Panasonic SA-XH50P, Service Manual

Page: 41 / 131

41
8.3. Basic Troubleshooting Guide for Traverse Unit (Backend P.C.B.)
Problems Checking Points Checking components
b) Check video signals (CVBS) LB8317, R8325 (CVBS)
a) Check SDRAM address, data
bus, CLK and other control signals
waveform IC8051 1) Distorted picture or
abnormal sound is head
during the initialization
c) Check audio DAC circuitry
* Compare the above with
OK condition DVD Module
P.C.B
LB8422 till LB8428
*Check for solder short and/or
component missing/damaged
b) Check laser drive circuitry
(Voltages & current) Q8552, CL8510
Q8562, CL8520 (For DVD),
(For CD)
a) Check motor driver circuitry
(VCC PVCC) IC8251 Pin 8, (+9V), 21 (+5V) 2) No TOC/Long TOC
c) Check LSI IC connection to
motor drive circuitry
* Compare the above with OK
condition Main P.C.B.
IC8001 Pin 90, 93, 94, 95
IC8251 Pin 11 to 18
* Check for solder short and/or
component missing/damaged
a) Check connection from
Main to Traverse unit FP8251 3) Disc not spinning
4) Traverse not moving
5) Traverse and spindle
abnormal movement
b) Check motor driver circuitry on
the voltages and control signals
* Compare the above with
OK condition Main P.C.B. IC8251
* Check for solder short and/or
component damaged
6) Cannot read the disc but
spindle motor is spinning
- Cannot read CD/DVD
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.
Q8552, LB8551
(For DVD Laser Drive current)
Q8562, LB8561
(For CD Laser Drive current)
7) Block Noise during play a) Check SDRAM address and
data bus signal
IC8051
8) Jitter out of specification a) Check LD current
b) Check OPU (Change to other
unit and confirmed operating
condition)
OPU Unit (Traverse unit), FPC
connection (FP8531 & FP8251)