DX4000: Reset BIOS/CMOS

Hi, guys I made a connection to J23 and it does work good. So, I made an update to bios screen to 1024x768 from 800x600 then save and made restart. and it always stuck in A2 bios code. even I tried to press reset button and it does nothing. What can I do to clear BIOS/CMOS memory?


Only as a matter of curiosity: what do you mean for J23? thanks


J23 is an output port used the serial connection (like UART) on the mainboard.
Pinout is VCC, RX, TX, Ground.
Like shown here: http://cytekpr.com/index.php/2017/04/13/dx4000/

          |                       |
     J23  |   Vcc   RX   TX   Gd  |

Serial connection act just like SSH. Thanks

Interesting, so you managed to access BIOS via this serial connection, and once modified the resolution everything got stuck correct? What did you use to connect to the J23, standard PC?

J9 is the CMOS reset jumper. The pins are probably not installed on the PCBA.

Not sure how to insert a picture here but, there’s a single aluminum electrolytic capacitor just to one side of the smaller heatsink on the component side of the board. In the space between the capacitor and the heatsink, is J9. It’s marked on the board.

You can solder a 2 pin header there, or better yet, a right-angle 2 pin header on the back of the board for easier access. Then just push a jumper onto the 2 pins and that will kill power to the cmos memory. For the soldering phobics, you can short the two pins with the tips of a pair of tweezers on the back of the board.

I don’t know the procedure, but I expect it follows a standard motherboard practice. I have some dim memory that you install the jumper, then power up and the bios sees that cmos lost power and checks the jumper state and then reinitializes cmos with default values. Remove the jumper, power down and back up. Sorry, I’m not a motherboard expert. I could be wrong.

Edit: I looked up the cmos reset procedure in the ICH9 spec and it appears that with the power completely disconnected from the unit, you put a jumper on jp9, leave it there for a few seconds, then remove it and then reconnect power to the unit.

You must completely disconnect power from the unit, not just that it’s “powered down”, as many of the internal supply voltages are still present as long as the power supply brick is connected to the DX4000.


Hi every one, I’m also in th same case: stuck after changing the resolution in the bios.
the error message is:
ERROR: Type:2; Severity:40; Class:3; Subclass:0; Operation: A
I’ve dumped the bios and opened it but there is almost nothing in it, looks like it is corrupted.
I’ve passed a lot of time looking for that bios version to download, I think the only solution is that someone dump his bios and share it.
Did someone has found another solution?
Can someone please share his bios dump?
The chip is U26 Winbond W25X20BL


hello, I think I have a problem with the resolution, the bios screen stays on A2, did you find a solution?


i have same Problem too, and J9 not do anything, when i short just can not turn on and after remove come same as last, and cmos not cleared,

anybody tested another graphic card like as PCIe (by x1 to x16 Riser) or USB3 graphic for this A2 Problem?


i chech this Way but the PCIe in the board not PCIe as normally and when connect the Riser porn the board not powering on

this is not bios clear pin or not working i do every thinkable short pin but CMOS not changing , i release battery for many days and short all capacitor in the board also, nothing

J9 is definitely the cmos clear pin. The problem here, is that when you change the setting for the screen resolution, that is not saved in the cmos memory. It is programmed into the bios flash chip. No amount of resetting the cmos, will fix that.

The only solution, is to re-flash the bios back to the state before you changed the resolution setting.

The only way that I know how to do that, is to remove the bios flash chip from the circuit board and re-flash it with a good copy of the bios using a flash programmer.

Update here: Since I have a board with a socketed bios flash chip and I can easily re-flash in case of disaster, I decided to try all of the possible display resolution settings. The only ones that I found do not result in the dreaded A2 error or otherwise didn’t work were:

800 x 600
1024 x 768
1280 x 600 (actually the monitor claimed it was 800 x 600)
1280 x 800

So, don’t try any other resolution unless you have the means to reprogram the bios flash chip.

Thankyou User000001 for your Information, ok i got it, When we change resolution and save this will be copy to flash chip and can not clear the Coped data, ok
can you help us which one is flash chip and how to find the Bios image File for re-flashing?
and also for programming again we need which model programmer Board?
and Which Resolution is Stable?
Thanks Dear for your guide

The SPI serial flash chip for the bios is shown in the picture below:

The best place to get a good copy of the bios, is to save it away before doing anything that may cause the so-called A2 issue. If you copy from a different system, there are a number of custom settings that will not be correct for your system. For the most part, those settings will not cause a problem, but you never know. These settings are: WD Model#, Serial Number#, Number of Disks, etc, etc. If you try reinstalling the original OS on the DX4000, these settings may cause issues.

The most popular (and very inexpensive) programmer for the SPI serial flash chip is the venerable CH341A of which there are many different manufacturers. I have no direct experience with this one, but it comes highly recommended, as it can be had very inexpensively (~$13).

Only the 4 resolution values 800 x 600, 1024 x 768, 1280 x 800, 1280 x 600, would work for me. Once you have a programmer, you’re free to experiment with any resolution you like, since you can easily revert to the original.

Thanks Dear USER000001
For CH341a V2.2.0.10 Read IC
Bios Editor Tool

Dear User000001 , if you have 25L1606E bin file , please Share, Because i change the LCD Panel Type Resolution and save, and Write to chip, But actually same A2 Problem

i think i have another config problem or when change the resolution in flash chip this not change in system board

Sent link to bios, by PM 1 week ago.

Dear User000001,
Is that possible to share the MX25L1606E’s bin file to me?

Thanks in advance.

got trouble,i need your help.send the bios ,pls.