Marantz 4100 User manual

TABLE OF CONTENTS
SECTION
PAGE
IMtrOCUCTION
—
..ceseesseessessesceeecessesseenceneseaeseeneeeneeaseauaauonensesecansaaentanenssavaucanconazenrcaaatanen
sees
nenaes
1
Service
NOtes
..csccscsscccssccsscssseeeesescceesenenseecesnessanenseesussuennnensensaeansaasaonsauseneeaeanseasuaneesanenets
1
Selector
SWitch
.cccccssssssesscesecececeeessesesssessensaesseseeeseensesssansessnsaeanesacanenaesesssesnsensenanenguanseseges
1
Mode
Switch
...cessssssccceccsssecseneseeersesenseesenscsnecnnansareneesensanscuensuannsananasenesanacersneuananeatogensnaas
1
Pre-Amplifier
......:cccccecscssssseeessessssescsessorssssenensnaeeenensesnenananeeaesesaneuusussensatercnaeaneaagateogenass
2
Balance
Control
cecccscccsscccessessecsssseesateneestssseesnensnsenensasseesausaenaneatesanenenuesensontanenegaeaesseaenenas
2
Main
Amplifier
.....ccsssessssssssescsesseeceeesestensesseensssasaeacasseesesenenssnensasannanacscnenenesncnsaseneaunenneges
2.
BTL
(Balanced
Transformerless)
Commection
......:ceeesssesssseeesenscneceneeennserentannensneennensnas
3
Power
Supply
Unit:
.....ssessscescseesssessessesesreeseesesenesscasnanssesenanenaneneanaacsnusneacausanareuasananenaenengs
3
Trouble
Analysis
....s...cccccscsssessecsssseseessesessesseenacasarenssseeusesesenenenenscsnsneasneenecsnentarsseonensaeneaes
3
Power
Amplifier
Adjustment
“whe
cain
d.cton
lace
acehieia
df
shsdO
ch
de
iaacls
m
oulechfanl
cede
aantacteatontetinientsdales
3
Power
Supply
Adjustment
......csscssssesererstseeeesseneessseeesenseassenaretansatenasavatsenanensaneneuancaeeeos
3
Meter
Adjustment
...c.ssscsssecsscecsrsseserssesseessneessesesessenenseceeaeasausccsnacanasenenansnansnenanseangenaten
3
Phono
Amplifier
Adjustment
........csscseeeescsssensresssseeeseseneasnesesenssnacensenaneaneenannanennenagsenses
4
Test
Equipment
Required
for
Servicing
........ssssscssssssssenenetersenesssneteeennnnenesnnenenanenenesannenes
4
Performance
Verification
.......ccccssccsscsescsneseeseesnnnesneeensneesnasennacsaedennneeceaesseseassuneuaacaaeeaees
5
Parts
List
—
.ccsccccscssssecsesseecesssecnssesossesseaesseseresssesasaneeeesensnassasaneusussacemneneeeatantsesuneaunnanses
17
~
25
Technical
Specifications
......csscsssesesseseseeseesneeeeeentesestscanansnnncnenenntissenenenasauaceuaecnansaeseaananeneeys
26
LIST OF ILLUSTRATIONS
FIGURE NO.
4.
AC
Power
Control
Box
Simplified
Schematic
—
......:csccscsssneenesscessseseeestsesesnsenseenenees
6
2.
Amplifier
Output
Load
Box
Simplified
Schermatic
........ceccsesscecserrenseerssersesensinnsenaees
7
3.
Front
Panel
Adjustment
and
Component
Locations
—...cssssessssccsrsressersseerscennneveeceanenes
7
4.
Main
Chassis
Component
Locations
(Top
View)
....--.::scscsssssssensnsnsnenrsentetnennesanenenes
8
5.
Rear
Panel
Adjustment
and
Component
Locations
.......:cscseseseseeetiserereneseenasensnssonenene
&
6.
Main
Chassis
Component
Locations
(Bottom
View)
—
...ccsessesssssesseseesecsenttersserasoseeness
9
7.
Tape
Mon.,
Hi
Filter
Unit
Assembly
P250
Component
Locations
...cccsscsesesseneentenerss
9
8.
Main-Remote
Speaker
Switch
Unit
Assembly
P300
Component
LOCATIONS
...cccanseeonnerns
10
9,
Loudness
Unit
Assembly
P350
Component
Locations
........::sscesesssseeseeereeenrnasesenensanns
10
10.
Tone
Amplifier
Assembly
P400
Component
LOCATIONS
..escscccsessesseeeeesrseutatsnesneeneenentes
10
11.
Vari-Matrix
Unit
Assembly
P500
Component
Locations
.........sccsseecrsesscereertnernennssenes
11
12.
Meter
Rectifier
Unit
Assembly
P550
Component
Locations
....cssssssseressetsnseeese
anes
11
13.
Temparature
Compensation
Unit
Assembly
P580
Component
Locations......ccccseeesesers
11
14.
Power
Amplifier
Assembly
P600
Component
Locations
........ssecccssersrssersnsestsneneeesenens
12
15.
Phono
Equalizer
Amplifier
Assembly
P700
Component
Locations
......1..cceeceseseseoeneeenes
13
16.
Tone
Contro!
Unit
Assembly
P750
Component
Locations
.........cssceseserscesenreeesrsenins
13
17.
Power
Supply
Unit
Assembly
P800
Component
LOCATIONS
..cccccccecccecsccerensssensnecssenseensce
14
18.
AC
Rectifier
Assembly
P850
Component
Locations
......cessssessesnnceneereneeseanenenenes
14
19.
Balance
Variable
Resistor
Unit
Assembly
P9200
Component
LOCATIONS
..cesssseereeeseneeers
14
20.
Schematic
Diagram
.......c.ccscscsssescsseseseseestesesnenseeeceeeersnseeansanecneceeensnnennsmeencentanenee
15,16

INTRODUCTION
This
service
manual
was
prepared
for
use
by
Authorized
Warranty
Stations
and
contains
service
information
for
Marantz
Model
4100
Solid-State
Quadradial
Console
Amplifier.
Servicing
information
and
voltage
data
included
in
this
manual
are
intended
for
use
by
the
knowledgeable
and
experienced
technician
only.
All
instruction
should
be
read
carefully.
No
attempt
should
be
made
to
proceed
without
a
good
understanding
of
the
operation
in
the
circuits.
The
parts
list
furnish
information
by
which
replacement
part
may
be
ordered
from
the
Marantz
Company.
A
simple
description
is
included
for
parts
which
can
usually
be
obtained
through
local
suppliers.
1. SERVICE NOTES
As
can
be
seen
from
the
circuit
diagram
the
chassis
of
Model
4100
consists
of
the
following
units.
Each
unit
mounted
on
a
printed
circuit
board
is
described
within
the
square
enclosed
by
a
bold
dotted
line
on
the
circuit
diagram.
1.
Tape
Mon.,
High
Filter
Unit........-..--2.000--
mounted
on
P.W.
Board,
P250
2.
Main-Remote
Speaker
Switch
Unit
..............
mounted
on
P.\W.
Board,
P300
3.
Loudness
Unit
.......
0...
cece
ee
eee
ene
mounted
on
P.W.
Board,
P350
4.
Tone
Amplifier...
0.0...
ccc
eee
eee
eee
mounted
on
P.W.
Board,
P400
6.
Vari
Matrix:
Uniti
nc
ciccdsecnae
cc
2
ee
wader
ee
mounted
on
P.W.
Board,
P500
6.
Meter
Rectifier
Unit...............06-
Disha
amcetals
mounted
on
P.W.
Board,
P550
7.
Temperature
Compensation
Unit..............-.
mounted
on
P.W.
Board,
P580
8.
Power
Amplifier
........
00.
e
eee
eee
ee
renee
mounted
on
P.W.
Board,
P600
9.
Function
Indicator
Unit
..........
2002
eee
eee
mounted
on
P.W.
Board,
P650
10.
Phono
Equalizer
Amplifier
............00500e-
mounted
on
P.W.
Board,
P700
11.
Tone
Control
Unit
........
2...
cc
eee
eee
eee
mounted
on
P.W.
Board,
P750
12.
Power
Supply
.......00
cece
scene
cee
sect
eeens
mounted
on
P.W.
Board,
P800
13.
AC
Rectifier
.......2..0000eeee-
nahctid
ashe
Ness
mounted
on
P.W.
Board,
P850
14.
Balance
Variable
Resistor
Unit..............006-
mounted
on
P.W.
Board,
P900
2. SELECTOR SWITCH
-
Signals
from
the
PHONO
jacks
are
applied
to
the
phono-amplifiers
and
equalized
to
match
the
RIAA
curve
for
flat
frequency
response.
The
outputs
of
the
phono-amplifiers
and
signals
from
the
TUNER,
TAPE
1,
2
and
AUX
jacks
are
led
to
the
SELECTOR
switch,
S001.
The
SELECTOR
switch
selects
one
set
of
signals
from
PHONO,
TUNER,
TAPE
1,
2
and
AUX
jacks
and
sends
them
to
the
TAPE
MONITOR
switch
and
TAPE
OUT
jacks.
The
selected
signals
are
then
applied
to
the
MODE
switch,
SOO2.
PHONO
and
TUNER
jacks
are
for
2-channel
input
signals,
that
is
stereo
signals.
AUX,
TAPE
1,
2
and
TAPE
OUT
jacks
are
4-channel,
that
is
quadraphonic
signals.
3. MODE SWITCH
MODE
switch
S002
has
positions
of
MONO,
2
CH,
DISCRETE,
VARI-MATRIX
and
SQ
DECODER.
In
the
MONO
position
all
input
signals
are
mixed
together
and
delivered
to
all
four
channels.
In
the
2
CH
position
stereo
signals
are
directly
routed
to
the
pair
of
front
left
(LF)
and
front
right
(RF)
channels;
the
same
signals
at
the
LF
and
RF
channels
are
fed
to
the
rear
left
(LR)
and
rear
right
(RR)
channels,
respectively.
When
quadraphonic
signals
are
applied
to
the
input
terminals,
the
LF
and
LR
signals
and
RF
and
RR
signals
are
separately
added,
thus
the
(LF
+
LR)
signal
is
delivered
to
the
LF
and
LR
channels
and
the
(RF
+
RR)
signal
is
delivered
to
the
RF
and
RR
channels.
In
the
DISCRETE
position
the
quadraphonic
input
signals
are
separately
routed
as
4-channel

stereophonic
signals to
each
channel.
At
this
position,
for
ordinary
stereo
input
signals,
neither
LR
nor
RR
channels
no
signal
to
carry.
In
the
VARI-MATRIX
position,
2-channel
stereo
input
signals
are
converted
into
quadra-
phonic
signals
through
the
vari-matrix
circuit;
the
input
right
and
left
channel
signals
are
fed
directly
to
the
LF
and
RF
channels,
while
the
signals
to
the
LR
and
RR
channels
are
synthesized
from
the
2-channel
input
signals
under
the
control
of
the
DIMENSION
control.
The
LR
and
RR
channel
signal
components
are
controlled
by
the
DIMENSION
control
as
shown
below.
DIMENSION control setting
Bottom
Center
Top
LR output RR output
RF+LF
When
the
DIMENSION
control
is
set
at
the
bottom
the
LR
and
RR
channel
signals
become
monaural,
at
the
center
are
stereophonic,
and
at
the
top
are
out
of
phase,
thus
providing
vanished
sound
image
positioning.
In
the
SQ
DECODER
position,
‘compatible
stereo-quadraphonic
(SQ)
record’’
developed
by
CBS
is
ideally
decoded
into
4-channel
signals.
This
requires
incorporation
of
the
adapter,
Model
SQA-1,
into
the
set.
When
the
TAPE
MONITOR
switch
is
set
to
the
ON
position,
signals
from
the
TAPE
OUT
terminals
are
in
discrete
mode
regardless
of
the
MODE
switch
setting.
In
the
OFF
position,
the
signals
are
processed
into
the
mode
indicated
by
the
MODE
switch
in
the
MONO,
2
CH,
or
DISCRETE
position
of
the
MODE
switch,
while
signals
remain
in
discrete
mode
in
the
VARI-
MATRIX
and
SOQ
DECODER
positions.
4. PRE-AMPLIFIER
Mode
processed
signals
are
led
through
the
respective
VOLUME
controls
to
the
tone
control
circuits.
Hi
and
low
frequency
response
can
be
varied
with
the
BASS
and
TREBLE
controls.
These
controls
permit
separate
adjustment
of
front
stereo
pair
of
channels
(LF,
R
F)
and
rear
stereo
pair
of
channels
(LR,
RR).
5. BALANCE CONTROL
Signals
passed
through
the
tone
controls
go
into
the
balance
control
circuit,
in
which
the
signals
are
controlled
by
three
balancers:
the
FRONT
L-R,
REAR
L-R,
and
FRONT-REAR.
By
setting
the
FRONT-REAR
balancer
to
the
““
FRONT
”
side
and
the
FRONT
L-R
balancer
to
the
“
L
“”
side,
for
example,
only
the
front
left
(LF)
channel
is
drived.
The
balance
control
circuit
is
provided
with
the
REMOTE
CONTROL
switch
which
mé&es
the
Model
RC-4
Remote
Control
Box
operative
when
the
switch
is
set
in
the
“REMOTE”
position.
In
the
“REMOTE”
position
the
balancers
on
the
Model
4100
become
ineffective
since
signals
are
led
to
the
Model
RC-4._
The
volume
can
be
varied
by
the
control
either
on
this
set
or
Model
RC-4.
However,
the
maximum
volume
level
available
by
adjustment
of
the
Model
RC4
is
determined
by
the
master
VOLUME
control
on
the
Model
4100.
6. MAIN AMPLIFIER
The
output
signals
from
the
BALANCE
control
are
led
to
the
main
amplifier
through
the
highpass
filter
circuit.
The
transistors
H601
and
H603
from
a
differential
amplifier,
directly
coupled
to
the
transistor
H605.
The
transistor
H605
drives
the
inverters
H611
and
H613
which,
in
turn,
drive
the
pover
stage
consisting
of
HOO1
and
HOO2.
Transistors
H607
and
H609
compose
a
protecion
circuit.
The
protection
circuit
will
operate
when
an
excessive
current
flows
into
the
power
transisor,

‘to
limit
current
or
to
contro!
the
power
transistors
so
that
do
not
operate
beyond
the
safety
area.
In
case
either
excessive
current
flows,
or
the
load
becomes
almost
entirely
reactive,
in
the
power
stage,
the
transistors
H607
and
H609
and
the
diodes
H622
and
H624
are
operated
through
the
resistors
R642
and
R644,
so
that
the
power
transistors
are
protected
from
damage.
7.
BTL
(Balanced
Transformerless)
CONNECTION
This
power
amplifier
is
designed
to
operate
in
either
2-channel
or
4-channel
modes,
depending
on
the
setting
of
the
AMPLIFIER
MODE
switch
that
incorporates
phase-conversion
and
power
switch
for
BTL
connection.
With
this
switch
placed
in
the
25Wx4
position,this
unit
operates
as
a
25W.4channel
amplifier.
With
the
switch
placed
in
the
GOWx2
position,
the
unit
operate
as
a
GOW
2
channel
amplifier,
in
which
case,
the
power
output
is
obtained
only
from
REAR
SPK
terminals.
The
transistor
H626
convert
the
phase
of
1
channel
amplifier
and
3
channel
amplifier.
8.
POWER
SUPPLY
UNIT
The
power
supply
unit
consisting
of
the
transistors
H801
and
H802,
operating
as
an
auto-
matic
voltage
regulator,
provides
+35V
DC
to
all
the
amplifiers
except
the
main
amplifier.
The
transistors
H803,
H804
and
H805
operate
the
relay
L801
that
protects
speakers
from
destruction,
and
has
a
time
lag
of
from
three
to
five
seconds,
for
other
transistors
to
work
stably.
9.
TROUBLE
ANALYSIS
1.
Excessive
line
consumption
a.
Check
for
shorted
H851
through
H854,
C003,
C004.
b.
Check
for
shorted
transistor
HOO1
through
HO08.
Check
LOO1
for
short.
2.
Noline
consumption
or
zero
bias
a.
Check
line
cord,
fuse,
shorted
H581,
H582.
b. Check for open rectifiers H851 through
H854, or open L001.
3.
Excessive
hum
and
noise
a.
Check
filter
capacitors
C003,
C004,
H801,
H802.
4.
Parasitic
oscillation
a.
Check
for
defective
C607,
C608,
C619,
C620,
C621,
C622.
10.
POWER
AMPLIFIER
ADJUSTMENT
1.
Connect
a
VTVM
between
J629
and
J613
and
adjust
the
trimming
resistor
R628
until
the
VTVM
reads
10mV
DC. For
the
other
channel,
connect
the
VTVM
between
J630
and
J614
and
adjust
the
R629
for
the
same
reading.
2.
Connect
a
VTVM
between
J623
and
J629
and
adjust
the
trimming
resistor
R613
until
the
VTVM
reads
OV
DC.
For
the
other
channel,
connect
the
VTVM
between
J623
and
J630
and
adjust
the
trimming
resistor
R614
for
the
same
reading.
11. POWER SUPPLY ADJUSTMENT
Connect
a
VTVM
between
J802(—)
and
J804(+)
and
adjust
R806
until
the
VTVM
reads
35.0V under no signal condition.
12. METER ADJUSTMENT
Connect
the
audio
oscillator
to
the
AUX
input,
set
audio
oscillator
frequency
to
1KHz.
Set
SELECTOR switch to AUX.
2.
With
the
distortion
analyzer
connected
across
the
output
load
(8-ohm),
set
the
analyzer
on
the
30V
AC
scale.

trimming resistor R551 until the meter indicator reads +2.
~PHONO AMPLIFIER ADJUSTMENT
Connect
the
audio
oscillator
to
the
PHONO
input,
set
audio
oscillator
frequency
to
1KHz.
Set SELECTOR switch to PHONO.
2.
Connect
the
distortion
analyzer
to
the
TAPE
OUT
terminal
that
is
terminated
by
the
47K
ohm,
set
the
analyzer
on
the
30V
AC
scale
and
connect
the
oscilloscope.
3.
Increase
the
audio
oscillator
output
gradually
until
a
slight
clipping
on
top
of
the
sine-wave
is observed on the oscilloscope.
For the other channel adjust R709.
14.
TEST
EQUIPMENT
REQUIRED
FOR
SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
Model
4100
Solid-State
Quadradial
Console Amplifier.
Distortion Analyzer
Audio Oscillator
Oscilloscope
VTVM
AC Wattmeter
AC Ammeter
(0 to 10 amps)
Line Voltmeter
(0 to 150 vac)
Variable Autotransformer
(0 to 140 vac, 10 amps).
Shorting Plug
Power Supply Bleeder
Resistor (10 ohms at 1 W)
Output Load Resistor
(82 + 0.5%, 100W)
Output Load Resistor
(4Q + 0.5%, 100W)
Manufacturer and Model No.
(or equivalent)
Apply
the
audio
oscillator
output
until
the
distortion
analyzer
indicates
15V
and
adjust
the
Adjust the trimming resistor R708 for equal clipping level.
Use
Hewlett Packard, Model 331A
or 333A
Weston Mode! CVO-100P
(NOTE: Less than 0.02 per-
cent residual distortion is re-
quired.)
Tektronix, Model 503; Data,
Model 555
RCA Senior Volt-Ohmyst,
Model WV-98C
Simpson, Model 390
Commercial Grade
Commercial Grade
Powerstat, Model 116B
Use phono plug with 600
ohms across center pin and
shell.
Commercial Grade
Commercial Grade
Commercial Grade
Measures distortion and vol-
tage of amplifier output.
Sinewave and squarewave sig-
nal source.
Waveform analysis and trou-
ble shooting.
Voltage and resistance mea-
surements.
Monitors primary power con-
sumption of amplifier.
Monitors amplifier output un-
der short circuit condition.
Monitors potential of primary
power to amplifier.
Adjusts level of primary power
to amplifier.
Shorts amplifier input to eli-
minate noise pickup.
Discharges power supply filter
capacitors prior to disassembly
or resistance measurements.
Provides 8-ohm load for ampli
fier output termination.
Provides 4-ohm load for ampli.
fier output termination.
Table 1. Test Equipment Required for Servicing

15.
PERFORMANCE
VERIFICATION
Test Procedure
A. Test Equipment
Refer
to
Table
1
for
required
test
equipment.
B. Preliminary Procedures
1.
3.
4.
Make
the
test
setup
shown
in
Figure
1
with
the
instrument
controls
set
in
the
following
positions:
Line Switch off
Variable-line Switch variable
Watt Meter Switch on
Variac 0 (fully CCW)
Load
8
ohms
(0.5
mfd
—
off)
Audio
Generator
Frequency
1
KHz
Output
5V
range
Gain minimum
AC
Volt
Meter
30V
range
Make
sure
that
connections
between
the
resistive
load
and
the
system
terminals
of
the
Mode!
4100
have
negligible
resistance
compared
with
the
resistance
of
the
load
itself.
Appreciable
resistance
in
wiring
adds
to
the
total
load,
resulting
in
inaccurate
measure-
ments
of
output
power.
.
Connect
amplifier
output
to
load
and
connect
AC
cord
to
line
power.
Connect
a
short-
ing
plug
to
the
PHONO
input
jack
of
the
model
4100.
Remove the top cover.
C. Total Hum and Noise Test
1.
3.
4.
With
shorting
plugs
connected
to
the
AUX
input
jacks
and
a
8-ohm
resistive
load
connected
across
the
speaker
system
output
terminals,
connect
a
distortion
analyzer
across the load.
NOTE:
In
this
test
and
tests
that
follow,
if
distortion
analyzer
used
does
not
contain
a
built-in
voltmeter,
a
VTVM
may
be
substituted.
Set
the
distortion
analyzer
controls
for
voltage
measurements
and
apply
power
to
the
amplifier.
Set the
VOLUME
control
fully
CCW.
Set
the
SELECTOR
switch
to
AUX
and
the
MODE
switch
to
DISCRETE.
If
the
distortion
analyzer
indicates
more
than
1.5mV,
refer
to
the
trouble
analysis
section
of
this
manual.
~
Set
the
VOLUME
control
fully
CW.
If
the
distortion
analyzer
indicates
more
than
2mV,
refer
to
the
trouble
analysis
section
of
this
manual.
D. Maximum Power Output
1.
Zu,
3.
Connect
the
audio
oscillator
to
the
AUX
input.
Set
audio
oscillator
frequency
to
1KHz.
Set
SELECTOR
switch
to
AUX.
With
the
distortion
analyzer
connected
across
the
output
load
(8-ohm),
set
the
analyzer
on
the
30V
AC
scale.
Turn
the
analyzer
on
and
increase
the
audio
oscillator
output
to
180mV,
and
verify
the
analyzer
indicates
more
than
14.2V.
E. Harmonic Distortion Test
1.
2.
3.
4
Set
the
frequency
of
the
audio
oscillator
and
the
distortion
analyzer
to
20K
Hz.
Set
the
controls
of
the
analyzer
for
voltage
measurement
on
the
30-volt
scale.
Adjust
the
audio
oscillator
output
level
until
the
analyzer
meter
indicates
10.9
volts.
Switch
the
distortion
analyzer
to
Set
Level
—
Manual
mode,
and
adjust
SENSITIVITY
for
full
scale
reading
on
0-1
scale.

9.
10.
1.
a AWN .
Measure
the
total
harmonic
distortion
with
the
analyzer
and
verify
it
is
less
than
0.3%.
NOTE:
Any
parasitic
oscillation
in
the
amplifier
will
be
displayed
on
the
oscilloscope,
when
capacitance
is.switched
into
the load.
Switch the distortion analyzer back to SET LEVEL MANUAL.
(Do not adjust sensitivity of analyzer.)
Change
the
frequency
of
the
audio
oscillator
and
distortion
analyzer
to
1KHz.
Adjust
audio
oscillator
output
as
necessary
to
have
a
full
scale
reading
on
the
O-1
scale
on
the
analyzer.
Measure the distortion, verifying it is no greater than 0.3%.
Repeat steps 7 and 8, changing frequency to 20Hz.
Distortion should be no more than 0.3%.
Check for parasitic oscillations; there should be none.
F. Channel Separation
Set
audio
oscillator
to
20KHz.
Connect
oscillator
to
front
left
channel
AUX
input
only,
with
shorting
plug
(10K
ohm)
in
all
other
channels
AUX
input.
Connect
distortion
analyzer
to
front
left
channel
speaker
output
terminals.
Adjust
oscillator
output
until
distortion
analyzer
indicates
0
dB
(2.8V).
Measure
RF,
LR,
RR
channel
output.
Distortion
analyzer
should
indicate
-30
dB
or
less.
Repeat
step
1
and
2
with
substituted
channel
driving.
If
indication
is
not
less
than
-30
dB,
adjust
input
wires
to
preamp
board
until
reading
is
-30
dB
or
less.
105 TO 125VAC
50/60 Hz
SLO -BLO
VARIAG
AC OUTLETS
WATTMETER
AC WATTMETER
O TO 150 WATTS
AC VOLTMETER
0 TO 150VAC
Figure 1. AC Power Control Box Simplified Schematic

f") (MOMENTARY
gW gy (O SWITCHI}
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6 6
0.5 MFO “Sy 8 CHMS 4 OHMS
300V £0.5% 20.5%
TOW toow AC AMMETER
O 0 TO 10 AMPERES O)
[ourrur]
GRO . : GRO |
Figure 2. Amplifier Qutput Load Box Simplified Schematic
$251-1 $251-2 $251-3. MOO6 M007 R907 M008 M009 $301-3 $301-1 $301-2
R001 S003 R767 R906 R768 RCO2 £S005
Figure 3. Front Panel Adjustment and Component Locations
JO21 J022 S001 S002 R905

Figure 4. Main Chassis Component Locations (Top View)
JO17 J019 JO036 JO24 JO34 J023 JO35 JO03 J001 J004
TRUON = FOR CONTINUED PR
TECTION AGAINST FiRE-HAZAR|
REPIACE, ON SiME
J0O18 JO20 $004 J025 JO37 JO26 J004 W001 J032 JO012 J002 J03)
Figure
5.
Rear
Panel
Adjustment
and
Component
Location: