7 DIAGNOSTICS
7.1
TROUBLESHOOTING AND REPAIR
This section contains some guides to aid the technician
in
troubleshooting the CDI player. The CD servo section and
Analog Audio section are similar
to
any CD player. Thus,
the same techniques for troubleshooting a CD player may
be used. Added features in servicing the COi player is the
Low Level Test and the Service Shell, see section 5."
Service Software". The Low Level Test needs a VT100
terminal(or equivalent)
or
a Service PCB as
an
extra tool to
run
and test the functioning of the MMC section .
The Service Shell provides tests for the Analog Video, CD
Servo, and Analog Audio circuits. Section 5.3 covers
all the Service Shell test procedures.
All circuit board assemblies can be serviced to the compo-
nent level except the MMC section. Due to the complexity
of
the MMC circuit, replacement is recommended when
defective. The CDM-9 CD Mechanism is also replaced as
an assembly. Disassembly instructions are provided on the
exploded views.
Troubleshooting hints:
Symptom:
Service Shell cannot bestarted with the test
plug.
Possible fault:
Connections between port
1 and Slave
Microprocessor may be bad. Test plug
could be wrong.
Slave Microprocessor
may
be defective.
Hint:
If the Player Shell cannot be started, perform the Low
Level Test (LL TEST).
7.1.2 Troubleshooting and Service the MMC parts
The monoboard
is
replaced
as
a module when parts of the
Multi Media Controller are defective. The technician must
know the functions of the MMC parts to diagnose a COi
player. The COi player contains some built-in diagnostics to
aid in troubleshooting. One diagnostic tool
is
the Service
Shell (see section 5.3) and the other is the Low Level Test
or
LL Test (see section 5.2). The LL Test should
be
per-
formed if there is access to neither the Player
Shell nor the
Service Shell. If the Low Level MMC test indicates a fault,
replace the complete monoboard. If the test Cannot be in-
itiated, check the power sources and main clock signals on
the MMC section. If all supplies and clock signals are pres-
ent, replace the MMC Unit.
7.1.3 Servo part and Audio Section Troubleshooting
A problem in the CD-I player can be isolated to a particular
circuit by carefully observing the symptoms. For example,
if there is no audio, but a picture from a CD-I disc is dis-
played, it
is
obvious that the CD Servo and decoding circuits
are functional. Therefore the fault can be isolated to the
audio decoding circuits only. Or the symptom may be
opposite, the audio circuits may be working, but not the
video. Again, the servo circuits must be functioning.
Troubleshooting
of
the video decoding should then be fol-
lowed.
When there is a symptom indicating a fault
in
the Servo
circuitry, troubleshooting techniques used
in
CD players can
be followed since the CD Unit portion of the CD-I player
is
basically a CD player (refer to the CD Unit schematic diag-
rams
in
the service manual).
If the COM does not start, check for Vdd, clock, and reset
on the CD Drive Microprocessor. If these signals are pres-
ent, perform the X-bus test
in
the Service Shell or Low Level
test. Also check for activity on the X-bus and SPl-bus.
If there is a communication failure, proceed with the MMC
Low Level Test to determine if there
is
a failure
in
the sys-
tem control circuitry. If the communication buses are func-
tional, check the CD servo circuits using the Service Shell
test modes. These modes are the standard CD servo test
modes
to
test the OPU, turntable and swing arm. If there is
a failure
in
the servo test modes, further checks with meas-
urements on the CD panel (see section 7.2.2) should reveal
the
fault.
If the servo circuits are functioning, check the decoder cir-
cuits. Activity should be seen on the
1
2
S (DAAB, CLAB, and
WSAB) and subcode (SCAB and SDAB) lines from the
SAA7310 Decoder IC.
If
there is no activity, check the sup-
ply (Vdd) and input signals (HF,
XIN).
If there
is
activity, check the ADOC circuitry.
When the servo and decoder circuits are functioning
properly, there may be a problem in the Analog Audio circuit.
7.1.4 Video Section Troubleshooting
The symptoms displayed can help the technician isolate the
problem to a particular circuit.
The
following examples illus-
trate how a fault can be isolated.
Symptom
1:
the player shell is displayed, but video from
the disc cannot be displayed. If this condition exists, the
Digital Video section and video analog circuits are function-
ing. Since the player shell is displayed, the video syn-
thesizer circuit
is
functioning. However, there must be a fault
on the MMC section, since this is where the video decoding
takes place. Thus the problem is isolated to the video decod-
ing section
on
the MMC section.
Symptom
2:
no video. This symptom may be caused by
either the DigitalVideo part or by the Analog Video circuit.
A few voltage and signal measurements can quickly isolate
the problem. Hint, also check all the video outputs: S-video,
RF,
and CVBS. If video is not present from any output,
check the RGB, composite sync, and power source inputs.
If these signals are present, the Digital Video circuits are
functional. Further checks of the Analog Video circuit can
isolate the problem further. Check the Video Encoder
IC.
Also check Vcc1 and Vcc2 to the Video Encoder
IC.
Symptom
3:
no color. This symptom is most likely caused
by a problem
in
the ENCODER circuit. Check the subcarrier
oscillator at Pin 6
of
the Video Encoder IC.
If
this signal is
present (correct frequency), check the chroma output signal
at Pin
15.
If there is no chroma output, IC7609 may be the
fault. Also check for short circuits between pins
of
the
lC.
If the chroma is present, check the chroma input at Pin 17.
If the chroma is not present here, check the coupling
components between Pins 15 and 17.
If
there
is
chroma at
this point, check the composite output
at
Pin 20.
If
the
chroma
is
missing, suspect the Video Encoder IC (IC7609).
PCS67662
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