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1.3 AUTOMATIC ADJUSTMENT FUNCTION
In this system, all the circuit adjustments are automated inside the CD of the LSI.
All adjustments are performed whenever a disc is inserted or the CD mode is selected by pressing the source key.
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Details of each adjustment will be explained below.
1.3.1 TE, FE, and RF offset auto-adjustment
In this adjustment the TE, FE, and RF amplifier offsets of the preamplifier block in POWER ON are adjusted to the
respective target values with the REFO as reference. (The target values for TE, FE, and RF offsets are 0 V, 0 V, and - 0.8
V, respectively.)
Adjusting procedure
1) The CPU of the LSI reads respective offsets through the CD of the LSI, when they are in LDOFF status.
2) The CPU of the LSI calculates the voltages for correction from the values read in 1), and substitutes the corrected
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values to prescribed places to adjust.
1.3.2 Tracking balance (T.BAL) auto-adjustment
This adjustment equalizes the output difference of the E-ch and F-ch from the pickup by changing the amplifier gain inside
the CD of the LSI. In actual operation, adjustment is performed so that the TE waveform becomes symmetrical on each
side of the REFO.
Adjusting procedure
1) After closing the focus loop,
2) Kick the lens in the radial direction to ensure the generation of the TE waveform.
3) The CPU of the LSI reads the offset amount of the TE signal calculated in the LSI at the time through the CD of the LSI.
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4) The CPU of the LSI determines the offset amount is 0, positive, or negative.
- When the offset amount is 0, the adjustment is completed.
- When the offset amount is positive or negative, the amp gains for E-ch and F-ch should be changed, following a certain
rule.
Then, steps 2) to 4) are repeated until the offset amount becomes 0 or the repetition reaches the limit number of times.
1.3.3 FE bias auto-adjustment
This adjustment is to maximizes the RFO level by optimizing the focus point during the play mode, utilizing the phase
difference between the 3T level waveform of the RF waveform and that of when focus error disturbance is input. This
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adjustment is performed at the same timing as the auto-gain control, which will be described later, since disturbance is
input to the focus loop.
Adjusting procedure
1) The CPU of the LSI issues the command to introduce disturbance to the focus loop (inside the CD of the servo LSI).
2) The waver of the 3T component of the RF signal is detected in the CD of the LSI.
3) The relation between the 3T component above and the disturbance is processed inside the CD of the LSI to detect the
volume and direction of the focus offset.
4) The CPU of the LSI issues a command and reads out the detected results from the CD of the LSI.
5) The CPU of the LSI calculates the necessary correction and substitutes the result to the bias adjustment term inside
the CD of the LSI.
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Additionally, in this adjusting, a series of steps are repeated for better adjustment accuracy, the same as in the auto-gain
control.
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CX-3195
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