DX4000: Reset BIOS/CMOS

#1

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?

Thanks

#2

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

Davide

#3

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/

          |----0----0----0----0---|
          |                       |
     J23  |   Vcc   RX   TX   Gd  |

Serial connection act just like SSH. Thanks

#4

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?

#5

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.

B.