Section 3 Electrical Adjustment - Sony MDR-NC6 Service Manual

MDR-NC6
SECTION 3
ELECTRICAL ADJUSTMENT
NOISE CANCELING AMOUNT ADJUSTMENT
Preparation:
AF oscillator
sine wave 250 Hz
Procedure:
1. Generate a sine wave of specific frequency (250 Hz) from a
AF oscillator, and output it from a speaker placed at the forward
position,
2. Remove the housing cap sub assy and sheet.
3. Mount this set on the head, and turn on the POWER switch.
4. With this set mounted, rotate the SFR1 (Lch) and SFR2 (Rch)
so that the volume from the speaker becomes lowest aurally.
(See below figure)
Adjustment Location:
SFR1 (L-CH)
SFR2 (R-CH)
housing cap sub assy
–MAIN (L) Board–
SFR1
4
speaker
amplifier
+
–
sheet
–MAIN (R) Board–
SFR2
SECTION 4
DIAGRAMS
• Note for Printed Wiring Boards and Schematic Diagrams
Note on Schematic Diagram:
• All capacitors are in µF unless otherwise noted. (p: pF) 50 WV or
less are not indicated except for electrolytics and tantalums.
• All resistors are in Ω and
1
/ W or less unless otherwise specified.
4
• C : panel designation.
• A : B+ Line.
• H : adjustment for repair.
• Power voltage is dc 1.5 V and fed with regulated dc power supply
from battery terminal.
• Voltages and waveforms are dc with respect to ground under no-
signal conditions.
• Voltages are taken with a VOM (Input impedance 10 MΩ).
Voltage variations may be noted due to normal production toler-
ances.
• Waveforms are taken with a oscilloscope.
Voltage variations may be noted due to normal production toler-
ances.
• Circled numbers refer to waveforms.
• Signal path.
F
: Audio signal (power off)
J
: Audio signal (power on)
Note on Printed Wiring Boards:
• X : parts extracted from the component side.
• Y : parts extracted from the conductor side.
•
: Pattern from the side which enables seeing.
• Waveforms
– MAIN (R) Board –
Q15 (Base-1)
1
820 mVp-p
66 µ s
500 mV/DIV, 50 µ s/DIV
Q15 (Base-2)
2
1 Vp-p
66 µ s
500 mV/DIV, 50 µ s/DIV