Kenwood KA 5700 Service Manual

Page 1

KENWOOD

Hl/FI STEREO COMPONENTS

SERVICE MANUAL

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km: W non-mu. am

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STEREO INTEGRATED AMPLIFIER

Page 2

CONTENTS

EXTERNAL VIEW ................................ 3
INTERNAL VIEW ................................ 4
DISASSEMBLY FOR REPAIR ........................ 5
BLOCK AND LEVEL DIAGRAM ...................... 6
CIRCUIT DESCRIPTION ........................... 6
DESTINATIONS' PARTS LIST ........................ 7
PARTS LIST ..................................... 8
ADJUSTMENT .................................. 9
PC BOARD

POWER AMP (X09-1250-11) ..................... 1O
SCHEMATIC DIAGRAM . . . . . . . . . . . . .. ............. 11
SPECIFICATIONS ................................ 12

The black front panel is mounted on KA-5750.

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ADJUSTMENT

VFl VR
m8 m7

I Meter Range

METER RANGE ADJUSTM ENT

1. Connect a dummy resistor and an SSVM to the speaker
terminals and an AG (1 kHz) to the AUX terminal.

2. Use AG and volume control to obtain a setting of 40W
(17.88 V/8 $2).

3. Turn semi-fixed resistors VRm7, 8 until 40W is indi-
cated at the power meter.

+ Vcc

20~l50mA

0e2|(22)

W

Voltmeter

(l3.2mV~)
99mV

0623(24)
-Vcc

Measurement of Bias Current

Rm55. 93

RmSG l 94

BIAS CURRENT

BIAS CURRENT ADJUSTMENT

There is no adjustment to be made by semi-fixed resistors
in a conventional manner. According to the type of set,
Rm93 and 94 (27 $2), or Rm55 and 56 (39 Q), or 2752
and 39 (2 in parallel connection are provided in place of
the semiofixed resistors.

The bias resistance value need not be changed even when
power transistor or a driver transistor is replaced. However,
it is necessary to confirm that the bias current is within
the range of 20 ~ 150 mA.

The current value may be changed widely if the varistor
(STV-4H) is changed. Therefore bias current must be
checked whenever this varistor has been replaced.

If adjustment is difficult to achieve, do not use the resistor
and instead use the following circuit consisting of a semi-
fixed resistor and a solid resistor. The printed circuit board
is provided with mounting holes so that the resistor can be
replaced by a semi-fixed resistor.

Semi-fixed resistor IOOQ(B) """" RI2-0052-05
$0: Resistor IOOQ 34w Rouevzemu

109(8)