Marantz 2245 - Power Amplifier Troubleshooting; Excessive Line Consumption; No Line Consumption or Zero Bias; No DC Balance

8.
Suggestions
for
Trouble
Shooting
of
Power
Amplifier
8.1
Excessive
Line
Consumption
3.
Check
for
shorted
rectifiers
HOO5;
also
check
C007
and
CO08.
b.
Check
for
shorted
transistors
H758
and
H759,
HOO1
and
HO02,
or
check
H760.
Check
for
open
control.
R763,
and
bias
diode
H761.
Check
L004
for
short.
CAUTION:
BECAUSE
THE
DRIVER
AND
OUTPUT
STAGES
ARE
DIRECT
COUPLED
COMPONENTS
MAY
FAIL
AS
A
DIRECT
RESULT
OF
AN
INITIAL
COM-
PONENT
FAILURE.
IF
A
SHORTED
TRANSISTOR
OR
ZENER
DIODE
IS
FOUND,
OR
CONTROL
OR
BIAS
DIODE,
BE
SURE
TO
CHECK
THE
REMAINING
DRIVER
AND
OUTPUT
COMPONENTS
FOR
SHORT
OR
OPEN
CIRCUIT
BEFORE
RE-ENERGIZING
THE
AMPLIFIER.
8.2
No
Line
Consumption
or
Zero
Bias
a.
Check
line
cord,
fuse,
transistors
H760, HOO1,
HOO2.
HOO3
and
HOO4,
bias
diode
H761.
b.
Check
for
open
rectifier
HOOS,
or
open
L004.
8.3
No
DC
Balance
3.
Check
R762
and
Zener
diodes
H762
and
H7/63.
9.
Voltage
Conversion
This
model
is
equipped
with
a
universal
power
transformer
to
permit
operation
at
100,
120,
200,
220
and.240V.
AC
50
to
60Hz.
To
convert
the
Model
2245
to
the
required
voltage
perform
the
following
steps:
(1)
Remove
the
top
cover.
(2)
Remove
the
Transformer
Wire
Connection
Terminal
Cover,
loosen
two
Cover
mounting
‘screws
on
the
rear
panel,
see
Fig.
1.
(3)
Change
the
jumper
wires
as
illustrated
in
Fig.
2
for
the
required
AC
voltage
and
replace
the
fuse as instructed.
CAUTION:
DISCONNECT
POWER
SUPPLY
CORD
FROM
AC
OUTLET
BEFORE
CONVERT-
ING VOLTAGE.
REMOVE SCREW
ene aan .
ea
je &|
bs
—*
Be
»REMOVE
THIS
COVER
_
Figure
1.
‘Remove
the
Terminal
Cover