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3. Checking audio signals
. When the check tool of "2-3-2" is used as an oscillator for tape playback and as the MIC signal of
each student while the level meter is used as the student monitor of the OPU, then all items of the
self-diagnosis can be performed. (Refer to the pair pattern table and the conference pattern table.)
. When the "random pair" and/or "group conference" functions cannot be used at all, check the
peripheral circuits and components of the audio switch shown on the simplified audio block
diagram.
. When an abnormality occurs in a specific student, check the parallel connections such as mutual
interconnections between different student booths, on the simplified block diagram.
. When an abnormality occurs in a specific student pair No., or in a specific group No., check the
serial connections on the simplified block diagram.
Simplified Block Diagram
Tape playback
and MIC of
each student
IC33
Monitoring of
each student of
OPU
Audio switch
IC33 to IC54
n
The input circuit and the output circuit of the cross-point switches are turned on and off by the same gate.
(IC1 and IC2), (IC3 and IC4), (IC5 and IC6), (IC7 and IC8), (IC9 and IC10), (IC11 and IC12), (IC13 and
IC14), (IC15 and IC16)
A
B
C
D
1
TP3
TP4
TP5
2
3
TP6
4
5
6
7
D4
CN6
8
D2
CN5
S1
9
D1
D3
LLC-8000A
IN 1
IC1
32
33
IC5
64
8
GP1
OUT 1
IC2
32
33
IC6
64
E
F
G
H
J
TP7
2-3. Self-diagnosis of the ASW-58 Board (LU-800B/LU-801B)
IC9
IC3
IC13
IC7
9
16
17
24
IC4
IC10
IC8
IC14
K
L
M
IC11
Cross-point
switch for
mixing inputs
IC15
25
32
Amplifiers
IC17 to IC32 of
each group
IC12
Cross-point
switch for
distributing
the outputs
IC16
2-13
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