Harman Kardon HK775 User manual

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Owner's Manual hk775
Your
investment
in
a
component
high
fidelity
system
indicates
you
have
a
greater
than
average
interest
in
music.
The
fact
that
your
investment
includes
a
Harman
Kardon
Monophonic
DC
Amplifier
shows
us
your
appreciation
of
uncompromised
reproduction
of
the
music
you
enjoy.
Throughout
the
design
and
manufacture
of
this
unit,
we
made
every
effort
to
assure
it
will
meet
all
of
your
expectations.
To
ensure
continuing
high
performance,
read
this
manual
carefully
before
you
connect
and
operate
your
hk775.
Warning:
To
prevent
fire
or
shock
hazard,
do
not
expose
this
appliance
to
rain
or
moisture.

Connections
For
the
moment,
leave
the
POWER
LINE
CORD
(4)
of
the
hk775
unconnected.
Put
the
unit
on
the
shelf
or
table
where
it
will
be
installed.
Leave
enough
working
space
so
you
can
make
all
connections
easily.
The hk775 requires adequate ventilation. It
should
not
be
installed
on
a
cushion
or
rug,
and
a
minimum
of
two
inches’
(5cm)
clearance
should
be
provided.
(However,
hk700
series
components
may
be
stacked.)
Connecting speaker
Use two-conductor stranded wire to connect
your speaker to the power amplifier. Eighteen
(1.5mm?) gauge lamp cord (zip cord) is
satisfactory, but a heavier gauge (16 or 14
gauge) (2.5 or 3mm’) is preferable, especially
for distances over 25 feet (8 meters).
Cut a cord long enough to reach the speaker.
Separate the conductors at each end of the
cord for a length of about two or three inches
(5 to 7cm). Then carefully remove about one-
quarter inch (5mm) of insulation from each
free end. Twist the strands of each conductor
so they are smooth and tight with no loose
strands.
Lamp cord usually provides a “code” that
differentiates between the two conductors. A
conductor may be coded by a rib, sharp
corner, or indentations along the length of the
insulation. In some cases a thin colored thread
is molded inside the insulation of one con-
ductor. In others, one wire is darker than the
other, or the insulation of each conductor is a
different color.
Connect one end of the lamp cord to your
speakeras follows:
Connect the coded conductor to the speaker's
red
‘’+"'
terminal,
and
the
uncoded
conductor
to the black ‘’—"’ terminal. Find the SPEAKER
CONNECTORS (3) on the amplifier marked
SPEAKER.
Turn the red plastic thumbscrew of the
connector marked G counterclockwise to
reveal the side opening.
Insert the bare end of the coded conductor
into the opening. Turn the plastic thumbscrew
clockwise until the conductor is firmly
tightened in its place.
Unscrew
the
black
plastic
thumbscrew
of
the
connector
marked
©
and
repeat the
same
procedure
for
the
uncoded
conductor.
Connecting the hk775 to your
preamplifier or receiver
Your hk775 is fitted with pin type RCA
connector. Using a standard pin type RCA
patch cord, connect the preamplitier output
connector with the INPUT connector (2) of
your hk775. Push the plug in all the way so it
is firmly seated, making good electrical
contact.
If your control amplifier does not accept a pin
tyoe RCA connector, consult your audio
dealer for a patch cord with a proper adapter.

AC convenience outlet*
The AC outlet (5) on the rear panel provides
power connection for your control amplifier or
other equipment drawing as much as 500
watts. The outlet is unswitched and provides
power regardless of whether the hk775 is on
or off.
Power connection
If you have completed the connections above,
you are now ready to place the hk775 in its
permanent position and plug the POWER LINE
CORD (4) into an AC outlet. To turn the unit
on and off, press the POWER SWITCH (8).
When power is on, the POWER indicator (6)
will light.
Power level display
The power output of the hk775 can be
monitored by observing the LEDs on the
POWER LEVEL DISPLAY (9).
The display may be turned on or off with the
DISPLAY
pushbutton
(10).
With
the
DISPLAY
SENSITIVITY pushbutton (11) in the x!
position
and
8
ohm
speaker
connected,
the
power output reading will range from 0.1
watts to 200 watts as indicated by the left 88
scale. When a 4 ohm speaker is connected,
reading should be taken from the right 482
scale
which
indicates
the
power
output
from
0.2 watts to 400 watts.
At
low
listening
levels
you
may
wish
to
in-
crease
the
display
sensitivity
by
pushing
the
DISPLAY
SENSITIVITY
pushbutton
(11)
to
the
x0.1
position.
In
this
position,
the
8
scale
ranges
from
0.01
watts
to
20
watts,
the
482
scale
ranges
from
0.02
watts
to
40
watts.
Filters
To
minimize
unwanted
super-high
frequency
noises,
depress
the
ULTRASONIC
filter
pushbutton
(13).
|
To filter out extremely low frequencies,
depress the SUBSONIC filter pushbutton (12)
to its ‘on’ position (in).
*In some countries, owing to Safety Agency
Electrical requirements, this AC receptacle is
covered.

The Harman Kardon
Model hk775
Monophonic Amplifier
-
Jechnical
Manual
harman/kardon

PRECAUTIONS
1. Always disconnect the chassis from power line when soldering. Turning the power switch OFF is not enough. Power
line leakage passing through the heating element may destroy the transistors.
2. Never attempt to do any work on the transistor amplifiers without first disconnecting the AC fine cord and waiting
unti! the power supply filter capacitors have discharged.
3. Replacement for output and driver transistors, if necessary, must be made from the same beta group as the original
type.
4. If one output transistor burns out (open or short) always remove all the output transistors in that channel and check
the bias adjustment, the control and other parts in the network with an ohmmeter before inserting a new transistor.
All transistors in one channel will be destroyed if the base biasing circuit is open on the emitter end.
5. When mounting a replacement power transistor, be sure that the bottom of the flange, the mica insulators and the
surface of the heat sink are free of foreign matter, for they may cause transistor failure.
6. Silicon grease must be applied between the transistor and the mica insulator, and between the mica insulator and the
heat sink for better heat conduction.
7. Fuses must be replaced with size and type indicated. Use of other types can expose components to destructive
current levels.
ALIGNMENT PROCEDURES
DC VOLTAGE BALANCE ADJUSTMENT
Equipment Required: DC Voltmeter
DC voltmeter to SPEAKER terminals VR401 OV +t10mV
IDLING CURRENT ADJUSTMENT
Equipment Required: DC Voltmeter
Connect
Output
Meter
To
Adjust
For
DC
voltmeter
to
TP1
(+)
and
TP2
(—)
VR402

ALIGNMENT PROCEDURES
POWER LEVEL DISPLAY SENSITIVITY ADJUSTMENT
Equipment Required: Audio Signal Generator and AC VTVM
Notes: 1. Connect signal source to INPUT jack.
2. Press in DISPLAY SENS. push button to x0.1 (button in) position.
Step Signal Source Connect Output Meter To Adjust For
8 ohm dummy load and AC
VTVM to SPEAKER terminals
Signal source
output level
1 kHz 12.65V on AC VI VM
1 kHz,
—1 dB output level
Topmost LED
lights to glimmer
Fig. 1 — Alignment Points Location

GENERAL UNIT EXPLODED VIEW
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