14
9. DVD Part: Introduction of MTK1379 maintenance
1.
Under normal power supply conditions, the maintenance plan for MT1379 mono-chip is: first the reset
circuit resets the MT1379, after the crystal oscillator circuit gave the clock signal to MT1379, MT1379 will
start the initialization check for Flash
、
E
2
PROM
、
SDRAM, after everything is checked to be normal, it will
start initialization check for 7Audio DAC, MT1336 and motor Driver.
2.
If the all the a.m. parts are good, then MT1379 will send signal to motor Driver to drive the servo system
，
pick up then to generate DVD light for collection, tracing the main shaft to check if there is any disc, and
confirm if it is CD format or DVD format disc. If the disc is in DVD format, the system will read the data
from the disc directly; if it is in CD format MT1336 will drive the CD laser to send out CD light and read the
data, the data then will be amplified through MT1336 and sent to MT1379 for data processing, released by
MPEG and resolved into video data and audio data, then they will be returned to analog signals through
VIDEO DAC
、
AUDIO DAC.
Decoder section
3.
There is power supply, clock and reset, but the system does not work.
1
）
Check if all the address wires required for FLASH are exist, and if they are in normal status,
especially check if the A0~A15 of FLASH have normal signals, if there aren
’
t, then inspect MT1379
to see if there is faulty soldering. If there are normal signals at A0~A15, check if the address data
signal of MT1379 and SDRAM is normal. If it is normal, then check the signal at A16~A19 of
MT1379; if there are also signals, then check the 8 video data wires; it there is no signal, then
check the corresponding pins of MT1397 to see if there is any short circuit, break or faulty
soldering.
2
）
If all the a.m. conditions are good, but there is still no video signal output, then the filter circuit after
MT1379 shall be checked.
4.
System in normal operation, but the audio has no sound.
1
）
Check if all the signals of DATA, MCLK, BCLK, LRCK and reset required by the Audio DAC are
exist, if there is signal missing, then check the signal line between MT1379 and Audio DAC. If the
line is connected properly, but there is no signal, then check if there is any welding problem at the
corresponding pins of MT1379. If it is still OK, it is probably the problem on MT1379 itself.
2
）
All the required signals are exist, while there is no audio output. Then you need to check the lower
passing amplifying circuit and the MUTE circuit at the back of Audio DAC. Also check if there is
any power supply to the Audio DAC.
3
）
Check if the power supply voltage required for playing is at normal level.
Servo Section
5.
After the LOGO of the machine shows normally, there is no OSD display. This problem mainly is caused
by the abnormality between servo and MPEG, possible problems may be:
1
）
T1336 and its surrounding circuits have problems.
2)
Servo part of MT1379 has problems.
6. OSD display is normal
，
while there is no action of servo part
（
feeding motor does not work, main shaft does
no turn, possible fault status are:
1)
The corresponding signals giving by MT1379 to DMSO
、
FMSO are missing, the reason may be the
problem of MT1379 or the communication between MT1379 and motor Driver.
2)
Not output from Motor Driver, the reason may be the problem on motor Driver or its corresponding
circuit.
7.
Servo part in good status, while there is no pick up action
（
no light, no focus
）
1
）
No light, check the power supply
（
power supply for pick up
）
, or the light producing driving circuit to see
if they are in normal status.
2
）
No focus, check MT1379 to see if there is signal output from FOSO
、
TRSO.
Secondly, check motor driver to see if there is F+
、
F-
、
T+
、
T-signal output.
Thirdly, check the external corresponding circuit of the motor driver to see if there is any problem.
8.
All the servo part has action, while it cannot read out the disc
1
）
Check MT1336 if there is RF net picture output, if there isn
’
t, then it must be the problem of MT1336
and external surrounding circuits, it there is output, then it might the problem of MT1369 and its
surrounding circuits.
2
）
There is RF signal
，
but not in normal status
，
then check MT1336 and surrounding circuits.
3
）
Everything is normal, but the disc cannot be read out, check MT1369 and its surrounding circuit
文件使用
"pdfFactory Pro"
试用版本创建
