Dokorder 7700 - 6 Adjustment; Adjustable Parts Location

6.
ADJUSTMENT
-ELECTRICAL-
rL-
PRECAUTION
1.
Before
actually
adjusting
the
parts, be
sure
to
first clean
the
heads'
pinch
rollerand
othertape-scraping
parts
aswellasthebelts,idlersandothertape-drivetorquetransmissionpartswithalcohol.Lubricate,foo,if
necessary'
Such
procedures
may
bring
back
the
performance
to
Within
tolerable
specifications,
eliminating
any
need
for
part
replacements
or
torque
re-adjustments'
Thepositionofthethruststopper,ifImproperlyset,maydeterioratethewow/flutter.Soitisadvisableto
remove
the
belt
and
then
turn
the
flywheel
with
your fingers
to
see
if
it turns
smoothlv'
2.
For
an
efficient
adiustment
of
record/playback
level
and
frequency
response'
follow
the
order
of
preferences
forthedifferentadjustingprocedures.Forinstance,ifyouadjusttherecordlevelbeforeadjustingtheplay-
back
level
or
without
checking
it,
you'll have
to
re-adjust
the
record
level
same
after
you
have
adiusted
the
,
fili::t:},::ll,,ln
,n.
overarr
response,
it
may
sometimes
become
necessarv
to
fine-adjust
the
previousrv-adjusted
parts.lnsuchacase,makesurethatthefine.adjustmentsarestillWithintolerableratings,beforeproceeding
a
1,".T:?::::0.r."
if
of
the
same
brand
and
type,
show
identicar
recordins
responses,
especiatv
in
the
hish-
frequencyrange'Thusifyouswitchtapesduringadjustments,youmayhavetore-adjustthepartsyouhave
alreadyadjusted.lfyouareusingatapeforttretlrsttime,it.softenadvisabletocheckitsresponsebefore-
hand,
to
know
how
different
it
is
in
response
from
the
previous tape'
NOTES
L
L
L
TheproceduresinthissectionapplytotheamplifiercircuitsoftheModelTT00.
ln
adjusting
the
amplifier
"i.cuits
following
the
instructions
in
this
section,
the
tapes
belowlisted
should
be
used.
1.
When
adiusting
the
playback
circuits:
lt
gffit|,Jjl:110
dB)
or
equivarents
{Adiustment
or
Plavback
Level
&
Frequencv
Response)
DTT-5113
(15
KHz
-10
dB)
or
equivalents
(Aiiustment
of
Head
Almuth
&
Playback
Frequency
Response)
DTT-5102
(50
Hz-10
dB)
or
equivalents
(Adjustment
of
Playback
Frequency
Response)
9.5
cm/sec
(3
3/4
iPs)
DTT-3106
(500
UtllOdB)
or
equivalents
(Adiustment
of
Playback.
Frequency
Response)
DTT-3110
(7.5
KHz
-10
dB)
or
equivalents
(Adiustment
of
Playback
Frequency
Response)
DTT-3102
(50
Hz
-10
dB)
or
equivalents
(Adiustment
of
Playback
Frequency
Response)
(orothertypesofatignmenttapeWiththelevelsasarerecordedontheabovetapes.)
,
H:::
llil':il.g
ff"ff;H:i:t'..",d
bias
and
the
record
equarizer
can
be
used
independentrv
of
each
other,
thereareseveraltypesoftapetobeused,foradiustmentsuchasthoselistedbelow.Foradjustmentofrecord
frequency
response,
the
Scotch
#212
and
Maxell
UD-35'
ADJUSTMENT
For
the
rocation
of
parts for
adiustment
on
each
of
the
amprifier
circuit
pc
board
(pcM-446),
refer
to
the
section
,,ADJUSTABLE
PARTS
LOCATION."
Adiustment
TaPe
Tape
Select
Mode
Equalizer
Switch
Scotch
212
or
equivalents
NORMAL
Maxell
UD-35
or
equivalents
SPECIAL
I
12