Philips CDF 100 Service Manual page 17

5.1.8 Analog video part
Digital to analog conversion
The retrieved digital video signal from the E.V.C. IC 7530
leaves as an eight-bit signal for luminance (Y) and
eight-bit for both the color difference signals U (=B-Y)
and V (=R-Y). These 3 x 8 bit signals are sent together
with a clock signal (= half £.V.C. system clock) to the
input of the video D.A.C. (Digital to Analog converter
MC44200=IC 7540).The analog luminance and color
difference signals are available at the output of the DAC.
Encoding
The encoder IC used is a muiti-standard type CXA1229p
position 7640.
Inputs
The color difference and luminance signals at pin 2,3 and
4, the switchable subcarriers at pin 6 ,the switchable
subcarriers at pin 6 and the also switchable composite
sync at pin 10.
Qutputs
By means of an interna! matrix and buffer the color
signals Red, Green and Blue on pin 23, 22 and 21 are
directly derived from the color difference and luminance
signals. The red green and blue signal is now available
on the scart connector pin 15, 11 and 7 modulation. The
color difference signals U and V are being quadrature
modulated with the subcarrier (3,58 MHz for NTSC and
4,43 MHz for Pal) resulting in a chrominance signal
CHR-OUT at pin 15.
The chrominance signal is sent through a band-pass filter
5649 which can be switched over for PAL and NTSC.
This band filter eliminates harmonic distortion caused by
modulation effects. The chrominance signal is then
amplified and sent two ways, one way back to the
encoder at pin 17; and second to the Y/C connector. The
luminance (Y) output at pin 16 is for chrominance loop
through compensation delayed in 5643 and then
available ... amplification at the Y/C connector and also
at the Y/C mixer in the encoder IC pin 18. in the encoder
takes mixing place between chrominance luminance and
sync. signals. This resutts in a CVBS signal at pin 20
available for the scart output as well for the RF-modulator
input.
PCS 67 272
6 THE SERVICE DIAGNOSTIC SOFTWARE
Target
With built-in service diagnostic software it is possible to
decrease the repair time of a photo CD player. The
principle is to divide the normal functioning procedure
into separate steps and every step can give error
messages. Due to that fact it is known in what area the
error occurs; then the real cause of the error has to be
examined.
The service diagnostic software consists of two parts:
- testing of the audio path with servo processor compact
disc mechanism, servo i.c.'s, decoder part, digital to
analog converters and op-amp's. This part of the service
software is almost identical to the service program in
normal compact disc players and compact disk
interactive players; an audio (test) disc is required.
- testing of the data path like compact disc block decoder
(CDBD), Eve Video Controller (EVC) and video digital to
analog converters. For this purpose a specific photo CD
(test) disc is necessary.
To activate the diagnostic software push buttons PLAY
and PAUSE together with power on. On the display SO
(=zero) appears.
Step 0: testing of communication between servo
processor and user processor.
in step 0 communication between the servo processor
and user processor are checked; if this is O.K. then the
software version number of the servo processor will be
displayed. On the position of the tracks on the display the
service step is displayed (S0.); the software version
number is on the position of the minutes and seconds i.e.
SO 12:21, this means service position 0; 12 is the
software version number of the user processor (1.2) and
21 is the software version number of the servo processor
(2.1).
If a communication error occurs an error message is
displayed also on the position of minutes and seconds:
SO Er:00.
Push "next" button to go to step 1.
Step-1: visual check of radial arm.
With the buttons search > and search < the arm can be
moved to the inside or to the outside; a visual check is
necessary the display now shows S1 0:00.
Push "next" button to go to step 2.
Step 2: testing of focus circuit and laser.
In step 2 the focus circuit and the laser are activated. If
focus is found, the message on the display is S2 FOC if
not, 16 times the circuit is activated. On display i.e. S2
0:07 (= after 7 times focus is found) you can see how
many times are necessary to find focus. After 16 times
focus finding will stop and the message S2 0:16 appears.
Push "next" button to go to step 3.
Step 3: visual check of motor and motor control circuit.
In step 3 the motor will start-up without the radial loop
closed. The disc wiil rotate with nominal speed. By
moving the arm the motor sneed must match to the
position of the arm.
Push "next" to go to step 4.
Step 4: testing of the radial 'oop.
In this step the loop is closed. If the arm does not follows
track an error message will appear: S4 Er:XX. If the arm
follows track then 00 will be displayed: S4 0:00; also
subcode is read.
If a subcode error occurs an error message appears:
S4 Er:XX.
During trackfollowing and no subcode error, subcode
time is displayed: track, minutes, seconds.
No service indication S is displayed.
Push "next" to go to step 5.
Step 5: testing op player in normal audio mode.
After "play" the player will start in the normal audio mode;
in this situation the TOC is read in. Alt function buttons of
the player can be used.
With open/close a photo CD can be inserted.
Push "next" to go to step 6.
Step 6: testing of registers of video controller (EVC).
In this step a number of internal registers of the
video-controller (EVC) are checked.
if an error occurs the message S6 Er:00 will appear.
If no error occurs 0:00 will be send to the display so S6
0:00 is displayed.
Push "next" to go to step 7.
Step 7: testing of compact disc block decoder (CDBD).
In step 7 the Photo CD is started-up and there is a jump
to address 00:02:00.
Two tests are carried out:
- searching for sync patterns: if no sync patterns are
found an error message will appear S7 Er:00 and if sync
patterns are found the following message appears: S7
0:01
- reading of headers: if not possible then an error
message will appear: S7 Er:01; if yes then S7 0:02 is
displayed.
Push "next" to go to step 8.
Step 8: testing of block decoder (CDBD) and video
controller (EVC).
Now data is read in from a(n) (ordinary) Photo CD; data
from address 00:02:00 is read. These data goes via
CDBD and EVC to the microprocessor.
If this functions then $8 0:01 appears; if not then
message S8 Er:00 is displayed.
Push "next" for go to step 9.
Step 9: measuring the datapath from CDBD (block
decoder} to EVC (video controller).
Now the specific Photo CD testdisc is required.
\n ston 0.9 onnnifin dnth AAYAMA Af AA dina ja aand beam
COBD to EVC during 30 seconds. At the CDBD output
from MSB to LSB a divided by 2 square wave pattern
must be present.
Push "autoplay" if you want to repeat this data pattern;
on the display S9 0:00 appears.
Push "next" to go to step 10.
Step 10: loading of an image.
In step 10 an image on the disc will be loaded; the player
is now in the normal Photo CD mode and all functions
can be checked.
Push "power off" to leave the service mode !
Note: Only in step 5 you can load a photo disc; so in step
5 you have to decide to use or not to use the Photo C.D.
test disc. .
To check the CDBD( step 9) you need this test disc!
Error messages ONLY for step 4.
XX
2 focerr : focus error
3 exenerr —: exentricity error
4 discerr : dise error
5 offerr : Tlis low during 50 uS
6 — jmperr : error during jump
7 suberr : subcode error
8 tocerr : error during read-in of TOC
20 overrun : overrun error: serial comm.error
21° framing __: framing error: serial comm.error
22 noise : noise flag err.: serial comm. error
23 sererr : common serial comm, error
30 grverr : number of tracks to jump to is too great
31 stimerr : time-out for subcode address
32 binerr : error during binairy search
Error message ONLY for step 5 and 10
XX
7 — suberr : subcode error