Denon PMA-757 - Method of Adjustments; Idling Current Adjustment Procedure; Neutral Potential Point Adjustment; Distortion Factor Adjustment

PMA-777/ 757
METHOD
OF
ADJUSTMENTS
Carry
out
adjustment
at
room
temperature
and
normal
humidity
with
the
power
source
Operating
at
the
rated
voltage,
ADJUSTMENT
OF
IDLING
CURRENT
(ETCO738,
ETCO738B)
—
Fig.
4
Preparation
2 Connect a digital voltmeter (be able to measure 0.01 mV through 1 mV DC) to the REC output (Lch and Rech). .
,
Connect
a
100-k
ohm
(1/4
watt
or
so)
resistor
across
the
test
point
{Lch
TP-3,
4
and
Rch
TP-5,
6)
on
the
EQ
Amp
unit.
Set the switches as follows:
1
Place
the
unit
in
normal
operating
condition,
avoid
such
good
ventilating
location
close
to
air
conditioner,
circulating
fan,
etc,
The
unit
circumference
temperature
must
be
in
15°
~
30°C.
Eas
2
Set
the
switches
as
follows:
.
Be
INPUT
SELECTOR
+
PHONO
*
POWER
SWITCH
>
OFF
;
Ree
-
REC
OUT
SELECTOR
>
Source
#
VOLUME
CONTROL
+>
—~(f))
ees:
CARTRIDGE
+
MM
©
DIRECT
COUPLE
>
DIRECT
ee
VOLUME
CONTROL
+
—e(%)}
*
SPEAKER
TERMINAL
~
Nol
D
k
istors.
‘EF
Yadjustment
;
;
Adjustment
eae
ea
ange
pipes
I
ccouinately
2
minutes
after
turning
on
the
POWER
switch,
rotate
—
VR103
(PMA-777),
VR101
(PMA-757)
and
adjust
1
Remove
top
cover
and
rotate
VA301
{Lich}
counterclockwise
(7\
)
and
VR302
(Reh)
clockwise
(C%)
on
the
ETC-738.
Connect
a
DC
voltmeter
to
the
test
point
({Lch
TP-1,
2
and
Ach
TP-3,
4).
5
2
Connect
the
power
cord
and
turn
the
POWER
switch
on.
Immediately
after
turning
on
the
power,
rotate
VR301
clockwise!
DC
or
less
value.
(C%),
VR302
counterclockwise
(")}
and
adjust
the
test
point
voltage
value
—
PMA-777:
2mV
40.2
mV
DC
PMA-757:
5mV
40.2
mV
DC
3
3
minutes
after
the
preparatory
adjustment
as
in
step
2,
rotate
VR301,
VR302
and
obtain
the
voltage
value
—
PMA-777:
11
mV
+2
mV
DOC
d
PMA-757:
13
mV
+0.5
mV
OC
Cada...
3
9@
|
Digital
Volimeter,
to RECOUT Termingt
CAUTION
VR301
and
VR302
of
the
present
model!
have
Opposite
turning
directions
in
adjustment.
In
the
future
by
changing
of
the
board,
adjustment
of
VR302
will
be
the
same
manner
as
of
VR301.
Therefore
after
the
board
has
changed
(222
1090
208),
adjust
the
VR302
with
the
possible
care.
\
ne
:
K
TP-60
7
DENON
\
.
-
(SEER
\\
t
ETC-739-]
>
ci
vRIO3
i:
oe
|
©)
OC
Vol!meter
:
900
TP-3
|
a
I
Le
)
|
1
I
|
|
—
J
L
ra)
1
‘
2
i
'
t
§
(Dts
tortion)
IT
6
ot6
ile
f
EQ
AMP
UN
VR302
o
0
(idting)
1
OT
¢
Fig.
5
TP-3_
TP-4
for
:
PMA-777
vR301
oe
[
as
(GENSA)
oO)
a®
Digital
Voltmeter
()
ra
me
fo
RECOUT
Terminal
ES
POWER
AMP
UNIT
|
fej
DENON
ADJUSTMENT
OF
DISTORTION
FACTOR
(Fig.
4}
1
Connect
a
8-ohm
loading
resistor
across
the
speaker
terminal.
2
Inject
20
kHz
sine
wave
signal
through
the
TUNER
terminal.
Operate
both
L
and
R
channels
and
obtain
50
watts
(20
Vrms)
output
power
across
the
8-ohm
loading
resistor.
3
Adjust
VR303
{Lch)
and
VR304
(Rch)
for
minimum
distortion
factor
(be
sure
to
put
bottom
cover
to
the
unit
during
the
adjustment).
EQ
AMP
UNIT
3
Fig.
5°
for
:
PMA-757