Pioneer DEH-42 Service Manual - Page 10
Browse online or download pdf Service Manual for CD Player Pioneer DEH-42. Pioneer DEH-42 50 pages. High power cd player with fm/am tuner
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6. TEST MODE
6.1 TEST MODE
1)Precautions
- This unit uses a single power supply (+5V) for the reg-
ulator. The signal reference potential, therefore, is
connected to REFO(approx. 2.5V) instead of GND.
lf REFO and GND are connected to each other by mis-
take during adjustments, not only will it be impossi-
ble 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 fol-
lowing.
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 usual-
ly at the same potential as the negative probe, change
the frame of the measuring instrument to floating sta-
tus.
lf by accident REFO comes in contact with GND,
immediately switch the regulator or power OFF.
- Always make sure the regulator is OFF when connect-
ing and disconnecting the various filters and wiring
required for measurements.
: Before proceeding to further adjustments and mea-
surements after switching regulator ON, let the player
run for about one minute to allow the circuits to stabi-
lize.
- 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 sys-
tem when making adjustment.
- Test mode starting procedure
Switch ACC, back-up ON while pressing the 4 and 6
keys together.
10
- Test mode cancellation
Switch ACC, back-up OFF.
+ 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 mal-
functions 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-posi-
tion the light source, move the unit or cover the
photo transistor.
+ When loading and unloading discs during adjustment
procedures, always wait for the disc to be properly
clamped or ejected before pressing another key.
Otherwise, there is a risk of the actuator being
destroyed.
+ Turn power off when pressing the button TR+ or the
button TR- key for focus search in the test mode. (Or
else lens may stick and the actuator may be dam-
aged.)
+ SINGLE/4TRK/10TRK/32TRK
will continue to operate
even after the key is released.Tracking is closed the
moment C-MOVE is released.
- JUMP
MODE resets to SINGLE as soon as power is
switched off.