Technics RS-CH7 - Page 8

| RS-CH7
RS-CH7
Mm MEASUREMENTS AND ADJUSTMENTS
This tape deck (RS-CH7) is powered by the amplifier (SU-CH7).
To adjust or check operations on the tape deck as a separate unit, follow the steps below.
1. Apply a power supply voltage of AC 20 V to Eh and Eee] .
2. Short-circuit and (GND) (power supply switch: ON).
¢ HOW TO CONNECT
Note:
Apply a power supply voltage of AC 20 V
to and by using a Voltage
Controlier. If itis not available, use a
Power Supply Fixture (SZZA1058C)
instead.
Voltage controller
e Adjustment points
LINE OUT LINE OUT
(Rch) (Lch)
To AMP
(GND)
vr3ot (ey
LINE IN
(ch)
vee
vrs Gy
vr3 vrs
TP6O1
®Measurement Condition
Rec. levelcontrol; Maximum
© Reverse-mode selector switch;
®Edit-recording tape-speed selector; NORMAL
®Timer-recording switch; off
Measuring instrument
®@EVM (Electronic Voltmeter)
® Oscilloscope
© Digital! frequency counter
® AF osciliator
Test tape
®Head azimuth adjustment (8 kHz, —-20 dB); QZZCFM
®Tape speed adjustment (3 KHz, —10 dB); QZZCWAT
® Playback frequency response (315 Hz, 12.5 kHz, 10 kHz, 8 kHz,
4 kHz, 1 kHz, 250 Hz, 125 Hz, 63 Hz, -20 dB); QZZCFM
Power Supply Fixture
(SZZA1058C)
power
O®
OOO
supply
OMOCOO
switch
Dolby NR switch; Off
Make sure heads are clean
Make sure capstan and pressure roller are clean
@Judgeable room temperature 20+5°C (68+9°F)
@ATT (Attenuator)
@DC voltmeter
© Resistor (600Q)
Playback gain adjustment (315 Hz, 0 dB); QZZCFM
Overall frequency response, Overall gain adjustment Normal
reference blank tape; QZZCRA
CrOz reference blank tape; QZZCRX
Metal reference blank tape; QZZCRZ
HEAD AZIMUTH ADJUSTMENT (DECK 1/2)
1. Playback the azimuth adjustment portion (8kHz, —20dB)
of the test tape (QZZCFM). Vary the azimuth adjusting
screw until the outputs of the L-CH and R-CH are
maximized and the tissajous waveform, as illustrated,
approaches 0 degrees.
Note: If L-CH and R-CH are not maximized at the same point,
adjust to the point where the levels of each channe!
are maximized and equal.
2. Perform the same adjustment in the play mode.
3. After the adjustment, apply screwlock to the azimuth
adjusting screw.
TAPE SPEED ADJUSTMENT (DECK 1/2)
Norma! speed
1. Shift the edit-recording tape-speed selector to NORMAL”.
2. Playback the middie portion of the test tape (QZZCWAT).
3. Adjust Deck 1=VR721 and Deck 2=VR723 so that the output
is within the standard value.
Standard value: 3000+15Hz (NORMAL speed)
High speed [Set the unit to forward (FWD) mode.]
4. Push the edit speed button (SPEED). This will set the high speed
mode.
5. Playback the middle portion on the test tape (QZ2CWAT).
6. At that time, check if the output from DECK 1 is within the
standard value.
Standard value: 6000+600 Hz (HIGH speed)
7. Adjust VR722 so that the output frequency of DECK 2s within
+30 Hz of the value of the output frequency of DECK 1.
PLAYBACK GAIN ADJUSTMENT (DECK 1/2)
1. Playback the gain adjusted portion (315Hz, OdB) of the
test tape (QZZCFM).
2. Adjust Deck 2=VR85 (L-CH) [[VR6 (R-CH)]} and Deck 1=VR3
(L-CH) [[VR4 (R-CH)]] so that the output is within the standard
value.
Standard value: 400 mV+0.5 dB
PLAYBACK FREQUENCY RESPONSE (DECK 1/2)
1. Playback the frequency response portion (315Hz,
12.5kHz~63Hz, —20dB) of the test tape (QZZCFM).
2. Assure that the frequency response is within the range
shown in Fig. 6 for both L-CH and R-CH.
(Leh)
_REA (Lh)
Oscitoscope
RIP, HEAD (DECK 2)
P. HEAD (DECK 1)
E. HEAD (DECK 2)
Azimuth Screw (Forward) Azimuth Screw (Reverse)
Fig. 2
0 GSS ae)
Orgital trequency
counter
Fig. 3
(Lh)
Fig. 6