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HITACHI
DA-500/DA-501
SERVICE POINT
1.
How to remove the cover (Fig. 1)
Remove
the screws
( (2 pieces), and
pull the cover
backward.
. How to remove the front panel (Fig. 2)
After removing the cover, loosen the screws @) (2 pieces),
@) (3 pieces) and pull the front panel forward.
. How to remove the loading mechanism (Fig. 3)
After removing the front panél, loosen the screw
© (4
pieces).
Disconnect
the connectors
(3 positions) and
connector ® (1 position), then take off the loading me-
chanism upward.
Note:
Be sure to disconnect
the connector ® of the flexible
P.W.B. as well.
| Otherwise, there is a danger that the flexible P.W.B. may
be damaged since the connector is pulled by lifting the
loading mechanism.
4. How to remove the tray mechanism (Fig. 4)
(1)
(2)
Note:
Note that the lifter cam
is disengaged from the disc sup-
port and the disc support is lowered, if the disc support is
pushed down.
If the disc support should be lowered, open the tray, and
push up the disc support from the underside.
With this
procedure, the disc support will be restored to the origin-
al position.
Put the tray in open
status, disengage the rail from the
claw of the tray as shown in Fig. 4 and then move the
tray in the arrow @ direction.
Take off the tray upward while holding the rail.
5. Mounting the tray mechanism (Fig. 5)
(1)
(2)
(3)
Before mounting the tray mechanism,
hook the pin of
the latch to the edge of the tray rack. (Fig. 5)
Put the tray in open status, and mount the tray mechan-
ism.
Move the rails in the arrow ® direction as shown in Fig
A, and fix the tray.
6. How to Remove the Tray Panel (Fig. 6)
(1)
(2)
(3)
Open the tray.
Push up in the © direction the claw of the tray in con-
tact with the stopper located at the left bottom of the
tray panel.
Push up the claw, and extract the tray panel in the ®
direction.
7. How to remove the P.W.B.
Types of P.W.B.
PYP.W.B.:
Key P'W.B.
PX P.W.B.:
= Main circuit P.W.B.
PS P.W.B.:
| Power supply P.W.B.
Volume PWB (DA-5011 only)
Headphone PWB (DA-501 only)
PY P.W.B. (Fig. 7)
After removing the front panel, loosen the screw © (5
pieces), and remove the claws (2 positions).
PX P.W.B. (Fig. 8)
After removing the securing screws ® (5 positions) and
@
(1 position),
remove
the
connectors
(6 position
[DA- 500] 9 position [DA- al and connector
@ (1 po-
sition).
(3) PS PW.B.
Open the tray, remove the power transformer
securing
screws @) (2 positions) and P.W.B. securing s crews ®
(3 positions).
After removing the soldered parts (2 positiors) of the
power cord, remove the power switch connector.
8. How to replace the Belt (Fig. 10)
(1)
Turn the pulley gear keeper counterclockwise
with a
conventional type screwdriver, and remove the belt.
In this case, lift the tip of the pulley gear keeper a little.
(2)
While turning the pulley gear by hand, open
the tray.
(Stop the turning on approx. 20 mm
inner side than the
full open status.)
(3)
After setting the belt to the motor pulley with tweezers,
set it to the pulley gear. (Set the belt to the pulley gear,
while turning it. This is an easier method.
Be careful
not to damage the belt with tweezers, etc.)
(4) Wipe off the oil getting on the belt with an applicator
damped
with
Freon. (While turning then applicator
damped with Freon. (While turning the pulley gear, wipe
all the four faces of the belt clean.)
(5) Turn the pulley gear keeper with a conventional type
screwdriver until it is fixed.
Note:
When turning the pulley gear keeper, lift its tip a little, and
execute turning gently. Otherwise, the pulley gear keeper
may be damaged.
If the pulley gear keeper is damaged, replace the loading
plate ass'y, or pulley gear keeper.
9. Checking the object lens (Fig. 11)
Take care not to dirty the objective lens of the lens actua-
tor. When the unit is not used for a long time, the lens
sometimes
REComes dirty. Clean the lens with a cotton
swab.
10. Checking the laser
The laser unit operates on 40 — 80 mA current.
If the
laser operation current.in the circuit exceeds
100 mA,
the laser may be defective.
(The current can be mea-
sured at the ends of R209 (0.48 ~— 0.96V at the ends of
12Q).
. 11. Precautions on repair service
(1)
Semiconductor laser (Fig. 12)
The
semiconductor
laser requires
more
attention
to
electrostatic breakdown or surge current. Be very care-
ful not to touch the terminals
of the semiconductor
laser and those of the flexible P.W.B. by hand or with a
tool.
The
current
—
light intensity
characteristic
became
sharp
abruptly after passing
the threshold
value
as
shown in Fig. 12. The threshold current value is a little
different in each laser unit. Therefore, when setting the
laser beam amount after replacing the unit mechanism,
be sure to turn the control variable resistor R205 fully
counterclockwise to set it off once, and then increase
the level to the specified value.
an:
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