Hp 6235a Service manual

Table of contents

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TRIPLE

OUTPUT

POWER

SUPPLY

MODEL

6235A

OPERATING

AND

SERVICE

MANUAL

FOR

SERIALS

1752A-00101

AND

ABOVE

*

For

Serials

above

1752A-00101,

a

change

page

may

be

included.

HEWLETT

M

PACKARD

m

CERTIFICATION

Hewlett-Packard

Company

certifies

that

this

instrument

met

its

published

specifications

at

the

time

of

shipment

from

the

factory.

Hewlett-Packard

Company

further

certifies

that

its

calibration

measurements

are

traceable

to

United

States

National

Bureau

of

Standards,

to

the

extent

allowed

by

the

Bureau

s

calibration

facility,

and

to

the

calibration

facilities

of

other

Inter¬

national

Standards

Organization

members.

WARRANTY

AND

ASSISTANCE

This

Hewlett-Packard

product

is

warranted

against

defects

in

materials

and

workmanship

for

a

period

of

one

year

from

the

date

of

shipment

[,except

that

in

the

case

of

certain

components

listed

in

Section

I

of

this

manual

the

warranty

shall

be

for

the

specified

period],

Hewlett-Packard

will,

at

its

op-

lon,

repair

or

replace

products

which

prove

to

be

defective

during

the

war¬

ranty

period

provided

they

are

returned

to

Hewlett-Packard,

and

provided

the

preventive

maintenance

procedures

in

this

manual

are

followed.

Repairs

neces-

^

b

y

misuse

°f

the

product

are

not

covered

by

this

warranty.

NO

01

HER

WARRANTIES

ARE

EXPRESSED

OR

IMPLIED

INCLUDING

BUT

NOT

LIMITED

TO,

THE

IMPLIED

WARRANTIES

OF

MERCHANT¬

ABILITY

AND

FITNESS,

FOR

A

PARTICULAR

PURPOSE.

HEWLETT-

PACKARD

IS

NOT

LIABLE

FOR

CONSEQUENTIAL

DAMAGES.

Service

contracts

or

customer

assistance

agreements

are

available

for

Hewlett-

Packard

products.

For

any

assistance,

contact

your

nearest

Hewlett-Packard

Sales

and

Service

Office.

Addresses

are

provided

at

the

back

of

this

manual.

TABLE

OF

CONTENTS

Section

Page

I

GENERAL

INFORMATION.

1-1

1-1

DESCRIPTION.

1-1

1-7

SPECIFICATIONS

AND

SUPPLE¬

MENTAL

CHARACTERISTICS.

1-1

1-9

OPTIONS..

1-1

1-12

SAFETY

CONSIDERATIONS

....

1-1

1-14

ACCESSORIES..

1-1

1-16

INSTRUMENT

AND

MANUAL

IDENTIFICATION.

1-2

1-

1

8

ORDERING

ADDITIONAL

MANUALS.

1-2

II

INSTALLATION.

2-1

2-

1

INITIAL

INSPECTION

.

2-1

2-3

Mechanical

Check.

2-1

2-5

Electrical

Check.;

.

2-1

2-7

INSTALLATION

DATA.

2-1

2-9

Location.

2-1

2-11

Outline

Diagram.

2-1

2-13

Rack

Mounting.

2-1

2-15

Input

Power

Requirements.

2-1

2-18

Power

Cable.

2-2

2-

2

2

REPACKING

FOR

SHIPMENT

...

2-2

III

OPERATING

INSTRUCTIONS

...

3-1

3-

1

INTRODUCTION.

3-1

3-3

CONTROLS

AND

INDICATORS.

.

3-1

3-4

Line

Switch.

3-1

3-5

Voltage

and

Current

Metering

....

3-1

3-8

Voltage

Controls.

3-1

3-10

TURN-ON

CHECKOUT

PROCEDURES.

3-1

3-13

LINE

VOLTAGE

OPTION

CONVERSION.

3-2

3-15

OPERATION.

3-2

3-17

Tracking

Ratio.

3-3

3-19

Overcurrent

Protection.

3-3

3-21

Operation

Beyond

Rated

Output

.

.

3-3

3-23

Connecting

Loads.

3-3

3-26

Parallel

Operation..

.

3-3

3-28

Special

Operating

Considerations

.

.

3-3

Section

Page

IV

PRINCIPLES

OF

OPERATION

...

4-1

4-1

OVERALL

OPERATION.

4-1

4-5

0

TO+18V

REGULATED

SUPPLY.

4-1

4-8

Constant

Voltage

Operation.

4-1

4-12

Current

Limit

Operation.

4-2

4-14

Circuit

Protection

Components

.

.

.

4-2

4-16

0

TO

-18V

REGULATED

SUPPLY.

4-2

4-

20

0

TO

+6V

REGULATED

SUPPLY

.

4-2

V

MAINTENANCE.

5-1

5-

1

INTRODUCTION.

5-1

5-4

TEST

EQUIPMENT

REQUIRED

.

.

5-1

5-6

PERFORMANCE

TEST.

5-1

5-8

General

Measurement

Techniques.

.

5-2

5-15

Rated

Output,

Tracking,

Meter

Accuracy,

and

Current

Limit

.

.

5-2

5-17

Load

Effect

(Load

Regulation)

...

5-3

5-19

Source

Effect

(Line

Regulation).

.

.

5-4

5-21

PARD

(Ripple

and

Noise).

5-4

5-29

Load

Transient

Recovery

Time

.

.

.

5-5

5-32

TROUBLESHOOTING.

5-6

5-35

Troubleshooting

Procedure.

5-6

5-38

Open

Fuse

Troubleshooting

.....

5-6

5-40

REPAIR

AND

REPLACEMENT.

.

.

5-7

5-41

Series

Regulator

Replacement

....

5-7

5-43

Semiconductor

Replacement.

5-7

5-46

ADJUSTMENT

AND

CALIBRATION

.

5-7

5-47

Current

Limit

Adjustment

.

5-7

5-50

Meter

Calibration

.

5-7

VI

REPLACEABLE

PARTS.

6-1

VII

CIRCUIT

DIAGRAMS

.

7-1

n

SECTION

I

GENERAL

INFORMATION

1-1

DESCRIPTION

1-2

The

Model

6235A

Triple

Output

Power

Supply

is

a

compact

general

purpose

bench

supply

particularly

useful

for

powering

developmental

!C

circuits,

both

linear

and

digital.

This

constant-voltage/current-limiting

supply

com¬

bines

two

0*

to

±18V

tracking

outputs

rated

at

0.2A

with

a

single

0*

to

+6V

output

rated

at

1

A.

The

+18V

and

—18V

tracking

outputs

can

also

be

used

in-series

as

a

single

0

to

36V,

0.2A

output.

Connections

to

the

outputs

are

made

to

binding

posts

on

the

front

panel.

The

+6V

and

±18V

outputs

share

a

common

output

terminal

which

is

isolated

from

chassis

ground.

The

chassis

ground

terminal

is

located

on

the

supply's

rear

heat

sink

assembly.

1-3

Each

output

is

protected

against

overload

or

short-

circuit

damage

by

separate

fixed

current

limit

circuits.

The

+18V

and

—18V

outputs

are

each

limited

to

0.255A

±15%

and

the

+6V

output

is

limited

to

1.275A

±1

5%.

1-4

Voltage

controls,

output

terminals,

and

a

combin¬

ation

voltmeter/ammeter

are

located

on

the

front

panel.

One

voltage

control

sets

the

0

to

+6V

output

and

another

simultaneously

adjusts

the

0

to

+18V

and

0

to

-18V

dual

tracking

outputs.

A

tracking

ratio

control

sets

the

ratio

between

the

+18V

and

-18V

outputs.

It

can

set

the

nega¬

tive

supply's

output

to

any

value

between

a

minimum

that

is

less

than

0.5V

and

a

maximum

that

is

equal

to

the

positive

supply's

output.

A

1:1

ratio

is

useful

when

powering

opera¬

tional

amplifiers

and

other

circuits

that

require

balanced

positive

and

negative

voltages.

Once

the

tracking

control

has

established

a

voltage

ratio

between

the

positive

and

neg¬

ative

outputs,

the

ratio

remains

constant

as

the

±18V

volt¬

age

control

varies

both

outputs.

1-5

The

front

panel

also

contains

a

line

pushbutton

switch

with

a

simulated

(non-electrical)

on-off

indicator,

and

four

meter

select

pushbutton

switches.

One

meter

push¬

button

selects

either

voltage

or

current

monitoring

and

the

remaining

three

pushbuttons

select

the

output

to

be

monitored

and

the

proper

meter

range.

1-6

In

addition

to

the

standard

104-to-127Vac,

47-to-

63Hz

input,

a

240Vac

nominal

line

voltage

option

is

avail-

*Each

output

has

a

minimum

operating

voltage

of

<

50m

V.

able.

The

supply

is

furnished

with

a

permanently

attached

5-foot

3-wire

grounding

type

line

cord.

The

ac

line

fuse

is

in

an

extractor

type

fuseholder

on

the

rear

heatsink.

1-7

SPECIFICATIONS

AND

SUPPLEMENTAL

CHARACTERISTICS

1-8

Table

1-1

provides

specifications

and

supplemental

characteristics

for

Triple

Output

Power

Supply,

Model

6235A.

Specifications

describe

the

supply's

warranted

performance

characteristics.

The

supplemental

characteristics

are

typical,

but

non-warranted,

performance

characteristics

and

are

intended

to

provide

additional

information

useful

in

applying

the

power

supply.

1-9

OPTIONS

1-10

Options

are

factory

modifications

of

a

standard

instrument

that

are

requested

by

the

customer.

The

follow¬

ing

options

are

available

with

this

instrument.

OPTION

NO.

DESCRIPTION

028

Input

power:

208-250Vac,

47-63Hz,

single

phase.

910

One

additional

operating

and

service

manual

shipped

with

the

power

supply.

1-11

Before

the

supply

is

shipped

from

the

factory,

an

internal

line

voltage

selector

switch

is

set

and

the

proper

fuse

installed

for

the

line

voltage

specified

on

the

order.

A

label

on

the

rear

heatsink

identifies

this

line

voltage

option.

The

user

can

convert

an

instrument

from

one

line

voltage

option

to

the

other

by

following

the

instructions

in

para¬

graph

3-13.

1-12

SAFETY

CONSIDERATIONS

1-13

This

product

is

a

Safety

Class

1

insturment

(pro¬

vided

with

a

protective

earth

terminal).

The

instrument

and

manual

should

be

reviewed

for

safety

markings

and

instructions

before

operation.

1-14

ACCESSORIES

1-15

The

accessory

listed

below

may

be

ordered

from

your

local

Hewlett-Packard

field

sales

office

either

with

the

1-1

power

supply

or

separately.

(Refer

to

the

list

at

the

rear

of

the

manual

for

addresses.)

.HP

PART

NO

.

DESCRIPTION

14522A

Rack

Mounting

Tray

for

mounting

one

or

two

6235A

supplies

in

a

standard

19"

relay

rack.

1-16

INSTRUMENT

AND

MANUAL

IDENTIFICATION

1-17

Hewlett-Packard

power

supplies

are

identified

by

a

two

part

serial

number.

The

first

part

is

the

serial

number

prefix,

a

number-letter

combination

that

denotes

the

date

of

a

significant

design

change

and

the

country

of

manufac¬

ture.

The

first

two

digits

indicate

the

year

(10

=

1970,

11

=

1971,

etc.)

the

second

two

digits

indicate

the

week,

and

the

letter

A"

designates

the

U.

S.

A.

as

the

country

of

manufac¬

ture.

The

second

part

is

the

power

supply

serial

number.

A

different

sequential

number

is

assigned

to

each

power

sup¬

ply,

starting

with

00101.

1-18

If

the

serial

number

on

your

instrument

does

not

agree

with

those

on

the

title

page

of

the

manual,

Change

Sheets

supplied

with

the

manual

or

Manual

Backdating

Changes

define

the

difference

between

your

instrument

and

the

instrument

described

by

this

manual.

1-19

ORDERING

ADDITIONAL

MANUALS

1-20

One

manual

is

shipped

with

each

power

supply.

(Option

910

is

ordered

for

each

extra

manual,

see

paragraph

1-9.)

Additional

manuals

may

also

be

purchased

separately

from

your

local

Hewlett-Packard

field

office

(see

the

list

at

the

rear

of

this

manual

for

addresses).

Specify

the^model

number,

serial

number

prefix,

and

the

HP

Part

Number

pro¬

vided

on

the

title

page.

Table

1-1.

Specifications

and

Supplemental

Characteristics

SPECIFICATIONS:

The

following

specifications

describe

the

6235A's

warranted

performance

characteristics.

Source

Effect

(Line

Regulation);

Given

for

any

line

voltage

change

within

rating.

0

to

+6V

Output:

8m

V

DC

Output:

0

to

±18V

Outputs:

15mV

Voltage

span

over

which

output

may

be

varied

using

front

panel

controls.

*

Minimum

operating

voltage

for

each

output

is

<

50

millivolts.

PARD

(Ripple

and

Noise):

All

Outputs:

Less

than

1mV

rms

and

5mV

p-p

(20Hz

to

20MHz),

0

to

+6V

Output:

Maximum

rated

output

current

is

1

A.

Short

circuit

output

current

is

1.275

±15%

and

a

fixed

current

limit

circuit

limits

the

output

to

this

maximum

at

any

output

voltage

setting.

Load

Transient

Recovery

Time:

All

Outputs:

Less

than

50qsec

for

output

recovery

to

within

15m

V

of

nominal

output

voltage

following

a

load

change

from

a

full

load

to

half

load

(or

vice

versa).

0*

to

±18V

Output:

Maximum

rated

current

is

0.2A

for

each

output.

Short

circuit

output

current

is

0.255A

±15%

and

fixed

current

limit

circuits

limit

the

output

of

each

sup¬

ply

to

this

maximum

at

any

output

voltage

setting.

Unbal¬

anced

loads

within

current

rating

are

permitted.

Temperature

Ranges:

Operating

0

to

+40°C

ambient.

From

40°C

to

55°C,

out¬

put

current

is

derated

linearly

to

50%

at

55°C.

Storage:

-40°C

to

+75°C.

Meter

Ranges:

Input

Power:

Standard

Option:

104-127Vac

(120Vac

nominal),

47-

63Hz,

single

phase.

(240Vac

line

voltage

option

available,

see

paragraph

1-9.)

0

to

+6V

Output:

0

to

7V,

0

to

1,2A

0

to

+18V

Output:

0

to

21V,

0

to

0.24A

0

to

-18V

Output:

0

to

21V,

0

to

0.24A

Meter

Accuracy:

Load

Effect

(Load

Regulation):

Voltage

load

effect

is

given

for

a

load

current

change

equal

to

the

current

rating

of

the

supply.

0

to

+6V

Output:

8mV

0

to

±18V

Outputs:

lOmV

Voltmeter:

All

Outputs:

±3%

of

full

scale

Ammeter:

All

Outputs:

±4%

of

full

scale

Weight:

Net:

5

lb

(2.3

kg)

Shipping:

7

lb

(3.2

kg)

1-2

Table

1

-

1

.

Specifications

and

Supplemental

Characteristics

(Continued)

SUPPLEMENTAL

CHARACTERISTICS:

The

following

characteristics

are

intended

to

provide

information

useful

in

6235A

applications

by

giving

typical,

but

non-warranted,

performance

parameters.

Regulation

and

Ripple

(Typical

performance

parameters):

The

maximum

load

regulation,

line

regulation,

and

ripple

specifications

listed

on

page

1-2

are

given

for

0

to

40°C

temperature

range.

At

an

ambient

temperature

of

25°C,

ty

pical

performance

characteristics

are

as

follows:

Load

Regulation:

0

to

+6V

Output:

4mV

0

to

±18V

Output:

6mV

Line

Regulation:

0

to+6V

Output:

4mV

0

to

±18V

Output:

6mV

Ripple:

All

outputs:

0.2mV

rms.

Tracking

Accuracy

(±18V

Outputs):

The

output

voltage

tracking

ratio

remains

constant

(within

1

%)

over

the

voltage

range

from

1

to

18

volts

for

any

TRACK

control

setting.

Temperature

Coefficient:

All

Outputs:

Less

than

0.04%

+

2mV

voltage

change

per

degree

Celsius

over

the

operating

range

from

0

to

40°C

after

30

minutes

warm-up.

Drift

(Stability):

All

Outputs:

Less

than

0.1%+10mV

(dc

to

20Hz)

during

8

hours

at

constant

line,

load,

and

ambient

after

an

initial

warm-up

time

of

30

minutes.

1-3

SECTION

II

INSTALLATION

2-1

INITIAL

INSPECTION

2-2

Before

shipment,

this

instrument

was

inspected

and

found

to

be

free

of

mechanical

and

electrical

defects.

As

soon

as

the

instrument

is

unpacked,

inspect

for

any

damage

that

may

have

occurred

in

transit.

Save

all

packing

materials

until

the

inspection

is

completed.

If

damage

is

found,

file

claim

with

carrier

immediately.

The

Hewlett-Packard

Sales

and

Service

office

should

be

notified

as

soon

as

possible.

2-3

Mechanical

Check

2-4

This

check

should

confirm

that

there

are

no

broken

knobs

or

connectors,

that

the

cabinet

and

panel

surfaces

are

free

of

dents

and

scratches,

and

that

the

meter

is

not

scratched

or

cracked.

2-5

Electrical

Check

2-6

The

instrument

should

be

checked

against

its

elec¬

trical

specifications.

Section

V

includes

an

"in-cabinet"

performance

check

to

verify

proper

instrument

operation.

2-7

INSTALLATION

DATA

2-8

The

instrument

is

shipped

ready

for

bench

opera¬

tion.

Before

applying

power

to

the

instrument,

see

the

CAUTION

notice

in

paragraph

3-11.

2-9

Location

2-10

This

instrument

is

air

cooled.

Sufficient

space

should

be

allotted

so

that

a

free

flow

of

cooling

air

can

reach

the

rear

of

the

instrument

when

it

is

in

operation.

It

should

be

used

in

an

area

where

the

ambient

temperature

does

not

exceed

40°C

(up

to

55°C

with

derating).

2-11

Outline

Diagram

2-12

Figure

2-1

illustrates

the

outline

shape

and

dimen¬

sions

of

this

supply.

2-13

Rack

Mounting

2-14

One

or

two

6235A's

may

be

mounted

in

a

standard

19-inch

rack

panel

using

rack

mounting

tray

HP

Part

No.

14522A.

Installation

consists

of

bolting

the

rack

mounting

tray

to

the

19-inch

rack

and

sliding

the

power

supply(s)

Into

the

slot(s)

provided

in

the

tray.

The

power

supply's

rubber

feet

are

seated

in

holes

in

the

bottom

of

the

tray.

2-15

Input

Power

Requirements

2-16

The

supply

may

be

operated

continuously

from

a

nominal

1

20V

or

240V

(47-63Hz)

single

phase

power

source.

The

supply

is

shipped

from

the

factory

ready

to

be

operated

from

one

of

these

power

sources.

A

label

on

the

rear

heatsink

identifies

the

line

voltage

option

of

your

supply.

The

input

voltage

range

and

input

current

required

for

each

of

the

nominal

inputs

are

listed

below.

The

maxi¬

mum

input

power

(high

line,

full

load

conditions)

required

for

either

input

is

35

watts.

Line

Voltage

Maximum

Option

Range

Input

Current

Standard

(1

20Vac)

104-127Vac

.26A

028

(240Vac)

208-250Vac

.14A

_

2-

1

7

If

desired,

the

user

can

convert

the

unit

from

one

option

to

another

by

following

the

instructions

in

paragraph

3-

1

3

.

A

unit

is

converted

by

resetting

an

internal

line

volt¬

age

selector

switch,

replacing

the

fuse

and

line

cord

plug,

and

changing

the

line

voltage

label.

TOP

TERMINAL

Figure

2-1.

Outline

Diagram

2-1

2-18

Power

Cable

2-22

REPACKAGING

FOR

SHIPMENT

2-19

To

protect

operating

personnel,

the

National

Electrical

Manufacturers

Association

(NEMA)

recommends

that

the

instrument

panel

and

cabinet

be

grounded.

This

instrument

is

equipped

with

a

three

conductor

power

cable.

The

third

conductor

is

the

ground

conductor

and

when

the

cable

is

plugged

into

an

appropriate

receptacle,

the

instru¬

ment

is

grounded.

The

offset

pin

on

the

power

cable

three-

prong

connector

is

the

ground

connection.

In

no

event

shall

this

instrument

be

operated

without

an

adequate

cabi¬

net

ground

connection.

2-20

To

preserve

the

protection

feature

when

operating

the

instrument

from

a

two-contact

outlet,

use

a

three-prong

to

two-prong

adapter

(if

permitted

by

local

regulations)

and

connect

the

green

lead

on

the

adapter

to

ground.

2-21

Model

6235A

is

equipped

at

the

factory

with

a

power

cord

plug

appropriate

for

the

user's

location.

Figure

2-2

illustrates

the

standard

configuration

of

power

cord

plugs

used

by

HP.

Below

each

drawing

is

the

HP

Part

Num¬

ber

for

a

replacement

power

cord

equipped

with

a

plug

of

that

configuration.

Notify

the

nearest

HP

Sales

Office

if

you

require

a

different

power

cord.

2-23

To

insure

safe

shipment

of

the

instrument,

it

is

recommended

that

the

package

designed

for

the

instrument

be

used.

The

original

packaging

material

is

reusable.

If

it

is

not

available,

contact

your

local

Hewlett-Packard

field

office

to

obtain

the

materials.

This

office

will

also

furnish

the

address

of

the

nearest

service

office

to

which

the

instru¬

ment

can

be

shipped

and

provide

the

Authorized

Return

label

necessary

to

expedite

the

handling

of

your

instrument

return.

Be

sure

to

attach

a

tag

to

the

instrumenfwhich

specifies

the

owner,

model

number,

full

serial

number,

and

service

required,

or

a

brief

description

of

the

trouble.

Figure

2-2.

Power

Cord

Plug

Configurations

2-2

SECTION

III

OPERATING

INSTRUCTIONS

3-1

INTRODUCTION

3-2

This

section

describes

the

operating

controls

and

indicators,

turn-on

checkout

procedures,

and

other

opera¬

ting

considerations

for

the

Model

6235A

Triple

Output

Power

Supply.

WARNING

Before

the

instrument

is

switched

on,

all

protective

earth

terminals,

extension

cords,

auto-transformers

and

devices

connected

to

it

should

be

connected

to

a

protective

earth

grounded

socket

Any

inter¬

ruption

of

the

protective

earth

grounding

will

cause

a

potential

shock

hazard

that

could

result

in

personal

injury.

Only

fuses

with

the

required

rated

current

and

specified

type

should

be

used.

Do

not

use

repaired

fuses

or

short

circuited

fuseholders.

To

do

so

could

cause

a

shock

or

fire

hazard.

3-3

CONTROLS

AND

INDICATORS

3-4

Line

Switch

3-5

The

LINE

pushbutton

switch

(item

(?)

,

Figure

3-1)

is

pushed-in

to

turn

the

supply

ON

and

released

(out

position)

to

turn

the

supply

OFF.

A

simulated

(non-electri¬

cal)

ON

indicator

(within

the

pushbutton)

"lights"

when

the

button

is

pushed-in

whether

or

not

power

is

applied

to

the

unit.

3-6

Voltage

and

Current

Metering

3-7

Four

meter

select

pushbutton

switches

(items

(5)

and

(3)

)

permit

the

output

voltage

or

current

of

any

one

supply

(+6V,

+1

8V,

or

—18V)

to

be

monitored

on

the

VOLTS/AMPS

meter

(?)

.

The

V/A

pushbutton

(2)

selects

either

voltage

(out

position)

or

current

(in

position).

The

+6,

+18,

and

-18

output

select

pushbuttons

(s)

connect

the

desired

output

to

the

metering

circuit

when

the

applicable

button

is

pushed-in.

The

three

output

select

pushbuttons

are

mechanically

interlocked

so

that

only

one

can

be

pushed-in

at

a

time.

The

voltmeter

and

ammeter

ranges

selected

by

the

+6,

+18,

and

-18

pushbuttons

are

listed

below.

The

shaded

areas

on

the

meter

scales

indicate

the

amount

of

output

voltage

or

current

that

may

be

avail¬

able

in

excess

of

the

normal

rating.

OUTPUT

METER

RANGES

VOLTS

AMPS

+6V

0-7

0

-1.2

+18V

0-21

0-0.24

-18V

0-21

0-0.24

3-8

Voltage

Controls

3-9

The+6

VOLTAGE

control

(

5

)

sets

the

output

voltage

level

of

the

+6V

supply

and

the

±18

control

(6)

sets

the

output

voltage

levels

of

the

dual

tracking

±1

8V

sup¬

plies.

Precise

tracking

of

the

+18V

and

—18V

outputs

is

achieved

by

controlling

the

positive

output

and

using

it

as

a

reference

voltage

for

the

negative

supply.

The

TRACK

VOLTAGE

control

(?)

sets

the

ratio

between

the

—18V

and

+18V

output

voltages.

Once

the

ratio

is

set,

the

+18

VOLTAGE

control

will

control

both

outputs

with

a

constant

ratio

maintained

between

the

two

outputs.

The

voltage

controls

(cermet

potentiometers)

have

infinite

resolution;

thus,

the

resolution

obtained

depends

only

upon

the

user's

care

in

setting

the

controls.

Greater

accuracy

in

setting

the

controls

can

be

achieved

by

using

a

DVM

to

measure

the

outputs.

3-10

TURN-ON

CHECKOUT

PROCEDURES

3-11

The

following

steps

describe

the

use

of

the

Mode!

6235A

front

panel

controls

and

indicators

illustrated

in

Figure

3-1

and

serve

as

a

brief

check

that

the

supply

is

opera¬

tional.

Follow

this

checkout

procedure

or

the

more

detailed

performance

test

of

paragraph

5-6

when

the

instrument

is

received

and

before

it

is

connected

to

any

load

equipment.

Proceed

to

the

more

detailed

performance

test

beginning

in

paragraph

5-6

if

any

difficulties

are

encountered.

——

CAUTION-

Before

the

supply

is

switched

on,

check

the

label

on

the

heat

sink

to

make

certain

that

the

supply's

line

voltage

option

agrees

with

the

line

voltage

to

be

used.

The

supply

will

be

damaged

if

its

internal

switch

is

set

for

a

120Vac

input

and

240

Vac

input

power

is

applied.

a.

Connect

line

cord

to

power

source

and

push

LINE

switch

(?)

in.

b.

Set

meter

select

switches

(2)

,

(3)

to

monitor

3-1

i

Figure

3-1.

Controls

and

Indicators

+6V

supply

s

output

voltage.

With

no

load

connected,

vary

the

+6

VOLTAGE

control

©

over

its

range

and

check

that

the

voltmeter

0

responds

to

the

control

setting.

c.

Monitor

the

+18V

supply's

output

voltage.

With

no

load

connected,

vary

the

±18

VOLTAGE

control

©

over

its

range

and

check

that

the

voltmeter

responds

to

the

control

setting.

d.

Monitor

the

—18V

supply's

output

voltage.

Turn

TRACK

VOLTAGE

©

control

fully

clockwise.

With

no

load

connected,

vary

the

±18

VOLTAGE

control

©

over

its

range

and

check

that

the

voltmeter

responds

to

the

con¬

trol

setting,

e.

Monitor

the

±1

8V

output

and

adjust

±18

VOLTAGE

control

for

+18V

indication

on

voltmeter.

Monitor

the

-18V

output

and

check

the

effect

of

the

TRACK

VOLTAGE

control

on

the

voltage

of

the

-18V

output.

The

-18V

out¬

put

should

be

adjustable

from

less

than

0.5

volts

to

a

maxi¬

mum

of

1

8

to

21

volts

as

the

TRACK

control

is

rotated

from

its

fully

CCW

to

its

fully

CW

position.

f.

Turn

the

+6,

±18,

and

TRACK

VOLTAGE

controls

fully

CW.

Connect

ammeter

(e.

g.

Simpson

Multimeter,

Model

269),

in

turn,

between

each

output

and

COM.

The

internal

resistance

of

the

meter

is

low

enough

to

overload

the

supply

so

that

the

output

will

current

limit.

Verify

that

the

current

limit

circuit

in

each

supply

is

limiting

the

output

current

to:

Supply

Current

Limit

+6

V

1.275A

±15%

+18V

0.255A

±15%

-18V

0.255A

±15%

g.

R

e

m

o

ve

meter

and

connect

loads

to

the

output

ter¬

minals

(see

paragraph

3-23).

3-1

2

If

this

brief

checkout

procedure

or

later

use

of

the

supply

reveals

a

possible

malfunction,

see

Section

V

of

this

manual

for

detailed

test,

troubleshooting,

and

adjustment

procedures.

3-13

LINE

VOLTAGE

OPTION

CONVERSION

3-14

To

convert

the

supply

from

one

line

voltage

option

to

the

other,

proceed

as

follows:

T

Disconnect

line

cord

from

the

power

source.

2

.

Remove

top

cover

from

supply

by

removing

2

screws

in

rear

of

supply

and

sliding

cover

to

the

rear.

The

line

voltage

selector

switch

(S2)

is

mounted

on

the

circuit

board

behind

the

meter.

3.

Set

S2

to

the

desired

position

(see

Figure

3-2).

The

forward

switch

position

(toward

front

panel)

selects

120

V

ac

input

and

the

rear

switch

position

(toward

heat

sink)

selects

the

240Vac

input.

4.

Check

the

rating

of

the

installed

fuse

and

replace

it

with

correct

value,

if

necessary.

For

120Vac

input,

use

a

0.4A

slo-blow

fuse

(HP

Part

No.

2110-0340).

For

240Vac

input,

use

a

0.2A

slo-blow

fuse

(HP

Part

No

2110-0235).

5.

Install

proper

line

cord

and

plug

(see

paragraph

2

-

2

1

)

.

6.

Mark

the

supply

clearly

with

a

tag

or

label

indicating

the

correct

line

voltage

to

be

used.

3-15

OPERATION

3-16

This

power

supply

can

be

operated

individually

or

in

parallel

with

another

supply

(see

paragraph

3-27).

All

output

terminals

are

isolated

from

chassis

ground.

The

±6V

and

±1

8V

outputs

use

a

single

common

output

terminal

©

This

common

(COM)

terminal

or

any

one

of

the

other

out¬

put

terminals

may

be

grounded

to

the

chassis

ground

termi¬

nal

which

is

located

on

the

supply's

rear

heat

sink.

All

out¬

puts

may

also

be

left

floating.

Loads

can

be

connected

separately

between

each

of

the

0

to

18V

output

term

inals

and

the

COM

terminal,

or

between

the

+18V

and

—1

8V

terminals

for

a

0

to

36V

output.

A

single

load

can

also

be

connected

between

the

±6V

and

-18V

terminals

for

a

0

to

24V

output.

Figure

3-2.

Line

Voltage

Selector

(Set

For

120Vac)

3-2