ROLAND RS 505

Page 1

SEP.10 1978
PARAPHONIC
Rs-505 SERVICE NOTES
CONTENTS

PAGE
SPECIFICATIONS .............................................................. 1
CIRCUIT DESCRIPTION ........................................................ 2
BLOCK DIAGRAM ................................................... _ .......... 4
TONE DIVIDER & TONE GATE ............ GTH-9/10/11 ........................ 5
MOTHER BOARD ......................... OPH-28 ............................ 6
STRINGS VOICING 81 SYNTHESIZER ........ VCFH-2 ............................ 8
KEY TRIGGER & ENVELOPE GENERATOR .. ARH-1 ............................. 9
BASS VOICING & LFO .................... LFOH-2 ............................ 1o
PITCH SHIFT ............................. OPH-29 ............................ 11
ENSEMBLE MODULATOR .................. ETH-7 ............................. 12
POWER SUPPLY .......................... PSH-28/29/30 ....................... 14
PARTS LAYOUT .............................................................. 15
PARTS LIST .................................................................. 16
KEYBOARD PARTS ........................................................... 17
DISASSEMBLY

Cabinet H170
(081 H170)

Side Block H171
(081H171)

Panel H41

Bushing No.18 (072H041)

To open upper panel
remove six wood screws
3x16 oval

Keyboard SK-192A

Side Block H172
(081 H172)

Printed in Japan Sep. 82 E-2

H's-505

SPECIFICATIONS

Keyboard:

Strings Section
Tablets:
Controls:

Strings/Synthesizer Section

Control:

Synthesizer Section
Tablets:
Controls:

Switch:
Bass Section
Tablets:
Controls:
Balance Control:
Ensemble Switch:
Vibrato Control:
LFO Controls:
Pitch Shift
Controls:
Switch:
General
Controls:
Switch:
Rear Panel
Control:

Switches:
Jacks:

Power Consumption:

Dimensions:

Weight:

49-Note C Scale

Upper Strings, Lower Strings
4'-8 Mix lU/L), Attack

Release

Upper 4', Upper 8', Lower 4, Lower 8', Bass 8', Bass 16', Ensemble

Resonance, Cutoff Frequency, LFO Sensitivity, Envelope Sensitivity, Attack, Decay,
Sustain, Release

Second Touch On/Off

Cello 8', Tuba 16', Contra Bass 16, Ensemble
Attack, Release

Strings-Synthesizer, Bass Volume

Mode Selection

Depth

Rate, Delay Time

Manual, Time, Pitch Set
Auto/Off/Manual Selection

Tune, Master Volume
Power

Ensemble Tone

Output Level .......... Synth/Bass, Stereo/Mono

Output .............. Stereo, Mono, Bass/Synth, Trig, Gate
Input ............... Ext, Sustain, Pitch, VCF

14W

905 (W) x370 (D) x 145 (H) mm

14Kg

Page 2

"8-505
PCB & CIRCUIT DESCRIPTION

MOULATOR _ O OUTPUT
TOP MASTER 1 line TOPOCTAVE G ATE
V C O DEVIDER Circuit
SYNTH
"0 WT [KEYBOARD o A53
Controls OUTPUT

PIS-505 CIRCUIT DESCRIPTION

PCB AND CIRCUIT DESCRIPTION

1.
1-1.

Mother Board OPE-28

Master VCO

This is basically an LC oscillator whose frequency is variable by changing the
voltage applied to varicap diode.

Maximum pitch shift range is l octave.

Frequency stability is within 15 cents at normal working temperature.

Top Octave Divider

The VCO output is divided to create 12 notes by 106. The notes are octave downed
several times by the tone dividers at the next stage and routed to the corresponding
tone gates.

The top octave notes themselves are not supplied to the tone gates.

ENSEMBLE -O §§a€g

1-3.

1-4 .

2.

3.
3-1.

3-2.

SEP.10 1978

Tone Divider, Tone Gate (GTH-9, 10, ll)

Pressing a keyswitch applies negative voltage to the transistor keying circuit

91 (Q4, Q7 ....). This negative voltage is applied to the collectors of Q2, QB
(95, Q6 ....) where they are chopped by the signal outputs from the dividers
TC-4024's applied to the bases.

The negative voltage from a keyswitch also charges 02 (CS, CB ....) which discharges
upon releasing a key and holds 91 on. The discharge rate of this capacitor is
controlled by the frequency of the pulse that comes from Release Pulse Generator
via terminal No.4.

Bass Priority

Three 8-bit priority encoders TC-4532 generate 6-bit codes by the on/off action
of the bass keyswitches. These coded signals are fed to the two IC's (TC4042) and
latched. At the same time, the output of TC-4042 is sent to the 8-bit priority
decoders at the next stage and one out of 24 bass notes is selected. The latched
signals are held until a next bass key signal is given.

The bass gate signals for the bass AR envelope generator are also generated by this

priority circuit.

String Voicing 8c Synthesizer VCFH-Z

The VCF of the synthesizer section is an LPF of 24dB/oct. Its control voltage is
supplied through an Anti-log circuit. The control voltage of the VGA is also
supplied through an Anti-log circuit. The level adjusting trimmer pot is mounted

on each circuit .

Bass Voicing LFO LFOH-2

Bass Tone Gate

The output signals of the Bass AR Env (91, 92) are chopped by the bass tones at

95, Q6, and Q7. The output is sent to the tone filters and the VCF of synthesizer
section.

LFO

This is an R-C sine wave oscillator whose frequency is varied from about le to 15Hz
by the RATE control. Its oscillation is once stopped by the gate signal which is
generated by depressing a key, then it starts again and the amplitude is gradually
increased. The oscillation stop time until the start of oscillation is adjusted

by the DELAY TIME control.