Basic Troubleshooting Guide For Traverse Unit (Backend P.c.b.) - Panasonic SA-XH50P Service Manual

8.3.

Basic Troubleshooting Guide for Traverse Unit (Backend 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 (CVBS)
c) Check audio DAC circuitry
* Compare the above with
OK condition DVD Module
P.C.B
a) Check motor driver circuitry
(VCC PVCC)
b) Check laser drive circuitry
(Voltages & current)
c) Check LSI IC connection to
motor drive circuitry
* Compare the above with OK
condition Main P.C.B.
a) Check connection from
Main to Traverse unit
b) Check motor driver circuitry on
the voltages and control signals
* Compare the above with
OK condition Main 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
Main 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
LB8317, R8325 (CVBS)
LB8422 till LB8428
*Check for solder short and/or
component missing/damaged
IC8251 Pin 8, (+9V), 21 (+5V)
Q8552, CL8510 (For DVD),
(For CD)
Q8562, CL8520
IC8001 Pin 90, 93, 94, 95
IC8251 Pin 11 to 18
* Check for solder short and/or
component missing/damaged
FP8251
IC8251
* Check for solder short and/or
component damaged
Q8552, LB8551
(For DVD Laser Drive current)
Q8562, LB8561
(For CD Laser Drive current)
IC8051
OPU Unit (Traverse unit), FPC
connection (FP8531 & FP8251)