Grundig K 15 PFCD 2602 Txt Service Document page 16

DVD Part: Introduction of MTK1389D maintenance
NOTE:
MTK1389D is a type of LSIC for DVD decode .MTK1389D IC consists of RF,SERVO,DSP,DECODE,VIDEO DAC and AUDIO DAC.
1. Under normal power supply conditions, the maintenance plan for MT1389D mono-chip is: first the reset circuit resets the MT1389D, after the crystal
oscillator circuit gave the clock signal to MT1389D, MT1389D will start the initialization check for Flash：E2PROM：SDRAM, after everything is checked
to be normal, it will start initialization check for built-in Audio DAC, servo and motor Driver IC .
2. If the all the a.m. parts are good, then MT1389D will send signal to motor Driver to drive the servo system：pick up then to generate DVD light for col-
lection, 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 built-in servo will drive the CD laser to send out CD light and read the data, the data then
will be amplified through built-in RF amplifier and sent to MT1389D decode part for data processing, released by MPEG and resolved into video data
and audio data, then they will be returned to analog signals through built-in VIDEO DAC：AUDIO DAC.
Decoder section
3. There is power supply, clock and reset, but the system does not work.
- 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 MT1389D to see if there is faulty soldering. If there are normal signals at A0~A15, check if the address data
signal of MT1389D and SDRAM is normal. If it is normal, then check the signal at A16~A19 of MT1389D; if there are also signals, then check the
video output wires and AV filter circuit; if there is no signal, then check the corresponding pins of MT1389D to see if there is any short circuit, break
or faulty soldering.
4. System in normal operation, but the audio has no sound.
- Because the AUDIO DAC is built in MTK1389D IC.you need to check the lower passing amplifying circuit and the MUTE circuit at the back of the
LPF circuit. Also check if there is any power supply to the LPF circuit.
- 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 built-in RF and servo,
possible problems may be:
- Built in RF and its surrounding circuits have problems.
- Servo part of MT1389D 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:
- The corresponding signals giving by MT1389D to DMSO：FMSO are missing, the reason may be the problem of MT1389D or the communication
between MT1389D and motor Driver IC SA5668.
- 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：
- 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.
- No focus, check MT1389D 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
- Check MT1389D if there is RF net picture output, if there isn't, then it must be the problem of MT1389D and external surrounding circuits, it there is
output, then it might the problem of MT1389D and its surrounding circuits.
- There is RF signal：but not in normal status：then check MT1389D and surrounding circuits.
- Everything is normal, but the disc cannot be read out, check MT1389D and its surrounding circuit
K 15 PFCD 2602 Txt