Samsung LA40A650A1F possible eeprom problem

[maxvalutech]

This set previously had no standby voltage but that has been fixed and all power board voltages are correct when set is on. When turn on is activated the red light gives four slowish flashes as is normal the backlight comes on but red light is then blinking very fast with nothing else happening. Remote signals are received and will put set back to standby but no other results.I suspect ic1803 is the eeprom (not certain) and have tried reset but no change. Am now considering fitting new ic and have read elsewhere that the replacement would self program when set activates. ???? No nothing much about this. Main board is BN41 01022d but I can't supply good pics due no suitable camera. Anyone have experience with this model and eeprom?

[grumpy_one]

Re: Samsung LA40A650A1F possible eeprom problem

I have posted recently on that same model and approximately that problem, in this thread:
https://www.badcaps.net/forum/showthread.php?t=38510

Yes, the blank replacement AT24C256C IC should self-program when you power up the set, but it is likely to have some errors, and this will not be corrected by applying the Samygo fix to rewrite the EEPROM contents. I suggest you save a picture of the summary screen in the service menu, to get the type number of the TV - mine is 40A1UFOC, and I expect yours will be the same. Since you are in Australia, you need the Region to be Asia_DTV. I expect your tuner type will also be the same as mine, which is ALPS. Those three were the only setup problems that mine had after it had flashed the new EEPROM, but I did have to carry out a Service Reset to get everything working after manually correcting the three setup items I've listed. The only remaining issue was that the Time was two hours out, but it corrected itself when I changed the Australian state from the default (NSW) to Victoria.

In principle the original EEPROM should not have become unstable without a reason. It has been reported that the usual reason is a defective electrolytic capacitor, either on the power supply board or the main board. I checked the ESR of all of the electrolytics on the power supply, and the only two that were present on the main board, and all were good, so I ended up with no explanation of why the EEPROM had become damaged. Note that on my TV, the setup changed itself frequently - at least daily, sometimes more often - before I replaced the EEPROM, but has never changed since, so I feel confident that the original EEPROM was damaged or had been defective from new. I suggest that you check your electrolytics before you replace the EEPROM, rather than risk getting erratic results if you have a bad capacitor problem.

[syaoran123]

Re: Samsung LA40A650A1F possible eeprom problem

Even if they look fine, i would highly recommend swapping the capacitors on the psu because they will fail sooner or later. I have even seen it where the metal top of one capacitor was shorted to ground.

[maxvalutech]

Re: Samsung LA40A650A1F possible eeprom problem

Hi guys thanks for the info. The set I am working on was a factory second and new caps of higher tolerance were fitted before sale. The original fault was resistors to 5v standby were burnt out possibly from lightning strike in area. There are not any readable idents on the various ICS and I cannot find any info. Have a board same number but diff number on sticker and a number of circuit changes evident. No surd identity yet on eeprom. Have a tcon board coming to see if that will work as not at all sure that eeprom is bad. Will update again but in out hospital next 2 weeks for eye op.

[grumpy_one]

Re: Samsung LA40A650A1F possible eeprom problem

If you decide to focus on the EEPROM later, you'll probably find that it is the one circled in red in the attached picture of the area around the main processor on the main board.

Best of luck with the eye surgery, hope it works out well for you.

[maxvalutech]

Re: Samsung LA40A650A1F possible eeprom problem

Thanks for that info and your good wishes. Just to update while awaiting tcon. Believe now indented eeprom but no luck with pins 5 and 6 short trick. All voltages are good and hold up, backlight activates and stays on, the remote is received, but red light continues fast blinking after initial normal 5 slow blinks. Screen stays black although very light glow seen in darkness. All steps towards a start seem to work OK but just the last step to bring up a picture won't activate. Tcon fuses etc test OK and 12v is on that board.

[syaoran123]

Re: Samsung LA40A650A1F possible eeprom problem

Replace the whole EEPROM chip. I have never got it working trying the EEPROM reset, but replacing the whole chip has worked for me.

[grumpy_one]

Re: Samsung LA40A650A1F possible eeprom problem

I had to replace the EEPROM, not reset it. The Samygo trick (briefly shorting pins 5 and 8, not 5 and 6) is intended to get the TV working just enough to enable you to open the Service Menu, it isn't supposed to fix whatever is wrong. Did you try the Service Menu once you had the raster?

[maxvalutech]

Re: Samsung LA40A650A1F possible eeprom problem

Hi again. I could get the backlight but no indication of anything on screen and fast blinking continued. The various rc entries were tried but no go. However, today the tcon arrived from China and lo and behold the set fired up and after adjusting the screen settings etc it is now running a DVD via av2 and going good. I tried av1 first but got a various coloured vertical stripe about 50mm wide and a third of the way across from lhs. For a moment thought new tcon must be bad as well but then realised it could be the input circuit due to my mucking about over a few weeks. My reason for suspecting tcon in the first instance was this set was wall mounted and left in standby mode most of the time and the original problem of no standby was due to burnt out resistors on the feed circuit so it was likely a voltage surge may have happened from the number of storms we were having at the time. Now all being well I will need a good home for it - last one a 39" lcd went to 86yr old neighbours under the guise of "I need to give this a good test so could you do that thanks" then later "oh I have another I'm working on now and no room so would you mind keeping that one for yourselves". They were using a small set in their lounge and certainly noticed the difference. Thanks again all until the next saga.

[maxvalutech]

Re: Samsung LA40A650A1F possible eeprom problem

To update a too long screw going into main board from back cover caused the AV1 to play up. Replaced it with shorter one and now all OK. No screw there when I got it plus a few others also and with caps changed obvious it had been worked on before. When I asked owner he said no service call when they had it but it was a factory second buy.

[grumpy_one]

Re: Samsung LA40A650A1F possible eeprom problem

I'm guessing a factory second was worked on by a tech of some kind rather than an amateur, and this suggests that the missing screw had been left out for a reason. On the other hand I used to know a qualified radar tech who worked full time for a ship electronics contractor. I noticed that he had a habit of leaving out a couple of screws from the covers of everything he worked on. He said he did it deliberately, because otherwise people sometimes questioned whether he had actually worked on the set.
To me, a missing screw is a warning message, and I take out a corresponding screw from nearby, check its length, and try fitting an identical one to the empty hole. If all works well, I leave it installed. If not, I look into what is going on.

[maxvalutech]

Re: Samsung LA40A650A1F possible eeprom problem

Just a final update to say it wasn't the screws causing problems but the movement of set as put in and taken out. Started getting weird effects on screen set t turning on then off then on etc and all finished up being due to loose wire in connector main to tcon. Firmed this up and taped ribbon down at both ends securely and now all going OK for some weeks.