Pioneer CDX-P656 Service Manual - Page 42

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CDX-P650

7.2.2 TEST MODE

- CD 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.

If 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.

If 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.

• Disc detection during tray extraction and return oper-

ations is performed by means of the photo transistor

in this unit. Consequently, if the inside of the unit is

exposed to a strong light source with the outer casing

removed for repairs or adjustment, the following mal-

functions may occur:

*Even with a disc loaded, the unit detects "no disc"

and cannot start play.

*Although a 12-cm disc is loaded, the unit detects

"8cm disc" mistakenly.

When the unit malfunctions this way, either re-posi-

tion the light source, move the unit or cover the photo

transistor.

• During exchanging discs, do not press the keys for

the discs to be exchanged.

2) Test Mode

This mode is used for adjusting the CD mechanism

module of the device.

• Test mode starting procedure

Reset while pressing the 4 and 6 keys together.

• Test mode cancellation

Switch ACC, back-up OFF.

• If the 8 or 9 key is pressed while focus search is in

progress, immediately turn the power off (otherwise

the actuator may be damaged due to the lens stuck).

• Jump operation of TRs other than 100TR continues

after releasing the key. CRG move and 100TR jump

operations are brought into the "Tracking close" sta-

tus 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 auto-

matic adjustment value to the initial value.

• During exchanging discs, do not press the keys for

the discs to be exchanged.

Key to adjustment text

inside (12 keys type)

BAND

TRK+/FF

TRK-/REV

DISC-

SOURCE ON/OFF

HEAD UNIT (6 keys type)

BAND

TRK+/FF

TRK-/REV

DISC-

SOURCE ON/OFF