Pioneer FX-M8717ZT, Service Manual

Page: 58 / 94

58
FX-M8717ZT
1) Precautions
• This unit uses a single power supply (+5V) for the
regulator. The signal reference potential, therefore, is
connected to REFO(approx. 2.5V) instead of GND.
If REFO and GND are connected to each other by
mistake during adjustments, not only will it be
impossible to measure the potential correctly, but the
servo will malfunction and a severe shock will be
applied to the pick-up. To avoid this, take special note
of the following.
Do not connect the negative probe of the measuring
equipment to REFO and GND together. It is especially
important not to connect the channel 1 negative
probe of the oscilloscope to REFO with the channel 2
negative probe connected to GND.
Since the frame of the measuring instrument is
usually at the same potential as the negative probe,
change the frame of the measuring instrument to
floating status.
If by accident REFO comes in contact with GND,
immediately switch the regulator or power OFF.
• Always make sure the regulator is OFF when
connecting and disconnecting the various filters and
wiring required for measurements.
• Before proceeding to further adjustments and
measurements after switching regulator ON, let the
player run for about one minute to allow the circuits
to stabilize.
• Since the protective systems in the unit's software are
rendered inoperative in test mode, be very careful to
avoid mechanical and /or electrical shocks to the
system when making adjustment.
• Disc detection during loading and eject operations is
performed by means of a photo transistor in this
unit.Consequently, if the inside of the unit is exposed
to a strong light source when the outer casing is
removed for repairs or adjustment, the following
malfunctions may occur.
*During PLAY, even if the eject button is
pressed,the disc will not be ejected and the unit
will remain in the PLAY mode.
*The unit will not load a disc.
When the unit malfunctions this way, either re-
position the light source, move the unit or cover the
photo transistor.
2) Test Mode
This mode is used for adjusting the CD mechanism
module of the device.
• Test mode starting procedure
See page 59.
• Test mode cancellation
Switch ACC OFF.
• After pressing the EJECT key, do not press any other
key until the disk is completely ejected.
• If the TRACK UP or TRACK DOWN key is pressed
while focus search is in progress, immediately turn
the power off (otherwise the actuator may be
damaged due to adhesion of the lenses).
• Jump operation of TRs other than 100TR continues
after releasing the key. CRG move and 100TR jump
operations are brought into the “Tracking close”
status when the key is released.
• Powering Off/On resets the jump mode to “Single TR
(91)”, the RF AMP gain setting to 0 dB, and the
automatic adjustment value to the initial value.
6.3 CD SECTION