Hammond L Service Manual

SERVICE

IVIANmL

-

-^---^•'-ttiinrf

HO-735

HAMMOND ORGAN

COMPAIW

DIVISION

OF HAMMOND

CORPORATION

11700 Copenhagen

Court

/

Franklin Park,

lUinois

6013]

(312)

766-6950

TABLE OF

CONTENTS

Page

Introduction

.

iv

Specifications

iv

SECTION

I

-

How

the Organ Operates

1-1

General

1-1

1—2

Tone Source

1

—

1

1—3

Motor and Power

Switch

1—4

1—4

Tone Generator

1-4

1—5

Manuals 1—5

1—6

Harmonic

Drawbars

1—7

1-7

Pedal Drawbar 1-7

1-8

Pedal Keyboard

1-7

1—9

Expression Pedal

1—7

1-10

Control Tabs

1-8

1-11

Preset Tabs

1-8

1-12

Vibrato Tabs

.

1-8

1

—

13

Reverberation

Volume

Soft Tabs

1—8

'

1—

14 Percussion Control

Tabs

1—8

1-15

L-IOOA

Preset

Percussion

Unit

1-9

1-16

Selector Switch

1-9

1-17

Harmonic

Busbar

Switching

and

Reiteration

Split

...

1-9

1—18

L—

100—

1

Six-Voice

Percussion

Feature

.

1—9

1

—

19 Location of

Controls

1—9

1-20

Voicing

1-9^

1-21

Operation of

Controls

1—9

1—

22 External Equipment

1

—

1

1—23

Extension

Speakers

1—1

1—24

External

Sound

Source

1-1

1—

25 Earphones

1—1

SECTION

II

-

Theory

of Operation

2-

1 General

2-1

2—2

Preamplifier

2—1

2-3

Vibrato Phase

Shift

Amplifier 2-1

2—4

Percussion

Amplifier 2—2

2-5

Reverberation

and Power

Amplifier

2—2

2-6

Power

Supply

2-3

2—7

L-IOOA

Percusion Voicing

Circuitry

2-3

2-

8 Mode

Switch

2-3

2—9

Frequency

Divider 2—4

2-10

Cymbal

and

Brush 2-4

2-11

Brush

Keying

2-4

2—12

Cymbal

Keying

2—4

2—13

Bmsh

and

Cymbal

Amplification 2-4

2—14

Power

Supply

2-4

2—15

L-

1

00-1

Six-Voice

Percussion

Circuitry

2-4

2-16

Power

Supply

2-4

2-17

Push-Button

Circuits

2-5

2-18

Lower

Manual

Keying

Circuits

2—5

2-19

Pedal Keying

Circuit

^

2-5

SECTION

III

-

Disassembly

3-1

General

,

3-1

3-2

Access

,

. .

.

3-1

3—3

Upper

Manual Key

3—1

3—4

Lower

Manual

Key

3—1

3—5

Drawbar Contact

Spring

3—1

3—6

Drawbar,

Drawbar

Knob,

Drawbar

Assembly

3—1

3-7

Upper Manual

3-2

3—8

Lower

Manual

3—2

3—9

Generator

3—2

3-10

Motor

3-2

3-11

Pedal Keyboard

3-2

3—12

Swell Assembly

3—3

3-13

Tab

3-3

3-14

Pilot Light

on

Power Switch

3-3

3-15

L-IOOA

Percussion Circuitry

3—3

3—

16 L—

1

00—

1 Six-Voice Percussion

3—3

SECTION IV

-

Practical

Service

Suggestions

4-

1

General

4-1

4—2

Organ Performance

Check

4—1

4—3

Equipment

Required

4—1

4-4

Procedure

4—1

4-5

Vibrato

4-2

4—6

L—

1

OOA

Percussion

Performance

Check

4—3

4—7

L-

1

00-

1

Six-Voice

Percussion Performance

Check

and

Troubleshooting

4—4

4-8

Output

Level

Adjustments 4-4

4-9

One

Voice

is Silent

:

4-4

4-10

Programmed

Voice Does Not Speak

4-4

4—

1 1

All

Percussion Voices Silent

4—4

4-12

Both

Hiss

Voices

Silent

4-4

4—13

No

Voice

Response from

Pedals

4—4

4—14

No Voice

Response from Manual

4—4

4—15

No

Percussion Output

4—4

4—

16

Troubleshooting

4—4

4-17

Organ Does Not Play

4-5

4—18

Key Does

Not

Play

or

Harmonic

Missing

4—5

4-19

One

Note

is

Weak

4-6

4—20

Percussion Notes

Weak

or Missing (L—

100)

4—6

4-21

Full

Volume

Pedal Cipher

4-6

4-22

Hum

4-6

4—23

Replacing Tubes

4—6

SECTION

V

-

Diagrams

5—

1 General

5—1

SECTION VI -Parts List

Index

-

L-

1 00

Series

6-1

Index

-

L-200

Series

6-15

LIST

OF

ILLUSTRATIONS

Wigure

Page

1-1.

L-lOO

Console, Front View

1-1

1—2.

L— 100

Console, Rear

View

1

—

2

1-3.

Block Diagram,

L-

100

Series

1-3

1—4,

Typical Tone Generator

1—4

1—5.

Magnet

Locations on Tone

Generator

1—4

1—6.

Filter

Locations

and

Frequency

Terminations

on

Generator

Cover

1—5

1-7.

Manual

Wiring Chart

1-6

1—8.

Drawbars

&

Control

Tabs

(Partial View)

1—7

1-9.

Pedal

Keyboard

1-8

1-10.

L- 1

OOA Preset

Percussion

Unit

1-10

1-11.

L- 1

00-

1

Six-Voice Percussion

Controls

1-10

1

—

12.

Earphone

Adapter

Circuit

1—11

4—

1.

Vibrato

Adjustment

Waveform

4—2

5—

1.

Schematic Diagram,

L—

100

Organ

with

AO

-41

Amplifier

....

5—2

5—2.

Schematic Diagram, L—

100

Organ with

AO—

47 Amplifier

....

5—3

5—3.

Schematic

Diagram, L— 100 Organ with

AO—

47

Amplifier

and

LDR Expression

Control

5—4

5-4.

Schematic

Diagram,

L-IOOA,

L-

100-1

8l L-

100-2

Organ Consoles

5—5

5—5.

Schematic

Diagram and Parts

Layout, L—

lOOA

Percussion

Unit

5—6

5—6.

Schematic

Diagram

and

Parts

Layout,

L—

100—

1 Six-Voice

Percussion

5—7

5—

6A.

Schematic

Diagram and Parts

Layout,

L—

100—

1

Six-Voice

Percussion,

Early 1 970 Production

5—8

5—7.

Schematic

Diagram, L—

100-

1 Percussion Power Supply

....

5—9

5—8.

Schematic

Diagram

&

Parts

Layout,

Pedal Control Board ....

5—10

5-9

Wiring Diagram,

L- 100

Organ

5-11

5-10.

WiringDiagram,

L-

100-1

and L-

100-2

Organs

5-12

5—11.

Wiring

Diagram, Control

Panel,

L-lOO Series

5—13

5—

1

2.

Wiring

Diagram, Control

Panel,

L-

1

00

Series

Revised 5—14

5—13.

Wiring

Diagram,

Percussion

Unit, L—1

OOA

5—15

5—14.

Wiring

Diagram, Six-Voice

Percussion,

L—

100—

1

5—16

5-15.

PartsLayoutAO-41 Vibrato

Amplifier

5-17

5-16.

PartsLayoutAO-47

(126-000023)

Vibrato Amplifier

5-18

5-17.

PartsLayout,AO-42

(117-000019)

Percussion

Amplifier

..

5-19

5-18.

Parts

Layout,

AO-43

(126-000017) Power

Amplifier

5-20

5-19.

Power

Amplifier

Fuse

Location

(Canadian,

101—

000130)

....

5—21

INTRODUCTION

This

manual contains service information

for L—

100

Series

organs. The

series is

comprised

of

the following

models:

L-lOO

L-IOOA

L-100-1

L-100-2

L^200

The Model

L—

100

Hammond

organ is

a

completely

self-contained

console,

requiring no external tone

cabinet.

It

has

two

manuals

or

keyboards

of 44 keys

each, a

1

3

note

pedal

keyboard, and

an expression

(swell)

pedal

for controlling

the

volume.

All tones

are

produced by

electro-magnetic

tone generators and

electrically

amphfied.

Selection

of tone

colors is

made by

adjusting

1

7

drawbars

and

6

preset

tabs.

Other

characteristics

of the

music are

adjusted

by

means

of

10

other tabs.

A

toggle switch,

located

to

the right

\

of

the

console

above the

manuals, is

used

to

turn on the

organ.

A pilot Ught

shows when

the

organ

is

:

turned

on.

^

Model

L-lOOA is

similar to

Model L-lOO,

with the

addition

of

percussion voicing

circuitry, controlled

from the

lower

left end block.

Model

L—

100—

1 is

similar to

L—

100,

with a

six-voice

percussion

feature added.

Percussion controls are

mounted

in the

lower

right end block.

Model L-100-2

is

identical to

Model

L-100-1,

with

the addition

of the

''drawer" type automatic

Rhythm

II feature. No

service

information

for Rhythm

II

is

contained in tliis

manual, since

its

circuitry

\

is

independent

of

the organ.

For

Rhythm

II

service

information,

refer

to

the

Service Manual

for

Rhythm

II

I

HO~466.

Model

L—200 with inbuilt rhythm

is electrically identical to the L—

100—

2 organ.

Wiring of

the

rhythm

uni

to the

console

is

presented in Figure

5—20.

L—Series

organs

will

have

fuses added to

the

Canadian power

supply

(101—000130) to

comply

with

C.S.A.

standards. Location

and value

of

fuses

are shown in

Figure

5—19.

For

convenience in

location desired information, this manual is divided into the following sections:

For convenience in

locating desired information,

this manual

is divided into the following

sections:

I. How

the

Organ

Operates

II. Theory of

Operation

III.

Disassembly

IV.

Practical

Service Suggestions

V. Diagrams

VI.

Parts

List

SPECIFICATIONS

DIMENSIONS:

Width,

43y2";

Height,

44^2";

Depth,

23"

WEIGHT:

215

lbs.

POWER INPUT:

140

Watts

SECTION

I

HOW

THE

ORGAN

OPERATES

1-1.

GENERAL

-

This

section

contains

a

description

of the

operating

principles

of

L—100

Series

organs.

Figures

1—1

and

1

-2

depict

the

locations

of

the

various

subassemblies.

Figure 1

-3

is a

block

diagram.

1-2.

TONE

SOURCE

-

Most

tone

sources,

such

as

strings,

reeds,

or

pipes,

produce

complex

tones.

The

Hammond

tone-producing

mechanism,

however,

generates

individual

frequencies

which

can

be

combined

by

means

of

harmonic

drawbars

to

produce

any

desired

tone

quality.

The

block

diagram,

Figure

1-3,

shows the chief

components

of

the

instrument.

Electrical

impulses

of various

frequencies

are

produced

in the

"tone

generator

assembly"

whicli

contains

a

number

of

"tone

wheels"

driven at

predetermined

speeds

by

a

motor

and

gear

arrangement.

Each

tone

wheel

is a

steel

disc

similar

to a

gear,

with

high

and

low

spots,

or

teeth, on

its

edge

(see

Figure 1

-4).

As

the

wheel

rotates,

these

teeth pass

near

a

permanent

magnet,

and

the

resulting

variations

in

the

magnetic

field

induce a

voltage

in

a

coil

PEDAL

DRAWBAR

CONTROL

TABS

LOWER

MANUAL

DRAWBARS

PILOT

LIGHT

OFF-ON

SWITCH

UPPER OR

SOLO MANUAL

LOWER

OR

GREAT

MANUAL

PEDAL'KEYBOARD

EXPRESSION

(VOLUME) PEdAL

Figure

1-1.

L- 100

Console,

Front View

SELF

STARTING

SYKCHRONOUS

MOTOR

CONTROL

SWITCH

ASSEM.

PERCUSSION

CUT

OFF ADJUST

PEDAL

CLICK

FILTER

wound

on

the magnet. This

small

voltage,

when

suitably

filtered, produces

one

note

of

the musical

scale, its

pitch

or

frequency

depending

on the

number of

teeth passing

the

magnet each second.

A note

played

on

either

manual

of the

organ consists

of

a

fundamental pitch

and

a

number of

harmonics,

or multiples

of

the

fundamental

frequency. The

fundamental

and

harmonics

available on

each

playing

key are controllable by

means

of

drawbars.

By

suitable

adjustment

of these

controls

the

player

may

vary

the

tone colors

at

will.

Several pre-selected

tones

are

also

available by

use

of

the

preset tabs.

Mixed tones

from the

upper manual and

lower manual

and pedals

go

through

the

pre-amplifier and the

"vibrato

amplifier".

Vibrato

may be

added,

depending

on the

position of the vibrato

selector

tabs.

The

tones

then

pass

through the

expression

control and

additional stages

of amplifica-

tion

before reaching the

speaker.

Percussion tones

are

produced

by

borrow-

ing a

signal

from

the

upper manual

2nd

harmonic

drawbar, 3rd

harmonic

drawbar,

or both, and

conducting

the signal

through

the

percussion

amplifier, where

its

decay

characteristics

are controlled.

A

portion

of

this

signal

is

returned

to the

respective

drawbar.

The percussion

signal

is

then combined

with the

signal

from

the

manuals

after

the

vibrato system

but

before

the

expression

control.

The control tubes

are

keyed through the 6th

harmonic key

contacts and

busbar.

The pedal tones do

not

require drawbars

for

tone

color

variation, because

they are

produced as

complex

tones

by

special

tone wheels.

The

single

pedal drawbar

adjusts the

volume

of the pedals

relative

to that

of

the manuals,

and the

pedal signal

then

is

combined with

the

signal

from the

manuals

before passing into

the

matching

transformer.

LEGEND

NOTE:

L-100

SERIES

ORGAN

AMPLIFIER BLOCKS BEARING LIKE NUMBERS

ARE

ON

SAME

CHASSIS.

L-100A

SERIES

ORGAN 'FOLLOWING CONSOLES HAVE BRILLIANCE

TABLET ADDED:

L-10.0-1

SERIES ORGAN

"OOEL

L-101

SERIAL

#41622 AND

ABOVE

MODEL L-102 SERIAL «42028

AND

ABOVE

L-100-2

SERIES ORGAN

MODEL L-103 SERIAL «43102 AND ABOVE

Block

Diagram,

IrlOQ

Series

MAGNET-

COIL OUTPUT

TERMINAL

ONE

SIDE

OF

COIL

GROUNDED

-TONE

WHEEL

COIL

Figure

1

-4.

Typical

Tone

Generator

-3.

-4.

MOTOR

AND

POWER

SWITCH.

-

The

tone

generator

assembly,

in

which

all

tones

of

the

organ

originate,

is

driven

at

constant

speed by

a

self

starting

synchronous

motor,

operating

at

1800

RPM,

located

at

the left

side

(rear

view)

of

the

console

(Figure

1-2).

(In 50

cycle

organs,

the

generator

speed

is

1500

RPM).

A

toggle

switch

(Figure

1

power

to

the

organ.

-1)

controls

TONE

GENERATOR.

-

All

tones

of

the

organ

originate

as

electrical

signals

in

the

tone

generator

assembly.

It

contains

87

tone

wheels

having

various

numbers

of

teeth,

with

suitable

gears

for

driving

them

at

various

speeds

from

a

main

shaft

extending

along

the

center.

Each

pair

of

tone

wheels

is

mounted

on

a

shaft

and

between

them

is

a

bakehte

gear

held

by

a

coil

spring,

forming

a

mechanical

vibration

filter.

As

the

gear

is

not

rigidly

attached

to

the

shaft,

any

pair

of

wheels

which

may

be

stopped

acciden-

tally

will

not

interfere

with

the

operation

of

the

others.

Adjacent

to

each

tone

wheel

is

a

magnetized

rod

with

a

pickup

coil

wound

on

it.

These

magnets

extend

through

the

front

and

back

of

the

generator,

and

are

held

by

set

screws

which

can

be

loosened

in

case

adjustment

is

ever necessaiy.

Figure

1-5

shows

the

location

of the

magnet

for

any

frequency

number.

In the

illustration

the

dotted

lines

indicate

frequencies

whose

tone

wheels

are

on

the

same

shaft.

On

top

of the

tone

generator

assembly

are

small

transformers

and

condensers,

forming

tuned

filters

for the

higher

frequencies.

They

are

not

likely

to

need

replacing.

In

case

one

filter

becomes

inoperative,

both

the

transformer

and

condenser

must

be

replaced

with a

matched

set

from

the

factory.

Figure

1—6

shows

the

location

of

^

these

filters.

A

few

frequencies

use

untuned

filters

consisting

of coils

alone.

Wiring

from

the

various

filter

assemblies

leads

to

the

terminal

strip

on

the

long

edge

of the

generator.

The

output

frequencies

of

the

tone

genera-

tor

are

numbered,

for

convenience,

in

order

of

increasing

frequency.

The

lowest,

number

§)@)@(8l)@(g)@)@@@@)@)©

\®

\@

\0

\@

\e

\®

\<s

\0

\@

\e

\@

\@

s\

@)\

@\

@\

@\

60

(56)

g)\

e

SYNCHRONOUS

MOTOR

CNO

BACK

OF GENEBATOR

(AT BACK

OF

CONSOLE)

SyNCHRONOUS

FRONT

OF

GENERATOR

MOTOR END

DOTTED LINES

SHOW

FREQUENCIES

WHOSE

TONE

WHEELS ARE

ON

SAME

SHAFT

Figure

1—5.

Magnet

Locations

on

Tone

Generator

L

1

,

is

about

32

cycles

per

second,

and

the

^

highest,

number

9

1

,

is

about

6000

cycles

per

second.

Frequency

numbers

1

to

1

3

are

used

only

for

the

pedals;

numbers

14

to

17

are

omitted;

and

numbers

18

to 91

are

used

for

the

manuals.

Figure

1

-6

showing

filter

locations

also

shows

the

termination

point

i

»

of

each

frequency,

while

Figure

5-1

shows

typical

tuned

and

untuned

tone

generators.

I

^

In

case

any

generator

frequency

is

weak

or

[

absent,

refer

to

''Practical

Service

Sugges-

tions"

for

the

procedure

to

be

used

in

locating

and

correcting

the

trouble.

1-5.

MANUALS.

-

Musical

frequencies

from

the

tone

generator

go

through

the

manual

cable

to

terminal

strips

on

the

two

manuals

and

from

them

to

the

key

contact

springs.

Each

of the

two

manuals

has

44

playing

keys,

or

approximately

SVi

octaves.

The

two

manuals

do

not

cover

exactly

the

same

pitch

range,

but

they

are

arranged

so

that

keys

of

like

pitch

are

in

line.

Middle

"C" is

the

first

C

on

the

upper

manual

and

the

key

in

line

with

it

on

the

lower

manual.

Under

each

key

are

a

number

of

contact

springs

(for

the

fundamental

and

harmonics

of

that

key)

which

contact

an

equal

number

of

busbars

when

the

key

is

pressed.

All

contact

springs

and

busbars

have

precious

metal

contact

surfaces

to

avoid

corrosion,

and

the

manuals

are

sealed

to

exclude

dust

so

far

as

possible.

In

case

a

contact

becomes

dirty

in

spite

of

these

precautions,

a

busbar

shifter

is

provided

in

each

manual

to

slide

the

busbars

endwise

and

thus

provide a

fresh

contact

surface.

(See

paragraph

4-3b).

Looking

under

the

lower

manual

on

the

left

hand

end

(front

view)

a

black

wood

end

block

will

be

observed.

One

half

inch

from

the

front

of

this

block

is

a

drilled

hole.

Within

this

drilling

is

a

small

metal

tongue

with

a

punched

hole.

Using

either

long

nose

phers

or

a

hook,

this

tongue

can

be

moved

in

and

out

and

it

in

turn

moves

the

busbars.

The

upper

manual

shifter

is

in

a

similar

place

and

access

to

it

is

from

the

rear

of

the

console.

The

key

contacts

are

connected

through

resistance

wires

to

the

manual

terminal

strips.

The

manual

wiring

chart.

Figure

1-7,

shows

how

the

contacts

of

each

key

are

connected

to

the

proper

frequencies

to

supply

the

fundamental

and

harmonics

of

that

particular

key.

The

blank

spaces

indicate

that

no

key

contact

is

used,

inas-

much

as

the

higher

harmonics

of

these

keys

are

not

required.

Since

the

percussion

control

circuit

is

keyed

through

the

6th

harmonic

busbar,

the

blank

spaces

in

this

row

have

contacts

connected

to

ground

through

resistance

wires.

The

busbars

of

each

manual,

each

one

carrying

a

certain

harmonic,

are

wired

to

the

appropriate

harmonic

drawbars

for

that

manual

through

the

"Drawbars"

tab.

NUW&ERS

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MOTOR

END

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Figure

1-6.

Filter

Locations

and

Frequency

Terminations

on

Generator

Cover

1-5

ER

MANUAL

H/

SL

RMCN

C

BUSBAR

I LAD

COLOR

FRFQUENCY

NUMBERS

B-FUND

BROWN

18

20 2

1

22

23

24 25 26

27

28 29

30

31 32 33

3 4 35 35

37 38 39

40

42

43

44

45 46 47 48

49

50

51

52

53

54

58 b

I

FUND

ORANGE

30

31 32 33

34 3 5

36

37

38

39

40 4

2

43

4 4 45 46

47 48

49 50

5

1 52 53

3

+

55

56

57 58 59 60 6

1 62

63

64

65

6 6

67 && 69 /O

7 1 72

73

3RD

GREEN

49

50

51 52

53

54

55 565758

59

60 6

1

62 63

64

65 66

67 69

70

7

1 72

73 74 75

76

77

78 79

8

0

8

1

82

8 3

84

85

86 8 7

68

8

9

90

4TH

BLUE

54 55

56

57 58 59 60

6

1 62

63

64 65 66 6

7

58 59 70

7

1

72

73

74

75

76

7 7 78

79

80

8

1

82

83

8 4

8 5

66

8 7 88 8 9

90 91

STH

VIOLET

58 59

60 6

1

62

63

64 65 66

67

68 69

70 7 1

72 73

74

75

76

7 7 7

8

79 80

8

1

82

83

84

85 86

87

88 B9 90

91

8TH

WHITE

66

67 68 69

70

7

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73

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78 79

80 8

1

82

83 84

85

86 8

7

88

89 90

9

1

2

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YELLOW

42

43 44

4

5

46

47 4 8

49

50 5

1

52 53

54 55

56

57 58 59 60 6

1 62

63

64 65 66

67

68 69

70

7

1

72

73

74

75 76

77 78

79 80

6 1

82

83

84

85

SUB-3

RD

RED

37

38

39

40

41 42

43

44 45

46

47

48

49 50 5

1 52

53

54

55'

56

57

58

59

60 6 1 62 63

64

65 66 67

68 69

70 7172

73 74 75

76

77

78 79

80

6TH

GREY

61 62 63

64 65 66

67

68 69

70

71 72

73 74 75 76

77

78

79 80 81 62

83

84 85

86

87

88 69

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KEY NUMBERS

FREQUENCY

NUMBERS

BUSBAR

LEAD

COLOR

HARmO NIC

LOWER

MAh

i8

19

20

2

1

22

23

24 25 26

27 28 29

30

31

32

33

34 35 36

37 38

39

40 41 42

43

44

45

46 47

48

49 50 5

1

52 53

54 5 5 56

57

58 59

60 6

1

BROWN

FUND

30

31 32

33

34 35 3fe

37 38

39

40

4

2

43

44

45 46 47

48 49

50

51

52

53 545556

57

58 59

60

61 62

63

64 65

66

67

68 69

70

7 1

72 73

RED

2ND

46

47 46

49

30

51 52 53

54

55 56

57

58 59

60

6

1

62

63

64 55 66

6

7

68

69

70

7

1 72

73

74 75 76

777879 80 8

1 82

83

84

85

86 87 88

89

GREEN

5TH

49 50 5

1

52 53

54

55 56

57

58 59

60 6

1

62

63

64

55

66

6

7

6S

6

9

70 7 1 72

73 74

75

76

77

78 79

80

81 82 83

84 85 86

87 88

69

90

9 1

BLUE

6TH

54 55 56

5

7 56 59 60

6 1 62

63

64 65 66

6

7

68

69

70

7

1 72

73

7

5

76

7

7 76

79 80 8

1

82 83

84 85

8 6

87

88

89

90 9

1

VIOLET

8TH

37

38 39

40

42

43 44 45

46

47 48

49 SO5152

53

54 55

56

57

58

59

60

6

1 62

63

64

65 66

67 68

69

70

7

1

72

73 74

75 76

77

78 79 80

ORANGE

3RD

42

43

44

45

46

47

48 49

50

51

52

53 54

55 56

57 58 59 60

6

1 62 63

64 65 66

67

68 69

70

71

72

73

74

75

76

77 78

79 80

81 82

83 84

85

YELLOW

4TH

*

CONTACTS

GROUNDED

THROUGH

16

OHMS

Figure

1

-7.

Manual

Wiring

Chart

1-6.

HARMONIC

DRAWBARS. -The

left group

of seven

harmonic drawbars (Figure

1

—8)

is

associated with

the lower

manual,

and

the right

group of nine

drawbars

controls

the

upper manual. By sliding

these drawbars

in and

out,

the organist

is

able

to

mix the

fundamental and

harmonics (or

overtones)

in

various

proportions. The distance a

bar

is

pulled out determines

the strength

of

the

corresponding harmonic; and if

a

drawbar

is set

all

the

way in, the

harmonic

it

repre-

sents

is not present

in

the

mixture.

Neither

manual will play unless one

of

its

drawbars

. is pulled

out at least part

of

the way

with

the drawbar

tab

pressed, or

a

preset tab is

pressed.

The

drawbars

sUde

over

1

7

busbars,

repre-

senting intensity levels. As

the drawbar

moves, its contact is

touching

some

busbar

at all times,

and

therefore

there

is a smooth

change

in volume

of

that

harmonic.

These

busbars

extend the length

of

the

draw-

bar

assembly,

and

are connected

to

the

low

impedance

primary of

a matching

transformer. Signals

from

the

high

imped-

ance secondary

of

this

transformer go

to

the preamplifier input. The matching

transformer

is

located

within the preampli-

fier chassis.

1-7-

PEDAL DRAWBAR.

-

The center drawbar

adjusts the volume

of

the

pedals. Its

opera-

tion is similar to that

of

a manual drawbar.

1-8.

PEDAL

KEYBOARD.

-The

13

playing

pedals

are operated

by the

left

foot

and

are

con-

nected

to the

lowest

1

3

frequencies

of

the

generator.

Like

the

manuals, they have

light and

dark

keys

arranged in

the standard

octave

pattern. Figure

1

—9

identifies

the

pedals and

shows

the

generator

frequency

number

associated with

each. A

single

contact

on each pedal

closes

when

the

pedal

is pressed,

thereby

allowing the

correct

generator

frequency

to reach

the amplifier.

1-9.

EXPRESSION PEDAL.

-

The expression

pedal, sometimes called

"swell" pedal

(Figure

1-1)

is

operated

by

the player's

right foot and

varies the volume of

both

manuals and pedals together.

When the

pedal

is tilted back

(closed) by pushing on

the

player's heel

the music

is

softest,

and

when pushed forward (opened)

by the

player's toe

the music is loudest.

Figure 1

-8.

Drawbars &

Control

Tabs

(Partial

View)

PEDAL CONTACTS

Jlllll

lllllll

I

Figure 1

—9.

Pedal

Keyboard

1-10.

CONTROL

TABS.

-

There are

17

tabs

on

the

L-lOO

series

instrument, each

providing

some

change

in the

instrument's

operation.

To

have the

instrument

sound

after turn-

ing

it

on, tabs

such as

FULL ORGAN and

ENSEMBLE will

place the

upper and lower

manual

in

operation. A tab is

in use

when

in the

down

position.

Functions

of

the

various

tabs

from

left

to

right as

they

appear

on the instrument

are given in

the

following

paragraphs.

1-11.

PRESET

TABS.

-

Four

tabs

are provided

for

the

upper manual and

two

for

the

lower manual. As

indicated, they

provide a

choice

of

using

the

drawbars

or playing

the

preset tones

indicated

on them.

1-12.

VIBRATO

TABS.

-

The L-lOO

series

organs

are

equipped with 3

tabs

which

vary the

vibrato

effect.

Three

degrees

of

vibrato

are available

using

the

VIBRATO NORMAL,

VIBRATO

SMALL or both

together.

VIBRATO

CHORUS

can

be

used

with

VIBRATO

NORMAL,

VIBRATO SMALL,

or both, to provide

different

degrees

of

chorus.

1-13. REVERBERATION

AND

VOLUME SOFT

TABS.

-

Several

degrees

of reverberation

are obtained

by

the

use

of

either or

both

tabs

labeled

REVERB

I

and

REVERB 11.

These tabs,

in

addition to

turning

this

feature

on,

govern

the loudness

or amount

ofrever-

beration by

a

resistive

network used in con-

juntion

with the

speaker. The

VOLUME

SOFT tab

controls

the

overall volume

of the

organ and is

especially

useful where

playing

1-14.

PERCUSSION

CONTROL TABS

-

There are

four of these

tabs

which

operate

only

when

the

upper manual

DRAWBARS tab

is

de-

pressed.

Pressing

either the

SECOND

HARMONIC

or

THIRD

HARMONIC tab

will,

when the

upper

manUal is

played,

cause

the tone to

sound

percussively (in

addition

to sustained

organ

tones).

Both

tabs

can

be

depressed,

giving

a

combination

percussive

tone.

The

FAST

DECAY

tab

causes the

percussive tones to

fade away

with

greater

rapidity.

PERCUSSION

SOFT

reduces the

volume

for

the

percussive signal.

Operation

of the

electrical

circuits associated

with

this feature

is

described

in

subsequent

paragraphs.

1-8

1-15.

L-100A

PRESET

PERCUSSION

UNIT

(See

Figure

1-10).-

When added

to

the L-lOO

series

instrument,

this unit

adds

five

pre-

voice

percussion

effects,

including

reiter-

ation in

three speeds.

It

also

provides

three

percussion

effects, "Normal

(Non-

Vibrato)",

"Vibrato",

and

"Delayed

Vibrato".

For

the

rhythm

accompaniment

it

also

provides

a

"Cymbal-Brush"

effect,

the

"Brush"

being

on the

lower

manual, and

available

when

played

in

a

legato

fashion

each time

a

key

is

depressed.

The

"Cymbal"

is

available

on

the

pedal and

sounds

each time a

pedal

is

de-

pressed.

The

"Cymbal-Brush"

control

turns

these effects on

and selects

the

"Cymbal-

Brush" volume.

1-16. SELECTOR

SWITCH.

-

With

the

Selector

Switch in

the

"Drawbar"

position,

the

signals

from

the

upper manual

harmonic

busbars

are routed

to

their

associated

drawbars

in the

upper manual group.

The

following is a

breakdown

of

the

harmonic

switching used.

1-17. HARMONIC BUSBAR

SWITCHING

AND

REITERATION

SPLIT.

-

Upper

Manual.

The

Sub-Fundamental, sub-third

and

eighth

harmonics

are not switched.

The sixth

har-

monic

busbar is

used

for percussion

keying.

With the

Selector Switch

in

the

"Drawbar"

position,

all

harmonic

busbars

are routed

to

.

their associated

drawbars.

1-18.

L-100-1

SIX-VOICE

PERCUSSION

FEATURE

(See

Figure

1-11).

-

1-19.

LOCATION OF

CONTROLS.

-

The

rhythm

controls

are located on the

right

end

block

of

the

lower manual.

1-20. VOICING.

-

The

following

voices

are

available.

BLOCK

CYMBAL

BRUSH

BONGO

TOM-TOM

CLAVES

1-21.

OPERATION

OF

CONTROLS.

-

Any

of the

six

voices

may be

played

at

any

time

by

means

of the

momentary

push buttons

associated

with

the

rocker tabs.

The

BLOCK

and

CYMBAL voices

are

pro-

grammed

into

the

pedal

keyboard

when

their

rocker tabs

are

"on".

The

remaining

four

voices

are

programmed

into

the

lower

manual

keys

when their

rocker tabs

are

on .

Chime

REITERATION

SPLIT

"A"

CHANNEL

"B"

CHANNEL

2nd

3rd
4th

(5th

to

Freq. Div.)

(1-1/4

From

Freq.

Div.)

DRAWBARS

Fundamental

Guitar

Fundamental

3rd

4th

5th

2nd

Marimba

Fundamental

2nd

3rd

4th

5th

,

Xylophone

Fundamental

3rd

2nd

4th

5th

Banjo

2nd

3rd

4th

5th

Fundamental

1-9

Figure

1-10.

HOOA

Preset

Percussion

Unit

1-10

1-22.

1-23.

The

RHYTHM

VOLUME

control, mounted

1-24.

to the right of

the rocker

tabs, regulates

the loudness

of

the

rhythm

voices

relative

to the other organ

voices.

The

organ's

expression

pedal

also

affects

the rhythm

voices except

brush and

cymbal.

The BRUSH

and

CYMBAL

voices sound

without reverberation. The

remaining

voices

are

reverberated whenever

a

REVERB

tab

on the organ's control

panel

is depressed.

EXTERNAL

EQUIPMENT.

-

The

L-lOO

Series

organs

may be

equipped with

ex-

tension

speakers,

external

inputs

and

earphones.

EXTENSION

SPEAKERS.

-

A

Hammond

Model

PR-40

Tone Cabinet

may be used

as an extension

speaker.

A

Tone

Cabinet

1-25.

Control

Kit,

P/N

AO-22625-2

is

required

for

proper

interconnections.

Installation

instructions are furnished

with the kit.

EXTERNAL

SOUND SOURCE.

-

A record

player

or

microphone

equipped

with

a

suitable

preamplifier,

or a radio,

can

be

played through

the organ's

speakers.

The

device

used

should have

an output

level of

about

1/2

volt rms

maximum,

and

should

have

its own volume

control,

since the

organ

volume

controls

will

not affect

the

signal. The

organ

may be

played

at the

same time.

To

connect

an external

sound

source,

a

Switchcraft Type

330 Fl

"Y"

connector

is

required.

Remove

the

connector

cable

from

the WH

terminal

on the

power

amplifier.

Insert

the

''Y"

connector

into the

terminal,

and

insert

cable

previously

removed

into

one

arm of

the "Y".

Connect

external

sound

source

to the

other arm.

EARPHONES.

-

hi

order

to use

earphones,

the output

jack

and

network

shown

in

Figure

1-12

are

required.

When

earphones

are

in

use,

organ

speakers are

silenced.

GN.

BLK.

Organ

Spk.

wires

47a

SWITCHCRAFT

SF-JAX #25

OR

55

ji

Use

Koss

Model

SP-3.

Figure

1—12.

Earphone

Adapter Circuit

SECTION

II

THEORY

OF

OPERATION

2-1.

GENERAL.

-

This

section

contains

circuit

descriptions

of

the

ampUfier

chassis,

and

the

percussion

attachments.

There

are

three

amphfier

assembhes

in

the

L—100

series

instruments.

On

the

upper

shelf as

viewed

from the

rear, to

the

left is

the

vibrato

amphfier,

towards

the

center

the

preamplifier

and

percussion

amphfier,

while

the

reverberation

and

power

amplifier

is

located

on

the

lower

shelf.

2-2.

PREAMPLIFIERS

(See

Figure

5-1).

-

The

pre-

amplifier

(VI)

receives

all

signals

impressed

on

the

matching

transformer

secondary,

which

originate

by

use

of the

drawbars

or

preset tabs.

Should

any

percussion

tab

be

in

use, a

portion

of

the

second,

third

or

both

harmonics

of the

upper

manual

wiU

also

appear in

the

input circuit

of the

per-

cussion

amplifier

which

will be

discussed

further on.

2-3.

VIBRATO

PHASE SHIFT

AMPLIFIER

(See

Figures

5-1

through

5-4).

-

The

vibrator

system

varies

the

frequency

of the

tones

by

continuously

shifting

their

phase.

Circuit

components

include

three

series-

connected

vacuum tube

phase

shifter stages

(V2A,

V2B,

and

V3A),

associated

saturable

reactors

(SRIOI,

SR102,

SR103),

voltage

amphfier

(V3A),

vibrato oscillator

(V4A),

and

driver

stages

(V4B, V5).

A

single

low

frequency

oscillator

(V4)

provides

the

rate

for the

vibrato

system

(approx.

6.8

CPS).

With

either the

normal

or

small

vibrato

tab

in

use,

this

oscillator

impresses its

signal on

V4,

a

cathode

fol-

lower

and

isolation

stage.

Positive

pulses

now

appear

on the

grid

of

driver

tube

V5.

The plate

circuit

of this

tube

is

in

series

with

three

saturable

reactors

located

in the

plate

and

cathode

circuits

of the

phase

shift

stages.

Irrespective

of

which

vibrato

stop is

used,

the rate

remains

constant,

but

the

degree

of vibrato

is

determined

by

the

amplitude

of

the

positive

pulse on

the

driver

tube.

The

continuous phase

shift is

accomplished

by

using

180°

out-of-phase

signals

from

the

plate

and

cathode

of each

shifter

stage

and

controUing

them

with

the

saturable

reactors.

Plate

and

cathode

resistors

are

of

equal

value

and

consequently

signals

are

equal

in

amplitude

in

each

plate

and

cathode

circuit.

The

saturable

reactors

serve

as

a

means

of

providing

a

varying

composite

of

signals

from

both

plate

and

cathode

of

each

stage,

ranging

from

virtually

full

cathode

signal

to

full

plate

signal.

The

driver

tube

plate

current

varies

from

about

.5ma

to

5ma.

at

vibrato

rate.

This

current

varies

the

degree

of

saturation

in

the

reactor

cores

and

results in

a

smoothly

varying

impedance.

At

minimum

driver

current

(when

the

voltage

feeding

driver

tube

V5

is

negative

and

driver

tube

is

nearly

cut

off) the

reactor

impedances

are

maximum

and

are

large

compared

to

the

15000

ohm

plate,

circuit

series

resistors

Rl

04,

Rl

1

0,

Rl 1 5.

Therefore,

under this

condition

most

signal

will

emanate

from the

plate.

(The

reactors

being

virtually

short

circuited

by

the

plate

circuit

series

resistors)

and

phase

shift

will

be

maximum

-

approaching

1

80°

-

since

plate

voltage

is

180**

out

of phase

with

grid

voltage.

At

maximum

driver

current

(when

voltage

feeding

driver

tube

V5 is

positive

and

driver

tube is

conducting

maximum

current)

the

reactors

are

saturated

and

their

impedance

is

a

minimum

—small

compared

to

the

1 5OO0

ohm

plate

circuit series

resistors

R104,

Rl

10,R1

15.

Therefore,

most

signal

will

emanate

from

the

cathode

(the

saturated

and

low

impedance

reactors

virtually

short

circuit

the

plate

circuit

series

resistors)

and

phase

shift

will

be a

minimum

-

approach-

ing

0°

—

since cathode

voltage

is

in

phase

with

input

grid

voltage.

Between

these

extremes,

the

phase

varies

smoothly

under

control

of

the

saturable

reactors.

^

The continuous

change in phase

is

equi-

valent to a continuous frequency vari-

ation, and thus the frequency

varies up

and

down

at

vibrato rate.

PERCUSSION AMPLIFIER (See Figures

5-1

through

5-4).

-

The

2nd or

3rd

harmonic

signal,

or

both, when these

tabs

are de-

pressed, will be impressed upon the input

of the 2N306 transistor.

The

output

of

this transistor is resistance

coupled to the

one

half

of

VI 1

which

acts

as

a control

tube and is normally

conducting, so

when a

t

key

is depressed the percussive

note

first

sounds loudly.

It

passes through the control

tube and a band

pass

filter

and

is

impressed

on

the grid terminal of

VI.

Immediately

the note begins

to

fade away,

giving the characteristic percussion effect.

This

fading

is

accomplished

as

follows: When

jf

either

harmonic

stop is

depressed

the

key-

i

ing

wire

(normally

held at

plus 28 volts

through anti-spark resistor R21

5)

is

con-

nected

to

solo manual

6th

harmonic draw-

bar.

When a

key

is pressed

this

keying

hne

^

is

grounded

through the

key

contact

and

tone

generator

filter.

This

virtually

grounds

the

grid

and plate

of VI 1

(connected

as a

diode)

open-circuiting

the

tube

and

isolating

[

the

control

tube

grid

circuit.

The

grid

of

the

control

tube

drifts

from

its

operating

potential

of about

25

volts to a

cutoff potential

potential

(about

plus

1

5

volts) at

a

rate

determined by

the

time

required

for C210

3

to

discharge

through

R219 and

R409.

The

percussion

signal is now

blocked.

No

percussion

notes

can sound

until

all

keys

of

2-5.

the

solo

manual

are released and

the control

grid

again rises

to

plus

25

volts.

The time

of

this rise (that

is,

how

quickly

the

control

tubes

turn on

again

after the

key

is

released)

is

the

time

required to

charge

C2

1

0

to

plus

25 volts

through

R2

18.

When

a

''percussion"

tab is

pressed

the

solo

manual

second,

third,

or both

harmonic

*

manual

busbars

are

connected

to

the

green

percussion

signal

line and a

5

OHM series

resistor

is

connected

between

the

manual

bus

wire and

drawbars

providing

for

a sus-

tained

signal in

addition

to

the

percussion

signal.

The

6th

harmonic

drawbar

is dis-

connected

from

its

lead

wire

and

this

wire

(which

is

grounded

through

the

generator

magnets

when any

key

is

pressed)

is

used

to

turn

off the

control

tube.

Therefore the

6th

harmonic is

not

available

on the

upper

manual

when

the

percussion is

in use.

When

the

PERCUSSION

SOFT

tab

is

down,

it

reduces

the

volume by

shunting

resistor

R224 into

the dividing network

composed

of R222 and

R223.

The

PERCUSSION FAST

DECAY

tab

determines

how fast the sound

fades away

after

a

key

is

pressed.

When

the tab

is

up,

resistor R21 9

discharges capacitor C21

0,

re-

ducing

the D.C. voltage on the control tube

grids to

cut-off

in

about

2-1

/2

seconds.

When

the

tab is

down, resistor

R409 is

shunted across

resistor R21

9,

reducing

the

time to discharge

capacitor C210

and

there-

by

reducing

the D.C.

voltage

on the control

tube

grid

to cut

off

in

less

than one-half

second.

With either

or both

2ND

and 3RD

HAR-

MONIC

tabs

down,

the harmonic drawbar

wires

are

connected

to

the

-green signal

input

wire of the percussion amplifier. Either or

both signals are fed back to their respective

drawbars

by

resistors

R410

and

R41

1

which

are shorted

out when the

percussion

tabs

are not

in

use.

The percussion signals

as

well

as

the

signals

from

the

vibrato and phase shift amphfier

are combined in the input circuit of

cathode

follower

VI

and are

sent

to

the

expression

control, which is also connected to the

input

of

the

reverberation

and power

amplifier.

REVERBERATION

AND

POWER

AMPLIFIER

(See

Figure

5-4).

-

The

combined signals

from both

prior

mentioned

amplifiers

(after

the

expression

control has acted

upon them)

are

impressed

on the

grid

of V6 and in

turn

on V7, the

reverberation

drive

tube.

After

passing

through the

reverberation unit

the

signal is

again

ampUfied

by V6

and

passed

through

a

resistive

network,

components

of

which

are variable,

permitting

the

reverbera-

tion to

be available

in

several intensities

and

"off.

From

the input

of V7

(the

reverberation

drive

tube)

a signal is

shunted

around

the

reverberation

unit and its

control

features which provide a path

for

the

non-

reverberation

signal.

The input

of

V8

re-

ceives

this

signal

as

well as

a

reverberative

signal. This

common

input

line also

contains

the

VOLUME

SOFT tab

circuitry.

The

output

of

the

second

half of V8 is

a

phase inverter driving push-pull output

tubes V9

and VI 0. A feedback circuit from

the

output transformer

secondary

(R336

and

R337)

makes the

pedal

response

more

uniform

by

reducing

speaker resonance.

I

R336

is adjusted

at

the factory.

2-^6.

POWER

SUPPLY (See

Figure

5-4).

-

The

power

supply uses a 5U4 rectifier

tube

with conventional filtering

circuit.

2-7.

L-10QA PERCUSSION

VOICING CIRCUITRY

(See

Figure

5-5).

2-8.

MODE

SWITCH

-

With the ''Mode

Switch"

in any

of the reiteration

positions, the

harmonics

necessary to produce

the

"Chime",

"Guitar", and "Banjo" are all

fed into the "A"

reiteration channel only,

while the "Marimba"

and

"Xylophone"

effects

feed

harmonics

into both the

"A"

and

the

"B"

channels.

This

spht

into the

"A" and "B"

channels

only occurs

with the

use of reiteration.

Without

reiteration,

all

effects are routed into the regular

percussion

system. The two reiteration

channels are

identical.

You

will

note

that across the

secondary

windings

of the

two input

trans-

formers

is located

a

field-effect

transistor.

These gates

Q300

and

Q303,

are fed alter-

nating pulses from

a

bistable

multivibrator

which

supplies alternate

pulses

to

each

one

of

these

gates. That

is; one

is On, while the

other

is

off.

These gates

shunt the

signal

to ground, thereby

making

the channel

inoperative.

These

individual signals

are

further amplified

by

a

one

stage transistor

amplifier,

Q301

for

the

"A"

channel, and

Q302

for the

"B" channel.

They

are

then

mixed

together

and fed

to a common

amphfier,

Q307,

which

in turn feeds

this

percussion signal

to

the input

side

of

the

swell

pedal.

The

multivibrator

which

supphes the keying

pulse

for

these two

gates does not run

continually,

but

rather

is

turned

off

and on

each time

a

key

is

depressed

on the upper

manual. The

multi-

vibrator

consists

of

Q305

and

Q306.

The

multivibrator

rate varies

with

the

applied

base

voltage.

This

voltage

is applied through

the "Mode

Switch"

and R684

and R685.

Q304

provides

the

necessary

switch

pulse

to start the

multivibrator.

NOTE

Whenever

the

reiteration

is used,

it completely

bypasses the percus-

sion

section of

the AO—

42

amplifier.

With

the "Mode Switch" in

the

"Normal",

"Vibrato",

or

"Delayed Vibrato"

position,

the various pre-voiced

percussions

are

routed

to

a

percussion preamphfier

made

up

of

Q314

and

Q313.

These amplified

signals

are

then

routed

into

the regular

Hammond

percussion

system at

the

col-

lector of

Q201.

With

the "Mode Switch"

in the "Normal"

position all percussion

voices

sound

as normal; that is, they have

no

vibrato.

NOTE

To obtain the following vibrato

effects

it

will

be necessary

to

de-

press

one or

both of

the

VIBRATO

tabs.

With the "Mode

Switch" in the

"Vibrato"

position,

a

portion of

the

percussion

signal

is

taken from

the input

side of

the

Expres-

sion pedal and

routed

through R670,

the

"Mode

Switch", and

is then

fed

to

the grid

of

VI A

(Pin

2).

Here

the percussion

voices

are

amplified

and

fed

to

the

vibrato

phase

shift ampUfier.

All

voices

so

routed

now

appear with

vibrato.

With the

"Mode Switch"

in the "Delayed

Vibrato"

position,

a portion

of

the percus-

sion

signal

is

taken from

the

input

side of

the Expression

pedal, and routed

to a

voltage

divider

made

up

of R682

and

R681.

This weak signal

is

fed

to

the

base

of

Q3

1 2.

It

will

be noted that

the

emitter of

this

stage is not bypassed and that

the output

of

this

stage is

relatively

low. During keying,

after

a predetermined

time

lag

(.5

seconds),

the

charge

on C631

is depleted

by

Q308

and

Q309.

With this

charge depleted,

Q308

and

Q309

stop conducting

and

their

respective collectors

assume the

supply

potential

+

1 2

V. This

+

1

2V.

from

the

collector of

Q309

is

now apphed

to

the

base

Q3

1

0,

thereby

placing

Q3

1 0 and

Q3

1

1

in

a

state

of

conduction.

With

Q3

1 1 now

conducting, C633

is

placed across

the

emitter resistor

of

Q3

1 2.

This

materially

increases

the

gain

of this

stage,

and as

the

percussion

is

dying

away,

feeds

this ampli-

fied

portion of

the

fading

percussion signal

through

the

"Mode

Switch",

and

R683

to

the

grid

of

VI A

(Pin

2).

There the

signal

is ampUfied

and

fed

to the

Vibrato Phase-

Shift amphfier.

All voices

so

routed

now

appear

with

a

vibrato

tail-off.

Two positions

of

the ''Mode Switch",

"Vibrato",

and "Delayed

Vibrato"

also

effect

the

normal Hammond

percussions

I

when

they are in use

(See

Note

above).

2-9.

FREQUENCY

DIVIDER

-

When

using

the

"Chime"

voice,

it is

necessary

to create

a

\

1-1/4

harmonic for

the proper

reproduction

of

the "Chime"

tone.

This

is accompHshed

by routing

the

5th

harmonic

into an

ampli-

fier

made

up of

Q315

and

Q316. Q317

'

rectifies

and

further

amplifies

this

pulse

which

is then

fed

to

a two-stage

frequency

divider,

made

up

of

Q318,

Q319, Q320,

\

and

Q321.

The

output

of

this

second

I

frequency

divider

is then

routed

back

to

I

the "Selector

Switch",

and

is used

as

one

of

the

harmonics

in

the "Chime"

voice.

NOTE

j

Because

a

frequency

divider can

cv

I

handle only one frequency

at a

time,

any attempt

to play two

or

more

"Qiime" notes

at a

time will

result

in

distortion.

^

2-10.

CYMBAL

AND

BRUSH

-

The

"Cymbal-

Brush"

switch when

in

the

"off"

position

disables

the keying

functions

necessary

to

produce

the "Brush"

effect.

With the

"Cymbal-Brush"

switch

in any one of

the

"on"

positions,

the 8th harmonic of

the

lower

manual

is disabled

and

this

harmonic

busbar

is used for

keying

the "Brush"

effect.

The

pedal

signal (keying)

contact

is used

to

activate the "Cymbal"

effect

each

time

a

pedal

is

depressed.

,2-11.

BRUSH

KEYING

-

With

the

"Cymbal-Brush"

'

switch

in any

of

the

ON

positions,

the

base

of

Q322

is

routed

now

to

the

8th

harmonic

busbar

in

the lower

manual.

Anytime

a

key

is

depressed,

the base

voltage

of

this tran-

sistor

is routed

to

ground,

and this

stage

'

stops

conducting.

The

attendant

rise

in

collector

voltage

is

impressed

on one

plate

of

C608.

The

other

plate

of

C608

responds

by

driving

excess

electrons

off

to

ground

through

resistor

R624.

The

resultant

posi-

tive

voltage

is then

fed

through

D203

to

the

base of

Q323,

the

"Brush"

gate.

To

the

base

of

this

"Brush"

gate is

also fed

the

noise

from

the

noise

generator

Q324. This

noise

is

now

tuned

in

the

collector

circuit

and

fed

to the

"Cymbal

and

Brush"

ampUfier

i

which

comists of

Q325

and

Q326.

2-12-

CYMBAL

KEYING.

-

Anytime

a

pedal

is

depressed,

the

pedal

signal

is routed

to the

pedal

drawbar.

A portion of

this

same

signal

is also fed

to

Q327

and

Q328.

These

stages

amplify

and

shape

the

signal

and feed

it

through

R61

2

to

the

base of

Q330,

and

through

R613

and D205

to a R/C

storage

network

and

the

base of

Q329.

The

signal

developed

across

R616,

the

emitter

resistor

of

Q330,

is

rectified

by

D204

and

this

posi-

tive

voltage

is

applied

to the

base

of

Q331,

the

"Cymbal"

gate,

turning

it on. At

the

same

time,

the

output

of

Q328

is being

rectified

by D205

and

slowly

appUed

to the

base of

Q329.

When

Q329

is

biased

into

conduction

it

depletes

the

base

bias nor-

mally

supplied

to

Q330

through

R612

and

Q330

stops

conducting.

In

this

state,

no

signal

is

available

at the

emitter of

Q330

to be

rectified,

and

Q331,

the

"Cymbal"

gate,

slowly

turns

off.

To the

base of

this

"Cymbal"

gate

is

also

fed

the

noise from

the

noise

generator,

Q324.

This

noise

is

tuned

in the

collector

circuit of

Q33

1 and

fed

to

Q325

and

Q326

the

"Cymbal

and

Brush"

amplifier.

2-13.

BRUSH AND CYMBAL

AMPLIFICATION.

-

After

being ampUfied

by

Q325

and

Q326,

the

"Brush

and Cymbal"

signals

are

routed

to a

voltage

divider

consisting

of

R604, R605,

and

R606. It

is

then tapped

by the switch

and

routed

to

R602

the

overall level

control.

This

is

located

on

a terminal

strip on the

lower organ

shelf,

near

the

AO—

43

ampli-

fier. The

wiper of

the overall

level control

(R602)

now feeds

into the AO—43

ampli-

fier through R601

and C318

to

Pin

7

of

V8. To enhance

the "Brush

and Cymbal"

effects, a

small high frequency

speaker

is

attached

to the main ampHfier.

It

is located

under

the

lower

right hand end

block on

the organ.

2-14.

POWER

SUPPLY.

-

Power

supply

chassis

is

suppHed

with

+340

volts DC

from

AO-43

amplifier. +80

volts required for

percussion

assembly

is obtained from

voltage

divider

R690, and R69

1

.

+

1

2

volts

is obtained

from

Zener

Diode

D201.

2-15.

L-100-1

SIX-VOICE

PERCUSSION

CIR-

CUITRY.

-

2-16.

POWER

SUPPLY

(See

Figure 5-7).

-

Power

supply

components

are

located in

the

power

supply

chassis

assembly

(127-7

thru

-9). All necessary

DC

supply

voltages

for

the

rhythm

unit

are supplied

by this

chassis.

The

output

voltages

are 30

V DC,

15

V DC, and

5.5 V

DC. The 5.5

V

output

is

not used

in

the

Model

L-

100-1

organ.

120

V

AC

50/60

Hz

is

supplied to

the

power

transformer

from an

external source.

The

secondary

AC voltage is 40

V AC,

which is

then

rectified

by

the

full wave

bridge

of diodes

D

1

00,

D1

0

1

,

D

1

02

and

D103. This

DC voltage is

then

filtered

by

the

combination

of

RlOl,

R103,

ClOOA,

CI 01

and

appUed across the 30

V DC

Zener

diode

D104.

The

30

V DC is the supply

voltage

for the

amplifier

stages

Q106,

Q107

and

Ql 08 on the

rhythm

PWB

and

the

reference

voltage for

the 1 5

V

DC and

5.5 V DC suppUes.

The 30 V DC

is

supplied

to

the voltage

divider of

R107

&

R108

and

fed to

the voltage regulators Ql

00 &

Ql

02,

the output

of

which is the

1

5 V

DC which

is

used to supply all

other

circuits

on the

rhythm device.

The 30

V

DC is also supplied

to the

voltage

divider

R106

&

R105, and

fed

to

the

2-

emitter

follower QlOl

,

the emitter

output

of

which is

5.5

V

DC.

QlOl

is used as a

voltage

regulator and in conjunction

with

ClOOB provides the

filtering

for

the 5.5

VDC.

2-17.

PUSH

BUTTON CIRCUITS (See

Figure

5-6).

One side

of each push button is connected

thru R200,

2.2K ohm

resistor

to

the

15

V

DC

supply.

The 1

5 V DC

is

available to the

push buttons at

all times, and

if one

is

de-

pressed

at

any time,

that

particular voice

will

appear at the output.

When any

of

the

push buttons

is

depressed, that button

apphes 1

5 V DC

to

the base input

of

a

phase shift oscillator.

As

an example, if

the

BLOCK

push button

is depressed, 1 5

V DC

is

apphed to

the

junction of RIOOB and capacitor ClOOB.

This signal

is

differentiated by

CI

OOB and

the

resulting

pulse

is

fed thru DIOOB

and

Rl 05 to the

base

of Ql

OOB, turning

it

on.

This signal

is

fed

back to

the

base,

inverted

by

the phase shift network

C103B, C102B,

C104B, R106B,

and

R107B,

and

will

be

regenerative

for

a

period

of

time

determined

by

RIOOB,

ClOOB, and RIOIB.

The

decay-

time

of

the

collector output depends

upon

the values

of ClOlB,

R105B

and

R102B.

2

The

output

is

coupled through capacitor

C105B,

resistor

R104B, and

capacitor

CI 20

to

the base

of

ampUfier

stage

Ql

07,

and

after

amplification

by

Q

107

and

Q108,

it

is

connected to

R203, the

volume control.

TOM-TOM,

BONGO,

and

CLAVES

are

similar

in

operation.

The

frequencies

of

the

oscillators

are determined by

the

values

of

the

components in

the

phase shift

network.

When

the

BRUSH push

button is

depressed,

+

1

5 V DC

is

suppUed

to

the junction of

Rl 16 and

CI 1

1

,

and this

supphes

bias

through

D102 to

the base

of

Q103,

tuming

"on"

the

one shot

multi-vibrator stage,

Q103

and

Q104

for

one complete

cycle.

The

Brush Gate

transistor

Q

105 is

turned

"on"

for

a

period

determined

by

CI 13 and

R120

of the

multi-vibrator stage.

This

apphes

positive

bias

through R123, D104,

R124

to

base

of

Q105,

turning on

Q105

and

allowing

white

noise to

appear

on col-

lector

of Ql

05,

tuned by

CI

15 and

LI

01,

and

this

signal

is

then

routed through

CI

1

7

and

output level

control

R126

and

R127

to

hiss

amplifier

Q106.

LOWER

MANUAL KEYING CIRCUITS (See

Figure

5-6).

-

The lower manual

buss

line

is

connected

through

CI 24

and the

base

of

Q109,

which

is a

pulse

ampUfier

stage.

Re-

sistor

R147

provides base bias

to

the

stage,

so

that with

no key depressed,

the collector

is

at

approximately

4.5

V

DC. CI24and

R145 is a

differentiating

network

which

puts

a

pulse on the base

of

Q109.

This

pulse

is

amphfied

by

Q109,

and instanta-

neously the

collector of

Q

109 rises

from

4.5 V DC to

approximately

1 1

V DC This

change

is

routed through

R149

to

the

base

of Ql

10,

which at

an emitter

voltage

of

5.5

V and base

bias

of 4.5

V

was

"off".

With

1

1 V on

its base,

QUO turns

"on", and

its

collector, which was

at

1

5

V

drops to

5.5 V. This

change is

coupled

through

CI

26

and

R153 to

the base

of Qlll,aPNP

which

has

been

biased

"off" through

R152

and

R153. The change in bias turns "on"

QUI

and the

collector has an

instanta-

neous

output

of

+

1 5

V DC of

about 2

milliseconds

duration. This

trigger pulse

is

defined as

the

lower manual

trigger pulse.

The

pulse

is

routed

through

whichever

LOWER

tabs

are "on" to

trigger

the

selected

voices.

Output is

obtained

as

described

in

Paragraph

2—17.

19.

PEDAL KEYING

CIRCUIT (See

Figure

5-B).

-

A signal

of

approximately

75

mV

P-P

from the pedal

keyboard

is

connected

to

the input

T4. The first

two stages

using

transistors

Ql

&

Q2

are basically

ampli-

fiers

providing

a

+

1

3 V

square

wave

pulse

for

each

input

cycle.

The first

+

1

3

V

square

wave

pulse

appearing

on

transistor

Q2

collector

turns

on

Q4

providing

a

+

1

3

V pulse

at

output

terminal Tl

1

.

At

the

same

time

C4 is

charged

through R6.

This

icharging

time is

long

enough

to

delay

the

conduction

of

Q3

until

after the

first pulse;

then

Q3

conducts,

cutting

off

Q4

before the

second

pulse

can be

passed.

Effectively,

lieach time

a signal is

applied to

the

input

at

T4,

one

pulse

appears at

the

output termi-

j

nal

(Til),

which

connects to

terminal

F

of

voice

generator

board

124-0001

14.

Ql

15

is

normally

off.

The input at

T'

is

fed

through

R

163

to

the

base

of

Ql

1

5

to

turn

the

transistor

on.

When

Ql

1

5

is

on,

the

DC

voltage

at

its

collector

drops

from +

15V

to

Zero

V.

Note

that

pin

'G'

is

jumpered

to

pin

'C,

and

that

both

are

common

to

Ql

1

5

The signal

entering pin

is

fed

through

R160

to

the base

of Ql

14,

which is

nor-

mally

in

the "on"

condition

with

no

pedal

pressed

(collector at

OV DC).

When a pedal

is

pressed, the

negative

signal

applied to

the

base

turns

"ofV Ql

14,

and

the

collector

voltage

rises

to

+

1 5

V DC.

Point

"D" is

routed to

point

"A" and

coupled

through

CI

27 and

Rl 56 to

the base

of Ql

1

2.

Ql

1

2

which

is

normally

"off

is

turned

''on",

and its

collector

voltage

drops to

zero. The

collector

signal

of

Ql

1 2 is

then

fed

to

the

base

of

PNP

Ql

13,

turning

it "on'\

and its

collector

switches

to

+

1 5

V DC. This

+

1

5

V

DC pulse

on

the

collector

of

Ql

13

is desig-

nated as

the

pedal-down

pulse,

and is

routed

through

the

BLOCK

and/or

CYMBAL tabs,

when "on" to

trigger the

selected

voices.

Output

is

obtained

as

described

in

Paragraph

2-17.

SECTION

III

DISASSEMBLY

3-1.

GENERAL.

-

This

section

contains descrip-

tions

of

disassembly

techniques

peculiar to

L—

100

Series

organs.

3-2.

ACCESS.

-

For

access

to

some

of the parts

discussed

in

following

paragraphs, it

may

be

necessary

to

remove

organ

top,

back,

or

both.

3-3.

UPPER

MANUAL

KEY.

-

To

remove

an

upper

manual

key proceed

according

to

the

following.

3-5.

mounting screw; unhook

key from screw

and lift out

key.

h.

To

remove

a

white

key loosen its

key

mounting screw and

those

of

adjacent

black

keys. Unhook these keys

from

screws, push

them back,

and

lift out

white key.

DRAWBAR

CONTACT

SPRING.

-

To

remove

a drawbar

contact

spring

proceed

according

to the

following.

a.

Remove

four screws

which

secure

metal

cover

on

control

panel

assembly.

b.

Remove

two

large

screws

located at

ends

of

control assembly,

which

secure

it

to

upper

manual.

c.

To

remove

a

black

key, loosen its key

mounting screw,

lift control

panel

assembly

and

hft

out

key.

d. To

remove

a

white

key, loosen its

key

mounting

screw and those

of

adjacent

black

keys.

Lift

control panel, push the

keys back

and

hft

out

white

key.

NOTE

If

removal

involves the

lowest

three

keys, it will be

necessary

to

remove

or

loosen

drawbar

assembly.

See

Paragraph

3—6.

3-4.

LOWER

MANUAL

KEY.

-

To

remove

a

lower

manual

key proceed according

to the

following.

a.

Remove

four

screws

which

secure

metal

cover

on

control panel

assembly.

b.

Remove two

upper

manual

mounting

bolts

which

secure

manual

assembly

to

case

work.

c.

Remove

two

screws

which

pass

through

angle

brackets into

upper manual.

These

brackets are

located

inside

of

cheek

blocks.

These

screws

are accessible

from

front

of organ.

d.

Remove

AO-41

and

AO

-42

amplifiers

from

rear of

upper manual.

e. Tilt

manual

up

from front.

f.

Using 1

/4"

box

ratchet, loosen

key

mounting

screw.

g.

To

remove a black

key, loosen its

key

a. Remove

four

screws

which

secure

metal

cover

on

control

panel

assembly.

b. Push

drawbar

all the

way

in.

c.

Remove

screw at back

end

of

drawbar.

d.

Pull

out

contact

spring.

To

disconnect

spring

entirely,

unsolder

wire.

CAUTION

Do

not

under

any circumstances pull

drawbar

forward while contact spring

is

off,

as

damper

spring

will

catch

in slot

and necessitate

removal

of entire draw-

bar

assembly.

3-6.

DRAWBAR, DRAWBAR

KNOBS OR

DRAW-

BAR ASSEMBLY.

-

To

remove

any

of

these,

proceed according

to the following.

a.

Remove

four

screws

which secure

metal

cover

on

control panel

assembly.

b. Unsolder black

wire from "Full

Organ"

tab switch.

c.

Remove

two large screws located at

ends

of

control

assembly which secure it

to

upper manual. Turn

control

panel face

up, and

prop up

in this

position, being

careful not

to

stress wires.

d.

Remove four

hexagonal

machine screws

holding drawbar

assembly

to base.

e.

To

remove

knob, tilt

drawbar

assembly

up, and remove

screw

which

holds knob.

f.

To

remove

drawbar

and contact spring,

pull them out

at back

of

assembly, while

pressing

with

thumb

to release pressure

on contact.

g.

To separate

drawbar from

contact spring,

remove screw

at

back

end

of

drawbar.

h.

To remove

entire drawbar

assembly,

unsolder

all connecting

wires.

3-7.

UPPER

MANUAL.

-

To

remove

upper

f

manual

proceed according to

the

following.

a.

Remove

four

screws

which

secure

metal

cover

on

control

panel

assembly.

b.

Unsolder

black

wire

from

full

organ

tab

switch

going

to

drawbar

assembly.

c.

Disconnect

nine

colored

wires

emanating

f

from right

end

of

upper

manual

which

terminate

at

upper manual

control

tab

switches.

d.

Dismount

AO-41

and

AO-42

amplifiers

from

rear of

upper manual.

e.

Remove

heavy

grounding

wire

attached

to

manual just to

right

of

first

key

channel.

f. Remove

small

bracket

holding

pedal cUck

filter

to manual

(grey

wire

from pedal

drawbar

leads

to this

filter).

g.

Remove

two

upper manual

mounting

bolts

which

secure

manual

assembly

to

case

work.

h.

Remove two

screws

which

pass

through

angle

brackets

into

upper

manual.

These

brackets

are

located

on

inside

of

check

blocks.

The screws

are

accessible

from

front

of organ.

i.

Remove two

screws

securing

control

panel to

upper

manual and

tilt

control

panel

face up.

j.

Remove

four

hexagonal

machine

screws

holding

drawbar

assembly

to

base.

Control

panel and

drawbar

assembly can

be

folded

over and

rest

on

top

of

amplifiers.

k.

Replace

control panel

mounting

screws.

1.

Prop up

front of

upper

manual so

that

its

terminal

strip

is

accessible.

Be

careful

when

raising and

lowering

manual

that

its

terminal strip is

not

damaged

by

rubbing

lower

manual

keys.

m.

Unsolder

manual

cable

from

terminal

strip.

Lower

manual into

normal

position.

n.

Carefully

lift

manual

assembly

out

of

console.

3-8.

LOWER

MANUAL.

-

To

remove

lower

manual

proceed

aeeording

to

the

following.

a.

Perform operations a.

through

e.

of

Paragraph

3—7.

b.

Disconnect

9

colored

wires

emanating

from

right end

of lower

manual which

terminate at

lower

manual

control

tab

switch.

c.

Remove

four

screws

from

under

manual

assembly

(front)

which

secure

terminal

cover.

d.

Remove

lower

manual

end

blocks by

removing

two

screws

through

manual

frame

and

one screw

through

bracket

on

cheek

block.

e.

Unsolder

manual

cable

from

terminal

strip.

f. Tilt

upper

manual

up

from

front.

Remove

two

hexagonal

bolts that

secure

lower

manual

to

case

work.

g.

Loosen

four

hexagonal

head

studs

securing

lower

manual

to

front

rail.

(In

reinstaUing

manual

tighten

these

last.)

h.

Lift

out

lower

manual.

3-9. GENERATOR.

-

To

remove

generator dis-

connect

organ

from

power

source,

then

proceed

according

to

the

following.

a.

Remove

generator

power

panel

cover.

b.

Unsolder

all

wires

on

power

panel

except

yellow

and

grey wires

to

motor

and

starting

condenser.

c.

Dress

generator-to-manual

cable

and

generator-to-pedal

cable

down

and

un-

solder

from

terminal

strip.

d.

Unsolder

grey

wire

which

goes to

pedal

cUck

filter and

remove

heavy

grounding

wire

(black).

e.

Remove

four

hexagonal

bolts

which

secure

generator

to

mounting

angles.

Lift

out

generator.

3-10.

MOTOR.

-

To

remove

motor

disconnect

organ

from

power

source,

then

proceed

according

to

the

following.

a.

Remove

generator

power

panel

cover.

b.

Unsolder

grey

wire

to

motor.

c.

Unsolder

red

and

black

wires

on

starting

capacitor.

d.

Compress

coupling

spring

between

motor

and

generator and

remove

spring.

e.

Force

off

spring

clamp

which

secures

motor

to

mounting

frame.

Lift out

motor.

3-11.

PEDAL

KEYBOARD.

-

To

remove

pedal

keyboard

proceed

according

to

the

following.

a.

Dress

down

generator-to-manual

and

generator-to-pedal

cables,

unsoldering

latter.

b.

Remove

two

screws

in

lower

back

of

console

and

three

screws

between

ampli-

fier

and

front

of console.

c.

Lift

console

and

pull out

keyboard.

(When

reinstalling

pedal

keyboard

replace

two

screws

in back

of

console

first,

3-2