Teac A-400 - Electrical Checks and Adjustments; General Electrical Procedures and Equipment

4.
ELECTRICAL
CHECKS
AND
ADJUSTMENTS
GENERAL NOTICE
Before
performing
adjustments
on
the
amplifier
section
of
this
deck,
thoroughly
clean
and
demagnetize
the
entire
tape
path,
particularly
erase
head,
record/playback
head,
capstan
shaft
and
pinch
roller.
2.
In
general,
checks
and
adjustments
for
other
than
specified
items,
are
dene—in—the—sequence—of
teft-channel_then-right
channel.Double
designated
REF.
NO.
indicates
left
channel/right
channel
(example:
VR101/VR201).
3.
Value
of
“dB”
in
the
text
refers
to
0
dB
=
0.775
V,
except
where
specified.
Ifa
VTVM
calibrated
to0dB=1V
is
to
be
used,
appropriate
compensation
should
be
made.
4.
The
load
impedance
for
OUTPUT
terminal
is
50
k-ohms.
5.
The
load
impedance
for
Dolby
Test
Point
is
1
M-ohms
or
more.
6.
While
performing
all
electrical
alignments,
the
INPUT
switch
should
be
placed
in
the
LINE
position,
unless
otherwise
indicated.
7.
All
checks
and
adjustments
should
be
made
with
the
Cabinet
and
the
Front
Panel
removed.
(See
Section
2-1,
2-2)
TEST
EQUIPMENT
REQUIRED
1.
TEAC
test
tape:
For
playback
performance
alignment:
MTT-150:
For
Dolby
level
calibration
MTT-116L:
For
playback
frequency
response
check
For
record
performance
alignment:
MTT-505:
For
record
test
with
BIAS/EO
an
MTT-501:
For
record
test
with
BIAS/EQ
“gn
2.
AF
oscillator:
10
Hz
~
100
kHz
3.
VTVM:
0.1
mV
~300
V
4.
Attenuator
General
Purpose
5.
Distortion
analyzer:
Basic
frequency
400
Hz/1
kHz
6.
Oscilloscope:
General
purpose
7.
Band-pass
filter:
-
1
kHz
narrow
band-pass
type
8.
Test
load
resistor:
|
~
Non
inductive
type
8
ohm/1W
9. Non-inductive driver
10. Head demagnetizer TEAC E-1 or equivalent