Marantz PM400 - 6. Test Equipment Required for Servicing; 7. Performance Verification; B. Preliminary Procedures

§.
TEST
EQUIPMENT
REQUIRED
FOR
SERVICING
Table
1
lists
the
test
equipment
required
for
servicing
the
PM250/PM400
Stereo
Console
Amplifier.
The
wattmeter,
AC
voltmeter,
and
variable
autotransformer
may
be
assembled
as
a
test
fixture
as
shown
schematically
in
Figure
1.
The
load
resistors
and
AC
ammeter
may
be
assembled
into
a
second
test
fixture
as
shown
in
Figure
2.
7,
PERFORMANCE
VERIFICATION
TEST PROCEDURE
A. TEST EQUIPMENT
Refer
to
Table
1
for
required
test
equipment.
B.
PRELIMINARY
PROCEDURES
Make
the
test
setup
shown
in
Figure
1
with
the
instrument
controls
set
in
the
following
positions:
Distortion Analyzer
Audio Oscillator
AC Voltmeter
Oscilloscope
DC Voltmeter
Line Switch OFF
Variable-line switch Variable
Wattmeter Switch ON —
Variable
Autotransformer
0
V
(fully
CCW)
Load
8
ohms
(0.5
mfd—OF
F)
Audio
Generator
1kHz
Output 5 V range
Gain Minimum
AC Voltmeter 30 V range
Make
sure
that
connections
between
the
resistive
load
and
the
system
terminals
of
the
PM250/PM400
have
negligible
resistance
when
compared
with
the
resistance
of
the
load
itself.
Appreciable
resistance
in
wiring
adds
to
the
total
load,
resulting
in
inaccurate
measurements
of
output
power.
Connect
amplifier
output
to
load
and
connect
AC
cord
to
line
power.
Connect
shorting
plugs
to
the
Phono
input
jacks
of
the
PM250/PM400.
Manufacturer and Model No.
Sound Technology Mode! 1700B
Tektronix Model T932
Philips Model 3232
Model 313, Triplet Model 801
Fluke Model 8000 ‘‘Digital’’ Simpson
Distortion measurements
Sinewave
and
squarewave
signal
source
voltage
measurements
(AC)
Waveform analysis and trouble shooting and
ASO alignment
Trouble shooting
Voltage measurements (DC)
T
@ :
:
mee
AC
Wattmeter
Simpson
Model
1379
Monitors
primary
power
to
amplifier
Monitors
amplifier
output
under
short
circuit
AC
Ammeter
Commercial
Grade
(1
~
10
A)
ners
ani
piel
ower
condition
Simpson Model 1359
amplifier
Line Voltmeter
Variable Autotransformer
Superior Electronic Co.,
Powerstet Model 116B-10A
Monitors
potential
of
primary
power
to
Adjusts
level
of
primary
power
to
amplifier
| srortn Plug
Use phono plug with 600 ohm
across center pin and shell
Shorts
amplifier
input
to
eliminate
noise
pickup
|
Output
Load
.
Provides
8-ohm
load
for
amplifier
output
Commercial Grade ay
(8
ohms,
0.5%
100
W)
termination
Output
Load
.
Provides
4-ohm
load
for
amplifier
Output
Commercial
Grade
.
(4
ohms,
0.5%
100
W)
_|
termination
4
Output Load Capacitor
(0.5 mfd)
Mylar
Provides
capacitive
load
for
instability
checks
+
AC Power Control Box
Optional Item. Fabricate in
accordance with Figure 1
Monitors
and
controls
primary
power
for
amplifier
Amplifier Output Load Box
ene
|
Optional! Item. Fabricate in
accordance with Figure 2
Provides
various
amplifier
loads
and
can
|
monitor shorted output
—_—_4
2