Crown Studio Reference I Studio Reference II Service Manual page 25

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Studio Reference Service
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Manual
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mcrmwn*
Checkou
Procedures
t8,9
-10.31
1039
28.0 --10"26 10+26
21.7
.-.18.28 18.20
22.2 --16.14 1Qs?4
23.3 .-"i.09 1Q,$39
25.0 --toO~W 1O.W
25,6 --9.97 9.97
26.7
--8,9l 9.91
2 7 2 3 -.9+86 9.86
28,9 -9.80 9.80
30.0
-9.94
9.44
31.1 - 9 . 6 9 9-69
5,2 Standard initial Cowdltigns
32.2 -9.63 9.63
Level controls fully clockwise.
StereoBMano switch in Stereo.
Sensitivity switch in 26 dB fixed
gain
pasition.
It is assumed,
in
each step, that E h e conditions of the
amplifier
are per these initial conditions
unless other-
wise specified,
-ODEP
Proe8Bure:
Measure
pin
3 of 3500 and, if
news-
sary, adjust
R121
to obtain
V
, , , ,
a s specified
above.
Measure
pin
3
o f J700 and, if
necagsarx adjust
R22t
to obtain V , , , , as
s~ecifred above,
5,3
QC
Offset
+OOEP
~rocgiite:
~ e a s u r e pin 4
of
3500 and,
if
neces-
sary, adjust
R132 to obtain
V + , , , ,
as specified above.
Spgc;
8
WBC,
k 2 rnV
Measure
pin 4 of J700 and, if necessary, adjust R232
lnltial Ce~dttOax~gr Controls per standard, mputs shorted
oblasn
v + O L ) E P
as
Preeadurs: Msasure
DC
voltage at
the sutput canncc-
tors (rear panel). There
is
n s adjustment
for
output
off-
set. If spec
is not met, there
is
an
afectricai rnaifunc-
tian,
Sligh8fy
out of spec measurEment is
usually due
to U"iQiU204
0165:
of
tolerance,
5 . 4
Output Bias Adjustment
Spec: 300 ta
320
rnVDC,
ilnitiall
Gandstiaa$::
Contrais per standard, healsink
tern-
peratare
less
than 4 0 ° C
P~oeedurs:
Measwe DC
voltages or? the
output
mod-
ule
across
R02, adjust R26 if B-eecessary, Measure DC
voltages on t h e output module across
R21, adjerst R23
if
necessary.
Repeat for
second channel.
5,6 BC
Power Draw
Spbc::
70 Wazrs nmaximkam
quiescent.
initial Csnditions: Controls
per standard.
Procedure:
With
no
input s i ~ n a l and
BBQ
16ad,
measure
AC line wattage
draw.
if
current
draw is excessive,
check.
far high AC Iim voltage
or
high bias vsitaga.
5.7 High Line Gutout
Spec: Unit goes into standby when the AC
line
voftage
goes
^f 8% to
t o 12%
aabw
onominal,
lnltial Gondltionsl: Controls par standard.
Proeedgre: No load, no
signal,
Bring
up AC
line volt-
age
with
a
variac 10% to 12% high. Far 120VAC units
5.5 ODEP Voltage Adjustment
this
is
132VAC is 334.4VAC.
Unit should go
into
Spat: Bias
Per
Chart, ~ 6 , 4 V
DC.
standby. Adjust
R4
sn
the control
module if neees-
sary.
InltiaiP @oiaridition%: ContnaSs per
standard,
heatsink
at
room temperature 20 t o 30°C
(68 to
86°F)"
Note:
This
adjustrnerr"rh8ufd nsrmaliy be performed
wilhin 2
r~rintsts% 07 turn
an
from
ambient (esfd)
cornditions,
If
possible,
measure
healsink
temperature; if
not, msa-
sure
ambient room temperature. Use this infarmation
when referencing
the $.a/lawing chart,
5.8 Common
M o d e
Reje~tion
Spac: >70 dB at 1 kHz,
initial Cendilions:
Controls
per
standard,
Prosgdure: No
load, Inject
a 0
dBil(.775VRMS),
1
kHz
sine
wav@ into
each channel, one channel at a
time,
wieh inverting and
non-inverting
inputs
shorted to-
getkaer. Adjust R512 ( C h l ) and RE12 (Ch2)
for less
than 4,9mVRMS (-44 dBu) at the amplifier output.
Elcctrfcal Checkout
5-1