STUDER REVOX C279 Serviceanleitung Seite 103

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4.
ALIGNMENT
INSTRUCTIONS
CONTENTS
4.
ALIGNMENT INSTRUCTIONS
4.1
GENERAL
INFORMATION
1.1.1
0emagnetjzing the
mjcrophone
input
tnansformers
l+.1.2
Required measuring instruments
4.1.3
Pneparatory
steps
4.?
POhIER
SUPPLY
PCB
1.775.300
t+.2.1
PHANToM
suppLy
t+
.2
.2
+1
5
V
supp
Ly
t-.2.3
-15
V
supply
t+.3
DISPLAY
UNIT
'1
.775.310
1.3.1
ALigning
the output
meter
4.4
INPUT
UNIT
1
.775.334
1.4.1
ALignjng
the
harmonic
distontion
1.5
MASTER UNI
T
1
.775
.340
1.5.1
ALigning
the
harmonic
distontion
I+.6
MEASURING THE AUDIO
DATA
1.6.1
Harmonic
distortion
1.6.2
Output Level and
channeL balance
1.6.3
Fnequency response
t+.6.1+
channeL separation
4.6.5
SignaL-to-noise
ratic
Page
4.1
GENERAL INFORIIATION
CAUTIoN:
E[ectnic
shock hazard
rhen the
unit is
open!
Certain
components
are
energized
uith
tine
voLtage.
Modules
supptied by
STUDER
REVoX
can
be
instaLLed
rrith-
out
prjon
atignment.
RecaLibnation
of
the mixing consote
is
necessary
only
aften atteratjons
to
the
individuaL
moduIes. This
mixing
consote
generation nequires
no
scheduLed maintenance.
The
onLy maintenance
required
is
the occasionaL
demagne-
tjzation
of
the input
tnansfol"mens
as descnibed be[or.
1.1.1
Demagnetizing
the
micnophone
input
tnansformers.
Prohibited
connection
of
unbatanced
input
sounces
or
unintentionat
shor
t-cincuit to
chassis oJ
the
a/b
audio
conductors
of
the
microphone
inputs rdith
connected
phan-
tom
suppty dnive
the input
transformers
into
saturation
and cause permanent magnetization
(nemanence).
Thjs manifests
itsetf
disadvantageousLy
jn
form
of
signi-
{icantty
higher
harmonic
distortion
and so-catLed micro-
phonic
noise: tight
mechanicaL
action on the mixing
con-
sote, e.g.
tapping
on
it,
causes
an audibLe
moduLation
via
the outputs
even
when
the microphone
inputs
are
not
active.
Remanence
can
atso
accumuLate
over
extended
operation
per
j
ods
.
ALI microphone
inputs
shouLd
be demagnetized penjodjcaLLy
and
prior to
any
ca[ibration:
Pnocedure:
r
Suitch
off
the mixing
consote.
(To
protect the
connected speakers.)
r
Feed
a
fnequency
of
<32 Hz fnom an
AF
generaton
via
an
isolating
capacitor
to
the
micnophone
input.
-
Capacitor
C=1000 UF bLocks
DC
components.
- Resiston
R=600
Q
is
used
fon discharging DC
compo-
nents
{nom
the
capacitor'.
r
Increase
the
supply
LeveL
gradualty
{rom
0 V
to 3
V.
r
S
I
o
u
L
y
decrease
the
suppty
LeveL
to
0
V.
1
000uF
10v
G E
NE
RATOR
f 332H2
8v...3v...@u
E 4/1
E 4/1
E
4/2
E
4l?
E
t+12
E
1/2
E 4/2
E
1tz.
E
4/?
E
4/3
E
1t3
E
4/3
E
4/3
E
t,l1
E
4/4
E
t+/5
E 4t5
E
4/5
E
1t5
E t+/5
E t+/5