Mulja tv repair portal
Equipment Repairs => LCD TV forum => Topic started by: df8oe on April 07, 2017,03:20:04
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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
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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.
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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
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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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Which programmers are you using
Was looking into this for samsung eprom/s
Was looking at getting the TNM 5000 Programmer.
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I use this one:
http://www.embeddedcomputers.net/products/FlashcatUSB/
Greetz
Andreas