Low Voltage Detected

[Dr. Ricky]

Setting up an AxiDraw V3/A3 for the first time. I am in the US, plugging into standard power, and a MacBook Air with a USB-C to USB-A dongle. macOS Big Sur, Inkscape 1.1. Plug in the power, and green light comes on, and the stepper motor activates as it steps through a continuous cycle. Plug in the USB cable, and I try to do the AxiDraw Control extension to just check the pen up/down – get the error “Low Voltage Detected”). I checked the power supply and it seems to be the right one. Very baffled.

[Windell Oskay]

You say that “the stepper motor starts moving”, but can you please tell me if the XY movement of the machine is working correctly?

It is possible that the power supply is indeed producing a low voltage — if that is the case, then the power supply may indeed be failing (In your other message, you indicated that this is an older unit, and power supplies do sometimes fail), but then we would expect that the stepper motors are not moving correctly.

If the XY motion is working correctly, then it seems like the voltage sensor is not working correctly. If so, there is a hidden setting to disable the check, which will suppress the warning message. Please let me know what the situation is, and we’ll go from there.

[Dr. Ricky]

Thank you. How do I test the X-Y movement of the machine? I really haven’t gotten past that first step. What I am calling the stepper motor could be wrong – I am referring to the little white plastic arm right at the pen holder (controlling the Z axis). That starts moving as soon the power is plugged in.

[Windell Oskay]

*That* may actually be the problem. The white plastic arm is driven by the pen-lift servo motor, and it should not start moving when the machine is first plugged in. The pen-lift servo motor is a component that wears out over time, and buzzing when the machine first turns on may indicate that it is not working correctly. When it fails, it can sometimes draw excessive current, producing a low-voltage warning.

I would recommend to follow along with the AxiDraw User Guide for the general steps towards making your first plot, including testing to see if the pen lifts up and down correctly, and if it can make a plot correctly. If it does not move in XY when you try to make a plot, then try disconnecting the servo cable, and see if that makes a difference.

[Dr. Ricky]

Is there a way to repair the pen-lift servo motor? It isn’t buzzing but it *is* moving immediately. I cannot get past the low voltage warning to follow along the rest of the User Guide.

[Dr. Ricky]

I’ve been following along the PDF of The User Guide p 12 Section 2.3, which lists “The pen-lift motor cable and the pen clip are disconnected for shipping. Your first two steps, out of the box, are to re-attach these parts.”

But there are no actual directions for connecting the pen-lift motor or how to replace the pen-lift motor in the guide. It skips directly to attaching the pen clip.

[Windell Oskay]

Moving _once_ when power is plugged in, but not buzzing, does not suggest a problem, with this version of the controller board.

Can you please clarify why it is that you cannot get past the warning? It’s a warning message, not an error, and does not prevent anything else from working. If it’s just bothering you so much that you cannot get past it, then let’s temporarily disable that warning, so that you can move along. Otherwise, just ignore it for the moment.

You are correct that there are no directions in the user guide for connecting or replacing the pen-lift motor.

The “first two steps” are connecting the cable and installing the pen clip. That is why the directions there are for how to connect the cable and install the pen clip.

[Dr. Ricky]

My apologies, there’s a misunderstanding. What I meant by not getting past the warning is that every operation goes back to that warning. So I can’t seem to do anything else past it. I suspect you’re right that the pen-lift motor is the problem, as it isn’t moving just once but continuously in a jerky fashion. I’ve gone on the website and ordered a replacement motor but it seems that they’re not yet in stock for a while.

[Windell Oskay]

That warning does not prevent you from doing anything – it just reports that a low voltage was detected.

Can you please check to see whether XY motion works with the servo cable unplugged?

[Dr. Ricky]

To test this, I unplugged the servo cable (3 wires, black wire closest to the edge of the “Home” module). When I plugged the USB cable back in, there was a green light on. With the power supply plugged in, the blue pen lift motor didn’t move this time.

I went back into Inkscape, and pulled up Manual Control, went into Enable XY Control. When I hit Apply, the low voltage warning came up.

I tried to walk the carriage in either X or Y directions, but only got the low voltage warning. It didn’t actually move.

[Dr. Ricky]

I did check the firmware, and used the UpdateEBB app to update the firmware to the latest version 2.7.0

[Windell Oskay]

If that test was with the cable still unplugged, then this does seem like a power supply issue then; I’d recommend to replace the power supply.

[Dr. Ricky]

Yes, the servo cable was unplugged. Do you recommend a source for replacing the power supply? I think I found the thread with the specifications and can try to locate one locally.

[Dr. Ricky]

Oops, I just found the replacement power supplies listed, and ordered one. Hopefully it’ll work. I’ll keep you updated when it arrives.

[Dr. Ricky]

I just wanted to update everyone on the resolution of this problem. Turns out that the EBB board itself was the problem. The folks at EMSL let me order a new v2.6 board (turns out the original was v2.3), and I replaced it. A firmware update run, a new micro-USB cable – and the machine now responds to commands in Inkscape.

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