Arp 3620 keyboard service manual

Page 1

£33? MODEL 3620 KEYBOARD

SERVICE MANUAL

THIS SERVICE MANUAL SHOULD BE USED WITH THE ARP 2600 SERVICE MANUAL

TABLE OF CONTENTS

1. 3620 DESCRIPTION

1.1 Introduction
1.2 Spemfications
1.3 Function Descriptions

2. CIRCUIT DESCRIPTIONS

2.1 Keyboard Current Source

2.2 Second Voice Memory

23 Upper Voice Summation

2.4 Control Voltage Memory

2.5 Master Summation

2.6 Gate Generator

2.7 Memory Control

2.8 Low Frequency Oscillator

2.9 Vibrato Delay 8: Wave Shaping

TRIMS 81 ADJUSTMENTS

BOARD TEST POINTS

3620 THREE BUS CONVERSION BOARD
3620 CONTACT MAINTENANCE
ASSEMBLY/DISSASSEMBLY

3620 DRAWINGS
8.1 Board Layout
8.2 Board Schematic

9N9???

9. PARTS LIST
10. REVISIONS

ARP INSTRUMENTS, INC.
45 Hartwell Avenue
Lexington, MA 02173
(617) 8616000

'12) 1977, ARP INSTRUMENTS, INC.

DOCUMENT NO. 9000400

NM

(0 (D m \l 0') mmmbbbbbb

11

13

Page 2

SECTION 1 3620 DESCRIPTION

1.1 INTRODUCTION

The 3620 keyboard replaces the 3604? keyboard for
the 2600? synthesizer. Features included are: two
separate memorized control voltages, interval latch,
repeat modes, LFO, delayed vibrato, transpose and
pitch bend controls.

This manual should be used in conjunction with the
2600 service manual for complete understanding of
the functions it contains.

1.2 SPECIFICATIONS

UPPER VOICE CV OUTPUT: -3 volts to +10 volts,
1V/OCT

LOWER VOICE CV OUTPUT: -3 volts to +7 volts,
1V/OCT

LFO TRIANGLE OUTPUT: 15 volts, 10 volts peak
to peak

LFO SOUARE WAVE OUTPUT: +10 volts, 10 volts
peak to peak

LFO DELAYED SINE WAVE OUTPUT: 13 volts,
6 volts peak to peak

EXTERNAL VIBRATO INPUT: Accepts 110 volts
maximum

VIBRATO DEPTH SLIDER: 10 volts yields approx.
1 octave shift

VIBRATO DELAY SLIDER: Delays sine wave from
0 sec. to approx. 2.5 seconds

LFO SPEED SLIDER: .25Hz to approx. 25H!

mu

IIVIOLIO
OIL 302°

PITCH BEND CONTROL: :1 octave, calibrated

TRANSPOSE SWITCH: 12 octaves, calibrated

PORTAMENTO SPEED SLIDER: Imsec. to approx.
2sec.

PORTAMENTO FOOT SWITCH: Accepts only ARP
foot switch

INTERVAL FOOT SWITCH: Accepts only ARP foot
switch

GATE OUTPUT (ON 2600 PANEL): 0 volts keys up,
+10 volts key down

TRIGGER OUTPUT (ON 2600 PANEL): +10 volts
on key depression, .Srnsec duration

1.3 FUNCTION DESCRIPTIONS

CONTROL

CIRCUIT FUNCTION

MUSICAL USE

PITCH BEND CONTROL

When turned clockwise or counter-
clockwise from center, an offset
voltage is summed with the upper
and lower voice control voltages.
The Pitch Bend control is calibrated
to a maximum :1 octave.

Manually Bends' the pitch of the
oscillators sharp or flat. Also can
be used as a :1 octave transpose.

TRANSPOSE SWITCH

Up and down two octave positions
sum 12 V offset voltage with upper
and lower voice control voltages.

Changes the playing range of keyboard