Technics RS-M226 - Page 5

® Playback frequency
response
Condition
+ Playback mode
* Tape selector
-- Normal position
Equipment
*VTVM
+ Test tape---
* Oscilloscope
QZZCFM
ony
fig. 3.
Test equipment connection is shown in
ITEM MEASUREMENT & ADJUSTMENT
Playback frequency response chart
RS-M226
@ Playback gain
Condition
* Playback mode
* Tape selector
-»Normal position
Equipment
*VTVM
* Test tape--:
* Oscilloscope
QZZCFM
@ Erase current
Condition
* Record mode
* Tape selector
-- Metal position
Equipment
«VTVM
* Oscilloscope
2.
Place
UNIT
into
playback
mode
aig
100
hee
7
+6d8
3. Playback the frequency response test rade Se - ee are $hc8
tape
(QZZCFM)
sae
m@annuiaeal
4
Measure
output
level
at
315Hz,125kHz
|
#8
:
2H
haa
8kHz,
4kHz,
1kHz,
250Hz,
125Hz
and
=
|7
288
ial
248
63Hz. and
compare
each
output
level
4
erie
q
foe
“To
408
with
the
standard
frequency
315
Hz.
at
eG
oon
|
eas
r
ai
This
*
rivets
LINE
OUT
200Hz
500
Hz
GkHz
10kHz
5. Make measurement for both channels ,
6 Make sure that the measured value is Fig. 9
within the range specified in the frequency response chart (shown in fig. 9).
1 Test equipment connection is shown in fig. 3.
2. Playback standard recording level portion on test tape (QZZCFM 315Hz), and using VTVM measure
the output level at LINE OUT
3. Make measurement for both channels
Standard value: 455mV+1dB [around 280 mV: at test points TP3 (L-CH) and
TP4 (R-CH)]
Adjustment
RQ
tf measured value is not within standard, adjust VR3 (L-CH), VR4 (R-CH) (See fig. 1 on page 3).
After adjustment. check “Playback frequency response’ again
Test equipment connection 1s shown in fig. 10.
Press the record and pause buttons
1
2
3. Set the tape selector to metal position
4
Read voltage on VT VM and calculate erase current by
following formula
Erase current (A) =
Voltage across both ends of R124
1 (Q)
Standard value: 155+15mA (Metal position)
5. If measured value is not within standard, adjust as follows
Adjustment
1. Open the point (A) and short the point (B) on the main circuit board in the wiring connection diagram
(See page 15).
2. Make measurement for erase current
3. Make sure that the measured value is within the erase current of 140 mA to 170mA
4. If it is beyond the value, carry out the following adjustments
* If the erase current is less than 140 mA, short the point (A)
* {f the erase current is more than 170 mA, open the points (A) and (B)
© Overall frequency
response
Condition
* Record/playback mode
* Tape selector
-- Normal position
--CrOQ. position
--Metal position
* Input level controls --- MAX
Equipment
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (60002)
* Test tape
(reference blank tape)
---QZZCRA for Normal
“+ QZZCRX for CrOz
*-QZZCRZ for Metal
Note :
Before measuring and adjusting, make sure of
the playback frequency response (For the
method of measurement. please refer to the
playback frequency response}
Overall frequency response adjustment by recording bias current
Note 1:
On RS-M226. overall frequency response
1S adjusted with tape selector set at Normal
Note 2:
Recording equalizer is fixed
1. Make connections as shown in fig. 12.
- 24 dB signal through
LINE IN. Place the set in record
2. Input a 1 kHz.
mode
Erase head
Record mode
=! vM Oscilloscope
Fig. 10
Overall frequency response chart (Norma!)
50Hz 100Hz 200Hz
300 Hz
500Hz LkHz 2kHz 4kHz 8kKHZ10kHz
Record/playback !
head
TP] (L-CH)
TP2 (R-CH)
R1 (t-CH)
R2(R-CH)
Ground
3. Fine adjust the attenuator to obtain
0.4V LINE OUT output.
+ Make sure that the input signal level
is 24+4dB with 0.45V output voltage
Fig. 11
VRQ (L-CH)
VR10 (R-CH)
LINE
VIVM
——
For overall frequency
response measurement
oscilloscope
VTVM FVM oscscoe
arse ears bias current measurement.
Fig. 12