Author Topic: NAND Flash worn out  (Read 197 times)

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df8oe

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NAND Flash worn out
« on: April 07, 2017,03:20:04 »
Hi folks,

I figured out many LCDs using Vestel-based boards with "only blinking LEDs" have worn out NAND flash chips. If power supply is working well (no capacitor problem) NAND flash is main problem. I unsoldered NAND128W3A from Vestel 17MB70 which normally should have 16MB capacity but when reading it with a NAND programmer it shows nearly 5MB bad blocks! Some mainboards do have one big NAND, some do have two (one big and one small)...

My question is: Has anybody tried to swap faulty NAND with a brandnew (empty) flash and tried a firmware update via USB? Is that possible or is bootloader which starts USB update located in NAND, too so that using a new (empty) flash update cannot start? Because of it is TSOP48 package I do not want to try without need....

Greetings
df8oe

Mulja tv repair portal

NAND Flash worn out
« on: April 07, 2017,03:20:04 »

michael first

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Re: NAND Flash worn out
« Reply #1 on: April 08, 2017,17:55:01 »
Hi,I tried another method,i.e.to use the programmer to write the spi flash with the file usually employed via a USB dongle.

Unfortunately,the result was deceiving,it didn't cure the fault.

df8oe

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Re: NAND Flash worn out
« Reply #2 on: April 10, 2017,07:16:42 »
I have tested following:

- desoldering big NAND from two boards (one working and one not) and swapping them to the other. esult:
Now the former dead board was working and the former working one was blinking...

So it is guaranteed that fault *is* NAND flash.

But you cannot easily flash a file..... Big NAND contains two different parts:
1) a binary part which consists of the bootloader and some I/O stuff
2) a file system which is damaged.

You cannot copy a filesystem using dd or a bytewise copy because of you copy whole bad sectors list of old NAND to new one running this way.

I figured out that at USB update for my device there exist a file named sysinit.txt comtaining a line
setenv -p FIRST_BOOT 0
so my idea is that only bootloader and I/O stuff must be transferred to new NAND and then you must walk through an USB update with setting this variable to "1". I hope that a new file system is created on brand new NAND and all neccessary files where placed ther during update. I will test this next time.

Greetz
df8oe

Mulja tv repair portal

Re: NAND Flash worn out
« Reply #2 on: April 10, 2017,07:16:42 »

tv tony

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Re: NAND Flash worn out
« Reply #3 on: April 11, 2017,09:59:49 »
You seem keen to resolve this but the interest shown on here does not seem to be fothcoming. But over the last few months I have been experiencing events similar to yours. I bought two high end programmers and got myself  a few free nights but got nowhere. Ill dig out my notes.
Tony Walker
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zomikula

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Re: NAND Flash worn out
« Reply #4 on: April 11, 2017,12:36:54 »
Which programmers are you using
Was looking into this for samsung eprom/s

Was looking at getting the TNM 5000 Programmer.

df8oe

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Re: NAND Flash worn out
« Reply #5 on: April 12, 2017,11:47:18 »

Mulja tv repair portal

Re: NAND Flash worn out
« Reply #5 on: April 12, 2017,11:47:18 »

 

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