Samsung corrupt mainboards

[PowerAmpFreak]

Hi all.
I meet once in a while Samsung mainboards which appear to, for some reason, has become non-operational due to some corrupt memory locations.
Some models can be cured by changing one EEPROM ic and some by shorting I2C communication during start up.
BUT, my question is as follows:

One some mainboards there are a couple of EEPROM's, like 24C256, and I wonder if they all will be re-programmed if replaced.
OR, will some of them only be programmed after manufacture of the board?

If they will be re-programmed after replacement it could be worth to change all those EEPROM's and see if it's possible to have the mainboard operational again.

Any comments to this?

[tom66]

Re: Samsung corrupt mainboards

Some EEPROMs are for different parts of the board like the SUB MICOM (older Samsung boards) or the FRC or another chip. Usually only the main processor one would be reprogrammed.

I suspect, since these TVs run Linux, the typical failure mode is corrupted filesystem of the FLASH chip, leading to a "kernel not syncing" error. This could be fixed if the filesystem could be extracted off the flash. A filesystem repair utility could run.

[goontron]

Re: Samsung corrupt mainboards

Some EEPROMs are for different parts of the board like the SUB MICOM (older Samsung boards) or the FRC or another chip. Usually only the main processor one would be reprogrammed.

I suspect, since these TVs run Linux, the typical failure mode is corrupted filesystem of the FLASH chip, leading to a "kernel not syncing" error. This could be fixed if the filesystem could be extracted off the flash. A filesystem repair utility could run.

it could also be a bad ram chip because i have seen the kernel do wacky things with bad ram, yah know, exec of /sbin/init failed!!! which results in Kernel panic - not syncing: Attempted to kill init', but whats worse is when it says 'Kernel panic - syncing:' then you just written your HDD with crap or you tv's flash chip or the fstab is broken...

[tom66]

Re: Samsung corrupt mainboards

Most of them have UART. If I do get a Samsung with a corrupt mainboard, I'll try dumping the debug output to see what it says, out of interest maybe they're fixable. But I haven't had one yet.

[tibimakai]

Re: Samsung corrupt mainboards

How would I know that I have a corrupted mainboard?

[tom66]

Re: Samsung corrupt mainboards

Power supply works, main board doesn't activate PSON/BLON and all power and other circuits appear to be working on main board.

[PowerAmpFreak]

Re: Samsung corrupt mainboards

In some cases, PSON/BLON is going on and off at a constant rate

[tibimakai]

Re: Samsung corrupt mainboards

I had that with a Samsung UN46C6300.

[goontron]

Re: Samsung corrupt mainboards

In some cases, PSON/BLON is going on and off at a constant rate

like the num-lock and caps-lock keys flashing when the linux kernel crashes on a computer?
i have only seen that once, and it was caused by a bad AMD video driver.

[tom66]

Re: Samsung corrupt mainboards

I expect it's more of a boot loop caused by the watchdog. When the kernel fails to load the main Samsung application the watchdog resets the processor.

[PowerAmpFreak]

Re: Samsung corrupt mainboards

So, the only way of repairing those corrupt mainboard is to have access to factory programming jigs and correct FW...

[tom66]

Re: Samsung corrupt mainboards

I'd imagine so.

[Ltank]

Re: Samsung corrupt mainboards

How do you know if the EEPROMS you buy at ShopJimmy have the correct data?

[tom66]

Re: Samsung corrupt mainboards

Trust, honesty...

[wreksta]

Re: Samsung corrupt mainboards

And you can if my info is correct just use blank eeprom the mains board will rewrite the data to it this can cause a short deay with tv trying to power on down to the main reprogramming blank eeprom but should eventualy fire up

ive read a lot about this issue and apperently the above info works

[PowerAmpFreak]

Re: Samsung corrupt mainboards

A couple of days ago I've recieved a number of FOUR Samsung LED-TV's with obviously mainboard problems.
All of them power up OK, but three of them power down once in a while, completely random without logic pattern at all.
The 4th set differs in that it will work perfect in 30 seconds. Then system hangs up and watchdog resets it.
On one of the above units I tried FW upgrade, but that didn't help.
So I suspect some BIG ISSUE with those mainboards.
The models are:
UE46C6005
UE46C6705
UE55C6705
UE55D6537 (this one hangs after 30 seconds)

The top 3 units does probably use very similair mainboards and seriously suspect a problem in the FW, production process

[freakaftr8]

Re: Samsung corrupt mainboards

I have a mainboard that appears to have a bricked eeprom as well. Pn58b650. That one suffered some damage to a voltage regulator that in turn wiped the eeprom. Someone before me was fooling around not knowing what he was doing.
it was doing the power up reset thing. Click click.

[tibimakai]

Re: Samsung corrupt mainboards

These EEPROMs can't be replaced as the Vizio ones?

[tom66]

Re: Samsung corrupt mainboards

Probably not EEPROM but flash. The vizio flashes are in an 8 pin SO8 package which is replaceable, most Samsung use BGA flash, not replaceable without very good equipment.

[sleepingAwake]

Re: Samsung corrupt mainboards

Bringing this back from the dead since I can't start a new thread.

Picked up a UN46c6300sf. Upon power on the relay clicks once.
BL_ON doesn't receive power but all other voltages seem correct.

Seems to mimic the corrupt eeprom issues. I tried shorting the sda line to vcc as suggested by samygo forums but hat didn't work.
Purchased another main board on eBay that was supposed to be good but all the 5.3v pins are shorted to ground. I realized it immediately as the relay starts clicking like mad the instant it's plugged in.

Has anyone every found a schematic for these boards???
I'd love to be able to repair mine butthe time involved in trying to figure out the circuit is ridiculous.
If anyone has a working one for sale for under $75 I'd be interested as well.