Technics RS-M5 - Page 8

| _ RS-MI5 RS-M5
. q
ITEM MEASUREMENT & ADJUSTMENT ITEM MEASUREMENT & ADJUSTMENT
9. Adjust ATT so that input level is
—-20dB below standard recording
level (standard recording level =0 VU).
6. At this time, LINE OUT level indicates
0.039V.
7. Record each frequency 30 Hz, 100 Hz,
1kHz, 4kHz, 8kHz and 10 kHz
(12kHz for CrO2 and Metal).
8. Playback and express in dB the
difference between playback output
level of each frequency based on
playback output level of 1 kHz.
9. Change test tape to CrOz (QZZCRX) 2kHz 10kHz
and metal {(QZZCRZ). a
10. Set the tape selector to each position.
11. Measure as same as manner above.
12. Make sure that the measured value is
within the range specified in the
overall frequency response chart for
CrQz2 and metal tape shown in fig. 18,
19 and 20.
Adjustment — Using bias current
1. When the frequency response between the middle and high
frequency range becomes. higher than the standard value,
as shown by the solid line in fig. 21 increas, refer to bias
current adjustment. 0
2. When it becomes lower, as shown by dotted line, refer to eae
bias current adjustment.
Note: IkHz
For the method of bias current measurement, refer to “Bias Fig. 21
current adjustment” on page 6.
Adjustment
1. Open the point (A) and short the point (B) on the main circuit board in the wiring connection diagram
(See page 8).
2. Make measurement for erase current.
3. Make sure that the measured value is within the erase current of 145mA to 165mA.
4. {f it is beyond the value, carry out the following adjustments:
¢ If the erase current is less than 145 mA, short the point (A).
¢ if the erase current is more than 165mA, open the points (A) and (B).
Overall frequency response chart (CrO2)
© Bias current
Condition:
* Record mode
* Tape selector
-++ Normal position
--» CrO2 position
--+ Metal position
Equipment:
* VTVM * Oscilloscope
. Test equipment connection is shown in fig. 16.
2. Place UNIT into record mode, and tape selector to normal beet
Overall frequency response chart (Metal)
12kHz
position.
3. Read voltage on VTVM and calculate bias current by following
formuia:
Value read on VT VM (V)
10 (Q)
Bias current (A) =
Fig. 16
| Standard value: around 400A (Normal position)
. lf measured value is not within standard, adjust VR301 (L-CH) and VR302 (R-CH) (See fig. 8 on page 3).
. Set the tape selector to each position.
. Make sure that the measured value is within standard.
Oo &
Standard value: around 550A (CrO2z position), around 830A (Metal position)
@® Overall gain
Condition:
* Record/playback mode
* Input level control --- MAX
_ Test equipment connection is shown in fig. 17.
2. Place UNIT into record mode, and tape selector to normal
position.
3. Supply 1 kHz signal (—24dB) from AF oscillator, through
ATT to LINE IN.
2kHz
S8kHz 12kHz
Record/playback head
* Standard input level: ah
MIC Gaseas : .—72+4dB 4. Adjust ATT until monitor level at LINE OUT becomes Neer SNE Test tape
LINE IN.-- —24+3dB 0.39 V. | Record/playback © Level meter _ Test equipment connection is shown in fig. 22.
Equioment: o. Using test tape, make recording. head Condition: 2. Supply 1kHz signal from the AF oscillator, through the ATT oe
| . 6. Playback recorded tape, and make sure the value at LINE to the LINE IN. =~ — 5
*
VTVM
+
AF
oscil
*
Record
mode
|
6000
—
au
ee : A eae OUT on VTVM becomes 0.39V (—7dB). eal pg oe + Input level control «-. MAX | 3: Adjust ATT so that the monitor level at LINE OUT becomes Of ar eon — [ES] [CF
*
Resistor
(600
Q)
P
7.
\f
measured
value
is
not
0.39
V,
adjust
VR5
(L-CH),
VR6
Test
tape
|
*YD8CK
Mode
VTVM
0
a
|
0.39V.
AF
oscillator
1yye
jn
Record
mode
v'r
ym
Oscilloscope
»
Test
t
(R-CH)
(See
fig.
8
on
page
3).
Fig.
17
quipment:
.
4.
Check
to
see
that
the
level
meter
stays
within
the
range
of
Fia.
22
iigoe blank tape) 8. Repeat from step (2). es ai gince ~~ TdB to +1dB. .
* ATT * Oscilloscope | 5 If it is beyond the range, carry out the following adjustments:
--» QZ77CRA for Normal
* Resistor (600) ¢ Open soldered points (C) (L-CH) and (£) (R-CH) indicated as “DOWN” where level more than +1 dB.
* Open soldered points (D) (L-CH) and (F) (R-CH) indicated as “UP” where level less than —1 dB.
(See wiring connection diagram on page 8.)
Note:
Before measuring and adjusting, make sure
of the playback frequency response (For
the method of measurement, please refer
to the playback frequency response). +2dB
@ Overall frequency
response
Condition:
* Record/playback mode
* Tape selector
-«« Normal position
‘Overall frequency response chart (Normal)
@. Dolby NR circuit
Condition:
* Record mode
* Dolby NR switch --» IN/OUT
. Test equipment connection is shown in fig. 23.
2. Place UNIT into record mode, set the Dolby NR switch to
OUT position and supply to LINE IN to obtain —34.5dB
at TP7 (L-CH), TP8 (R-CH) (frequency 5 kHz).
50Hz 100Hz
1. Test equipment connection is shown
+++
CrO2
position
nie
ag:
—248
See
ane
pot
ee
3.
Confirm
that
the
value
at
IN
position
is
8(+2.5)
dB
greater
|
--+
Metal
position
2.
ae
the
test
tape
(QZZCRA)
in
the
—44B
c
ae
=
Ee
er
than
the
value
at
OUT
position
of
Dolby
NR
switch.
re
een
13
raat
:
See
eo
eens
cassette
holder
ae
S0Hz
an
ie
|
LINE
IN.
[>So
Equipment:
3.
Place
UNIT
into
record
mode,
and
Fig.
18
‘
ee
‘
:
a
rs
aC
*VTVM
*
AF
oscillator
tape
selector
to
normal
position.
*
Resistor
(600
Q)
ATT
Record
mode
*
ATT
*«
Oscilloscope
4.
Supply
1
kHz
signal
from
AF
oscillator
Fig.
23
*
Resistor
(600
Q)
through
ATT
to
LINE
IN.
=
*
Test
tape
(reference blank tape)
--> Q7ZCRA for Normal
-+» Q7ZCRX for CrOz
--» QZZCRZ for Metal