Seeburg LS 1 - 3. ADJUSTMENTS AND MAINTENANCE; a. Short Circuit Protection Circuit Adjustment

SERVICE IIANUAL
40.22
Page 3
SOLID STATE STEREO
AMPLIFIER,
TYPC T5A6
Vheo
the
oute rel,ay
is enetgized,
contacts
1Al1 close
coopletiog
a circuit
to the
trip
soleooid
in the
oecbaoiso, Cootacts
1Al
aod
1A21 close
to oute the
aoplifier.
Coo-
tacts
141
grouod the audio
sigaal froo the
top of
the right channel
voluoe
control.
Coo'
tacts
1421
ground thc audio sigaal
ftoo thc
top of
the lcft chgoocl
voluoe control.
Whcn
contacts
1A12 opeo,
the
grouod
circuit
to dual
diodc CR5106
is opcncd.
This allows
capacitors
C5120
asd C5121
to charge
ia
the
dircction
indicated
vhich rcsults
io diodcs
CR5104
and CR5105 beiag
for*ard biased.
Forward
biasiag diode CR5104
aad
CRJ1O5
glouods thc iaput signal
to
the base of thc
amplificr
stage
(Q5103)
throuSh
C5103.
Vhcq
the
outc relay
is dc-cocrgizcd
aad cootacts
1A12
closc, capacitor
C5121 dischargcs
slowly
through R5132'
This
results in a
slow
unoutiog
ol the anplifier
rathcr thao
a
sharp
rcturn
to music.
B. ADJUSTMENTS
AND MAINTENANCE
a. Short Circult
Protection Circuit
AdjE8tnert
The
duel
DELAY
TIME
potentiooetcr
is
used
to adjust
the short circuit
protectioo circuit.
This
control
is pteset at dre
factory aod
normally
does
not require fufihe!
adiustoeot.
If
however, adiustoent
does
becooe oeces'
sary,
a
pulse test record, Secburg
Part No.
25144
is
requitcd,
This
7 ioch 45 rpo.
re'
cord
includes verbal
iosructioos
for adjust-
iog
the
DELAY
TWE
poteatioaeter.
XOTE:
APPLY SILICONE
GREASE
TO
CLOTH SIOES
OF iIICA WA5HER
BEFORE REPLACIIIC CHASSIS.
Figure
2.
b. Driver
Traaslstor Replacemetrt
If
thc
drivcr traasistors,
Qrf07, Q5108,
Qr113
ot
Q5114,
occd
to be rcplaced, thcy
Bust be oouotcd as shov! in
Figurc 2. Be
sure both sidcs
of
thc
oica n,asher are
coated vitb silicooc
grease.
c.
Biae Adjuetnent fot
Output Traneietors
Thc bias adiustoent poteotiooeter located
in
the comcr of
each
voltage
aoplifier
printed circuit board is
used
to properly
ad-
lust
bias
oo
the
output traosistors. Thie ad-
justment
should not
be touched
unleas
componetrts
in the Predriver, Driver or
Output Stagee
are
changed. For
proper
ad-
jusuent
of
bias
see Note No.9 oa the
scheoatic diagrao.
EHOULOEi
trA3HgI IFIS
ER}
FLAI WASH