DOWNLOAD Harman Kardon AVR 645 Service Manual ↓ Size: 18.07 MB | Pages: 117 in PDF or view online for FREE

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Page 97 of 117

SUPPLY (BOTTOM VIEW)

SERVICE PROCEDURE

ALIGNMENT PROCEDURES

1.MAIN AMP idling Adjustment

SET CONDITION

1) SEMI VOLUME POSITION at MAIN/SURROUND AMP Board

MAIN:VR71.VR72
SURROUND:VR73.VR74

NO Signal/No Load
AC Line Voltage:120V/60Hz.230V/50Hz

2) After turning on the unit keep it over than 25min (keep the power/Driver TR as normal temperature)
3) Adjust the voltage value of primary&secondary of wafer to be 25mV by rotating the semi volume of each channel 

to the right

CHANNEL

ADJUSTMENT

MEASUREMENT

VOLTAGE

FRONT-L CH

VR71

P817

23+/-2mV

FRONT-R CH

VR72

P805

23+/-2mV

SURROUND-L CH

VR73

P818

23+/-2mV

SURROUND-R CH

VR74

P806

23+/-2mV

4) CAUTION

In case that power TR or DRIVER TR is needed to be replace for repairing the corresponding channel should be 
adjusted again

FRONT AMP:Q437.Q433.Q435.Q439.Q438.Q434.Q436.Q440
SURROUND AMP:Q333.Q329.Q331.Q335.Q334.Q330.Q332.Q336

2.SURROUND BACK AMP idling Adjustment

SET CONDITION

1) SEMI VOLUME POSITION at CENTER/SURROUND  BACK AMP Board

CENTER:VR501
SURROUND BACK:VR201.VR301

NO Signal/No Load
AC Line Voltage:120V/60Hz.230V/50Hz

2) After turning on the unit keep it over than 25min (keep the power/Driver TR as normal temperature)
3) Adjust the voltage value of primary&secondary of wafer to be 25mV by rotating the semi volume of each channel 

to the right

CHANNEL

ADJUSTMENT

MEASUREMENT

VOLTAGE

CENTER

VR501

P501

23+/-2mV

SURR BACK-L CH

VR201

P201

23+/-2mV

SURR BACK-R CH

VR301

P301

23+/-2mV

4) CAUTION

In case that power TR or DVIER TR is needed to be replace for repairing the corresponding channel should 
be  adjusted again

CENTER AMP:Q519,Q517.Q516,Q518
SUR BACK AMP:Q319.Q317.Q316.Q318.Q219.Q217.Q216.Q218

3.Cautions for main adjustment

1) At MAIN/SUPPLY BOARD.use the below capacitor after discharging for sufficent time for preventing 

possible damage from electrical spark

MAIN

C571.C572

AVR745/645 15000/63V

BOARD

C571.C572

AVR445 12000/63V

SUPPLY

C201,C202

AVR745/645 10000/63V

BOARD

C201,C202

AVR445 8200/63V

2)The checking for MAIN/SUPPLY BOARD should have the discharging circuit discharge

over 30sec.through(4R7Ohm 10W)resistor after push power sw off

harman/kardon

Page 98 of 117

harman/kardon

Page 99 of 117

harman/kardon

Page 100 of 117