Kenwood PD8-20 User manual

COO/AN>DI

CONSTANT-VOLTAGE

CURRENT

POWER

SUPPLY

PD8-20(D)

PD8-30(D)

PD18-20(D)

PD18-30(D)

PD35-20(D)

SERVICE

MANUAL

TRIO-KENWOOD

CORPORATION

WARNING

The

following

instructions

are

for

use

by

qualified

personnel

only.

To

avoid

electric

shock,

do

not

per-

form

servicing

other

than

contained

in

the

operating

instructions

unless

you

are

qualified

to

do

so.

SAFETY

Before

connecting

the

instrument

to

a

power

source,

carefully

read

the

following

information,

then

verify

that

the

proper

power

cord

is

used

and

the

proper

line

fuse

is

in-

stalled

for

power

source.

If

the

power

cord

is

not

applied

for

specified

voltage,

there

is

always

a

certain

amount

of

danger

from

electric

shock.

Line

voltage

This

instrument

operates

using

ac-power

input

voltages

that

100/120/220/240

V

at

frequencies

from

50 Hz

to

60

Hz.

Power

cord

The

ground

wire

of

the

3-wire

ac

power

plug

places

the

chassis

and

housing

of

this

instrument

at

earth

ground.

Do

not

attempt

to

defeat

the

ground

wire

connection

or

float

this

instrument;

to

do

so

may

pose

a

great

safety

hazard.

The

appropriate

power

cord

is

supplied

by

an

option

that

is

specified

when

the

instrument

is

ordered.

Waming

If

groundings,

especially

points

|

(Vg)

and

¥

(Ig),

are

short-

circuited

during

servicing,

it

could

lead

to

pattern

damage

due

to

large

amount

of

current

flow

on

the

PCB.

Take

ap-

propriate

care.

CONTENTS

SPECIFICATIONS.

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DISASSEMBLY

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BLOCK

DIAGRAM

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CIRCUIT

DESCRIPTION

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TROUBLESHOOTING.

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PARTS

LIST

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SCHEMATIC

DIAGRAM.

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DISASSEMBLY

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SEMICONDUCTORS

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SPECIFICATIONS

[

Model

PD

|

8-20

(D)

|

8-30

(D)

18-20

(D)

[

18-30

(D)

|

35-20

(D)

|

Output

voltage

10-positions

0to8V

Oto8V

Oto

18

V

Oto

18

V

ae

Oto

36V

Resolution

(theoretical)

1.4

mV

1.4

mV

3

mV

3

mV

6

mV

Output

current

1-position

|

Oto

20A

Oto

330A

0to

20A

0

to

30A

Oto

20A

Resolution

(theoretical)

30

mA

45

mA

30

mA

45

mA

30

mA

Voltage

regulation

(CV)

With

input

changes

of

+

10%

Note

1)

0.005%

+1

mV

With

load

changes

of

0

to

100%

Note

1)

0.005%

+1

mv]

0.005%

+2

mV

Ripples/noises

(10

Hz

to

1

MHz}

rms

Note

2)

0.5

mV

rms

Transient

response,

(standard

value)

100

ysec,

typical

Temperature

characteristic,

(standard

value)

100ppm/°C,

typical

Remote

control

resistance/voltage

approx.

O

to

10

kQ/0

to

10

V

|

Current

regulation

(CC)

With

input

changes

of

+

10%

2mA

3mA

5

mA

5

mA

5

mA

With

load

changes

of

0

to

100%

5

mA

5

mA

!

5

mA

5

mA

5

mA

Ripples/noises

(10

Hz

to

1

MHz)

rms

Note

2)

10

mA

|

10

mArms

|

10

mArms

10

mArms

Remote

control

resistance/voltage

Protection

Operation

Temperature

detection

Overvoltage

protection

level

(standard

value)

Meter

and

indications

Voltmeter

(class

2.5)

F.S

Ammeter

(class

2.5)

F.S

Voltage

at

digital

display

(Auto

range)

D

type

Current

at

digital

display

(Fix.

range)

approx.

O

to

10

kQ/O

to

10

V

turns

off

power

switch

100°C

15

to

110%

of

rated

output

voltage

;

19.99

V,

199.9

V

(FS)

two

ranges

+(0.1%

rdg+1

digit)

23°C

+5°C;

Less

than

80%

RH

99.9

A

(FS),

+(0.5%rdg+

1

digit)

23°C

+5°C,

Less

than

80%

RH

Indication

of

constant

voltage

operation

CV

green

LED

lights

Indication

of

constant

current

operation

CC

red

LED

lights

Indication

of

output

OUTPUT

red

LED

fights

when

turned

on

Function

Output

switch

Turns

on

and

off

output

(preset

voltage

indicated

with

meter

during

off

time)

Voltage/current

check

switch

Preset

voltage

and

current

indicated

with

meters

during

on

time

Overvoltage

preset

(OVP)

Indicates

the

over

voltage

protection

level

on

the

voltmeter

during

on

time

Remote

sensing

Via

the

rear

panel

senser

terminal

Series

control

Master/slave

control

Parallel

control

Master/slave

control

|

Operating

conditions

Temperature

0°C

to

40°C

Humidity

Less

than

80%

Cooling

Fan

Output

polarity

Plus.

or

minus

Withstand

voltage

to

ground

}—+-_

|__|

+

250VDC

SPECIFICATIONS

[

Model

PD

i

8-20

(D}

|

*

8.30

(D)

|

18-20

(D}

|

18-30

(D)

35-20

(D)

Insulation

resistance

Chassis-input

line

30

MQ

or

more

at

500

VDC

Chassis-output

tine

20

MQ

or

more

at

500

VDC

Power

supply

]

Input

voltage

100/120/220/240

VAC

+10%,

1

¢

selectable

internally

Approx.

420

W

Approx.

590

W

Approx.

620

W

Approx.

930

W

Approx.

1

kW

Power

consumption

(at

AC

100)

[{~—__—_——}

Approx.

670

VA

|

Approx.

960

VA

|

Approx.

1

kVA

|Approx.

1.4

kVA

|

Approx.

1.6

kVA

Dimensions

and

weight

{W)

208 208

a

208

Enciosure

dimensions

(H)

147 147

147

j

(D)

348

457 420

457

420

r

=:

(Ww)

208 208

208

zi

208

{

Maximum

dimensions

({H)

168

({D}

410 519

482

|

519

482

Weight

Approx.

15

kg

Approx.

20

kg

Approx.

19

kg

Approx.

24

kg

Approx.

23

kg

Accessories

Instruction

manual

1

1 1

Se

100

V,

120

V

area

2-core

cabtyre

cable

(3

m)

Input

power

cord

(3-core

cabtyre

cable,

3

m)

220

V,

240

V

area

3-core

AC

cable

(2

m)

100

V,

120

V

area

1AXx2

15

Ax2

15

Ax2

20Ax2

Note:

1.

Measured

via

the

sensing

terminal.

2.

Measured

with

plus

or

minus

grounded.

Rack

adaptor

RK-601

(U4

of

EIA

standards)

is

optionally

available.

B®

Circuit

and

ratings

are

subject

to

change

without

notice

due

to

developments

in

technology.

20Ax2

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CIRCUIT

DESCRIPTION

OF

BLOCK

DIAGRAM

10.

11

.

Voltage

selector

and

surge

absorber.

Selects

rated

input

voltage

and

limits

external

noise.

.

Power

switch

(circuit

protector)

This

function

as

a

power

switch,

and

breaks

the

power

supply

in

event

of

an

accident

in

the

power

sourcé.

.

Power

transformer

Provides

auxiliary

windings

to

operates

the

main

and

accessory

circuits

in

the

transformer.

.

SCR

control

rectification

circuit

A

rectification

circuit

to

control

the

DC

level

syn-

chronized

with

AC,

with

the

gate

pulse

from

the

phase

control

circuit.

.

L,

C

smoothing

circuit

Averages

the

rectified

output

from

the

choke

coil

and

capacitor.

The

choke

coil

limits

transient

current

for

a

high

power

factor

and

low

ripple.

.

Phase

control

circuit

Generates

a

trigger

pulse

AC

synchronized

with

the

SCR

control

rectification

circuit

to

maintain

the

Vc

of

the

series

transistors

at

a

constant

voltage.

.

Series

control

circuit

Used

to

control

high

output

with

a

small

signal

by

Darl-

ington

connecting

the

high

output

power

transistor.

.

Current

detecting

circuit

A

stable

detection

voltage

is

obtained

by

effecting

adequate

derating,

using

resistor

with

a

low

temperature

factor.

.

Voltage

detecting

circuit

A

stable

detection

voltage

is

obtained

using

a

highly

precise

metal

oxide

film

resistor

with

a

low

temperature

factor.

CC

error

(differential)

amp

A

highly

precise

amplifier

which

uses

a

high-gain,

low-

drift

OP

Amp

and

compares

output

from

the

current

detecting

circuit

with

the

current

reference

voltage.

.

CV

error

(differential)

amp

A

highly

precise

amplifier

which

uses

a

high-gain,

low-

drift

OP

Amp

and

compares

output

from

the

voltage

detecting

circuit

with

the

voltage

reference

voltage.

12.

13.

14,

15.

16.

17.

18.

19.

20.

21.

OR

circuit

Selects

automatically

one

(using)

the

OR

circuit

from

the

CV

or

CC

amp

depending

on

output

and

setting.

Circuit

power

source

Supplies

regulated

DC

voltage

to

operate

the

control

circuit

and

provides

a

protection

function.

Voltage

reference

circuit

This

circuit

is

within

the

control

power

source

feed-

back

loop,

and

stably

drives

the

temperature

compen-

sation

zener

diode.

Current

reference

circuit

Drives

the

temperature

compensation

zener

diode

us-

ing

the

constant

current

circuit

to

provide

a

stable

out-

put.

OVP

circuit

Detects

output

voltage

within

a

range

of

15%-110%

of

the

rated

output

voltage,

according

to

the

external

overvoltage

setting.

,

Overcurrent

detecting

circuit

Detects

when

the

current

reaches

a

level

of

125%

of

the

rated

current,

using

the

signal

from

the

current

detecting

circuit.

Temperature

detecting

switch

Detects

when

the

heat

sink

of

series

transistor

becomes

100

°C

with

the

thermal

relay.

Constant-current

circuit

A

discharge

circuit

for

series

transistor

leakage

current

and

the

output

capacitor.

Circuit

protector

drive

circuit

Drives

the

protector

with

the

signals

that

come

from

the

respective

detecting

circuits.

It

provides

a

constant

and

discharge

circuit

to

minimize

influence

from

small

noise,

etc.

Meter

amp

Selects

output

voltage,

voltage

or

reference

voltage

with

the

V/I,

OUTPUT

and

OVP

and

passes

it

through

the

buffer

amp

to

provide

stablized

meter

output

-

CIRCUIT

DESCRIPTION

1.

MAIN

POWER

SOURCE

The

AC

input

voltage

is

rectified

by

D1-D4,

and

the

output

smoothed

by

the

choke

coils

T2

and

C1.

The

thyristors

D1

and

D2

are

controlled

in

the

phase

control

circuit.

The

rec-

tified

voltage

goes

through

the

series

control

transistors

Q1-Qn

and

current

detecting

resistor

R10,

and

is

supplied

to

the

output

+OUT

terminal.

The

—OUT

terminal

goes

through

D6

and

returns

to

the

recitification

circuit.

2.

REFERENCE

VOLTAGE

CIRCUIT

This

circuit

generates

the

control

circuit

power

source

and

a

variable

reference

voltage

for

voltage

and

current

(V,.,,

|).

The

AC

voltage

is

recitified

by

D1

and,

a

constant

voltage

of

+15

V

is

generated

in

the

constant

voltage

cir-

cuit

which

consists

of

Q1-Q8,

U1

and

D14.

The

reference

voltage

of

+15

V

is

generated

by

the

zener

diode

D14.,

—15V

is

generated

by

the

error

amplifier

U1

(1/2),

reference

voltage

(D14)

and

the

dividing

resistors

R20

and

R21.

+15

V

is

generated

by

the

error

amplifier

U1

(2/2)

and

dividing

resistors

R9

and

R10.

The

GND

of

the

+15

V

is

indicated

by

4

V<

on

the

circuit

diagram,

and

is

connected

to

the

+OUT

terminal.

The

power

source

of

this

differential

amplifier

U1

is

supplied

by

the

zener

diodes

D6

and

D9.

V..

is

the

variable

reference

voltage

for

constant

voltage

control,

and

the

V,.,

voltage

(0-10

V)

is

output

between

the

rear

terminals

(3)-(5)

from

U3

(2/2),

VR1

[VOLTAGE].

lL.

is

the

variable

reference

voltage

for

constant

current

control,

and

the

V,.,

voltage

(0-10

V)

is

output

to

the

rear

terminals

(8)-(11)

from

U3

(1/2),

VR2

[CURRENT].

3.

VOLTAGE/CURRENT

CONTROL

CIRCUIT

(See

Fig.

2)

With

the

floating

type

of

voltage

control,

the

control

circuit

is

controlled

using

the

+

OUT

terminal

as

a

reference

GND.

The

GND

of

the

contro!

power

source

+15

V

(4V¢)

is

therefore

of

equal

potential

to

the

+

OUT

terminal.

The

+

OUT

terminal

voltage

and

a

voltage

divided

by

the

voltage

detecting

resistors

R42

and

R43

are

applied

to

the

voltage

control

feedback

amplifier

U4.

Both

input

terminals

of

U4

are

operated

to

keep

the

same

potential.

The

output

from

the

feedback

amplifier

U4

goes

through

D26,

is

amplified

by

Q12

and

Q13,

passes

through

Q7

(Y86),

and

drives

the

base

of

the

current

amplification

circuit

Q1-Qn.

The

voltage

at

both

ends

of

the

constant

current

detecting

resistor

R10

(0.025

ohms,

40

W)

is

used

as

a

reference

for

the

current

operation.

This

point

is

the

GND

during

constant

current

operation,

is

indicated

by

¥l_

on

the

circuit

diagram,

and

becomes

the

reference

point.

When

the

output

current

|,

flows,

the

voltage

produced

in

the

current

detecting

resistor

R10

is

applied

to

the

control

amplifier

U5.

The

voltage

divided

to

I,.,;

voltage

feedback

by

R45

and

R46

is

applied

to

U5.

When

the

voltage

at

both

ends

of

R10

exceeds

this

divided

voltage

(R45

and

R46),

U5

is

operated

to

drive

as

the

con-

stant

current

through

D27.

The

output

from

U5

drives

Q1-Qn

(series

regulators)

through

the

same

route

as

during

constant

voltage

opera-

tion.

When

the

current

exceeds

the

constant

current

set-

ting

value,

the

operation

of

the

feedback

amplifier

circuit

U4

is

simultaneously

stopped,

and

the

D26

route

is

inter-

rupted.

Namely

D26

and

D27

are

control

OR

circuits.

4.

METER

CIRCUIT

The

voltmeter

indicating

circuit

detects

voltage

from

the

+OUT

terminal,

which

goes

through

U2

(2/2),

the

OVP

CHECK

switch,

U6

(1/2),

the

V/I

CHECK

switch,

the

OUT-

PUT

ON/OFF

switch,

meter

amp

U7

(2/2)

and

is

applied

to

the

voltmeter.

When

V/I

CHECK

is

on,

the

V,.,;

voltage

is

applied

directly

to

the

meter

amp

U7

(2/2).

The

voltage

detected

by

the

current

detecting

resistor

R10

for

the

ammeter

circuit

goes

through

the

V/I

CHECK

switch

and

is

applied

to

the

ammeter

amp

U7

(1/2).

During

V/I

CHECK,

the

I,.,

voltage

is

applied

directly

to

the

meter

amp

U7

(1/2).

Q1-Qn

(series

regulators)

are

controll-

ed

by

010, Q12,

Q13

(X73)

and

Q7

(Y86),

by

operating

the

OUTPUT

ON/OFF

switch,

to

turn

output

voltage

ON

and

OFF.

5.

OVP

CIRCUIT

AND

OCP

CIRCUIT

The

D5

(zener diode)

reference

voltage

that

is

divided

with

VR1

and

the

+OUT

terminal

voltage

divided

by

R3,

Ré4

is

applied

to

the

OVP

voltage

detecting

comparator

U1

(1/2).

When

the

output

voltage

exceeds

the

voltage

setting

of

VR1

(OVP

setting

VR),

the

output

of

U1

is

inverted.

The

in-

verted

output

goes

through

D8,

Q1

and

D9,

drives

thyristor

D10

and

turns

the

breaker

switch

$1

OFF.

The

reference

(GND)

of

the

OVP

circuit

is

the

same

as

the

+

OUT

terminal

V,

of

the

voltage

control

circuit.

The

detecting

voltage

generated

by

the

current

detecting

resistor

R10

and

the

reference

voltage

of

D28

(zener

diode)

is

applied

to

the

OCP

current

detecting

comparator

U6

(2/2).

If

an

excessive

amount

of

current

flows

(overcurrent),

the

output

of

U6

(2/2)

is

inverted,

it

goes

through

D7,

Q1

and

D9

to

drive

the

thyristor

D10

and

turns

the

breaker

switch

$1

OFF.

Furthermore,

the

thermal

relay

provided

on

the

heat

sink

to

prevent

overheating

of

the

series

regulator

transistor

detects

abnormal

temperature

rise,

and

turns

the

breaker

switch

S1

OFF

through

D6.

The

OVP

circuit,

OCP

circuit

and

overheating

prevention

protective

circuit

drive

the

breaker

switch

S1

with

the

OR

7

CIRCUIT

DESCRIPTION

circuit

that

consists

of

D6,

D7

and

D8.

6.

PHASE

CONTROL

CIRCUIT

The

PD

series

power

source

features

a

phase

control

circuit

to

control

the

thyristors

D1

and

D2

of

the

main

power

source

rectifying

bridge,

in

order

to

minimize

power

loss

of

the

series

control

transistors

(Q1-Qn)

by

maintaining

the

voltage

between

the

Q1-Qn

collectors

and

emitters,

regardless

of

load.

The

GND

of

this

phase

control

circuit

consists

of

the

emitter

of

the

series

control

transistors

Q1-Qn,

with

an

independent

floating

circuit

from

the

unit

power

source.

A

stable

+15

V

is

generated

for

the

phase

control

circuit

power

source

by

U10

and

U11.

A

sawtooth

wave

that

is

synchronized

with

the

AC

power

source

line

is

generated

by

D42,

D43

and

U12.

This

sawtooth

wave

is

applied

to

U13

(2/2).

(See

Fig.

3)

The

collector

voltage

(Vce

detecting

voltage)

of

the

series

control

transistor

is

applied

to

the

error

amplifier

U13

(1/2).

The

DC

voltage

of

U13

(1/2)

is

added

to

the

sawtooth

wave

of

U12

(2/2)

and

applied

to

the

input

of

U13

(2/2).

The

pulse

width

modulated

(PWM)

output

of

U13

(2/2)

is

finely

differentiated

by

C64,

etc.,

to

drive

the

one

shot

multi

014.

The

output

of

U14

(trigger

gate

pulse)

is

separated

from

the

GND

of

the

phase

control

circuit,

and

amplified

by

022

and

Q23

to

drive

the

thyristors

(D1

and

D2).

Note:

GND

indication

of

respective

circuits

Case

+

Unit

GND

(Case

or

Chassis)

Ve

b

Voltage

control

circuit

GND

Ie

¥

Current

control

circuit

GND

(one

end

—

point

‘’a’’

of

current

detecting

resistor

R10)

thr

Phase

control

circuit

GND

(emitter

point

of

series

control

transistors

Q1-Qn)

Caution:

Do

not

short

the

insulation

to

the

GND

of

the

respective

cir-

cuits

when

repairing

breakdowns.

This

may

result

in

burning

of

the

wiring

and/or

printed

cir-

cuit

board.

7.DPM

UNIT

(D

type

only)

The

digital

panel

meter

unit

consists

of

the

voltage

in-

dicator

circuit

and

current

indicator

circuit,

which

both

function

the

same

electrically.

U1

(U31)

is

the

3-1/2

digit

indicaion

A/D

converter,

with

a

7

segment

LED

driver

incorporated.

U2

(U32)

generates

the

reference

voltage.

The

optimum

value

is

set

with

VR1

(VR31),

and

VR2

(VR32)

is

for

full

scale

adjustment.

The

A/D

converter

is

provided

with

an

external

circuit

constant

to

enable

full

scale

indication

of

1999

when

1.999

V_

is_

input,

regardless

of

voltage

indication,

current

indication

and

type

of

unit.

Namely,

these

circuit

constants

are

R1

(R31),

C3

(C33),

C4

(C34)

and

C5

(C35).

The

main

amp

output

of

the

amp

unit

(X37)

is

fed

to

the

at-

tenuator

which

consists

of

R20

(R50)

and

the

amp

unit

R81

(R73).

Voltage

indication

is

3-1/2

digits,

but

a

2nd

at-

tenuator

is

provided

for

2

step

auto

range

in

case

of

indica-

tion

20

V

or

higher.

When

the

indication

in

the

U3

circuit

exceeds

1999,

a

range

up

signal

is

output,

and

a

range

down

signal

is

ouput

when

the

indication

is

1000

or

lower.

This

signal

is

latched

to

the

RS

flip

flop

which

comprises

U4,

is

passed

through

Q1,

Q2

and

drives

the

decimal

point

LED.

Simultaneously,

Q3

drives

the

analog

switch

Q4.

Since

the

ground

levels

for

the

meter

output

of

the

voltage

and

current

are

different,

the

respective

power

supplies

are

isolated.

CIRCUIT

DESCRIPTION

PRINCIPLE

OF

THE

FLOATING

REGULATOR

Vref:

Reference

voltage

at

CV

lref:

Reference

voltage

at

CC

Va:

Ground

at

CV

Is:

Ground

at

CC

The

output

voltage

at

CC

operation

2

e

loRs=

P=

Iretice

Ope.)

__

Vo=

R,

Vref

The

output

current

at

CC

operation

_

Ry

R,

+R,

Ip=

Bs

Iref

(where

K

=

)

s

Vref

_Vo

RI

~R2

Fig.

2

With

the

PD

series,

the

constant

output

voltage

and

cur-

rent

are

obtained

by

changing

the

Vref

and

Iref.

———

28

V

U12,

2

Rectified

waveform

—OVv

10

ms

(50

Hz)

8.3

ms

(60

Hz)

L

—+14V

U12,

1

Comparator

output

—-14V

—7V

U12,

7

Integrated

output

——-

OV

U13,

7

ead

PWN

output

—-14V

U14,

3

One

shot

I

|

}

output

—oOvV

01,

D2

cathode

SCR

output

OFF

ON

Fig.

3

ADJUSTMENT

To

obtain

the

best

performance,

periodically

calibrate

the

unit.

Sometimes,

only

one

mode

nead

be

calibrated,

while

at

other

times,

all

modes

should

be

calibrated.

When

one

mode

is

calibrated,

it

must

be

noted

that

the

other

modes

may

be

affected

When

calibrating

all

modes,

perform

the

calibration

in

specified

sequence.

The

following

calibration

required

an

accurate

measuring

instrument

and

an

insulated

adjusting

flat

blade

screwdriver.

For

optimum

adjustment,

turn

the

power

on

and

warm

up

this

equipment

sufficiently

(more

than

30

minutes)

before

starting.

Before

calibrating

the

unit,

check

the

power

supply

voltage

and

the

zero

of

the

voltmeter

and

ammeter.

TEST

EQUIPMENT

REQUIRED

The

following

instrument

or

their

equivalent

should

be

used

for

making

adjustment.

Multimeter

8810A

FLUKE

Oscilloscope

CS-1040

TRIO

Item

Control

and

setting

Specifications

PREPARATION

FOR

ADJUSTMENT

1)

The

control

and

switch

settings

listed

below

should

be

used

for

each

adjustment

procedure.

Exceptions

to

these

setting

will

be

noted

as

occur.

2)

Power

cord

should

be

correctly

connected.

3)

Short

bar

should

be

connected

as

follows.

®-¢9.

©

-

©,

O-@

@-@

©-@,

®-@,

@©-

O

lon

the

front

panel)

4)

Heat

sink

should

be

insulated

with

respect

to

the

chassis.

5)

Unless

otherwise

specified,

set

each

control

as

follows

after

completion

of

each

adjustment.

POWER

ON

VOLTAGE

Maximum

counterclockwise

position

CURRENT

Maximum

counterclockwise

position

OUTPUT

OFF

(

@

)

V/I

CHECK

OFF

(

#

)

OVP

CHECK

OFF

(

#

)

OVP

adj.

control

Maximum

clockwise

position

Procedure

C1

Voltage

check

Less

than

10V

Connect

a

multimeter

to

measure

the

voltage

between

C1

(+

side)

and

(—side).

+

15V

check

+15V

+0.5V

Connect

a

multimeter

to

measure

the

voltage

between

OUTPUT

(@)

on

the

front

panel

and

+

15V

test

points

on

the

AMP

unit,

respectively.

Vee

voltage

coar-

|

VOLTAGE;

maximum

se

adjustment

clockwise

position

CURRENT;

maximum

clockwise

position

Approx

4.5V

Connect

a

multimeter

to

measure

the

voltage

between

collector

and

emitter

of

the

transistor

on

the

heat

sink.

See

Fig.

4.

dss

OUTPUT;

OFF

VOLTAGE;

maximum

counterclockwise

posi-

tion

CURRENT;

maximum

clockwise

position

Vrer

Offset

ad-

justment

0V+0.5mV

Connect

a

multimeter

between

OUTPUT

terminal

GS)

and

control

terminal

NO.3

on

the

rear

panel.

Vref

gain

adjust-

|

VOLTAGE;

maximum

ment

clockwise

position

CURRENT;

maximum

clockwise

position

——}—

10.25V

+0.03

V

Connect

a

multimeter

between

OUTPUT

terminal

¢S

and

control

terminal

NO.3

on

the

rear

panel.

ts

VOLTAGE;

maximum

counterclockwise

posi-

tion

CURRENT;

maximum

clockwise

position

V

meter

offset

adjustment

10

D

type;

OV

+0V

Make

adjustment

while

observing

the

V

meter

on

the

front

panel.

Kenwood PD8-20 User manual

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