Technics RS-M250 Service Manual

_ | RS-M250
NOTES: Keep good condition, set switches and controls in the following positions, unless otherwise specified.
@ Make sure heads are clean. @ Timer start switch: OFF
@ Make sure capstan and pressure roller are clean. @ Memory switch: OFF
@ Judgeable room temperature: 20+5°C (68+9°F) @ Multiplex filter switch: OUT
@ Dolby NR switch: OUT @ Input level controls: Maximum
@ Tape selector: Normal © Output level control: Maximum
®@ input selector: Line in
ITEM MEASUREMENT & ADJUSTMENT
@® Head azimuth Record/playback head adjustment
adjustment 1. Test equipment connection is shown in fig. 2.
Condition: 2. Playback azimuth tape (QZZCFM 8kHz).
* Playback mode 3. Adjust record/playback head angle adjustment screw (B) in test tape Playback mode VTVM Oscilloscope:
Equipment: fig. 3 so that output level at LINE OUT becomes maximum. Fig. 2
* VTVM 4. Measure both channels, and adjust levels for equal output.
5. After adjustment lock head adjustment screw with lacquer.
* Oscilloscope
* Test tape (azimuth) Erase head adjustment Record/playback head Erase head
+ QZZCFM
* Tape path viewer Q 1. Test equipment connection is the same above but use the tape db
++ QZZCRD path viewer (QZZCRD) instead of test tape (QZZCFM). ©
2. Playback this tape. ©)
3. Adjust screw (C) shown in fig. 4 so that the tape may not Fig. 3 Fig. 4
get curled or malformed by tape guide of the erase head.
. After adjustment, lock head adjust screw with lacquer.
© Tape speed Tape speed accuracy pene ney LINE OUT
Condition: 1. Test equipment connection is shown in fig. 5. eo oT 0°
*
Playback
mode
2.
Playback
test
tape
(QZZCWAT
3,000Hz),
and
supply
a
2.
* Tape selector playbeck signal to frequency counter. Tees SEES, «Rete er ae
--»Normal position | 3. Measure this frequency. Fig. 5
Equipment: 4. On the basis of 3,000 Hz, series: Ng by following formula:
* Digital electronic counter Tape speed accuracy = ——— x 100 (%
+ Test tape --- QZZCWAT iid "3,000 (%)
where, f = measured value
5.. Take measurement at middle section of tape.
Standard value: +1.5%
Adjustment method
1. Playback the test tape (middle).
2. Adjust so that frequency becomes 3,000 Hz.
3. Tape speed adjustment VR shown in fig. 1.
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:
fi—fe 6
3000 X 100 (%)
f: =maximum value, f2 = minimum value
Tape speed fluctuation =
Standard value: Less than 1.0%
@ Playback frequency . Test equipment connection is shown
response in fig. 2. Playback frequency response chart
Condition: 2. Place UNIT into playback mode. satis eae
* Tape selector 3. Playback the frequency response test ;
--+ Normal position tape (QZZCFM).
* Playback mode 4. Measure output level at 12.5kHz, 8kHz,
4kHz, 1 kHz, 250Hz, 125Hz and 63Hz,
and compare each output level with the
standard frequency 315 Hz, at LINE OUT.
. Make measurement for both channels.
6. Make sure that the measured value is
within the range specified in the frequency
response chart. (shown in fig. 6).
Equipment:
+ VTVM
* Oscilloscope 5
* Test tape --- QZZCFM

Technics RS-M250 Specifications

General

Brand	Technics
Model	RS-M250
Category	Cassette Player
Language	English