Basic Troubleshooting Guide For Traverse Unit (Dvd Module P.c.b.) - Panasonic SA-PT70EB Service Manual

7.2.

Basic Troubleshooting Guide for Traverse Unit (DVD Module P.C.B.)

Problems
1) Distorted picture or
abnormal sound is head
during the initialization
2) No TOC/Long TOC
3) Disc not spinning
4) Traverse not moving
5) Traverse and spindle
abnormal movement
6) Cannot read the disc but
spindle motor is spinning
- Cannot read CD/DVD
7) Block Noise during play
8) Jitter out of specification
Checking Points
a) Check SDRAM address, data
bus, CLK and other control signals
waveform
b) Check video signals (Y,C)
c) Check audio DAC circuitry
* Compare the above with
OK condition DVD Module
P.C.B
a) Check motor driver circuitry
(+5V)
b) Check laser drive circuitry
(Voltages & current)
c) Check LSI IC connection to
motor drive circuitry
* Compare the above with OK
condition DVD Module P.C.B.
a) Check connection from
DVD Module to Traverse unit
b) Check motor driver circuitry on
the voltages and control signals
* Compare the above with
OK condition DVD Module P.C.B.
a) Check laser drive circuitry
(voltages and current)
- Check CD Laser Drive
- Check DVD Laser Drive
* Check voltages and LD current
and compare with OK condition
DVD Module P.C.B.
a) Check SDRAM address and
data bus signal
a) Check LD current
b) Check OPU (Change to other
unit and confirmed operating
condition)
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Checking components
IC8051
LB8315, R8321, R8323,
LB8316, R8325, R8327
IC8422 (Pin 9 to 11 & 17 to 22)
LB8426, LB8427, LB8428
*Check for solder short and/or
component missing/damaged
IC8251 Pin 8, 21
Q8551, Q8552 (For DVD),
Q8561, Q8562 (For CD)
IC8001 Pin 66, 67
IC8251 Pin 15 to 16
* Check for solder short and/or
component missing/damaged
FP8251
IC8251
* Check for solder short and/or
component damaged
Q8551, Q8552, LB8551
(For DVD Laser Drive current)
Q8561, Q8562, LB8561
(For CD Laser Drive current)
IC8051
OPU Unit (Traverse unit), FPC
connection (FP8531 & FP8251)
(Y)
(C)