Pioneer YPM-2106ZF Service Manual - Page 41

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5) Focus and Tracking Automatic Gain Control

This function is used for implementing automatic con-

trol of the focus and tracking loop gain.

The following is the adjustment procedure :

(1) Inject disturbance to the servo loop.

(2) Extract the error signal (FE and TE) generated at

when the disturbance is applied to obtain the sig-

nals G1 and G2 via the B.P.F.

(3) The microcomputer reads the G1 and G2 signals via

the LSI.

(4) Based on the necessary correction calculated by the

microcomputer, the LSI performs the loop gain

adjustment.

Above adjustments are repeated several times to

ensure higher adjustment accuracy.

6) Automatic RF Level Adjustment (RFAGC)

This adjustment is used for implementing intended sig-

nal transmission successfully by adjusting unevenness

of the RF signal (RFO) levels, that results from disc and

machine relevant factors, to a target value. The adjust-

ment is actually done by varying gain of the amplifier

provided between the RFI and RFO.

The following is the adjustment procedure :

(1) Using the command, the microcomputer reads the

output from the RF level detection circuit on the

servo LSI.

(2) Based on the read value, the microcomputer calcu-

lates an amplifier gain that will produce the target

RFO level.

(3) The microcomputer sends the corresponding com-

mand to the servo LSI so that the above gain value

may be set.

Gain of entire RFAMP

+ 12dB

+ 6dB

TYP

Play at +6dB increases due to stained lens or other reasons

(the typical gain is employed for the initial setup)

Fig.19 : CONCEPTUAL DIAGRAM OF PRE-AMP GAIN ADJUSTMENT

This adjustment takes place at the following timing :

• When the focus close alone is completed during the

setup process.

• Just before the setup is completed (just before the

play takes place).

• After the off-focus has been corrected during the play.

7) Adjustment of Pre-Amp Stage Gain

It is used for adjusting the entire RFAMP (FE, TE and RF

amplifiers) to +6dB or +12dB depending on given gain

level when reflected light from the disc is significantly

below the required level due to stained lens. This phe-

nomena can be noticed when playing back the CD-RW.

The following is the adjustment procedure :

When reflected light from disc is judged to be signifi-

cantly below the required level during the setup, set the

entire RFAMP to +6dB or +12dB. In this case, if the gain

is modified, the setup have to be repeated from the first

step.

Through the adjustment, if you judged the play

becomes available by setting the entire RFAMP to +6dB,

+6dB should be selected for the setup next time on.

See the figure below :

Play the CD-RW with the gain being set to +12dB

y y y y y y y

Play is started with +6dB

judging the lens is stained

YPM-2306ZF

Time