[SOLVED] LG LH-T6447 Home Teater firmware or hw repair !?

[KnutOlafson]

LG LH-T6447 Home Teater firmware upgrade or hw repair !?

Dear friends,

I have an, now outdated but loved, home theater (DVD player + FM/AM tuner) from LG. Model is LH-T6447 and have problem with programming radio stations in FM/AM tuner that is build in.

Here is dumb troubleshooting:
1) Everything working fine except FM/AM radio
2) Even radio is working except I cannot store radio stations in memory
3) If I am listening an radio station (tuned manually while receiver is on) and turn device off. After I turn it on again I have that frequency (radio station) present - it is not lost.
4) I can tune (switch to) any frequency I want but device only remembers last visited frequency, and cannot store any other in memory.

I tried to find any new firmware for this device on Internet (the idea was to upgrade firmware...) but with no success. Even on device, in menu, there is no sub-menu where is listed hardware version and firmware version, at all. Everything looks like it is not possible to change firmware that is built in.
There is no system port on back side of device for firmware upgrade. Didn't opened device to see pcb - if there is some breakout pins that are used for connecting and firmware upgrade.

Now,don't know what to do - hardware repair, maybe ?

I have found Service Manual on Internet, just scroll down through 57 pages with diagrams end schematics and think so that this should be problem related with some chip that stores "user configuration" but don't know which one. Is it one chip for all (DVD player and Tuner) or it is separated!?

I have some experience with soldering and other stuff but not quite sure where to look for problem on such A/V device.

Any help would be appreciated.

Knut

 

[pradeep.g.belchada]

their is a problem in am/fm tuner module. can you find out which ic is used in tuner module. because in service manual it is not given

 

[KnutOlafson]

Yes, that was my question... if someone knows.

OK, I need to check Service Manual in deap and/or to open device to look pcb details. After that I will come here again with more details.

 

[KnutOlafson]

Ok, I have check Service Manual (didn't opened device yet) and here are my conclusions and questions:

1) Device is consist of multiple "sections" (power supply, DSP, Amplifier, I/O, MPEG chip (MediaTek MT1389) with neighborhood, and MINICOM)
2) MINICOM part, what ever it can be is responsible for communication with user (main chip in this part is Sanyo LC876764 or Sanyo LC87F68C8, not sure because in Service Manual on one page is one and on another is other one,confusing). External buttons on this device and Remote Control Receiver are connected directly to this MINICOM chip. This chip is 8-bit Microcontroller by Sanyo.
3) That specific Sanyo microcontroller chip is connected to "Tuner Module" which, among other things is consisted of Sanyo LV2300 (Single-Chip Tuner IC for Radio/Cassette Players)
4) Regarding Firmware upgrade in any part of this system - As far as can see, on this PCB there is only one breakout pins on board intended for "Download". It seams like serial communication on TTL level or something like that. This "Download" pins are connected to MPEG chip ONLY(!!!) On its pins SPDAT and SPMCK - since it has only 2.3V, GND, RxD and TxD - there is no PIN for addressing device for programming multiple devices on board. This means that is possible to "upgrade" MPEG chip and relevant things - probably related to codecs and subtitles, maybe. In futher, this MPEG chip has connected external Flash ROM chip and SDRAM chip.
5) My conclusion is, there is no upgrade of firmware for rest of this system, except MPEG.
6) Back to the FM/AM tuner - this Sanyo microcontroller chip looks like brain in whole system, at least responsible for communication, as I have mentioned above, is connected to user's buttons and RemoteControl Receiver module. On another side is connected to TunerModule. It is connected to menu other sections but it is irrelevant for my problem (DSP, AMP, I/O...).
7) Now, what I don't know where are frequencies, I want to store, located (stored) !? - in Sanyo microcontroller OR in TunerModule Chip LV23000.
8) As far as I can see, TunerChip LV23000 has inputs and outputs, but in datasheet I cannot find anything about storage capacity - so it looks like it is not configurable except on bases of its inputs while it is powered.
9) If I am right, then my problem is Sanyo microcontroller (his memory), OR communication lines between microcontroller and TunerChip !?!?

Just to mention, repairing Sanyo microcontroller for me would be mission impossible since I don't have programmer and don't have Hex file to be loaded in any way. In further, as I have write above - manufacturer didn't provide any breakout pins for firmware upgrade for this chip, as well.

What to do?

 

[pradeep.g.belchada]

can you upload your service manual. because in my service manual only tuner module is shown. or give me the downloadable
link

 

[KnutOlafson]

View attachment LH-T6447D.pdf


Here you go !

- - - Updated - - -

And datasheets ...

 

[pradeep.g.belchada]

sanyo micro is not having inbuilt eeprom , parameters are stored in ic606 24c02, try replacing this, and my question is
is dvd stores the last track information. check it

 

[KnutOlafson]

I have made the test you asked - started an DVD, play it for few minutes and "stop". After that I "play" it again and it starts from beginning not continuing from place (chapter) where it is stopped. I have done it few times and it sometimes it continues from same place and sometimes starts from beginning.

It looks like you diagnostics is correct that EEPROM could be the problem.

If you don't have any further tests I can do, I shall try to buy and solder new Eprom and get back here with news.

Thank you very much for you effort.

 

[pradeep.g.belchada]

dvd should store the last track information . when we switch off the mains power and switch on again at that time it should
resume from where it left

 

[KnutOlafson]

@pradeep.g.belchada

Hi!

There was no 24C02 (2k of memory) that is required so I have bought 24C01(1k of memory) - for the test - until 24C02 comes to the store. Same pin-out on both. I have soldered this 24C01 and now I can store my radio stations (You were right and thank you !!!). After I power-off device and power it on all radio stations are there as they should be. In further, while I was closing chassis of the device it was unplugged from power and after powering it again all stations are there. Now, it looks like problem has gone.

Now it looks everything is OK, but is not!
I have two questions:

1) If I keep this 24C01 instead of having 24C02 (because soldering of SMD component is nightmare...) I will have only half of capacity to store radio stations or I have to put 24C02 because this eeprom can be (is used) for other purposes except storing radio stations and dvd information!?? (I don't need 50 radio stations to store, as by User's Guide, 10 of them is quite enough for me)

2) When I have done my job soldering, new problem occurs - I can see any frequency on display I have tuned, and I can store it (because I know particular radio station frequencies in my head) and switch between stations on my remote control, BUT on that particular freq. all I have is "noise" from loudspeakers. Then I took my headphones and the same noise from them as well. It means there is no problem with connecting loudspeakers and AMP part of device. In further, I didn't make any change on the device except of soldering 24C01. Is it possible that having half EEPROM memory I made this problem OR it is irrelevant for emitting radio signal (IC606 - 24C0x is on I2C BUS and other chips are as well)?

Next, what should be a "noise problem" by your opinion ?

Thank you.
Knut

- - - Updated - - -

Just thinking - if LG programmed firmware to write eeprom in continual manner than 24C01 should work as 24C02 should with half storage capacity. But, If they programmed firmware to write data in eeprom in another way (jumping from address to any other address in other half of eeprom memory) than in that scenario (having half capacity eeprom) can be a problem.

For example, If they need to write 2x1Byte of memory in eeprom for one radio station, then they can write that in two consecutive addresses in eeprom, OR can use 1Byte in first half of eeprom memory and another 1Byte to write in another half of eeprom memory.


I cannot have 24C02 at the moment so I would like to check if I can stay on 24C01.... and resolve "noise problem"...

 

[pradeep.g.belchada]

noise can be of weak radio signal. if in dvd also noise presents then their will be amp problem. by the way if you really wants
thank giving then you can press helped me button

 

[KnutOlafson]

Of course, I already pressed button, and now once more.

DVD is working fine, no noise. Just on listening radio over loudspeakers and using headphones. Even FM antenna is plugged in. Btw, there is no radio signal at all, just noise.

 

[pradeep.g.belchada]

but before changing that 24c02 ic the radio was working fine. isnt it.now after changing the ic it gives the problem

- - - Updated - - -

try replacing with same type of eeprom, same manufacturer, same number

 

[KnutOlafson]

As I have described above - DVD and radio was working fine before I have changed eeprom. Only problem was storing radio stations in memory.

Using Service Manual I have concluded that eeprom was from Samsung, model KS24C02

But on that possition on pcb board was, one I pulled out is:
A21SC
J444
...Google doesn't help in finding datasheet for this one...

and I have replaced it with
Atmel 502
24C01A

So, I cannot find original anywhere. Next week I shall try with 24C02 from Atmel or Microchip since it is only I can buy.

 

[KnutOlafson]

OK, problem solved by replacing old with new EEPROM discussed above. All credits go to @pradeep.g.belchada.

But, here is complete story.

As I have told that I shall do, I have bought 2K EEPROM, and only one I could buy was Microchip 24AA02E48, and have soldered it. Nothing ! No sound at all... not even noise at all, too. )

Then I have checked soldering part and couldn't find any of problems. Then I took datasheets of original chip (Samsung) and one I have from Microchip and I have concluded that 24AA02E48 is version of 2K EEPROM that don't use half of pins that are present on it. It don't use A0,A1,A2 pins for addressing and don't use pin for read/write protection. Then, since I couldn't find any other EEPROM ic, I found one of 512K (24LC512) which is for DIP socket and make small and tiny wire bricks and solder it on place (using brick wires) on the place of EEPROM which was SMD socket.

I have turned the device ON and it was working as it should. PINs A0, A1, A2 are soldered to the GND meaning that EEPROM has default address on I2C bus and it was necessary to work.

That's it !