SoundCraft SPIRIT 8, Руководство пользователя

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Page 9
Fault Finding Guide
Repairing a sound mixing console requires specialist skills, but basic Fault Finding is
within the scope of any user if a few basic rules are followed.
l
Get to know the Block Diagram of your console (see page 34).
l
Get to know what each component in the system is supposed to do.
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Learn where to look for common trouble spots.
The Block Diagram (see page 34) is a representative sketch of all the components of
the console, showing how they connect together and how the signal flows through the
system. Once you have become familiar with the various component blocks you will find
the Block Diagram quite easy to follow and you will have gained a valuable understanding
of the internal structure of the console.
Each Component has a specific function and only by getting to know what each part
is supposed to do will you be able to tell if there is a genuine fault! Many `faults’ are the
result of incorrect connection or control settings which may have been overlooked.
Basic Troubleshooting is a process of applying logical thought to the signal path
through the console and tracking down the problem by elimination.
l
Swap input connections to check that the source is really present. Check both Mic
and Line inputs.
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Eliminate sections of the channel by using the insert point to re-route the signal to
other inputs that are known to be working.
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Route channels to different outputs or to auxiliary sends to identify problems on the
Master section.
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Compare a suspect channel with an adjacent channel which has been set up identical-
ly. Use PFL and AFL to monitor the signal in each section.
l
Insert contact problems may be checked by using a dummy jack with tip and ring
shorted together. If the signal appears when the jack is inserted it shows that there is
a problem with the normalling contacts on the jack socket, caused by wear or dam-
age, or often just dirt or dust.
Signal Operating Levels
dBu
+30
+20
+10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
-110
-120
-130
L
I
N
E
+28dBu max.
+22dBu max.
+4dBu +4dBu
+6dBu
Channel
Fader
Channel
Inserts
Group
Out
Mix/Group
Bus
Group
Fader
Group
Inserts
Direct
O
utput
Mix
F
ader
Mix
Inserts
Mix
O
utput
Mic input EIN -129.5 (150 ohm source)