Sony Discman D-180AN Service Manual page 3

Precautions for Checking Emission of Laser Diode
Laser light of the equipment is focused by the object lens in the optical
pick-up so that the light focuses on the reflection surface of the disc.
Therefore, be sure to keep your eyes more then 30cm apart from the
object lens when you check the emission of laser diode.
Laser Diode Checking Methods
During normal operation of the equipment, emission of the laser diode
is prohibited unless the upper panel is closed while turning ON the S801
(push switch type).
The following two checking methods for the laser diode are operable.
Method-1 (In the service mode or normal operation) :
Emission of the laser diode is visually checked.
1. Open the upper lid.
2. Push the S801 as shown in Fig. 1 .
3. Check the object lens for confirming normal emission of the laser
diode. If not emitting, there is a trouble in the automatic power
control circuit or the optical pick-up. During normal operation, the
laser diode is turned ON about 2.5 seconds for focus searching.
S801
Fig.1 Method to push S801
Method-2 (In the service mode or normal operation) :
Check the value of current flowing in the laser diode.
1. Remove the upper panel.
2. Read the current printed on the rear side of the optical pick-up.
(Print on the rear side of the optical pick-up)
A C 2 2 1 1 3 9 7
current value
A : less than 48 mA
3. Connect a level meter as shown in Fig. 2
4. Press the ^ key.
5. Calculate the current value by the reading of the digital voltmeter
Reading of the tester (V) ÷ 4.7 ( Ω ) = current value (A)
(Example) Reading of the digital voltmeter of 0.2256 V :
0.2256 V ÷ 4.7 Ω = 0.048 (A) = 48 mA
6. Check that the current value is within the following range.
[MAIN BOARD] (Conductor side)
year
month
date
shift No.
line No.
version
– 3 –
+5
• Current value of the label
-11
Variation by temperature : 0.4mA / °C
Current increases with temperature increased.
Current decreases with temperature decreased.
If the current is more than the range above, there is a trouble in the
automatic power control circuit or the laser diode is in deterioration.
If less than the range, a trouble exists in the automatic power control
circuit or the optical pick-up.
TP547
IC501
TP506
Fig. 2 Digital Voltmeter Connecting Location
mA(25°C)
digital voltmeter
TP506
TP547