Do Not Power Off - SCAN loop (quick fix)

[Lapwing]

39" E-motion LCD TV
Model: 39/66G-GB-3B.FTCU-UK.

This had the fault of getting stuck on the "Do not power off" "SCAN" loop each time the tv was turned on.

I was all set for replacing a corrupt eeprom after reading various posts here and via google. So i had the tv apart to write down the board numbers and to give it a good visual check over.

Everything looked fine. Anyway while i had it apart i thought i would give the eeproms and the SMD components around them a minute or two blast with my heat gun.

I remembered that years ago this fixed an eeprom issue on a cable tv STB. ( stuck on TUNE )


Its been two days now and the tv starts up every time as it should. Everything else with the tv works as it should also.

So, worth a try for a quick fix before you order a new eeprom.

[tom66]

Re: Do Not Power Off - SCAN loop (quick fix)

Won't be permanent. Flash memory is affected by heat, what's going on here is they use cheap flash memory with poor data retention. It will just die in a few weeks.

[Lapwing]

Re: Do Not Power Off - SCAN loop (quick fix)

It's my old man's tv so i will definitely report back if/when the error returns Tom.

I have a question, if the eeprom is corrupt and that is why they get stuck in a SCAN loop and we need to buy a pre-programmed chip, then how did this eeprom work again ?

[tom66]

Re: Do Not Power Off - SCAN loop (quick fix)

It's not an eeprom, it's an SPI serial flash which although also a memory device operates differently. It stores the software for the TV's operation. When it gets corrupted the TV software misbehaves. Heating it up is hiding the corruption, which might only be on a few single bits.

[Alastair E]

Re: Do Not Power Off - SCAN loop (quick fix)

While its still functional--Is it not possible (Somehow!) to maybe remove that SDI, Read its contents and then flash a quality replacement with the code?

[tom66]

Re: Do Not Power Off - SCAN loop (quick fix)

It might be possible, but the OP would need an SPI flash programmer.

[Lapwing]

Re: Do Not Power Off - SCAN loop (quick fix)

An interesting development.

If you so much as nudge the tv, the Input Source menu will appear and the tv will scroll up and down the Source list in a random fashion until it sees fit to select one.

Same thing if you touch the HDMI lead or plug anything else into it like headphones or scart.


About the SPI flash programmer. I have a few old (very) programmers somewhere.
I have found this LPT thing, iam sure i used this to read and write eeproms a million years ago

[flocko]

Re: Do Not Power Off - SCAN loop (quick fix)

That would be the random uses of the heat gun on the main board coming back to haunt you spooky! Flocko

[Lapwing]

Re: Do Not Power Off - SCAN loop (quick fix)

Just having another look at this today.

I think this might have something to do with the spooky goings on with the source menu.

The wires from the Buttons PCB. It was laying across a screw hole when i opened it up.

My fault i think

[SteveNielsen]

Re: Do Not Power Off - SCAN loop (quick fix)

Had it been worked on prior to the initial problem?

[Lapwing]

Re: Do Not Power Off - SCAN loop (quick fix)

Ok...... it was my fault

The quick fix is still fixed though

[steviewonder]

Re: Do Not Power Off - SCAN loop (quick fix)

Bit of a old thread,But can confirm the above trick works.Have done a few of these with the slanted scanning issue,and no sets have bounced.
Interesting fix for sure!

[4cc3ss]

Re: Do Not Power Off - SCAN loop (quick fix)

Myself came across 22" logik tv with do not power off - scan from plugin, it was hit or miss to skip this check.
i resolved the issue by applying 470uf 16v cap across the eeprom Vcc and Vss, up to now
it hasn't scanned, i'm not saying this is a final fix but seems to work for now.
I have no doubt the eeprom is corrupted and cap is acting as a filter.

Regards
4cc3ss

[liam]

Re: Do Not Power Off - SCAN loop (quick fix)

Had this problem with a 40" Technica LCD TV.. Continuos scan loop, could not enter menu,. nothing but nothing worked for me. Had to buy a second hand main board for TECHNIKA LCD40-270 40" LCD TV (T.MSD306.8B-2 11164)..
Got this on ebay for under £15.. A cheap fix.. working perfectly..
Regards, liam

[ocf]

Re: Do Not Power Off - SCAN loop (quick fix)

Any more ideas guys?

[Mikeyboy2007]

Re: Do Not Power Off - SCAN loop (quick fix)

i resolved the issue by applying 470uf 16v cap across the eeprom Vcc and Vss, up to now

Hi have you got a picture ? Cant find datasheet to find out what legs are Vcc and Vss ? Its a 32 inch Logik i have with same issue.

[Th3_uN1Qu3]

Re: Do Not Power Off - SCAN loop (quick fix)

Here you go:



It's a standard pinout for all SPI EEPROM chips. Vss = ground, pin 4, VCC, usually 3.3v but there are some 1.8v ones, is pin 8.

[Mikeyboy2007]

Re: Do Not Power Off - SCAN loop (quick fix)

So 470uf 16v cap across Vss to Gnd ? Im guessing negative leg goes to ground ?

[Mikeyboy2007]

Re: Do Not Power Off - SCAN loop (quick fix)

Here you go:



It's a standard pinout for all SPI EEPROM chips. Vss = ground, pin 4, VCC, usually 3.3v but there are some 1.8v ones, is pin 8.

So 470uf 16v cap across Vss to Gnd ? Im guessing negative leg goes to ground ?

[Th3_uN1Qu3]

Re: Do Not Power Off - SCAN loop (quick fix)

Vcc to GND. And yes negative of cap goes to ground, because VCC is a positive voltage.