I have the same problem with my M4. I sent e-mails to Mini-Box and finally received a reply. I've posted my e-mail and their reply below. and if I've done it right the new firmware should also be attached. I haven't used the new firmware because I found ways around the problem before they responded, but the M4 working correctly would definitely have been best.
Originally Posted by timmay33
(e-mail from Mini-box 5/18/2011)
Thank you for contacting us and your interest in our products! We are sorry for the late reply. Have you tested another timing mode and see if you can change the thump timeout? Can you please reset the power supply? Just in case, i have attached the latest firmware for the M4-ATX power supply. Looking forward for your reply.
On Thu, 28 Apr 2011, xxxxxxxxxxxx wrote:
> Hello, I've been using an M4-ATX for over a year and have always had a
> problem with the timing of the anti-thump feature. I sent an e-mail
> last year but never received a response. I'm hoping you may have a solution now.
> The problem is, I'm not able to change the timing for the thump timeout.
> When the ignition is turned on the anti-thump signal is sent at 3
> seconds, then the PC is turned on at 5 seconds and I get a loud thump
> through the amplifier. The configuration software appears to be
> working because the values I enter for the delay stay in its
> configuration even after shutdown and I can also see the voltage and
> temperature readings in real-time. I've tried numerous values for the delay without any effect on the actual timing.
> I've also tried setting the value and then removing power without any
> success. I have the 2.1 version of the firmware. Is there anything I
> can do to make the anti-thump delay change?