Pioneer FX-MG8517ZT/UC Service Manual Download Page 81

Page: 81 / 112

FX-MG8517ZT,MG8817ZT

7. GENERAL INFORMATION

7.1 DIAGNOSIS

7.1.1 TEST MODE

CD Test Mode

1) Precautions on Adjustment
• The unit employs a single voltage (+5V) for the

regulator, thus the reference potential of the signal is
RFOUT (approximately 2.5V) rather than GND.
Inadvertent contact of REFOUT and GND during
adjustment can result not only in disabling normal
potential measurement but also in exposing the
pickup to strong impacts due to malfunctioning of the
servo. Therefore, you are requested to observe the
following precautions.

• Make sure that the negative probe of the measuring

instrument is not connected to RFOUT or GND.
Special care must be exercised so that the channel 1
negative probe may not be connected to the
oscilloscope and the channel 2 negative probe to
GND. Since the frame of the measuring instrument is
usually at the same potential as the negative probe,
the frame of the measuring instrument must be
changed to floating status.
When RFOUT is inadvertently connected to GND, you
must immediately turn off the regulator or power
supply.

• The regulator must be turned off before mounting or

dismounting filters or wiring materials.

• You should not start adjustment or measurement

immediately after the regulator is turned on. It is
recommended to run the player for approximately
one minute so that it may stabilize.

• When the test mode is turned on, various protective

functions from the software become unavailable.
Thus, you must make sure that undesirable electric or
mechanical shocks are not be given to the system.

• This model employs a photo-transistor for detecting

discs at their loading or ejection. Thus, if its outer
case is removed during repair work and internal parts
are exposed to light of strong intensity, malfunctions
including the following can result:

∗

The eject button becomes inoperable during play.
Pressing the eject button does not eject a disc and
play is continued.

∗

Loading becomes unavailable.

If a malfunction is recognized, appropriate remedial
actions must be taken. Such actions include
changing the light source position, changing the unit
position and applying a cover to the photo-transistor.

• When you press the EJECT key to eject a disc, you

must not touch any other key until the ejection is
complete.

• If you press the SEEK UP or SEEK DOWN for the

focus search in the test mode, you must turn the
power off immediately. (Otherwise, the lens will be
forced to stick to the top or bottom, potentially
resulting in the burning of the actuator.)

2) Description of the Test Mode
• Turning on the Test Mode

See page 83.

• Ending the Test Mode

Apply the reset (the reset will be applied two minutes
after the power is turned from off).

• Operation of TR JUMPs (except 100TR) continues

after your finger has left the key. CRG, MOVE and
100TR JUMP are forced to the tracking close mode as
soon as the key is released.

• Turning the power on or off resets the JUMP MODE

to the Single TR.