Fisher TAC-M82 - Double Cassette Deck Electrical Adjustment Procedures; Measuring Instruments Required; Normal;Double Tape Speed Adjustment; Head Azimuth Adjustment

DOUBLE
CASSETTE
DECK
ELECTRICAL
ADJUSTMENT
PROCEDURES
MEASURING INSTRUMENTS REQUIRED
Dualtrace Oscilloscope
AC VTVM (AC voltmeter with high impedance)
Frequency Counter
Audio Signal Generator
Dummy Load (60 60watts resistor)
Test Tapes
+ 3kHz Test Tape (Example: TEAC MTT-111) for Normal
Tape Speed Adjustment
10kHz Test Tape (Example: TEAC MTT-114) for Azi-
muth Adjustment
400Hz Test Tape (Example: TEAC MTT-150) for Play-
back Sensitivity Adjustment
Test Tapes for Recording and Playback Operations
+ Normal Tape (Example: TDK AC 223)
+ CrQ2 Tape (Example: TDK AC 512)
+ Metal Tape (Example: TDK AC 712)
t
NORMAL/DOUBLE TAPE SPEED ADJUSTMENT
1. Connect the Dummy load (60 60watts resistor) and the
frequency counter to the Speaker terminal (Left channel).
2.
Short
the
circuit
between
test
point
TP5
and
TP6
on
the
Main
P.C.Board.
(The
unit
will
be
set
to
the
High
Speed
mode.)
3. Load Deck 2 with a test tape (Example: TEAC MTT-111)
and set it in the playback mode.
4.
Adjust
potentiometer
P852
on
the
Mecha
P.C.Board,
so
that
the
reading
on
the
frequency
counter
is
6000Hz
~
6060HZz.
5. Disconnect connecting wire from test point TP5 and TP6.
6.
Load
Deck
2
with
a
test
tape
and
Adjust
potentiometer
P851, so that the reading on the frequency counter is
3000Hz ~ 3030Hz.
HEAD AZIMUTH ADJUSTMENT
1. Connect the dualtrace oscilloscope and AC VTVM to the
Dolby test point TP301 and TP302 (Left and Right channel)
on the Main P.C.Board.
Then, set the dualtrace oscilloscope as follows:
£ O MODE. ani seccscccscescseccseetenniccacsdsesvsccosecte CHOP (chopped)
INT (internal), CH1 or CH2
AUTO (automatic)
NOTE:
Adjust
the
field
on
the
oscilloscope
with
the
VOLT.
ADJ.
and
TIME
ADJ.
2.
Load
Deck
2
with
a
test
tape
(Example:
TEAC
MTT-114)
and
set
it
in
the
forward
playback
mode.
3.
Adjust
the
azimuth
adjustment
screw,
so
that
the
wave
forms
become
maximum
on
the
oscilloscope
and
the
Right
channel
wave
form
overlaps
with
the
Left
channel
one.
4. Perform the same adjustment for Deck 1.
5.
After
the
adjustment,
secure
the
adjusting
screw
with
paint or glue.
PLAYBACK OUTPUT LEVEL ADJUSTMENT
1. Connect the oscilloscope and AC VTVM to the Dolby test
point TP301 and TP302 (Left and Right channel) on the
Main P.C.Board.
2. Load Deck 2 with a test tape (Example: TEAC MTT-150)
and set it in the playback mode.
3.
Adjust
potentiometer
P101,
so
that
the
output
level
be-
comes
548mV
+0.5dB
:
Dolby
1IC305
CXA-1101
(650mV
+0.5dB
:
10305
HA12136).
4.
Adjust
potentiometer
P102
for
the
Right
channel
by
fol-
lowing the same procedures as described for the Left
channel.
RECORDING BIAS LEVEL ADJUSTMENT
1.
Connect
the
audio
signal
generator
to
the
Left
channel!
of
the
AUX
input
terminal,
and
the
AC
VTVM
to
the
Dolby
test
point
TP301
and
TP302
(Left
and
Right
channel)
on
the
Main
P.C.Board.
Load Deck 2 with a normal tape (Example: TDK AC223)
and set it in the recording mode.
Function switch to the AUX position.
Set the Input Level ATT so that the output level becomes
30mV: IC305 CXA-1101 (36mV: IC305 HA12136) and feed
the signals of 1kHz and 12.5kHz from the audio signal
generator into the unit. Then, record the signals on the
tape.
Playback the recorded signals and adjust potentiometer
P301 for the Left channel, so that the difference in output
of the 1kHz and 12.5kHz signals become +1, —OdB.
Adjust potentiometer P302 for the Right channel by fol-
lowing the same procedures as described for the Left
channel.
RECORDING FREQUENCY CHARACTERISTIC
RESPONSE ADJUSTMENT
1. Perform the same procedures as described for the RE-
CORDING BIAS LEVEL ADJUSTMENT.
Then perform the recoding and playback operations us-
ing the CrO2 tape (Example: TDK AC 512) and METAL
tape (Example: TDK AC 712). After that adjust P103 and
P104
until
the
recoding/playback
frequency
meets
the
specifications.
2.