JVC PC-70L User Manual

PC-70 L/LB/LD/LS
Main Adjustments
[1]
1. Electrical adjustment
1) Electronic voltmeter
2) Audio frequency oscillator
(range:
50—
20 kHz and output OdB with im-
pedance 600 Q)
3) Attenuator
4) Standard tapes for REC/PB
Maxell UD —
TDK SA — Chrome tape (TS-6)
JVC ME — Metal tape (TS-7)
5) Reference tapes for playback (JVC Test Tape)
VTT702 (for head azimuth adj.)
Normal tape (TS-5)
\ or equivalent
VTT712 (for motor speed, wow flutter adj.)
(H]
1. Adjustment
Mechanical Adjustment
Procedure of Cassette Mechanism
Equipment and Measuring Instruments used for Adjustment
VTT664 (for reference level 1 kHz)
VTT739 (for playback frequency response)
VTT6447 (for music scanning)
VTT6448 (for music scanning)
6) Resistors
600 © (for attenuator matching)
2. Mechanical adjustment
1) Torque testing cassette gauge.
3. Tuner section adjustment
SSG (standard signal generator).
Sweep signal generator.
(Adjust the mechanism or confirm that it is in normal operating condition prior to the adjustment of the electrical circuit.)
Item Adjustment Adjusting | Standard Remarks
point value
Adjusting Connect a speed meter (an electronic | Semi-fixed |3000 Hz If the speed meter functions as a
motor speed counter) to the Speaker out terminals. | resistor in wow and flutter meter, also, connect
Play back the VTT712 test tape. the DC {the deck to the INPUT terminals of
Adjust the semi-fixed resistor in the the meter.
motor until the reading of the speed
meter is 3000 Hz.
Checking wow | Connect a wow and flutter meter to 0.08% If the reading becomes moving value
and flutter Seaker out terminals. (WRMS) even if conforming to the standard, a
Play back the VTT712 test tape. 0.18% reclaim may be raised. Repairs are
Check to see if the reading of the (DIN necessary.
meter is within 0.08% (WRMS). 45500)
Checking play- | Employ a torque testing cassette tape 40—70 If the standard torque is not obtained,
back torque CTG-N for the checking, or remove gr-cm replace the take-up disc assembly.
the cassette cover and use a torque
gauge.
Checking fast | Measure the torque in the fast forward More than If the standard torque is not obtain-
forward torque | mode in the same manner as in the 80 gr-cm___|ed, perform the following.
above. 1. Clean the capstan belt, the idler
circumference, the motor pulley,
the take-up reel disc circumfer-
ence, the flywheel circumference,
etc.
2. Replace the belt and idler.
Checking Measure the torque in the rewind More than |If the standard torque is not obtain-
rewind torque mode in the same manner as in the 80 gr-cm__|ed, clean the capstan belt, idler,
above. motor pulley, flywheel circumfer-
ence, rewinding idler circumference,
left reel disc circumference, etc.
Adjusting 1) Use TMT702 or equivalent and set | Head Maximum |
record/ the output to maximum. mount
playback head 2) Adjust(A)or(B)to obtain the max- | azimuth
position imum value in both forward and | screws
@ ® reverse modes. Confirm the adjust- | and
Ahestad ment by recording and reproducing
Forwano/ “| reverse a 14 kHz signal and checking the
Forward Reverse normal level.
12 (No. 1543)

JVC PC-70L Specifications

General

Brand	JVC
Model	PC-70L
Category	Stereo System
Language	English