Band Sensor Gain Adjustment; Address Sensor Adjustment; Oscilloscope Waveform; Waveform Adjustment - Pioneer PL-88F Service Manual

Nofes.'
* VRz ard VR7 are the band sensor gain djustment
controls. Always djust the band, eensor gain after
completing the band sensor off*t adjustment.
* Reold,er the Pl and P2 lead wires back into position
after completing the band. sensor offet adjustment.
9.5 BAND SENSOR GAIN ADJUSTMENT
1. Remove the bonnet, press the OPEN/CLOSE
key, and pull the slide base out forwards.
2.Place the GGF-021 test record on the
table platter, press the manual key, and
the tonearm into position.
3. Shade the record surface from strong illumination
sources by using the record jacket or other
suitable shade.
4. Position the tonearm for "locate out" operation
(shift of the tonearm outwards) between the
eighth and tenth tracks ofthe testrecord. Perform
this step by using the STOP and START keys.
5. Connect an oscilloscope to observe the voltage
differences between P2(+) and PB (TP terminals)
of CN8.
6. The waveforms shown in Fig. 9.5 should be
obtained in the inter-track sections between
tracks 8 and 9, and 10.
7. Adjust VR 2 and VRB (see Fig.9.4) to obatin a
waveform peak-to-peak voltage of.2.6 t 0.2Vp-p,
and an average value in the sound track portion
of t0.1V.
9.6ADDRESS SENSOR ADJUSTMENT
Referring to the time charts described in the
service manual (ARP-143), adjust as follows.
1. Remove the bonnet, press the OPEN/CLOSE
key, and pull the slide base out forwards.
2. Place a record on the tumtable platter, and press
the START key for lead-in of the tonearm.
3. Use an oscilloscope to observe the waveforms of
the voltage changes between P12(+) and GND
(address A sensor), and between P13 (+) and
GND (address B sensor) of IC1.
4. Adjttst VR201 to obtain the waveform shown in
Fig. 9.8, for address A sensor, and adjust V&2O2
to obtain the same kind of waveform for address
B sensor.
Note:
To ad.juat VR2OL and VR202,
first switch the PL-88F
power off, disconnect CN3, short Pl ard P2, pull the
slid.e base out by hand (to the position where the VR can
be turned, through the adjustment hole), and then switch
the power bach on.
Wheneuer the tonearm is to be moued, always use the
operation keys. Do not tnoue it by hand.
5. After the adjwtment is completed, connect P12
and P13 of IC1 to a dualdisplay oscilloscope,
and proceed with lead-in of the tonearm from
the spindle to the outer edge (start operation
or manual tonearm setting).
Fig. 9.5 Oscilloscope Waveform Display
Tonearm
locate out
2 . 6 t 0 . 2 V
o v
f @ , ^ ,
;i+*
f@,*
turn-
bring
Adjustment
hole
Switch the power off and pull the slide base out.
Fig. 9.7 Address Sensor Adjustment
t c 1 P 1 2
l c l P l 3
Fig. 9.8 Oscilloscope Waveform
Final waveform
v R 2 0 |
/
vRzoz
N r/
\s,t",
rum
Fig. 9.6 Band Sensor Gain Adjustment
a , b , c , d = I 2 m s e c
Fig. 9.9 Waveform Adjustment
2 5