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2.8.9 PLAY AGC
Overview
The SGC voltage is adjusted during playback according to the RF
signal level. (For details on SGC, see section 2.8.6.)
Only for CDs, this adjustment is made only once immediately after
AFB during startup. In Test mode, it synchronizes with AGC ON/
OFF. The operation is achieved through adjustment in the Servo
DSP (LC78650), and the SGC voltage is output via AUX0 (pin 44).
Using the Function in Test Mode
(the Remote Control Keys to be Used are Indicated
in Brackets)
As the function is to be synchronized with AGC, turn on and off
AFB by pressing [TEST] + [7].
2.9 Additional Descriptions of Error
Generation
This section describes the major errors of the mechanism-control
computer.
(1) DISC Distinction Error (Error 38)
The most common error. The tracking overcurrent error (Error c3),
Defocus error (Error 33), spindle errors (Errors 41 to 4b), auto
sequence errors (Errors 51 to 55) and code misread errors (71 to 74)
often lead to this error.
(2) Search Errors (Errors 11, 12, 19)
Almost all cases where playback suddenly stops may involve these
errors. They may be generated because of defects on the disc . As
with the code misread errors below, they can also be generated by a
dirty disc or bad jitters.
(3) Code Misread Errors (Errors 71 to 74)
Almost all cases where the inserted disc does not start or immediately
stops playing may involve these errors. They may be generated
because of a dirty disc or bad jitters. A bad jitter may be caused by
a dirty disc, decentering, surface deflection, birefringence (double
reflection), or a pickup problem (dirty lens, etc.), misadjustments of
the pickup, improper automatic adjustment, or incomplete
adjustments.
(4) Spindle Errors (Errors 48, 49)
An FG transition timeout (Error 48) may be generated because of
instability of the FG signal or unavailability of spindle drive voltage.
A PLL transition timeout (Error 49) can be generated with a dirty
disc.
(5) Automatic Sequence Errors (Errors 51 to 55)
If any automatic sequence (auto execution command) of the servo
DSP is not completed, these errors are generated. The causes differ
among error numbers. They may be caused by abnormalities in the
communication line between the mechanism-control computer
(PD4889A) and the servo DSP or instability of the XABUSY
connector (pin 38) of the mechanism-control computer.
(6) DSP Communication Errors (Errors a1 to a6)
These errors will be generated if the mechanism-control computer
cannot properly communicate with the servo DSP. They may be
caused by instability of the XCBUSY connector (pin 8) of the
mechanism-control computer, instability of the communication line
between the mechanism-control computer and the servo DSP, or a
defect in the servo DSP.
(7) DVD Block Noise, etc.
Block noise and momentary picture freeze (
∗
) with a DVD are not
regarded as errors, but the causes of these symptoms in the Servo
system may be:
(1) A search takes a long time (leading to a search error if it worsens).
(2) Codes cannot be read clearly (leading to a code misread error if
it worsens).
If the value to the right in the “ER: : e–” indication displayed
on the screen by pressing the ESC and DISP keys of the remote
control in Test mode is greater than 5, the cause may be (1). If
the value is less then 3, the cause may be (2).
(
∗
) With a specific 2-layer disc with which playback continues from
layer 1 to 2 or vice versa, the picture may be seen momentarily
stop. This may be attributed to the performance of the player.
Players of other manufacturers have the same symptoms to
varying degrees.
