Technics RS-M228X - Page 7

RS-M228X RS-M228X
Adjustment @: Adjustment ®: @ Fluorescent meter . Make connections as.shown (See fig. 17).
When the curve exceeds the overall frequency When the curve falls below the overall frequency Condition: 2. Connect a wire between TP301 and peak reset
response chart specifications (fig. 12) as shown response chart specitications (fig. 12) as shown * Record mode terminal (See fig. 18).
in fig. 14. in fig. 15. * Input level controls --» MAX . In the recording pause mode, apply 1 kHz
+ Output level control --» MAX (—24dB) to LINE IN.
eat _ Adjust ATT so that output level at LINE OUT
Equipment: is O.4V
* VTVM * AF oscillator
«ATT —40dB adjustment
5. Adjust ATT so that the level adjusted at step
4 is reuced by 40dB.
6. At this time, check that — 40 dB indicator is
kHz
2kHz
Wars
SSE
10
kHz
ax
So
10kHZ
lighted
halfway
(intermediate
brightness
3kHz/ /6kH
aki SikHz 71 ‘AC Hi / feu kare between full brightness and light-out: See fig.
19).
Fig. 14 Fig. 15 7. \f the indicator is not lighted halfway as
1)
Increase
bias
current
by
turning
VR9
(L-CH)
1)
Reduce
bias
current
by
turning
VR9
(L-CH))
described
in
step
6,
adjust
VR301.
and VR1G (R-CH). and VR10 (R-CH). OdB adjustment
See fig. 1 on page 5.) 2) Repeat steps 6 and 7 to confirm. i :
2) Repeat steps 6 and 7 to confirm. (Proceed to steps 8, 9, 10 and 11 if the 8 ete ae 4 (set LINE
Proceed to steps 8, 9, 10 and 11 if the curve iS now within the charted specifica- Rion a EN ot lots . . : ;
curve is now within the charted specifica- tions.in fig. 12) . time, ee oe le is lighted halfway (intermediate brightness between full
tions is fig. 12.) 3) If the curve still falls below the charted i iaprone: edie yeaa ig. 20).
if th till h ificati ificati i i : ;
3) e curve still exceeds the specifications specifications (fig. 12), reduce bias current ” Repent adyistmien|e: and chiaciealestene 4 G26: 78) S anal 0 tae Ge tarde tines
fig. 12), i bi t further and furth t re ; ; ,
ee
7
on
aey
aie
Dive
aee
Letras
iene
Disconnect
the
wire
between
TP301
and
ground
terminal,
which
had
been
connected
at
step
2
. Place UNIT into CrO2 tape mode.
ee,
Been
Borne
A
Overall
frequency
response
chart
(CrO2,
Metal)
©
Dolby
NR
circuit
1.
Test
equipment
connection
is
shown
in
fig.
21.
jezdcny
|
Tralee
es
4kH e
kH
ions
a
1D
a
TO
Condition
2. Place
UNIT
into
record mode,
set
the
Dolby
NR
switch
|1C3(R-CH)
2, 2 OINEIES 2 ANG) 9 Bitz HT | Pe a scardaned to OUT position and supply to LINE IN to obtain a
signals.
Then,
playback
the
signals
and
Foner
adie
oa
—34.5¢B
at
PIN
@
[IC2
(L-CH).
C3
(R-CH)]
check
if
the
curve
is
within
the
limits
asi
Z|
‘
aerate
Sie
ie
ae
(frequency
5
kHz}
-
.
shown in the overall frequency response * Input level controls --- f Bak The val IN :
: : t +2.5)dB
chart for CrO2 tapes (fig. 16). it Yt TU Equipment: COON! Weel eee IN Dostonse | ial
Hi aunt greater than the value at OUT position of Dolby NR e
. Place UNIT into metal tape mode change HH or ee ad Ht * VTVM * AF oscillator awiten 5°
test
tape
to
QZZCRZ,
and
record
50Hz,
fligots
$300
Hz
hy
xu
ate
Tt
N72
Sie
*
ATT
*
Oscilloscope
:
100Hz, 200Hz, 500Hz, 1kHz, 4 kHz, uy fa ae \\\g20H| 4kHz NE Rte * Resistor (600 2) Fig. 21 Genin
8kHz, 10kHz and 12.5kHz signals 400 Hz 600 Hz 700 Hz \ §kHz 7kHz
Then, playback the signals and - Fig. 16
check if the curve is within the limits :
shown in the overall frequency response chart for metal tapes (fig. 16).
. Confirm that bias currents are approximately as follows when the UNIT is set at different tape mode.
* Read voltage on VTVM and calculate bias current by following formula:
Value read on VTVM (V)
10 (Q)
Connection
AF
oscillator
ATT
Record
ii
Bias current (A)
Standard value:
around 340 uA (Normal position)
around 440 ZA (CrO2 position) : measured at TP1(L-CH) and TP2 (R-CH)
around 710A (Metal position)
@ Overall gain Test equipment connection is shown in fig. 17.
Condition: 2. Place UNIT into normal tape mode, and load the test Record /playback
* Record/playback mode tape (QZZCRA).
+ Normal tape mode _ Place UNIT into record mode.
* Input level controls --» MAX . Supply 1kHz signa! (—24 dB) from AF oscillator. 2 as
*
Output
level
control
---
MAX
through
ATT
to
LINE
IN.
AF
oscillator
A
Lune
in
Record
mode
* Standard input level; . Adjust ATT until monitor level at LINE OUT becomes
MIC «+++ —72+3¢dB OAV.
LINE IN--» —24+3dB _ Playback recorded tape, and make sure the value at
LINE OUT on VTVM becomes 0.4 V.
_ (f measured value is not 0.4V, adjust VR5 (L-CH),
VR6 (R-CH). Test tape
. Repeat from step (2)
Test tape
Playback head LINE OUT
Equipment:
* VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
+ Test tape
(reference blank tape)
--QZZCRA for Normal
Playback mode “yrym
Oscilloscope
Fig. 17