Technics RS-M14 User Manual

Ee he ae
ITEM MEASUREMENT & ADJUSTMENT
2. Make measurement for erase current.
3. Make sure that the measured value is within the erase current of 140mA to 170 mA.
4. lf it is beyond the value, carry out the following adjustments:
@® Bias current
Condition:
* Record mode
* Tape selector
-- Normal position
--Fe-Cr position
--CrOz position
-- Metal position
Equipment:
*VTVM * Oscilloscope
@ Overall gain
Condition:
* Record/playback mode
* Input level controls --- MAX
* Standard input level;
MIC +++++++- —72+4dB
LINE IN--- —-2444dB
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
--CrO2 position
-- Metal position
* Input level controls --- MAX
Equipment:
*VTVM * AF oscillator
* ATT * Oscilloscope
* Resistor (600 2)
* Test tape
(reference blank tape)
--QZZCRA for Normal
--QZZCRY for Fe-Cr
--QZZCRX for CrOz
--QZZCRZ for Metal
. Test equipment connection is shown in fig. 31.
. Place UNIT into record mode, and tape selector to normal
. Read voltage on VT VM and calculate bias current by
4
3;
6
Note:
Before measuring and adjusting, make sure of
the playback frequency response (For the
. Place UNIT into record mode, and tape selector to normal
p
° If the erase current is less than 140 mA, short the point (A).
° If the erase current is more than 170mA, open the points (A) and (B).
VR7 (L-CH)
VR8 (R-CH)
oa Record/playback
head
position.
Record mode
TP1(L-CH) ;
TP2IR-CH)
R1 (L-CH)
R2 (R-CH)
following formula:
Value read on VTVM (V) VTVM_ Oscilloscope
10 (Q)
Bias current (A) =
Fig. 31
Standard value: around 410A (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 value: around 440A (Fe-Cr position), around 545A (CrO2 position),
around 800A (Metal position)
est equipment connection is shown in fig. 32. Kasnitiaiies
head i
osition.
. Supply 1kHz signal (—24dB) from AF oscillator, through
ATT to LINE IN.
djust ATT until monitor level at LINE OUT becomes Record/playback
39V.
head
Record mode
Test tape
AF oscillator
A
0.
. Using test tape, make recording.
. Playback recorded tape, and make sure - value at LINE
—7 dB).
. If measured value is not 0.39 V, adjust VR5 (L-CH), VR6
(R-CH) (See fig. 22 on page 5).
. Repeat from step (2).
Playback mode yTVM Oscilloscope
Fig. 32
OUT
on
VTVM
becomes
0.39
V
(
Test
tape
Overall frequency response chart (Normal)
10kHz
seit 100s 640 Hz 2kHz 4kHz
method of measurement, please refer to the
playback frequency response).
1.
2.
3.
. Supply 1kHz signal from AF oscillator
. Record each frequency 1 kHz, 50Hz,
Test equipment connection is shown in
fig. 32.
Place the normal test tape (QZZCRA) in
the cassette holder.
Place UNIT into record mode, and tape
selector to normal position.
: 100Hz Fig, Hz 2kHz
33
50Hz
Overall ee response chart
(Fe-Cr, CrO2, Metal)
2kHz
12kHz
through
ATT
to
LINE
IN.
200
Hz
640
Hz
. Adjust ATT so that input level is —20dB
below standard recording level (standard
recording level=0 VU).
. At this time, LINE OUT level indicates
0.039V.
200 Hz. 640 Hz
200Hz, 4kHz, 8kHz and 10kHz (12kHz
Fig. 34
for
Fe-Cr,
CrOz
and
metal).
mee
50Hz
. Playback and express in dB the difference between ‘plavbaek output level of each frequency based on
playback output level of 1 kHz.

Technics RS-M14 Specifications

General

Brand	Technics
Model	RS-M14
Category	Cassette Player
Language	English