Technics RS-M14 User Manual

ITEM MEASUREMENT & ADJUSTMENT
® Playback frequency
response
Condition:
* Playback mode
* Tape selector
~ ++»Normal position
Equipment:
*VTVM — * Oscilloscope
* Test tape--- QZZCFM
@ Playback gain
Condition:
* Playback mode
* Tape selector
--- Normal position
Equipment:
*VTVM — * Oscilloscope
* Test tape--- QZZCFM
Tape speed fluctuation
Make measurements in same manner as above (beginning, middle and end of tape), and determine the
difference between maximum and minimum values and calculate as follows:
f= F2_ 5 100 (96)
————— f1=maximum value, f2 = minimum value
3,000
Tape speed fluctuation =
Standard value: Less than 1%
Note:
Please use non metal type screwdriver when you adjust tape speed accuracy on this unit.
Pe
Playback frequency response chart
12.5kHz
1. Test equipment connection is shown in
fig. 24.
2. Place UNIT into playback mode.
3. Playback the frequency response test
tape (QZZCFM).
. Measure output level at 315Hz, 12.5kHz,
8kHz, 4kHz, 1kHz, 250Hz, 125Hz and
63 Hz, and compare each output level
with the standard frequency 315 Hz, at
LINE OUT.
. Make measurement for both channels.
. Make sure that the measured value is
within the range specified in the frequency response chart.
63Hz 125Hz
200Hz 500Hz 1KHz
500Hz 1kHz
Fig. 28
63Hz125Hz 200 Hz
. Test equipment connection is shown in fig. 24.
. Playback standard recording level portion on test tape (QZZCFM 315Hz), and using VT VM measure
the output level at LINE OUT.
. Make measurement for both channels.
| Standard value: around 0.39V
Adjustment
1. If measured value is not within standard, adjust VR1 (L-CH), VR2 (R-CH) (See fig. 22 on page 5).
2. After adjustment, check “Playback frequency response” again.
@ Bias leakage
Condition:
* Record mode
* Input level controls --- MAX
* Tape selector
--» Metal position
Equipment:
*VTVM — * Oscilloscope
@ Erase current
Condition:
* Record mode
* Tape selector
--» Metal position
Equipment:
*VTVM — * Oscilloscope
1. Test equipment connection is shown in fig. 29. page
2. Place UNIT into record mode.
3. Adjust trap coil L1 (L-CH), L2 (R-CH) so that measured
value on VTVM becomes minimum.
4. Take adjustment for both channels.
TPS(L-CH)
Record /playback
head
Record mode
Fig. 29 Vtvm_ Oscilloscope
1. Test equipment connection is shown in fig. 30.
2. Press the record and pause buttons.
3. Set the tape selector to metal position.
4. Read voltage on VT VM and calculate erase current by
following formula:
Erase head
Voltage across both ends of R301
1(Q)
Era
rrent
(A)
=
VIVM
Oscillos
se
curre
t
(
)
VTVM
Oscilloscope
Fig. 30
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 10).

Technics RS-M14 Specifications

General

Brand	Technics
Model	RS-M14
Category	Cassette Player
Language	English