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[GUIDE] Flash BIOS with CH341A programmer

CH341A details

This guide is based on the winbond 25Q64 bios chip.

Special thanks to Lost_N_BIOS for your help.

CH341A programmer:

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PINs details:

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PIN 1 on the BIOS chip:

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If you receive this error(s) with the CH341A programmer connected to bios chip:

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This error(s) is caused by the bad connection of the clip or by the wrong software version.

Try the following steps:

Exit form C341A software.
Disconnect ch341a programmer from USB.
Disconnect the test clip from the bios chip.

Connect the test clip to bios chip.
Connect ch341a programmer to USB.
Run C341A software.
Press detect button.


Please try another software version.

Under construction Smile


Download  here the CH341A tools (Thanks to Lost_N_BIOS)

Unzip the downloaded pack and install the ch341a drivers (run CH341PAR.EXE)

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Remove CMOS battery from your motherboard.
Connect the test clip to bios chip.
Connect ch341a programmer to USB.
Run CH341A_c.exe from CH341A programm v1.29 folder.

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Go to "Auto" and uncheck "Erase" and "Blank check" options:

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Press "Read button" and wait until the process is finished:

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Now press "Verify" and wait until the process is finished:

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Attention, before continuing with the PART 3, please check the content of the backup file.

You can compare the backup file with the original bios file from manufacturer site, using one hex editor software.

The contents of the files is not the same but it is very similar.

Lost_N_BIOS Wrote:Run read, then verify, once it says "Chip/Buffer match" then that is verified, click save and then open that file in hex editor and make sure it's valid BIOS and not all FF's.

If it is all FF's, that's verified invalid blank and you need to use another software version or CHIP ID and try again until you get verified and valid backup).

Lost_N_BIOS Wrote:Then install driver in above package. Then open software of your choosing to try first, I already try newest version first. Hit detect and if it detects your chip by ID OK, then select that one. Sometimes you might need to choose less than full ID, or different than ID too, like BIOS ends in FV sometimes BV works better, but you'll figure that out later if it comes to that. Once you've done that, hit read and when it's done hit verify. If it verified good, then you hit save BIOS. Verify after reading it should tell you chip and buffer or memory match, then that is possibly a good verified file (not always). Open that file in hex editor and make sure it's not all FF"s. Then repeat that a time or two and compare those two verified files, if they're always good files and match then probably OK. Save this BIOS somewhere safe as backup. Make sure it opens properly and looks correct in any BIOS editing tools you are familiar with too, then you'll know it's OK.

Backup file examples (OK and wrong):

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After checking and saving your backup press the "Erase" button and wait until the process is finished:

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Now press the "Blank" button and wait until the process is finished:

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If the next window appear, when you press the blank button:

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Lost_N_BIOS Wrote:Chip Main Memory Not Null = this means you erased (Should be all FF) and then ran blank check and it found not all FF's (Some other data still) so erase not complete. Also will say that if you do not erase, and just run blank check when you know there is data there.

Possible solution:

Please Re-Erase chip and check Blank again OR use another software version.

If it does not work, you can try this (You can use a heat shrink tube.):

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If the "Chip Main Memory are blank" message appear, you can continue with the next step. Press "Open" button and find your new bios file:

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After the new bios file is opened press "Auto" button and wait until the process is finished:

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Thank u for that nice Tutorial u made.

I have an Asus S56CB Notebook. The Notebook will start but it just flickering some LEDs. So i thought its a BIOS Problem. Flashing by USB wont work. I Ordered a EEPROM Programmer and made a dump from the actual BIOS -> It worked. But, If I write the now BIOS that i download from Asus the Notebook wont do anything if i push the powerbutton. If I write back the dump i made -> it will power on but the LEDs are flickering. I think its the VGA Chip what broken. But why will it not turn on with the BIOS i downloaded from the web?

Do I need to modify the downloaded BIOS from ASUS that i can write it to the Chip?

best regards
Upload a copy of your BIOS dump and I will make BIOS for you to write with programmer, you can't just write BIOS from download because it's usually only a partial BIOS from Asus. Hopefully you verified it was a good valid dump before you wrote anything (ie made sure it was BIOS not simply failed dump all FF or 00)

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