Technics RS-646DS-D User Manual

Overall gain
Equipment:
* AF oscillator
* VTVM
+ ATT
* Oscilloscope
* Test tape
(reference blank tape)
+--+ C-RF for CrO2
«+» C-RA for Normal
MEASUREMENT & ADJUSTMENT
1. Test equipment connection is shown in fig. 19.
VTVM
Fig. 19
2. Place UNIT into record mode, and bias selector to “LOW”, and
selector to “1204S”
3. Supply 1kHz (—24dB) from AF oscillator, through ATT, to signal
LINE IN.
Adjust ATT until monitor level at LINE OUT becomes 0.42 V (—7 dB).
Using test tape (C-RA), make recording.
Playback recorded tape, and make sure the value at LINE OUT on
VTVM becomes 0.42 V.
7. |f measured value is not 0.42 V, adjust VR7 (L-CH), VR8 (R-CH) (See
fig. 28 on page 17).
Repeat from step (2).
For CrO2 bias selector to “HIGH”, and EQ. selector to "70uS” change
test tape to (C-RF), and take the same steps for normal but to adjust,
use VRQ (L-CH) and VR10 (R-CH). (See fig. 28 on page 17).
How to check recording current
Playback mode
Test tape Oscilloscope
EQ.
Hoar
Role)
LINE IN
6000 .
Record mode
R7(L-CH)
AF Oscillator ATT
Oscilloscope VIVM
R/P Head
Fig. 20
1. Test equipment connection is shown in fig. 20.
2. Stop bias oscillation by unsoldering point L302 shown in AMP circuit
board on page 20.
3. Supply 1 kHz signal (— 24 dB) again and adjust ATT until monitor level
at LINE OUT becomes 0.42 V.
4. Measure voltage and then calculate recording current by formura given
below.
Value read on VTVM (V)
Recordi urrent =~ - : ~
ve 10 (Q)
| Standard value: 40+5uA |
5. At this time, set the bias selector to “HIGH”, and EQ. selector to
"70S" and confirm variation of recording current.
| Standard value: 60£5uA |
REMARKS
* Record/playback mode
* LINE IN level control
we MAX
* Standard input level:
—72+4dB
LINE IN --» ~24+4dB

Technics RS-646DS-D Specifications

General

Brand	Technics
Model	RS-646DS-D
Category	Cassette Player
Language	English