Hitachi DA-5000 - Adjusting the Player; Laser Diode Output Adjustment; Focus Servo Offset Adjustment; Tracking Servo Gain and Offset Adjustments

HITACHI DA-5000
ADJUSTING THE PLAYER
When you have made the following work (1) or (2), be sure to
perform adjustment 1 — 5.
(1) Disassembly of the unit mechanism and replacement 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
No. position
Adjustment
Center
Center
Center
Center
Laser diode output R205
Focus servo offset RO10
Tracking servo gain R126
Tracking servo offset RO20
Adjustment should be made in the following sequence.
1. Adjustment of laser diode output (Fig. 22)
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.6 (EFM) and TP.7 (GND).
[2] Load a disc in the player, and set the player to play
mode.
{3] Adjust R205 so that the EFM signal level becomes
1.3V.
Note: (Fig. 20)
However if the signal level is in range of 1.1V — 1.5V, it is
normal and no adjustment is necessary.
2. Adjustment of focus servo offset
(1) Instrument to be used
@ Oscilloscope
@ DC Voltmeter
(2) Adjusting procedure
[1] Connect the oscilloscope to TP.6 (EFM) and TP.7 (GND).
[2] Load a disc in the player, and set the player to play
mode.
3] Adjust RO10 so that the EFM signal amplitude beco-
mes maximum.
4] After adjustment, check that the center voltage of the
RO10 is 2-3 V with a DC voltmeter.
[5] lf the center voltage is not within the specified value,
readjust as follows.
Less than 2V: Set to 2V.
More than 3V: Set to 3V.
3. Adjusting the tracking servo gain
(1) Instrument to be used
@ Signal generator
@ Oscilloscope
(2) Adjusting procedure
1] Connect the sine waveform signal generator and the
connector as shown in Fig. 22.
2] Adjust the signal generator so that its frequency beco-
mes 1.6 kHz and its output 2.5 Vp-p.
3] Load a disc in the unit and set the unit to playback
mode.
4] Adjust R126 so that Lissajours’ figure on the oscillos-
cope indicates the figure shown in Fig. 22.
4. Adjustment of tracking servo offset
(1) Instrument to be used
DC voltmeter
(2) Adjusting procedure
{1] Connect the DC voitmeter to TP.10 (TER).
(2] Put the set in stop mode.
[3] Adjust RO20 so that the DC voltmeter indicates +10
mV.
5. Adjusting PLL
Do not make adjustment except when any part
(other than R407, R408, R410 and R411) in the PLL
block has been replaced.
(1) Instrument to be used
@ Frequency counter
®@ Oscilloscope
(2) Adjusting preparation
[1] Connect the above instruments as shownin Fig. 22
(3) Adjusting procedure
[1] Preset L401 so that the frequency at T?.15 (PLCK) is
4500 + 50 kHz with the set stopped.
[2] Put the set in playback mode. Turn L401 clockwise (in
the core entering direction) until the level of TP.2 (GFS)
goes low. Then, turn L401 counterclockwise (in the
core pulling direction) and find the positiom where the
level goes high.
[3] Put the set in stop mode and read the frequency (f1} of
TP.15 (PLC).
[4] Put the set in playback mode. Turn L401 counterclock-
wise until the level of TP.2 (GFS) goes low. Then, turn
L401 clockwise and find the position were the level
goes high.
[5] Put the set in stop mode and read the frequecny (f2) at
TP.15 (PLCK).
[6] Adjust L401 so that the frequency at TP.15 is (f1 + f2) x
1/2.
(4) Checking of operation
After making adjustments [1] throught [5] above, dis-
connect TP.13 and TP.14 and put the set in playback
mode.
Check that the frequency at TP.15 (PLCK\is 4321.8 +
400 kHz. Ascertain that the waveform at TP.2 (GFS)
exactly as shown in Fig. 21.
The level at TP.2 (GFS) may happen to be hw.
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