Error: 140405 Undervoltage

Like I said on other post, two PSUs was one of my mayorn concerns about SC2 Pro to not buy it and go for the Sport. Potential failures x2 (home failures or SC2 failures or both)

@mika reading your suggestions about diagnosis test (testing with only one PSU on the Pro), I have deduced thats NEW safety firmaware is necesary on the Pro, SC2 must know in every moment if both PSUs are running or not.
Imagine that @andre was with one faulty PSU for a long period without issues or thinking that is a HandsOffDetection feature… That would damage the SC2 base?

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That’s a great suggestion @Alfye20.

It would be a reassuring feature to have in True Drive if at all possible.

Perhaps a line of text in the main startup tab, similar to the one that tells us if the emergency stop is released or not. A couple of check boxes that are ticked, showing that each of the supplies are detected?

The hardware does not have means to measure voltages separately.

Hi @Andre, one possibility is that the two PSUs are not perfect matches for each other. I.e. if their voltage output is too much different, then one PSU would get overloaded and shut down on peaks.

Do you happen to have a multimeter which you could use to check the output voltages of PSUs while disconnected from SC2?

@Tero, yes I have a multimeter to test, but I need the pin assignment, so there is no short circuit.

@Mika, i will test this evening after work

Good! Could you measure voltages of both PSUs? Here’s how:

Just avoid any contact with skin and shorting the pins for safety. It’s ~48 VDC on the pins.


@Tero & @Mika
Have tested things:

  • Output voltage of both power supplies 48.63VDC & 48.33VDC

  • Input voltage of both power supplies remains constant at 232VAC in a crash

  • Power supply 1 in the IN1 -> at the end stop quick steering movement -> error does not occur

  • Power supply 1 in the IN2 -> at the end stop quick steering movement -> error does not occur

  • Power supply 2 in the IN1 -> at the end stop quick steering movement -> error does not occur

  • Power supply 2 in the IN2 -> at the end stop fast steering movement -> error does not occur

What I noticed is that in a crash with both power supplies, the LED’s go out and are immediately back.


It could be the case that the voltage difference between two PSUs is large enough to cause this issue.

SC2 draws power from PSU that has higher voltage, so if difference is large enough, then higher voltage PSU faults before lower voltage PSU begins supplying. It would cause chain reaction where higher voltage PSU trips first, then all load goes to lower voltage PSU and that trips too (so both PSUs will be off then).

Perhaps easiest solution here is that we’ll replace one of the PSU’s with unit that has better matching voltage. How does it sound?

I am grateful for any help I receive from you.

If the replacement of the power supply is the first guess of you, then I accept the help thankfully and we can try it out.

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Glad to hear your feedback! I’ll arrange someone from us to handle the case. Lets think overnight whether the PSU swap is the best approach, or do we get better ideas.

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If you are going to swap power supplies it would make sense for you to choose 2 at the factory.
And make sure they are closely matched and replace both to the customer?



Do the power supplies for the SC2 Pro have trim pots that could be used to adjust the DC output voltage like on the SDR-480-48?


No, the brick type PSUs don’t have the trimmers.

@Tero, do you have any news for me?

We’ve got things rolling towards PSU swap :slight_smile: Our support will contact you for arrangements.

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Hi Andre

Please fill in our RMA form to start the replace process. I’ll contact you via email when I have you information.

Kind regards,

Hi Esa,

I completed the RMA form.

Thank you

Hi @Tero,

thanks again, according to TNT tracking, the two power supplies come on Friday.
Hope I can test this right now.
Should I take the base with me to the Expo?

Hi Andre,

We do not have a stand/booth at the Expo, but we will visit there. Testing the system might be difficult in a meaningful way in the conditions on-site at the expo, but please let us know the results with the new PSUs as soon as you can.

The PSUs were delivered yesterday by TNT.
Thanks for that.
After the first test, the error has not occurred.
I will keep watching it and get back to you when needed.

Thanks alot