Pioneer DVH-335UB/XNRC, Service Manual

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DVH-335UB/XNRC
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8. EACH SETTING AND ADJUSTMENT
8.1 DVD ADJUSTMENT
1) Precautions
This product uses 5 V and 3.3 V as standard voltages.
The electrical potential that is the reference for signals,
is not GND, but VREF (approximately 2.2 V) and VHALF
(approximately 1.65 V) .
During product adjustments, if the reference voltage is
mistakenly taken as GND, and a grounding contact is
made, not only would it be impossible to measure the
accurate electrical potential, but also the servo motor
would malfunction, resulting in the application of a
strong impact on the pick up. The following precautionary
measures should be strictly adhered to, in order to
avoid such problems.
The reference voltage and GND should not be confused
when using the minus probe of a measurement device.
When an oscilloscope is being used special care should
be taken to make sure that the reference voltage is not
connected to the probe of ch1 (on the minus side),
while the probe of ch2 (on the minus side), is connected
to GND. Further, since the body frame of most measurement
devices have the same electrical potential as
the minus side of the probe, the body frame of the
measurement device should be set to floating ground.
If the reference voltage is connected to GND by
mistake, turn the regulator OFF immediately, or
turn the power OFF.
Remove the filters and wires used for measurements
only after the regulator has been turned OFF.
After the power supply is turned on, regulator ON the
following adjustment and measurement are promptly
done.
Whenever the product is in the test mode, the software
will not take any protective action. For this reason,
special care should be taken to make sure that no
mechanical or electrical shock could be applied to the
product when taking measurements in the test mode.
Whenever the EJECT key is pressed to eject the disk,
no other keys, other than the EJECT key, should be
pressed until the disk eject action has been completed.
Press the EJECT key only after the disk has stopped
completely.
If the product hangs up turn the power OFF immediately.
Laser didoes may be damaged, if the volume switch for
the laser power adjustment of the pick up unit, is turned.