Technics SL-PC25

SS os O40) S) Hd OY 40)
TOC READ OPERATION - PLAY OPERATION
INDIVIDUAL CONDITIONS CONTROL BLOCK/MAJOR PART OBSERVATION POINTS
Optical Pick-up
illuminate? Laser diode
Control circuit
Yes IC-101, Q101
System CPU
1C-401
Does taser diode
Is focus lens moved System CPU circuit
vertically for search No IC-401
operation? Servo control circuit
(visual check) 1C-101, 1C-102
Optical pickup
Yes Focus coil
(none repairable)
Does spindle motor start | No System CPU circuit
to rotate? 1C-401
Spindle drive circuit
Yes 1C-351
Q351, Q352, Q353
DC spindle motor
Does focus loop servo No Focus error amplifier
operate? 1C-101, IC-102, 1C-103
Yes
Does tracking loop servo | No System CPU circuit
operate? 1C-401
Servo control circuit
Yes 1C-101
Tracking error amplifier
IC-102, IC-103
Optical pickup
® Tracking coil
(none repairable)
— 53 —
INDIVIDUAL CONDITIONS
U
®
Does traverse servo operate
correctly?
Yes
System CPU circuit
1C-401
Traverse drive circuit
1C-102, IC-103,
IC-101
Traverse coil
Is DSL circuit in normal System CPU circuit
mode? 1C-401
Yes
Is RF signal converted by the |No| Auto gain control circuit
AGC circuit to on ARF signal
with a constant amplitude?
CONTROL BLOCK/MAJOR PART
OBSERVATION POINTS
=HOW TO CHECK THE TRAVERSE=
* The sound skips every few
seconds in play mode.
* Optical pickup moves outward or
inward alternately.
* Optical pickup sticks at inner or
outer position.
=HOW TO CHECK AGC CIRCUIT=
* The level of {C-101 pin @ (ARF
signal) becomes 0.4Vp-p.
Yes
ls ARF signal converted by NO} Data slice circuit =HOW TO CHECK SRF CIRCUIT=
DSL circuit to SRF signal? 1C-102 * Check (SRF signal) at 1C-102 pin @.
Yes
ts SRF signal synchronized No Phase loop circuit
with PCK signal? IC-301, IC-102
Yes
is CLV servo changed to No! CLV circuit
phase-comparison mode? IC-301
Yes
Are both EFM and PCK clock No Phase loop lock circuit
signal activated? 1C-102
Yes
NO! DIF/DAC circuit
Is audio signal activated? cireut
IC-801
Yes
LPF circuit
IC-802, 1C-803
NORMAL OPERATION
— 54 —
=HOW TO CHECK SYNCHRONIZE =
* Check IC-102 pin @ by
oscilloscope in triggered mode with
RF signal and if output waveform at
IC-102 pin @ can be synchronized
in-phase, the level IC-301 pin @
becomes 2.4 volts.
=HOW TO CHECK PHASE
COMPARISON=
* Check waveform at IC-301 pin @
(EC signal).
=HOW TO CHECK EFM AND PCK=
* Check IC-102 pin @) for EFM
waveform.
* Check IC-102 pin € for PCK
waveform.
Printed in Japan
K900;O09500YY/TN