14 T865 Initial Tuning Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Page 58: ...B4 2 T865 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 84: ...B5 20 T865 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 86: ...B6 2 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 90: ...B6 6 T865 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 110: ...T865 Preliminary PCB Information T865 Grid Reference Index Page B6 26...
Page 112: ...CII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 114: ...C1 2 T867 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 148: ...C4 2 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 154: ...C4 8 T867 Functional Testing M860 00 Preliminary 30 06 98 Copyright TEL...
Page 170: ...C5 16 T867 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 172: ...C6 2 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 176: ...C6 6 T867 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 204: ...T867 Preliminary PCB Information T867 Grid Reference Index Page C6 34...
Page 206: ...DII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 208: ...D1 2 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 214: ...D1 8 T869 General Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 216: ...D2 2 T869 Circuit Operation M860 00 Preliminary 30 06 98 Copyright TEL...
Page 224: ...D3 2 T869 Initial Adjustment M860 00 Preliminary 30 06 98 Copyright TEL...
Page 230: ...D4 2 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 238: ...D4 10 T869 Fault Finding M860 00 Preliminary 30 06 98 Copyright TEL...
Page 240: ...D5 1 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 244: ...D5 2 2 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 254: ...D5 2 12 T869 PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...
Page 256: ...EII M860 00 Preliminary 30 06 98 Copyright TEL...
Page 258: ...E1 2 T860 VCO PCB Information M860 00 Preliminary 30 06 98 Copyright TEL...