Technics RS-M228X - Page 6

RS-M228X
ITEM
MEASUREMENT
&
ADJUSTMENT
@ Erase current 1. Test equipment connection is shown in fig. 11.
Condition:
2.
Place
UNIT
into
metal
tape
mode.
Evaga‘head
* Record mode 3. Press the record and pause buttons.
+
Metal
tape
mode
4.
Read
voltage
on
VTVM
and
calculate
erase
current
by
ane
—
Eau
t
following
formula:
Record
mode
aaos
aaIPnEN
Voltage
across
both
ends
of
R125
rare
soya
a
*VTVM
*
Oscilloscope
Erase
current
(A)
=
oo
we
1 (Q) VTIVM Oscilloscope
Standard
value:
155+15mA
(Metal
position)
|
Fig.
11
5. If measured value is not within standard, adjust as follows.
Adjustment
1. Short the points (b) and (c) on the main circuit {
board diagram (see page 25)
2. Make measurement for erase current.
3.
Make
sure
that
the
measured
value
is
within
the
|
:
'
erase
current
of
140mA
to
170mA
oe
|
Open
j
—2dB
|
—1dB
4.
If
measured
value
is
not
within
standard,
short
or
point
(c
;
open
connection
points
(b)
and
(c)
for
adjustment
|
Se
0.108
O08
(see
table
2).
Table
2
_ around 70mA (Normal position)
Reference ‘valle: around 95mA (CrQ2 position)
= 1
Connection point (b) |
Open Short
© Overall frequency Note: | Overall frequency response chart (Normal)
response
Before
measuring
and
adjusting,
make
sure
:
7
Condition:
of
the
playback
frequency
response
(For
*
Record
/playback
mode
the
method
of
measurement,
please
refer
ee
*
Normal
tape
mode
to
the
playback
frequency
response)
a
*
CrO>
tape
mode
Overall
frequency
response
adjustment
ee
*
Metal
tape
mode
by
recording
bias
current
—
408
*
Input
level
controls
---
MAX
s
no
ee
*
Cute
level
control
---
MAX
ieeusdingsequanagnle
wed)
nh
al
eae
ee
Equipments
1.
Make
connections
as
shown
in
fig.
13.
i
QDH2700He
4KHE
5
KHz
|
*v1VM
+
AF
oscillator
2.
Place
UNIT
into
normal
tape
mode
and
Fig.
12
mail
*
Oscilloscope
load
the
test
tape
(QZZCRA).
.
*
Resistor
(6002)
3.
input
a
1kHz,
~24
dB
signal
through
* Test tape LINE IN
(reference blank tape)
Place the set in record mode VR9(L-CH)
- QZZCRA for Norm! 4. Fine adjust the attenuator to obtain Rama dinveack {vanDeRc Pa
* QZZCRX for CrOs 0.4V LINE OUT output head = TART "AP oseilstor
*
QZZCRZ
for
Metal
*
Make
sure
that
the
input
signal
level
33
is —24+4d8 with 0.4V output TPL{L-CH) Piayback7
voltage.
aca
secede
FA
@)
5
Adjust
the
attenuator
to
reduce
the
input
mem
NY
°6)
ro
FLA
a
ering
VIVM_Oseiloscope
6.
Adjust
the
AF
oscillator
to
generate
50
Hz,
oo}
to
100
Hz,
200Hz,
500
Hz,
1kHz,
4kHz,
VTVM
Oscilloscope
For
overall
frequency
;
; ———— response measuremen
8kHz
and
10kHz
signals,
and
record
Far
bag
cuvent
these
signals
on
the
test
tape.
measurement.
7. Playback the signals recorded in step 6, Fig. 13
and check if the frequency response curve
is within the limits shown in the overall
frequency response chart for normal tapes
(tig. 12).
(If the curve is within the charted specifications, proceed to steps 8, 9, 10 and 11,)
If the curve is not within the charted specifications, adjust as follows;