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4-4
•
MUTE signal (pin 11; test point 67)
When Filter-B IC is applied, the MUTE input will not be
used.
IL CONTROL µP
IC6566
•
Reset (pin
2;
test point 100)
When the supply voltage is switched on a positive
voltage should be present.
•
X-tal (pin 5; test point 101)
The frequency of this signal should be 4 MHz.
• Data
(pin
25;
test point 102)
•
Clock (pin 26; test point 103)
There should be activity at test point
102
and
1 03
in
position play (dlsplay Information).
• 1
2
C
(pin
22;
test point
29)
•
1
2
0 (pin
23,
17; test point 31)
There should be activity at test point
29
and
31
in
position play.
•
POR (pin 28; test point 104)
When the supply voltage is switched on a negative
puts should be present.
Ill.
PHOTODIODE SIGNAL PROCESSOR IC6525
• SC
(pin 25)
SC(:: Start
Capacitor)
High Ohmic measurement
Position of player
SC (pin 25}
POWER ON
-4 V
PLAY
+5
V
Servicing pos.
1
+5 V
•
Si (pin 20;
test
point 21)
LO (pin 17; test point 9,
gA,
9
8 )
- With the Si signal (= Start Initialization) the laser
supply, among other things, is switched on.
When the Si signal is "low", the LO signal (= Laser
Out) should be "high".
Via the LM signal(= Laser Monitor) the power supply
for the laser diode is controlled.
Position of
POWER
Servicing
PLAY
player
ON
pas. 1•)
Si signal
"high"
"low"
"low"
LO signal
"low~
"high"
"high"
•
LM
(pin
16;
test point 11) to check LM
See general checkpoints 'check of the laser supply'
•
To check the laser supply, see General checkpoints
"Check of the Laser Supply".
•
To check the focus offset, see Genera! checkpoints
"Adjustment of the Focus Offet".
*) To ensure that the player stays in servicing position 1,
there should be a disc on the turntable.
cs
9 986
•
FE pin
(pin
5; test point 26)
-
The FE signal (= Focus Error) is used to drive the
focusing unit.
When the SI signal goes to "high", the focal point will
be searched
for.
-
When the player is brought into servicing position 1
without disc, the objective will search
1 Sx
for the focal
point.
At test point
26
the FE signal varies
16x
between
+2 V
and
-1,5
V.
- The FE signal ensures that the spot stays in focus.
When an error signal is injected, the FE signal will
correct.
Bring the player in servicing position 2 (with disc on
turntable).
Inject successively a voltage of +5 V and -6 V
(== +SA and -6B) via a
200
kO resistance to test point
25.
Signal injected
test point
25
IC7104A
+5
V
FE signal
negative
•
RD signal (pin 21; test point 24)
HIGH-OHMIC MEASUREMENT
-6
V
positive
The
RD
signal (= Ready) will go high when the starting
procedure of IC6525 has been completed.
PO Sm ON
PU\
YER
POWER
ON
SERVICE POSfTJON 1
J7_
POWER ON
•
D1 (pin 9 ; test point 4)
D2
(pin
10:
test point 6)
D3
(pin
8 ;
test point 7)
D4
(pin
7 ;
test point 8)
"HIGH"
PLAY
i.ow-
MDJ\,00363
T12 -638
- The signals D1
+04
are the error signals from the
photodetector circuits.
- When in servicing position
1
the disc is moved, the
focusing unit should keep in track.
When the disc is moving, there should be a changing
signal on test points
4, 6, 7
and
8.
-
Check of the photodetector.
Connected the circuit below
to
an atternating voltage
of 17,5 V.
o---~~OE
t - - - - - " J - -
1.15W
17.SV~
100
E-1.5
W
BAW62
CQY89
BAW62
- 4822 116 51096
- 4822 130
30613
- 4822
130 31332
.,,
'CQY89
39 368 A12
Switch on the supply voltage and bring the player in the
stand-by mode or in serciving position 0.
In this measurement, infrared diode CQY69 replaces the
function of the laser diode.
0
(_
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