Final Check; Service In Driver Circuits - Lab.gruppen SS 1300 Service Manual

2
8)
Final
check:
Then
the
signal
is
undistorted; replace
the
two
47^-resistors
with
fuses,
T
6.3A.
a)
Adjust the
railvoltage
by
TP2
to
82.5V
on
the
PSUB.
b)
Check the quisentcurrent
by measuring the current thru the F2, adjust
to
200
mA
by
PI.
c)
Check
output
by
a
sinewawe up
to
full
swing
into
4
O
load.
d)
Check
of short-circuit protection:
-
Adjust outputvoltage
to
10
V
AC.
-
Short
the
output by
a resistor 0.3
-0.50/
5W.
-
Check
symetry
of
the shortcircuitvoltage across the 0.3D-resistor
by
the
scope.
9)
Service
in
driver
circuits
a)
Desolder R12,
R24
and
R25.
b)
Connect
a resistor
33
kQ
between
point
R2£/
R27 and R1
2/
C3.
c)
Connect
a scope
at
R22/ R27.
d)
Apply a
sinewawe
to
the
amplifier,
and
the drivercircuits
can be checked
separately
without the
outputcircuits.
10)
Check
of
DC-
voltages:
a)
D1
+15V
ref.
to
ground.
b)
D2
-15V
n
c)
Q3
collector
-14V
»
d)
R4,
R5
-0.5V
it
e)
R8,
R9
-1.2V
ref.
to
+
Railvoltage.
f)
R14,
R15
-0.5V
ii
g)
R16,
R17
+0.5V
ref.
to
-
Railvoltage.