Sherwood S-9500c User manual

SI{ER\ TOOD
Function
Switch.
Controls
stereoor
monooperation.
Selector Switch.
Chooses phono,
tuner, or auxiliarr
inputs.
Preamp Level. Controls
preamp level only.
Tape Monitor Switch.
Normally set to left.
If depressed right will
connect in tape
monitor jacks on rear.
Hi Filter. Depress
right for l2db,/octave
attenuation of un-
desired tones such.
as record "scratcht'.
INPUTS:8high level (2 tapemonitor),2 (RIAA) Phono-
preamp.
TOTAL POWEROUTPUT: 4 ohms: 140watts i ldb;
115
watts IHF;90 watts RMS.8ohms:
100
watts t ldb;
80 watts IHF; 70 watts RMS.
OUTPUTSz 4 to lGohm left and right spkr. main and
remote; mono speaker, stereo headphone
and record
output.
INVERSE FEEDBACK: 35 db.
DAMPINGFACTOR: 30:l at 8 ohms.
FREQUENCY RESPONSE:
2OHz to 20 KlIz r 1 db.
TONE CONTROL RESPONSE:
FIat setting, 20 Hz to
20 KHz tl db.
TONE CONTROL RANGE: 15KHz, 15
db,boost or cut
4O
Hz 20 db, boost or cut.
PREAMP. EQUALIZER CURVES: AES,zRIAAphono.
SENSITIVITY: Radio - 0.25v Phono - 1.6
mv.
Tape
head 1.2mv. (PH and TP inputs are adjustable with
Preamp I-evel control).
Tone controls for both channels.
Adjustment of the Bass or Treble
control knob will varl' the tone of
both channel s simultaneouslv.
5 1s&c
MODEI S-95OOc
STEREOAMPLIFIER
SERVICE
MANUAL
Main control for Power on-off and
Loudness of both channels. Auto-
matieally boosts bass at low levels
(if switch below is at t'Loudness Int').
.S-.Controls left-to- right
stereo balance.
Pilot Light
Remote Speaker Set On-off Switch. ll'ill
disconnect this speaker set when
depressed right.
Main Speaker Set On-off Switch. lf ill
disconnect this speaker set urhen
depressed right.
Loudne ss Compensation Switch.
Normally set to left" If depressed
right, it removes circuit
whlch boosts bass at low
listening levels.
SPECTFICATIONS
*
MAX. INPUT CAPABILITY: Phono: 160mv. for less
than 1%
dist. Radio: 2.8v. for less than 1%
dist.
MAX. HUM and NOISE: Vol. control min., 90 db.
(weighted) below rated output. Tuner input (controls
max.), 80 db, (weighted) below rated output. Phono
input (controls flat), 60 db, below rated output.
INTERCHANNEL CROSSTALK: Less than -45 db, at
1KHz.
POWERCONSUMPTION:
115-125v, 60 Hz; 10 to l2O
watts fused.
TRANSISTOR
COMPLEMENT: 22 silicon transistors,
2 silicon rectifiers.
SIZE: 14 xl0-L/2 x 4 in. high.
SHIPPING WEIGHT: 22 lbs.
*All specifications takenwith l20V line.

5-9
500c
AMPLIFIER
SERVICINGAND
ADJUSTMENT
NOTE: To simplify the following descriptions only the left channel
and its related circuitries are deseribed. The right chan-
nel is identical except for reference symbol numbers. (
see
schQmatic diagrams )
Preliminary checks of the dc voltages present at various
points in the 5-9500c can indicate whether a transistor is
open, shorted, or functioning. FauLt isolation in the pre-
amplifier, tone amplifier, and driver stages can g
enerally
be isolated by checking the dc voltages or by comparing gain
measurements
of 1 KHz as indicated on the schematic or by
comparing the operating channeL with the defective channel.
FUSEAND
SPEAKER
5Y5TEM
CHECKS:
Your amplifier incorporates two speaker fuses, one for each
channel. If the fuse opens, check the speaker connections
for shorted wires ox a shorted speaker. (The speaker resist-
ance should not be less than 4 ohms.) If the speaker and
connections are not shorted replace the fuse with the Proper
val-ue as marked on the rear panel. If the speaker fuse still
opens your amplifier needs servicing.
lrr/hi1e
servicing the ampli.fier it will- be valuabl-e to opergte
the amplifier using a variable voltage power line (VnnIAC)
equipped with a line wattmeter to identify abnormal power
consumption. Increase the power line voltage upward while
observing the wattmeter. Power consumption shoul-d not ex-
ceed t
O-20 watts (
loudness control at volume minimum
) .= the
voltage is increased to the rated 1ZBVAC. If the power con-
sumption begins to exceed 2A watts, do NOT
increase the Power
line voltage any further and determine whether the malfunc-
tion is in the power supply, oI amPlifier section.
If the power amplifier is suspected, verify center-point
voltage on the dc side of the output el-ectrolyticr_C29O for
app=o*imately one-hal-f of the B+ supply voltage. If the cen-
ter-point voltage reads extremely ]ot r susPect a defective
output transistor on the l-ow
side (schematic shows transis-
tor as bottom device in each channel
)
. If center-point volt-
age reads extremely high r suspect a defective high side out-
put transistor.
If the output transistors are not at fau1t, then verify that
the output coupling electrolytic capacitor is not shortedt
other capacitors are not shorted, circuit board contains no
sol-der or etching shorts, open resistors r poor solder con-
nections or broken pads.
The following perfoxmance indicates a properly operating am-
plif ier with an I ohm
.resistive load.
v
\-1

\-,
1
. BIAS ADJUSTMENT:
Adjust potentiometer R284r so that crossover distortion
is at point of being eliminated (Class trABn operation).
N0TE: Class trArr
operation (continued Cld
rotation) will
cause the output transistors to draw excessive current
and overheat. C
LASS
ttABt'
IMPROPER
BIAS PROPER
BIAS
ADJUSTMENT ADJUSTMENT
OUTPUTBALANCEADJUSTMENT:
Increase audio drive until clipping can be observed
and
fine adjust R27Oso that cl-ipping is symmetrical-.
Less than A,25foIM
Distortion at 2.OV
Typically O,3/"
IM
Distortion at 1
0V
Typically 35 lrr/atts
Typically 4A Lr/atts
OUTPUT
TRANSI5TOR5
IMPROPER
ADJUSTMENT
or Harmonic (
I KHz
)
or Harmonic (
1
KHz
)
Dual Channel at O.8/o
Single Channel-
at 0.896
PROPER
ADJUSTMENT
2.
\-

5-9500c PARTS
LIST
SCHEMATICREFERENCENO. PARTNO.
PART
DEsCRIPTION
TRANSISTORS
AUD
I0 , L0!il
AUDI0,
LOW
AUDI0,
NPN
AUDI0,
NPN
DRIVTR,
NPN
OUTPUT,
NPN
CAPACITORS
SIGNAL
5
IGNAL
1uf @
40V
5uf @
20V
8uf @
40V
20uf @
50V
100uf
@
3V
500uf @
50V
1
500uf @ 45V
2710uf @
45V
3000uf @
80V
GENERAL
sECTION
INSULAToR,
MICA,
T0-3
FUSE,
2 AMP.
3AG
FU5E,
2+ AMP.
3AG
KNoBs,MEDIUM
(W/TNDICAT0R)
KN0B,SMALL
PLASTIC, UNMARKED,
PHI]NOLEVEL
LIGHT-BULE,
PILOT,
#SZ
c0NTR0L,
PHoN0
LtVEL, 1.5K
'0HM
c0NTR0L,
8A55, 100K
0HM
DUAL
c0NTR0L,TREBLE,
1
00K
0HM
DUAL
c0NTR0L,BALANCE,
1
00K
0HM
ctNTR0L,
L0UDNE55,50K
0HM
DUAL
!il/s\/dircH
P0T.
, P.C.
, 500
0HM,BIAS
P0T., P.C., 5oo
oHM,0UTPUT
BAL
R
E
CI TFI ER
, 5I LI C
ON
SocKET,
DRIVER
TRANSISTUR
(T0-5)
socKET,
ourPUTTRANSIST0R
(T0-3
)
STEREO
HEADPHONE
JACK
FUsEPOsT
5!'JITCH, RCITARY
' FUNCT
I0N
' 5 P05.
5l^rITCH,RCTARY,
SELECT0RT4 P05.
5!\,ITCH,
ROCKER,
(NON-SHORTING
)
I
DPDT
5!dITCH,
RoCKER,
(
SHORTING
) DPDT
TRANSF0RMER,
P0lrJER
' DOMESTIC'
6AHz
TRANSFORMER,
POti,ER'
EXPORT,
sa/6oHz
c21
1
,232r27O
332
t
370
,372
c242
,342
c24O,340
c27
1
,37
1
c200
,2o3
r26D
350
c11
4
,17
5
,11
6
c290,390
czga,3
9
0
c1
73
,272,31
1
,
,
300
r
303,
LI5T
PRICE*
.53
.91
.95
3.96
2
.47
3.82
.59
.59
.45
.58
.45
1
.66
2.70
2.70
4
.gg
Q2
01
,2O2,2O3,204,
3
01
,
3A2
r
303,304
Q205r207r305r307
Q205,306
Q209
r3O9
Q208r308
Q210r211r310,311
8C159/5169
5Ps41
sPs4
1
99
3522
403
5IF
/ 38132
s3
56
B120X7
6-2
B12AX6-2
B120XI
-2
812081
4-2
8120X24-2
8120830-2
A1
2AT
7
-4
A12
0T7
-5
41
20T1
2-u
F1
F2
13
R22OA
r22OB
R234
A
,2348
R24oA
,24O8
R253
R25O412508,54
R2B4,384
R270,370
xl
,2
szA
r2B
55A,
58,6A
r68,
7
A
r7B,
BA
8B
T1
T1 EXPORT
AO21
F1
-0 .05
31
2AO2. .1 5
31202.5 .15
8457X4-2 2.43
46AAB5-3 .1
5
530853 .18
451
0T11
-1 1
.89
A610T12-0 1
.94
A510T12-0 1.94
A610T7-3 1
.O4
A511T1-1 .90
A67
5T1
-0A .45
A67
5T1
0-0A .41
A5g2X1
6-0 1
.71
A7g0T4M-1 .27
A790T7-0 1
.30
A7g
5L1
-0 1
.08
A1g5X2j1
A 1
.04
A850K5-3 2.25
A850T7-0 3.50
A864122-7 .86
A854T23-7 .85
Bg22T3-1 19.30
Bg22T3-1
X 27
.70
\-/
*N0TE: PRICES
SUBJECT
T0 CHANGE
h/ITH0UT
NOTICE.

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THE ROTARY SWITCHES ARE IN THE
M0sT c cw P0stT tot{.
ALL RESTSTORS ARe t/2 WATT OR LESSr to./o
TOLERANCE, UNLESS OTHERWISE SPECIFIED.
ALL FRACTIONAL VALUE CAPACITORS
ARE lN yf.
OTHER CAPACITORS
EXCEPT ELECTROLYTICS
ARE lN pt.
ALL VOLTAGES ARE REFEREI{CED TO GROUND
UI{OER THE FOLLOWING COT{DITIOI{S:
DC:
NO SIGNAL.
AC:
t ] Ac STGNAL VOLTAGES
FOR RATED oUTpuT,
AT 8 OHMS LOAD, W|TH PHONO
LEV€L AND
VOL.MAX.
t9v
c2t2
lrl
25V
R?3?
2.2K
ALTERNATE
PRIMARY
HOOKUP FOR EXPORT
MODE
LS.
33:;5iluo'4,,''
crRcurr 1ll
auxrgfll
Yto'r?]on*'o
I ll
FUSE.
DoNor t .ll
use sr-6ffix,. wx 3;;
-jtl
I
to
-
t25vAc
5O-6OHr w/R Tl
CIRCUTT
T]il
lt.*rrlll
ffi*'[all
l-Jll SHERWOOD
S-95OOc
STEREO
AMPLIFIER
SERIAL NO. TOOTOO3 A UP
ilo-t25 vAc
60 Hr

TOXEAIPLIFIER BOARD r--- AUDIO
DR]VEREOARD
AOSITIE.IA
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lcE: -: 3ROUfi0
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I r:: .r-ED OUTPUT,
I t-:i: -aiE. AND VOL.HAX.
29v
trlru.
c2to
2?OOrl
rt
tv
c240
8rt
40v
q2O.l
sPsStTN
o.5v
RZ12
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HEAD-
PHOTES
5t-6V RzaO
6.tr
o207
sPs.rlto.tv
AD.'.
Reoa
500
R2t6
!!r
LOUDNESS
R2504
50x
LOUDilESS
rN ourlsSA
o.r5
R25t
3.3K [ruru]
HI FILT€R
ce60
lOOxl
3V
FLTR Q206
sPs4l
Y 56A
xoRr I I R25Z
56t( R264
47
5%
L--- 5t 4ne"r LEFT
rA|l{
COTPONENT VALUES ARE IOST
R€CETIT PRODUCTIOT.
Jf DO 1{OT U3€ SLO-BLOW FUSES. USE
STAiIDARD 2-II2A)IP. FUSES ONLY.
COXPOT{ENT VALUES ARE THE
sarE as THE LEFT cHAl{r{EL ,ornr&
AoovE, ExcEPT FORAt{
rilcREAsE oF roo rt{ THE panr FoR
rot{o
iIUIEERT FROIIC2OOTOCIOO.
STEREO
EALAI{CE
R2
55
roox RIGHT CHAIII{EL
AUDIO DRIVERBOARD +65v
rAOSITIE-IA
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nare R255 C234
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68f( C?74- 2f
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