dbx 463X - Troubleshooting and Alignment; Required Test Equipment; Initial Inspection and Disassembly; Power Supply Verification

Troubleshooting
and alignment
Before
attempting
any troubleshooting
or
alignment,
study
the
463X
owners
manual
to
familiarize
yourself
with the unit.
The
manual
covers
the
operation of
all
controls,
specifications
for Inputs
and
outputs,
correct
hook-up
etc.
The
following
procedures
assume a basic
understanding
of
the
operational
details
of the
463X.
1.
Instruments
Required:
A.
Audio-frequency
sine-wave
oscillator
with 50-ohm
output
Impedance
(Krohn-HIte
4200A
or
equivalent).
B.
Oscl
1
1 oscope
with
10-MHz bandwidth
and 2»V per
division
sensitivity.
(Philips
PM
3233 or
equivalent)
C. Dc
voltneter
capable
of measuring
lmV (Fluke
8060A
or
equivalent).
D.
Ac
voltmeter
with
rms
response
(Fluke
8086A
or
equivalent).
E.
Distortion
meter,
with
low distortion
oscillator If
necessary,
capable
of
measuring
THD
to
less than
0.02S.
(Sound
Technology
Model
1700B
or
equivalent)
2.
Inspection
and
warm-up:
Inspect
the
unit
for
any
signs
of
external
damage
such
as
a cut
line
cord
or
broken
controls.
Check
the
position
of
the
voltage
selector
switch
on
the
rear
panel
and ensure
that
It Is
set
correctly
for
the
ac
mains
voltage
you
are using. Connect
the
463X to a
live
ac outlet
and
let
it
warm
up
for
at
least
10 minutes
before making
any
adjustments.
3.
Disassembly:
Be
sure
the
463X
Is
disconnected from
any
ac outlet.
Refer
to the
exploded
mechanical
view
and
locate
the
four corner rear
panel
screws.
Remove
only
these
corner
screws
and
slide
out
the
rear panel
about
4
Inches.
Carefully
disconnect
the
transformer
secondary
cables from
the
main
PCB
by sliding
apart
at the
connector.
Pull
only
on the
connector
body,
If
you
pull
on
the
wires they
may
break. Set the rear
panel
aside
for
now
and
remove
the
four corner
screws
from
the
front
panel using
the
special
hex
wrench
supplied
In the
accessory kit. The
front
panel
and
main
PCB
will
now
slide
out
of
the
chassis
intact.
Inspect
the
PCB
for
any
signs
of
damage
such
as burnt-out
resistors or
broken
wires.
It
Is
not
necessary
to
remove
the
front
panel
from
the main
PCB
unless
service
is
necessary
on
the
LED
board
or
the
Level
Set
pot.
Reconnect
the
transformer
secondary
to the
main PCB, connect
the
line
cord
to
a
live
ac
outlet,
and let the
unit
warm
back
up
for
a
few
minutes.
4.
Power
Supply
Check:
Before
attempting any
calibration
or
troubleshooting,
check
that
the
power
supply
is
working
correctly.
Verify
the
following.-
i
Probe
location
TP9
TP10
|
TP7
J
TP8
Test Condition
+15.
OOv
-15.
OOv
+24
V
dc
-24
V
dc
Tolerance
+
/-
5
0 0
it.
V
+/-
500mV
+/-
3
V
dc,
+/-
?
V
dc,
750mV
ripple
750 mV
ripple
I