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INTRODUCTION
DISASSEMBLY
This
manual
provides
servicing
and
parts
infor-
mation
for
Maestro
Model
MFZ-271A
Fuzz,
manu-
factured
by
Moog
Music,
Inc.,
2500 Walden
Avenue,
Buffalo,
New
York
14225.
The
Maestro
Fuzz
gener-
ates
low
order
harmonic
distortion for
guitar,
bass
and
other
electroacoustical
music
signals.
Specifica-
tions for
the
Maestro
Fuzz
include:
Input
Impedance
Maximum
Recommended
Input Level
Output Impedance
Maximum
Output
Level
.
Equivalent Input Noise
.
.
.
Type
of Distortion
Power
Requirements
Recommended
Battery
Type
Estimated
Battery
Life
.
.
.
1
megohm
OdBm
20K
ohms (maximum)
+
5dBm
-
lOOdBm
Low
order
odd
harmonic
9.0
VDC
at
250
microamperes
NEDA
1604
3
months
CIRCUIT DESCRIPTION
a)
Pull
out plungers
on
battery holder
assembly
(1,
Figure 1)
and
remove
battery holder assembly.
Disconnect
battery
(2)
if
present
and
remove.
b)
Loosen
setscrews
(3)
securing
dial
assemblies
(4
and
5)
by
inserting a
1/16
inch Allen
wrench
through
holes
in
dial
assemblies
and
remove
dial
assemblies.
c)
Remove
nut
(6) using a half
inch
nut
driver,
lock
washer
(7),
three screws
(8)
and
screw
(9)
from
each
end cap
(10)
and
remove
both
end
caps.
CAUTION
Do
not
set
Maestro
Fuzz on
its
side
when
removing second end
cap
as
damage
to
rotary
pot
shaft
may
result.
d) Position
Maestro
Fuzz
face
down
and
care-
fully
slide
hinge
assembly
(11)
out
of
housing
assembly
(26)
making
certain
spring
(12)
around
push
switch
assembly
(17)
does not
fly
off
and
remove
spring.
The
Maestro Fuzz,
powered by
an
internal
9
volt battery,
generates
low
order
odd
harmonic
distortion
by
using
silicon
diodes
in
the
feedback
circuit
of
an
operational
amplifier.
Refer
to
Figure 3
for the
schematic diagram.
Either the fuzz
mode
or straight guitar
is
selected
by
foot switch
SW1.
In the fuzz
mode,
the input
signal
from
AXE
jack
J2
is
a-c
coupled
to
inverter
IC1A,
the
output
of
which
feeds
DRIVE
pot
R6.
Since
the
distortion
circuit
following
R6
is
level
sensitive,
R6
acts as a distortion
amount
control.
The
distortion
circuit
consists of
IC1B,
CR2
and
CR3.
Diodes
CR2
and
CR3
in
the
feedback path
of
IC1B
cause symmetrical
clipping of the
input wave-
form
generating the desired
distortion.
The
distorted
si
gnal
is
a-c
coupled
to
VOLUME
pot
R9
which
controls
the
Maestro
Fuzz
output
level.
In
the
straight
mode,
SW1
shorts
the
Maestro
Fuzz
output
to
ground minimizing
fuzz
circuit
bleed-thru
and
the input
signal
is
connected
directly
from
AXE
jack
J2
to
AMP
jack
Jl.
e)
Disconnect
three pin
connector
on
printed
circuit
board assembly
(15) noting black wire
on
left
side
of connector.
f)
Remove
nuts
(13)
using
a
half
inch
nut
driver
and
flat
washers
(14)
from
AXE
and
AMP
jacks
and
carefully
remove
printed
circuit
board
assembly
(15).
g)
Remove
screw
(16),
hex
nut
(18),
lock
washer
(19)
and
flat
washer
(20)
and
slide
out
push
switch
(22),
lock
washer and hex
ring.
h) Slide foot
pads out
of
their
channels
if
replacement
is
required.
TEST
AND
TROUBLESHOOTING
The
Maestro
Fuzz
requires
no
tuning
or
internal
adjustments.
When
troubleshooting,
refer
to
the
circuit
description,
schematic diagram,
and
replace-
ment
part
lists.
2
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