Technics RS-M13 - Page 9

RS-M13
ITEM _ MEASUREMENT & ADJUSTMENT
@® Bias current
Condition:
* Record mode
* Tape selector
-- Normal position
--Fe-Cr position
--CrQ2 position
--Metal position
Equipment:
*VTVM — * Oscilloscope
@ Overall gain
Condition:
* Record/playback mode
* Input level controls --- MAX
* Standard input level;
MIC veeeeee —72+4dB
LINE IN--- ~24+4dB
Equipment:
*VTVM _ * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
* Test tape
(reference blank tape)
---QZZCRA for Normal
© Overall frequency
response
Condition:
* Record/playback mode
* Tape selector
-- Normal position
--Fe-Cr position
--CrOz position
--Metal position
* Input level controls --- MAX
Equipment :
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (6002)
* Test tape
(reference blank tape)
---QZZCRA for Normal
++» QZZCRY for Fe-Cr
---QZZCRX for CrOz
--QZZCRZ for Metal
_ Make measurement for erase current.
_ Make sure that the measured value is within the erase current of 140mA to 170mA.
_ If it is beyond the value, carry out the following adjustments:
* If the erase current is less than 140 mA, short the point (A).
* If the erase current is more than 170 mA, open the points (A) and (B).
VR7 (L-CH)
Test equipment connection is shown in fig. 31. VR8(R-CH)
. Place UNIT into record mode, and tape selector to normal
position.
. Read voltage on VTVM and calculate bias current by Record mode
following formula: een ‘
Value read on VT VM (V) RI (L-CH)
10 (Q) R2 (R-CH)
og Record/playback
mM head
VTVM Oscilloscope
Bias current (A) =
Fig. 31
Standard value: around 410uA (Normal position) | =
. If measured value is not within standard, adjust VR7 (L-CH) and VR8 (R-CH) (See fig. 22 on page 5).
. Set the tape selector to each position.
. Make sure that the measured value is within standard.
Standard ire around 440uA Ags cr necition. round 545 uA, (CrO2 Basitiot |
around 800A (Metal position) |
. Test equipment connection is shown in fig. 32.
. Place UNIT into record mode, and tape selector to normal
position.
. Supply 1kHz signal (—24 dB) from AF oscillator, through
ATT to LINE IN. AF oscillator LINEIN Record mode
. Adjust ATT until monitor level at LINE OUT becomes Record/playback
0.39V. head
. Using test tape, make recording.
. Playback recorded tape, and make sure the value at LINE
OUT on VTVM becomes 0.39 V (—7 dB).
7. \f measured value is not 0.39V, adjust VR5 (L-CH), VR6
(R-CH) (See fig. 22 on page 5).
8. Repeat from step (2).
Record/playback
head
Test tape
LINE OUT
Playback
mode
“yTvM
Oscilloscope
Fig. 32
Test tape
Note 1: Overall frequency response chart (Normal)
Before measuring and adjusting, make sure 1kte
of the playback frequency response (For the 50Hz 100Hz rare
method of measurement, please refer to the 4 »gp
playback frequency response)
; +14B
Note 2: ‘Cae
Test tape QZZCRA to be supplied after July ce
1980 has higher recording sensitivity in the 100 Hz 640 Hz
middle and high frequency range. eB 20H Fig. 33
* This chart indicates the standard values for the new type of QZZCRA when in use.
<A"
* ~ me ] This chart indicates the standard values for the former type of QZZCRA when in use.
—*
The new type of QZZCRA is marked as shown in fig. 34.
Former type
OO
QZZCRA
New type
RS-M13
ITEM MEASUREMENT & ADJUSTMENT
@ Level meter
Condition:
* Record mode
* Input level controls --- MAX
Equipment:
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
@ Dolby NR circuit
Condition:
* Record mode
* Dolby NR switch --- IN/OUT
* Input level controls --- MAX
Equipment:
*VTVM «AF oscillator
* ATT * Oscilloscope
* Resistor (600 Q)
Measurement
Overall
frequency
response
chart
1.
Test
equipment
connection
is
shown
in
(Fe-Cr,
CrOz,
Metal)
12kHz
fig.
32.
2kHz
-
2.
Place
the
normal
test
tape
(QZZCRA)
in
a
200
Hz
640
Hz
oa
Z
the cassette holder. +408
3. Place UNIT into record mode, and thpe
selector to normal position. 0dB
4.
Supply
1kHz
signal
from
AF
oscillator
Siete
through
ATT
to
LINE
IN.
5. Adjust ATT so that input level is —20dB 200H2 40 Hz
below standard recording level (standard :
recording level =0 VU). Ma OR OFig. 35
6. At this time, LINE OUT level indicates
0.039V.
7.
Record
each
frequency
1kHz,
50Hz,
200Hz,
4kHz,
8kHz
and
10kHz
(12
kHz
for
Fe-Cr,
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.
Make
sure
that
the
measured
value
is
within
the
range
specified
in
the
overall
frequency
response
chart
(Shown
in
fig.
33).
10. Change test tape to Fe-Cr (QZZCRY), CrOz (QZZCRX) and metal (QZZCRZ).
11. Set the tape selector to each position.
12. Measure in the same manner from step (3) to step (8).
13.
Make
sure
that
the
measured
value
is
within
the
range
specified
in
the
overall
frequency
response
chart
for
Fe-Cr,
CrOz
and
metal
tape
(Shown
in
fig.
35).
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. 36, increases the bias current
by turning VR7 (L-CH), VR8 (R-CH).
2. When it becomes lower, as shown by dotted line, reduce the .
bias current by turning VR7 (L-CH), VR8 (R-CH). IRM RHE Baez l2kH2
Note:
Fig.
36
For
the
method
of
bias
current
measurement,
refer
to
“
@
Bias
current
adjustment”
on
page
8.
1. Test equipment connection is shown in fig. 37.
2. Supply 1 kHz signal from the AF oscillator, through the ATT cs LINE OUT
to
the
LINE
IN.
arr
cn
BS
ie
3. Adjust ATT so that the monitor level at LINE OUT becomes
0.39V.
4. Check to see that the level meter stays within the range of
—1dB to +1dB.
5. If it is beyond the range, carry out the following adjustments:
¢ Short soldered points (D) (L-CH) and (F) (R-CH) indicated as “DOWN” where level more than + 1dB.
Short soldered points (C) (L-CH) and (E) (R-CH) indicated as “UP” where level less than --1dB.
(See wiring connection diagram on page 10.)
AF ae LINE IN ri mode y Tym Oscilloscope
Fig. 37
. Test equipment connection is shown in fig. 38. irit-cuy TPS (L-CH)
. Place UNIT into record mode, set the Dolby NR switch IC2(R-CH) We; (RCH) VTVM
to OUT position and supply to LINE IN to obtain
—34.5dB at TP9 (L-CH), TP10 (R-CH) (frequency
5 kHz).
. Confirm that the value at IN position is 8 (+ 2.5) dB
greater than the value at OUT position of Dolby NR
switch.
AF oscilator ATT
Oscilloscope
E18
E26
E34