Harman kardon tu 940

Page 1

The Harman Kardon
Model TU-940

Manual A

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CONTENTS

LEAKAGE TEST .................................... 2 GENERAL UNIT EXPLODED VIEW ......... 21
SPECIFICATIONS .................................. 3 PRINTED CIRCUIT BOARDS ................. 22
CONTROL AND FUNCTIONS .................. 4 ELECTRICAL PARTS LIST ..................... 24
BLOCK DIAGRAM ................... ..7 IC FUNCTIONAL BLOCK DIAGRAM. .32
DISASSEMBLY PROCEDURES ............... 8 PACKAGE .......................................... 33
CIRCUIT DESCRIPTION ....................... 13 WIRING DIAGRAM .............................. 35
ALIGNMENT PROCEDURES ................. 16 SCHEMATIC DIAGRAMS ...................... 36
harman/kardon

Parts and Service Office

80 Crossways Park West, Woodbury, NY. 11797

Printed in Korea

Page 2

LEAKAGE TEST

Before returning the unit to the user, perform the

following safety checks:

1. Inspect all lead dress to makes certain that leads
are not pinched or that hardware is not lodged
between the chassis and other metallic parts in the
unit.

2. Be sure that any protective devices such as
nonmetallic control knobs, insulating fishpapers,
cabinet backs, adjustment and compartment covers
or shields, isolation resistor-capacity networks
mechanical insulators, etc. Which were removed for
servicing is properly reinstalled.

3. Be sure that no shock hazard exists; check for
leakage current using Simpson Model 229 Leakage
Tester, standard equipment item no. 21641, RCA

model WT 540A or use alternate method as follows:
plug the power cord directly into a 230-volt AC
receptacle ( do not use an isolation transformer for
this test). Using two clip leads, connects a 1500
ohm, 10-watt resistor paralleled by a 0.15 pF
capacitor, in series with all exposed metal cabinet
parts and a known earth ground such as a water
pipe or conduit. Use a VTVM or VOM with 1000
ohms per volt, or higher sensitivity to measure the
AC voltage drop across the resistor. (This test
should be performed with the power switch in both
the on and off positions.)

A reading of 0.35 volt RMS or more is excessive
and indicates a potential shock hazard which must
be corrected before returning the unit to the owner

TO EACH EXPOSED
METAL SIRFACE 0F
WIT UNDER TEST

HIGH
VOLTAGE
0R +LEAD

SIMPSON MODEL 229 ETC. FOR LEAKAGE TEST

10 AC GROUND SUCH
AS WATER PIPE BX CABLE
counur ETC.

GROUND
LEAD

TEST PROBE

T0 EXPOSED
METALID PARTS

CONNECT TD KNOVIN
EARTH GROUND