Original Website © Amplabs 2009 This new site created April 2018
Quad 303 services (further details)
Before
fault
rectification
and
refurbishment:
right
channel
defunct,
crackling
on
left
channel,
two
main
smoothing
capacitors
leaking
and
there
are
numerous
faulty
&
out
of
tolerance components. Rs, Cs, and semiconductors.
New
Nichicon
100V
105
oC
smoothing
and
output
capacitors
are
fitted
in
place
of
the
old
style
bracket
mounting types.
On
older
303s
with
the
crude
diode
bias
arrangement
we
can
fit
a
tiny
BIAS
modification
board.
This
provides
a
more
precise
adjustment
of
the
output
transistor
bias.
Incidentally
on
all
Quad
303
repairs
we
carefully
set
the
bias
to
the
sweet
spot
for
minimum
harmonic
distortion.
Too
much
and
THD
increases, to little, ditto.
We
mount
the
Nichicon
capacitors
using
our
specially
designed
capacitor
PCB.
This
correctly
mounts
the
modern
capacitors
in
place.
It
also
conveniently
allows
the
inclusion
of
L
&
R
+rail
fuses.
In
the
event
of
a
blown
output
device,
etc.,
a
fuse
blows
rather
than
a
vaporised
PCB
track.
In
this
example
we
replaced
a
failing
bridge
rectifier.
Some
3O3s
we
receive
for
service
are
in
a
very
poor
state.
e.g.,
rusty
case,
bottom
plate
and
front
panel.
We
can
restore
the
overall
look,
for
an
additional
cost,
by
stripping
and
re-spraying
these
parts
with
primer
and
top
coat.
The
re-sprayed
sections
(cover and bottom panel) will be in two tone colours similar to the original but not perfectly colour matched.
For ure listening pleasure