Adjusting The Player - Hitachi DA-600 Service Manual

HITACHI! DA-600
ADJUSTING THE PLAYER
When you have made the following work (1) or (2), be
sure to perform adjustment 1-6.
(1) Disassembly of the unit mechanism and replace-
ment of parts.
(2) Replacement of parts of the pickup part.
@ Adjustment of circuit
Preset each control before making adjustment
after replacing the pickup parts.
@ Presetting
Circuit Preset
Adjustment
No. position
Laser diode output
Slide motor offset
Tracking servo offset
Focus servo offset
Disc motor hall gain balance
Sample hold offset
Minimum
Center
Center
Center
Center
Center
Adjustment should be made in the following se-
quence.
1. Adjustment of laser diode output
Do not perform this adjustment except when the
pickup or laser circuit is replaced.
(1) Instrument to be used
Oscilloscope.
(2) Adjusting procedure
[1] Connect the oscilloscope to TP. (TDET) and TP.
(GND). (Fig. 18)
[2] Load a disc in the player, and set the player to
play mode.
[3] Adjust R629 so that the EFM signal level be-
comes 700 mV. (Fig. 18)
Note:
However if the signal level is in range of 500 — 900
mV, it is normal and no adjustment is necessary.
2. Adjustment of slide motor offset
(1) Instrument to be used
DC voltmeter
(2) Adjusting procedure
[1] Connect the DC voltmeter to TP. (SLM) and TP.
(GND). (Fig. 18)
[2] Load a disc in the player and set the player to play
mode.
[3] During playback connect R134 to PX. PW.B. TP.
(GND).
[4] Stop the play.
[5] After about 10 seconds, measure the DC level and
adjustR107 so that the DC voltmeter reads O +
50 mV. (Abb. 18)
3. Adjustment of tracking servo offset
(1) Instrument to be used
Oscilloscope
(2) Adjusting procedure
{1] Same as [1] and [2] of (2) Adjusting procedure of
Item "1. Adjustment of laser diode output".
[2] Adjust R603 so that the EFM signal amplitude
becomes maximum. (Fig. 18)
4. Adjustment of focus servo offset
(1) Instrument to be used
Oscilloscope
(2) Adjusting procedure
{1] Connect the oscilloscope to TP. (TDET) and TP.
(GND).
[2] Load a disc in the player, and set the player to play
mode.
[3] Adjust R116 so that the EFM signal amplitude
becomes maximum. (Fig. 18)
(1) Instrument to be used '
Oscilloscope
(2) Adjusting procedure
[1] Connect the oscilloscope to TP. (DMCA) and TP.
(GND) or to TP. (DMCB) and TP. (GND).
[2] Adjust R201 so that the output levels at TP.
(DMCA) and TP. (DMCB) become the same.
6. Adjustment of sample hold offset (Fig. 17, 18)
(1) Instruments to be used
e Oscilloscope
e Local defect simulation disc (The disc to which a
black tape approx.0.5 mm wide is stuck.)
A tape having the shape of wedge ( » ) may be
substituted for the above.
(2) Adjusting procedure
[1] Connect the oscilloscope to TP. (TDET) and TP.
(GND).
Load the disc in the player, and set the player to
play mode. Adjust R103 while monitoring the
playback sound, so that the track jumping be-
comes minimum.
A aH ae
~— 700 mV | EFM-Signal
ro
[2
i
Signal EFM
GND
Fig. 15
Abb. 15
R134
TP.( GND)
Fig. 16
Abb. 16
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