JAN. 10,1980

SPV-355

SPV-355 SERVICE NOTES

SPECIFICATIONS

VCF Controls REAR PANEL

Switch

SDG5K)01-l 100V

MACHINE SCREW

6M4X10

(001-215)

SDG5POO1-2

SYNTHESIZER SECTION controls DualVCO(VCO-1,VCO-2) WAVEFORM Switch Mojiu) RANGE Switch (4', 8', 16') MASTER TUNING Control (250 cents) A TUNING Control (1200 cents) B TUNING Control (1200 cents) TUNING INDICATORS (A, B)
VCO-1 SUB (1 octave down, ru )
CUTOFF FREQUENCY Control (10 Hz-20kHz) RESONANCE Control (0 - self

oscillation)

CV OUT Jack d V/oct)
GATE OUT Jack (OFF: 0V; ON: + 15V) ENV FOL'R OUT Jack (0- + 10V)
CV IN Jack (1 V/oct) GATE IN Jack (Threshold: + 3.8V)

(001-216)

ENVELOPE GENERATOR Controls ATTACK TIME Control (1 ms-3.5s) DECAY TIME Control (2ms-7s) SUSTAIN LEVEL Control (0-100%)

SDG5P-5O2 220/240V

(001-217)
Power Consumption: 13 W Dimensions:

RUBBER FOOT

CONNECTORS
Input and output INPUT Jack

K-15(111-037)

482(W) X 92(H) x 350(D) mm Fits standard 19" rack (EIA-2U)

Weight: 5.7kg

PORTAMENTO Controls
PORTAMENTO Control (0-3s>

PORTAMENTO ON/OFF

OUTPUT Jack (input/output level = 1:1)

Button

(016-009)
MACHINE SCREW 6-M4X12 BLK

Panel no.282

SLR-043 (001-278)

LED TLG-124 green

Switch SLR-023 (001-289)

Pot. EVH6PAP2OB15

(072-282)
Hexagon socket head bolt 4x8mm (123-013)

(026-490)

052-484-5 052-484-2 052-485 052-484-1 052-484-4

052-484-3

(019-028)

Knob Pot.

SLR-022 (001-280)

(016-078)

O52H195
052H185A Capacitors ECQ-E1O473MV ECQ-U1A473MC ECQ-E2A473MCS

100V 117V

EVH6PAP2OA54

(026-499)

0P-140

(149-140)

(053-319)

(053-310)

220/240V

Jack -6pcs-

Power transformer 022-085A-C or A-N 100V 022-085A-C 117V 022-085A-D 220/240V

HLJ-026401-030

LED TLR-124 red (019-028)

(009-030)

HLJ-O264-O1-O3O (009-030)

HLJ-O264-O1-O3O

Connectors Housing

Wafer terminal

SLR-022

Terminal no.41 Earth

(016-077)

(016-048)

C001-280)

5251-05 5251-06

5251-03 5251-04

5251-08 5251-10

5659-T

5251-07

(042-041)

Pin terminal

! Roland

Printed in Japan

5O45-O4A 5O45-O5A 5O45-O6A 5O45-O7A 5O45-O8A 5O45-1OA

8p lOp

4p 5p 6p 7p

Heat sink no.69

(048-069)

6UITAR

WOOP/BHASS ||(O nipvr

VCFRES

lC260b.29.28Ob

VCO-I SUB

EWWL'ROUT

BLOCK DIAGRAM

T/V PORTAMtWTO

C.&UITAR

n.s* rBM&S

RJIMMENTX

THRESHOLD

sv p-p tt

A&C
- Voltage Controlled Low Pass Filter - Filter Controlling Current Quadrature Phase Shifter Quadruple Rectifier

Cutoff Shifter

Cutoff Shifter (Q19-Q21)
tVC-LPF) & High Pass Filter tVC-HPF)

CIRCUIT DESCRIPTION

SPV-355, on its main portion, is divided func
sensing whether rectifier output volt

These two filters

They extract

constitute

a band pass

filter

age is more or less in comparison with

tionally into:

the Pitch-to-voltage conver

the Synthesizer section.

into these
from input signal a fundamental ton
reference voltage (to be determined by VR-6),

outputs control voltage corresponding to its detection to feed it to Q21 which converts

sion section and 2)

alone while suppressing all other

unnecessary

They together form a feedback loop in the VC-LPF.
The former is further sub-divided

circuit groups:

high harmonics and low noises,etc.(see Fig.beloV
The purpose is to provide a system

in which the

frequency response range of the band pass filter
is moved as input signal varies frequencies.
this voltage into current and

VC- LPF and HPF.

feeds it to

Fundamental Detector

2. Time to Voltage

3. 4. 5. It

(T/V) Converter
- VC-LPF UC4-IC7) They are all of the same type. point here is that they are made

characteristic

Suppose that,the incoming signal has changed its
The particular to have such
R95 assumes a minimum current to compensate
for no controlling current when Q21 has been

cutoff.

Logarithmic Converter Gate Generator
frequency to deviate,on the characteristic curve,
from the previously adjusted lOdB down point.
Envelope generator is assumed that the reader has some knowl

frequency response

controllable
If it were to higher frequency

output

side the filter

or if it

so that the input signal falls
down point on the slope of

always at

sid<
should be reduced in amplitude,

output be

edge on the synthesizers, our devoted effort

and we would confine

high frequency

to lower side

increased.
TIME to VOLTAGE CONVERTER
to those points alone that

of its characteristic

curve.

(We will

further

can be

change on output is detected by

above which then

system
(refer to Block Diagram B)
are particular to this SPV-355.
discuss how the frequency response band

produces control

current to
swept in accordance with in-coming signal
feed from Q21 to VC-LPF Filter to adjust

to always meet the

itself
At the comparator (IClla) the fundamentals
quencies in later section.)

1. FUNDAMENTAL DETECTOR

incoming signal frequency response curve.
(a) are converted to rectangular waves(b).
They then go through the pulse generators
(refer to Block Diagram A)
Audio signals that are produced at some exter

This makes

the passing signal amplitude

reduce*

the lOdB down point on its
and it is now to about 1/3 of the

level,

signa!
(IC12) to generate pulses (c) and (d).

Between them,

or to 5Vpp at 400Hz.0n its result,

Quadrature Phase Shifter

(Q11,Q12)

(d) lags behind

(c) by about
nal musical instrument are partly fed to IClb, ICla for amplication.(the rest to direct out)
all high frequency components
leave only the fundamental

can be removed t

Qll and Q12 are the constant gain shift circuits,
each having a capacitor for phase shift.
They are then go through LPF (IC2b) to atten
uate unwanted high frequency.

remained.

Voltage (e)

direction

increases in positive going
at the rate determined by R^Cl
The phase difference between

two output signals

time constant.

It is reset and turned

When INPUT SELECTOR switch is

MODE, there is one more

WOOD/BRASS

signal

is 90 in the range 6OHz-6OOHz.
Quadruple Rectifier (Q13-Q18)
(Pig. "B", "C")
OV every time SI is closed by (d).Here (d)
synchronize with the input signals. The

stage of LPF (IC2a)

VC-LPF
that the signal has to go through. After LPF, the signals are fed to the AGC

VC-HPF

intervals between pulses in (d) are
The two waves having 90 phase difference are fur
ther subdivided here through Q13,Q14 into waves
ing longer as the frequency goes higher. Accordingly, potential of (e) decreases as the input signal increases in frequency.
(IC3a,Q4 and Q5)where they are put to a con
stant voltage level at about 17.5Vpp.

having phase differences

0* , 90 , 180 and 270.
When they are further half-wave rectified through
Q15-Q18, the resultant wave shape of all combined

and closely crested one

32 is in the meantime, switched on by
pulse (c). During the interval between (c)
and (d) (of 4;as), (ej is sampled out.

&ATE

becomes so much dense

even in low signal

I SATE ST (DELAYED)

frequency ranges.

(see Block
The sampled voltage is almost the highest

- VC-HPF (IC8) HPF here

contents

Diagram A, Fig.

"D")

This means that

the time
voltage level (e) has reached before it is

re-set to OV by (d).

is to remove unneccessary and harmful
of low frequency range below fundamenta
constant of the ripple suppressing RC circuit(R89

C34) can be small and,

in turn,

changes in

IC14a on the next stage is a low-leak
voltage follower. It outputs (f) in the
such as vibration on strings

compass

LPF output are quickly mirrored on the rectified
waves even in the low frequency range.

other than those

being played on a guitar,
same vlotage level that was charged at C2.
noises produced while handling instruments,
D4 and D5 are for limiting the pulsating voltage.

HoldS^ (DELAYED)

line frequency pick-ups or hums,
53 is gated by {i), and conveys (f) to IC15b.

3. LOGARITHMIC CONVERTER

Q23,C39 are the quasi-sawtooth wave generator.

JAN.10,1980

The voltage variation here lags behind the var iation in input signal due to the R2, C3 time-
As in common, SYNTH Section of SPV-355 is con
trolled by CV tcontrol voltage) of logarithmic
The voltage charged at C39 through VR-2 and R101
is discharged every time Q23 conducts at the - T0.9b output

constant,

(more about these R2 and G3

later.) effect

discus

sion will be To reduce

in the rate of lV/oct. However,

results from this,

so far the out

is sim to

signal frequency rate.
IC10 is reset when There are become

RED LED

detrimental
put of fundamental ply a linear. There
through T:V circuit is therefore a need

this wave possible

(1) With
peak reaches H (yVDD). occurrences

the signal

two H.
54 is provided to be which

closed by

the pulse

(j) the

for this

frequency

is generated on the

GATE. It is

trailing edge of

the circuit

convert
this to such CV to suit for controlling

When it

delayed

to make

SYNTH.

When from T/V output the log curve out it becomes possible to con a way that having

doubled

intervals between positive-going pulses
base becomes longer, more charging In cur turn
as having R2 being shorted.

In practice,

put is obtained, trol SYNTH

change is

(i),(j)

a little

occur exactly at the same time but with
delay behind the trailing edge of GATE,

through VR-2,

R102,which
On the illustration as above,

firstly

let's suppose

slow rate.

to have

the wave

positive.

In practice the fre

that the

sounds

drop at a

as can be

seen on the waveforms

illustrated.

halved on SYNTH

section.

is adjusted by VR-2 to quency range of

(2) When

turn to H at or lower.

output decreases,

and Q22

base voltage

This is
in order to eliminate unstable pitch in

of the

To express this in mathematical formula Is:
F = 1/T or, VF = 1/VT (constant is ommited
Therefore, log 1 - log VT =

the current

through it both decrease

initial part

tended are

musical

sounds to be

the signal level

decreases:

It makes

impedance

sum with

R97 in

included

for clarity).

It also

decreses the voltage level fed to

enough for Q23

does not

increse,

creased.

and with it,

If, however,
the gain of IC9"b is

the sound drop is so

than its

during the

transient.
CV = log VF = log 1/VT = the undula

0 log VT = - log VT

conduct.
R2 and C3 are filter which smooth

result,

discharge

continues

there would

S3 is to

Signal from IC1 is fed to the (-J pin of IC9a. When this negative half becomes lower than that
on the R103, (+) pin (negative) determined by R102, IC9a output becomes "H". It is fed to "H".
allel with R97 impedance reverse
in its feedback loop.Since (C-E junction) the input, increases

the in

ilCl6 is an analog switch which is turned onoff in response to the GATE signal.The switch

of Q22

open and the output of (fjis disconnected from

proportion to

configuration
is to prevent unnecessary prolongation on the
output of the ENVELOPE FOLLOWER which occurs
Although (1,-L-) -together with this, the

ON too

regarded as
trailing edge of (i)- lags behind (kj, this is

circuit.

due to the
output voltage increases above

filter circuit time

is not directly

at negative.

constant.

grounded

is only
to help avoiding undesired sound, which
in before the desired sound, becomes HELD when the switching timing happened to be

early.

IC10 pin 8,
and causes G output to become
It sets at the same time the green light of LED (Dll) being lit to indicate the GATE ON.
When the input level at this (-) pin of IC9a

Here,pin

4 of IC16

(forward voltages:

D9,Q22 B-E junction),

the C-E

slightly biased

the current flows

resistance

through Q22.lt makes

to decrease
because that the circuits including the other

ICl6s are

as thia

regarded

goes positive with respect to the {+) pin,

decrease,

therfore

requring

negative

source.

So far
output of IC9a turns to L,but IC10 still

G terminal at H.

the gain the

effect

to maintain 1.2V.

switch

concerned,however,it

to a direct

in constant level,

approx.

equivalent

gounding.

SEMICONDUCTOR

no.282

POTENTIOMETER

PARTS LIST

072-282 Panel
CAPACITOR Bi-polar 100KB 5 OKA TUNE

O65HO6O

108H003

111-037

Cover (case) H60

Handle Chassis H3

K-15 Rubber foot
Transistor 017-016 2SK30ATM-GR FET

Rotary

017-107

026-490

EVH6PAP2OB15

032-190

ECEA50N1

lmfd 50V

061-261

no.261

017-103

017-106 017-105

2SK117-GR

2SC1815-GR 2SA1015-Y

026-499

EVH6PAP20A54

Slider

032-241 032-244

ECEA16N10 ECEA25N1O

Tantalum

lOmfd 16V lOmfd 25V

016-009

016-048

no.9 black

slider

017-116

2SAI015-GR

029-592

EVAHHPS2OB15 EVAHHPS2OA15

EVAHHPS20A26

100KB 100KA

029-603

029-607

029-606

032-224

032-226

lmfd 35V 2.2mfd 3.3mfd 35V 35V film

2MA IMA

016-077

016-078

rotary small

rotary large

018-078

1S2453

EVAHHPS20A16

032-227

018-014

1S2473

029-609
EVAHH7S20B15 100KB w/center -tap -click

Trimmer

Polyproplylene

018-082

SWITCH

bridge rectifier

035-091

ECQF2334MZ

O.33mfd

018-015

SDG5P001-1 power 100V 019-028

SDT-1000

TLR-124

thermistor

red LED

026-004 026-007

026-008

001-215

001-216

SDG5POO1-2 power

EVTR4AAB14 (SR19R) EVTR4AAB15

Polystyren

200KB 500KB

O.OOlmfd

0.0022mfd

150pF O.OOlmfd

019-029

TLG-124

green LED

001-217

001-280

001-278

SDG5P-5O2 power 220/240V

SLR-022 lever up-throw

SLR-043 lever

(SR19R)

035-279

035-321

ECQ31102KZ ECQS1222KZ ECQS1151KZ

ECQS1102JZ

EVTR4AAB25

020-097

uPC4558C

TL082CP

uA7815UC

dual op amp

FET dual op amp

regulator

026-009

EVTR4AAB55

CR19R CR19R CR19R

035-274 035-097

001-279

SLR-023 lever

020-153

020-100

020-208
NJM4559 high slew rate op

LF353N FET dual op amp

026-491

026-495 026-499

026-501 030-630

030-632

10KB 47KB 100KB 2KB

metal film

POWER TRANSFORMER

022-085A-C 022-085A-D

No.85A-C No.85A-D

100/117V 220/240V

020-108

MESCELLANEOUS

020-110

020-032

UA7915UC

UA726HC

PN822H202H

PN822H502H

042-041

065-262

Terminal no.41 earth

FUSE HOLDER.

020-169

MC14001BCP

MC14011BCP

030-629

PN822H102H

Cover (dust cover)no.262

PORTAMENTO CONT.

008-026

SGA0001

100/117V

020-170

065-263

RESISTOR

Cover no.263

Pedal cont.

w/10 slits

008-064

012-003

CEE T500mA

TF-758

020-210

MC14066BCP

065-264

001-015

Cover no.264 MIXER-2

020-179

MC14013BCP

020-160

BA662A

044-830

044-846

CRB25FX

selected
Long(sleeve)nut no.15 3x12mm

Cover no.261 lever

149-140

OP-140

1, 2, 3

(052-483)

LED Mounting

O2O-O96s

BA662Bs selected VCF

CRB25FX 100K |w selected

replace all resistors

048-069

065-261

052-485

052-486-

AUDIO MIXER-1

Replace exist 3A662B with only one dotted in the same color.

When replacing,

the affected group with 1% resistors
which have been tested and are within

052H185A

Fuse Mounting
0.1# of being identical in value,

052-484- 1,2,3,4

Pot. Mounting
(refer to Printed Wiring Layout)
* 052-xxx means PCB only.
Add word "assy" when ordering

assembled one.

PN822HH blue

SPV-35S

PORTAMBITO

VR-5 2MA

" VR-7

^ \OTB

TPCU CVT
Refer to the last 6 lines on page

- Circuit Description,

RBHOTE SW
IC14 - TL082CP only 1017,28,31- LP353N or TL082CP
IC15 - LP353N selected (yellow)

or (LP353N selected)

MC14O66BCP can be substituted by CD4O66BE or HP14O66BP

UPC4558C

TL082CP MC14O66BCP
Transistor: NPN -2SC1815-CJR

PNP -2SA1O15- Y or GR

Q19, Q21 - GR only Q49 - Y only

AUDIO MEXER-1

GONNECTOR: P-l INPUT JACK
P-2 P-3 P-4 p_5 P-6 P-7 P-8 P-9
CV&GATE HOLD. SYNTH ON/OFF PEDAL CONT. OUTPUT JACK AUDIO MIXER-2 TUNING A/B REMOTE TUNING A/B POT. AUDIO MIXER-1 PORTAMENTO LED RED GREEN

CV GATE

IN OUT

P-ll P-P-14

SEND RETURN ENV GEN VCF RES ENV CUTOFF POWER LED
K3O - 2SK3OA-GR K117 - 2SK117-GR

Not specified- 1S2473

LED(GRNJ

Diode:

Capacitor:

LED(redJ - TLR-124

- TLG-124
(C) - Ceramic (M) - Mylar

(S) - Polystyrene

SWL- INPUT
SW>- liANGE SW4. WAVEFORM

SW2-* SYNTH ON/OFF

SELECTOR

SW6- VCA

SW7- POWER

ENV GEN/FOI'R

SW5-- VCF MOD ENV GEN/FOL'R

PCB 052-484-4

052-484-1

P3B 052-485

ENVELOPE GENERATOR

052-484-2

TUNING

AUDIO MIXBR-2

ENVELOPE

GEN/FOLR

DIRECT

PITCH FOLLOWER

EVAHHPS20B1?

"S"

EVAHHPS2OB15 (029-592)

"D"

(029-592)

ENV VR-23 EVAHH7S2OB15

EVAHHPS20A26 (029-607)

EVAHHPS20A16 (029-606)

"A" VR-25

w/center tap

(029-609)

SW6 SLR-022

(001-280)

EVH6PAP2OB15 (026-490)

052-484-5

PEDAL CONT SENSITIVITY

PORTAMENTO

EVAHH7S2OB15 (029-609)

RES. VR-23 EVAHHPS2OA15

VCO-1 SUB VCO-1 VR-20

(029-603)

(029-607)

(100V)

CUTOFF FREQ.

021- 08? A -C

(220V)

052-185^LED TLR-124

Fuse holder

&LU

TF-758 (012-003)

(008-026] 100/117V

Oil- 0^5 A- t>

Fuse SGA0001A

CEE T50(taA

(008-06^) 220/240V

(yellow)

C32 R75
*:Factory selected Components in a unique serial no. have almost the same characteristic
When replace, BA662- in the same

color -

value.
Resistortwo three together.

LINEARITY^1

DN822HxxH

1017, 28,31:

OP-140(149-140)

selected)

SHEET of ADJUSTMENT
TEST POINTS (TP-**) and ADJUST TRIMMERS are red printed on
Printed wiring assembly drawing on page 9.

ADJUSTMENT

ADJUSTMENT and CHECKING should proceed in the order listed
below; accurate adjustment of each section depends on pre-

With some adjustments,

among adjustments,
interaction takes place between or

to other

or certain effects are brought

adjustments.

In the list be:.owt
"AS" indicates associate

Reading

VR(s) and "E" indicates affooted VR to be readjusted.

(within the range of)

-14.25V to -15.75V

ceeding adjustment.

+14.25V to +15.75V 1. 2. 3. 4. 5. DC SUPPLIES RANGE PRESET INPUT LEVEL GATE GENERATOR VOLTAGE CONTROLLED

FILTERS

TIMB to VOLTAGE

CONVERTER

+10V + 0.001V -9.800V to -10.200V

7. VCOs

8. 9. VCF VCA

RANGE PRESET VOLTAGE

OUTPUT

LEVELS

Connect Digital Meter to TP-6.

Set RANGE switch at 41.

CAUTION
Note the reading (call this X).
Adjust VR-10 for the voltages
Allow about 15 minutes for a v/armup.
Keep room temperature stable during servicing
Do not expose the SPV-355 being adjusted to

SPV-355.

in the
table right with the switch set at proper position.

the direct

heatings and coolings since P/V,

temperature sensitive.

VCO and VCF circuits are
3. SIGNAL LEVELS vs LED ON/OFF TIMING
As can be seen from the figure
NOTE right input signal versus
Replacing a particular IC with a new one will involve re
green LED on/off GATE signal
has non-linear hysteresis char-
adjustment of the following trimmerpot(s) pertaining

that circuit.

acterstic.

lights,

it will

stay on until

the signal decays at point "Cir.
Check input signal levels for the figures of table below
at 400Hz sine wave with THRESHOLD turned full clockwise.
INPUT Selector at GUITAR,

INPUT Selector at

-77.5dBv

-59dBv

-75.5dBm

-57dBm

0.4mV rms

l.lmV rms

unmeasurable

- DIRECT LEVEL -

5. FUNDAMENTAL GENERATOR (VC-LPF CUTOFF )
check that OUTPUT jack's signal is
PITCH to VOLTAGE CONVERTER

(TIME to VOLTAGE)

With 4OOH2 being input,

Connect:

400Hz square wave into INPUT jack. Scope to Q9 source.

Observe precautions:

equal to that at INPUT jack in amplitude in the following conditions:
plenty of warmup (15 minutes or more) avoinding direct heating/cooling
Increases to 6.5-7.5Vpp at lOOHz input signal.
Adjust VR-6 for 5Vpp at Q9 s. AUDIO MIXER-2 Selector
Make sure that Q9 output:
taking steps in order of number
Digital Meter to CV OUTPUT Reference Note into INPUT jack. jack.

MIX(S+D)

SYNTH knob at "0".

Decreases to 3.5-4.5Vpp

at 1kHz input signal.

SYNTH knob

anywhere
DIRECT knob at "5".

DIRECT knob anywhere

Set INPUT Selector at GUITAR.
Keep input signals at a level 6.
- AGC OUTPUT WAVEFORM, LEVEL -
just before Red LED goes on

TUNING INSTRUMENT

by turning THRESHOLD each time for different feet.

COARSE

For the adjustments concerned with P/V and VCO circuits
With 400Hz square wave input into INPUT jack, connect an a precise tone generator is required - E note is preferable. Shown below is an example of E scale generator circuit con
1) Set the generator at 32'E or 32'F. 2) Set VR-9 for approx. O.333V(E) or O.417V(F).(call this Y) 3) Set generator at 16' and adjust VR-8 for IV + Y.

but leave it varying

oscilloscope to R29 (IC3 pin !)
Screen will display waveforms similar to those in figures shown below when THRESHOLD is set just before red LED lights.

figuration.

It draws DC from SPV-355 +15V supply. an electronic organ or piano delivering the to 21 E(F)kcan be used.
Y will vary according to VR-8 turning; and keep VR-9 untouched.

1 + Y, e.g. Y = 0.346,

Alternatively, range of 32*

decreasing the input

signal gradually,

check that the

Only by turning VR-8 try to obtain

1 + Y = 1.346V.

waveform disappears from the green LED goes out,
scope at exactly the same time

In this case

for few beats -

"7.5|,

if oscillation does not

clocksise.

zero beat

is proportional to deviation.

slightl;/.

Adjust VR-27

for minimum click sound.

In the same manner produce few beats by turning VR-12
with the note set at 4'. - WIDTH -

Repeat steps

zero beat at 8'

and 41.

RESONANCE at

"10".

SYNTHESIZER OUTPUT RATING
Apply the same procedure for the following combinations.

Set CUTOFF

FREQ knob for lkBk oscillation. to/from 4', twice S1
While quickly switching RANG:; switch 81 adjust VR-31 so that 4' wave form

becomes

cycle.

Check 32'

them at 41

for beat sounds.

Adjust VR-13
to reduce Typical levels with panel set as above (input 400Hz).
If the adjustment results in undesirable, re-adjust from

step 1.

Finally, adjust VR-13 for the least beats at 41 and 8'.

- VCO-2 -

FREQUENCY -
VCO-l knob in AUDIO MIXER-1 at 0. VCO-2 knob at 10.

TUNING B at its center

for VUO-1.
Set PITCH FOLLOWER knob at "0".
CUTOFF FREQ knob at "HIGH"

The rest at the same

Adjust VR-32 for 20kHz oscil, ation. (50^s per cycle)
Slide CUTOFF FREQ down at "LOW". The oscillation must

Follow the steps

in VCO-l

section reading VRs:

VR-11 as VR-16,

VR-12 as VR-17,

VR-13 as VH-18.
be retained with its amplitude decreased.