Harman kardon hk 570 i service manual

Page 1

The Harman Kardon
Model hk570i

AM/FM/Stereo FM
Solid State Receiver

Twhmfiwfl Mama

harman/kardon

Page 2

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.

Never attempt to do any work on the transistor amplifiers without first disconnecting the AC line cord and
waiting until the power supply filter capacitors have discharged.

Replacement for output and driver transistors, if necessary, must be made from the same beta group as the
original type.

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.

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.

Siliconegrease must be applied between the transistor and the mica insulator, and between the mica insulator and
the heat sink for better heat conduction.

Fuses must be replaced with size and type indicated. Use of other types can expose components to destructive
current levels.

ALIGNMENT PROCEDURES

AM ALIGNMENT
Instruments: 1. AM Signal Generator modulated with 400Hz at 30%.

2. Oscilloscope
3. ACV.T.V.M.

Notes: 1. Set function selector switch to AM position.

2. Connect signal source to a loop placed to radiate signals into AM antenna loop stick (L251).

Step Signal Source Connect Output Meter To Dial Setting Adjust Adjust For
_ Maximum output on
1 YJ¥$¥ZES§§§3L°§°°W WM... XJZfleildi§VFS$5332n
oscilloscope
540kHz Same as above 540kHz L252 Same as above
1600kHz Same as above 1600kHz T6252 Same as above
Repeat steps 2 and 3 for optimum sensitivity
. Maximum output on
s sweaters matindcthisfrzn
oscilloscope
1400kHz Same as above Same as above T0251 Same as above

Repeat steps 5 and 6 for optimum sensitivity