Detection Of Tone Arm Position; Miscellaneous Remarks - Akai AP-M7 Service Manual

5-8. DETECTION OF TONE ARM POSITION (Refer to Fig. 5-8)
SHUTTER
1) REST (Stand-by) position is detected by the Rest
Position SW (SW1) on Rest Position SW P.C BOARD,
and its output is supplied to MI-COM ICS pin .
Accordingly, the level "H" at ICS pin @ means that
the Tone Arm is in the REST position, and "L"
means that it is out of the REST position.
2) LEAD-IN/OUT positions are detected by the Arm
Position Sensors (Photo-transistor PH-1 & PH-2) on
Arm Position Sensor (PTR) P.C BOARD, and their
outputs are supplied to MI-COM ICS pin @ & @
respectively.
The LEAD-IN position is detected when the Shutter
part ® (for 30cm records) or part ® (for 17cm
records) passes through the space between LED (D1)
and Photo-transistors (PH1/PH2).
The LEAD-OUT position is detected when the
Shutter part © (for 30 cm records) or part © (for
17 cm) passes through the same place.
5-9, MISCELLANEOUS REMARKS
(Fail Safe Functions, etc.)
1) The Auto Lift-up System will lift up the Tone Arm to
prevent the damage to the stylus when the power is
cut off during playback.
2) The Tone Arm will not be moved by the FWD/REV
buttons or lowered when the Tone Arm is out of the
playable area (between Lead-in and Lead-out position
for 30cm or 17cm records according to the size
indicator).
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SERVICE MANUAL AP-M7/S:
ARM POSITION.
SENSOR (LED) PCB
ARM POSITION
SENSOR (PTR) PCB
REST POSITION SW
(sw)
Fig. 5-8 Arm Position Sensors
the playable area, the Tone Arm will not descend but
will return to the rest position even if the START
button is depressed.
4) If no record is in AUTO mode, AUTO mode will be
cancelled and the Tone Arm will not be activated
even if the S/C button is depressed.
5) Fundamentally, the Auto Lead-in/Lead-out opera-
tions are not executed in the MANUAL mode.
However, the Auto Lead-out operation will the
executed for the one case when the Tone Arm
reaches the 17 cm Lead-out position.
6) The unit will not AUTO-START if the platter does
not start turning for some reason.
7) To avoid the unwanted impulse noise when muting,
the capacitor C10 (22uF/10) is connected to the base
of TR7 through R126 (4.7K), so that TR7 turns ON
& OFF gradually to reduce the ON/OFF impulse
noise caused by the Lead Relay (RL-1).
8) When playing transparent, colored (red, blue, white,
etc.) or irregular sized (not 30 cm nor 17 cm) records,
the Size Sensors cannot detect the correct amount
of light and MI-COM may malfunction. For such
cases, manual playback of the record must be
adopted.
9) Refer to the AP-MS Service Manual for the descrip-
tions of the Power Supply Circuit, Power Supply
Timing, Record Size Detection and Speed Determina-
tion, and to the AP-D30/C Service Manual for the
description of the FG Servo Motor since these have a
"Close similarity to those in the AP-M7/S.— ~~ ~~~