Philips CD304 MK II - Electrical Measurements and Adjustments

4-2
ELECTRICAL MEASUREMENTS AND ADJUSTMENTS
Specification measurement
CD PLAYER
S/N AND
DISTORTION
METER
FILTER
eg. SOUND TECHNOLOGY
ST 1700B
Fig. 8
30 459 AI2
To measure the specification use can be made of audio
test disc 4822 397 30085.
Use a 7th order filter, e.g. 4822 395 30204 (see Fig. 8), to
measure:
— Total harmonic distortion (THD).
— Intermodulation distortion.
— Signal-to-noise ratio (S/N).
Changing the transformer connections
TOP VIEW BOTTOM VIEW
FI=S025A/125 °C
Fig. 9
36 114 A7
If the unit has to be connected to a mains voltage devia-
ting from that mentioned on the type plate, the trans-
former connections should be changed as indicated in the
figure.
Attention
In case of adaptation to 110 V or 127 V the glass fuse on
the mains filter PCB must be changed from 200 mA-T to
400 mA-T.
CS 5 198 GB
Laser power supply (POS. VOLT. SH.)
For check and preliminary adjustment of the laser supply
see Service Manual C.D.M.
Adjusting the laser supply
Play track 1 of test disc 4822 397 30096 (disc without
defects).
Connect a DC voltmeter across resistor 3308 on the servo
PCB (= on emitter of transistor 6239 and ground).
Adjust the laser power supply with resistor 3180 until the
voltage across resistor 3308 is 575 + 75 mV.
Adjusting the focus bandwidth
6208(1/2}{B)
MC1458
cor
100n -1
3242 }3243 13245 |2228
Et}
36028 B12
Make a measuring arrangement according to the figure.
Play track 1 of test disc 4822 397 30096 (disc without
defects).
Adjust trimming resistor 3158 on PRE. AMPL. + LASER
PCB for a 180° phase difference between signals A and B.
This corresponds with a minimum distance D in the Lissa-
jous pattern.
R=47kN-1% 5322 116 54671
C=10nF-1% 5322 121 54154
Check of the AGC and offset circuits
(See SERVO PCB)
Play track 1 of test disc 4822 397 30096 (Disc without
defects).
The voltage between pin 1 of 1C6212 and 1 should be
-4Vt2V.
The voltage between pin 14 of 1C6215 and | should be
OVH2V.