Marantz 74 CD38 - Page 15

WARNING !!! LASER DAMAGE !!! Lightpath
For measurements on the laser (fiexconnector pin 1052-6), certain conditions are absolutely
necessary for precaution of laser damage.
The instruction and sequence for measuring laser current is as follows:
Laser supply
o.k. ?
-turn off mains power.
-wait for > 1 second
-connect a multimeter (high input impedance, not grounded accross resistor 3022. (*)
-turn on mains power and go to play mode.
-reading of measurement value (current = reading/4R7) (**)
-go to stop and turn off mains power.
-disconnect the multimeter.
Laser currrent
o.k. ?
In case of a laser voltage measurement, connect the multimeter accross elcap 2025,
using the same procedure as mentioned above.
** If current is > 95 mA, you can be sure that the laser is defect;
If the current is increasing during reading (within +/- 10 seconds), you can be sure
that the laser is severely damaged.
7
Repair
LD on voltage
*
1)-Laser
supply
0.k.?
0.k.?
Voltage accross C2025: 4...5V
** 2)-Laser current 0.k.? Y Clean Y
Voltage accross R3022: 150...450mV
3)-Lens clean?
Visual control. Check for dust,grease.
Take attention for the blue coating.
=z
18
Replace
N IC7061
Check input
1C7000
26 12
4)-Check inputs. Replace Replace
Switch back to service mode 0. ‘3 IC7000 Spann 7061
Connect a 2.4 MOhm resistor from
1052 - 9 to 5V: Voltage on pin 5 of IC7000 < 50mvV.
1052 - 10 to 5V: Voltage on pin 6 of IC7000 < 50mvV.
1052 - 12 to 5V: Voltage on pin 7 of IC7000 < 50mV.
1052 - 11 to 5V: Voltage on pin 10 of IC7000 < 50mV.
1052 - 8 to 5V: Voltage on pin 11 of IC7000 < 50mV.
Diodes test
o.k. ?
LD on voltage
0.k.?
5)-Diodes o.k.?
Use IR LED of remote control.
A half sine wave must be measured on the diodes (on pin 8,9,10,11,12 of conn. 1052) " =
in the 10mV range.
Replace
Job done IC 7000
* 6)-V guard o.k.?
Voltage accross C2025: 4...5V
Check
connections
7)-Check connections between main PCB and CDM
8)-Flex 0.k.? Y
Measure diode functions on CDM-flex
9)-Check components around IC7061
R3022,R3021,R3020
C2025,C2060,C2064
Flex o.k. ?
10)-LD ON voltage o.k.?
Y
Measure
on
pin
2
of
IC7000:4...5V.
20
2
a
Replace Replace Repair
1C7000 CDM
PCS 60 679