Faulty Reset Switch

+Just installed my new 3D Mini replacement for my K40 Nano controller.
Unit does come up but is randomly resetting and losing computer connection. Looks like the RESET switch is bad on the board. The PLAY button has a nice “click” on push but the RESET does not push in and is loose. RESET does not “click” . If I jiggle it, the unit boots and will stay on at times, but when the motors move it resets again.
I am a long time Engineer and certified solder tech. If you can just send me the switch, I will gladly replace the bad one. I would already have done that but I do not have any of the right-angles switches. I have some orders to get out so thought this would be a quick swap ad setup. Please send switch or we can swap boards, as fast as possible. If it will take more that a few days, week, to arrive, I I may pull the switch and mount an external one unit the correct one arrives.

Don Loocke

Hi Don,

Welcome to the forum! I’m checking on possible alternatives for your C3D LaserBoard and will get back with you soon.

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First, we should confirm the cause of the “randomly resetting and losing computer connection” before we go tearing into the board, as this can be caused by many things.

I would recommend grabbing a multimeter in continuity mode and metering the 2 pins from the reset switch on the bottom of the board to see if there is continuity even when the switch is not pressed.

It may help you to visualize that we want the 2 top pins here, as the lower ones are just part of the mounting body.

There is also a header directly behind the switch so that you can hook up a “big red button” in its place - you can also meter these to see if there are the same behaviours here.

Please let us know what you find so that we can advise on next steps.

I have done all of that and more.

Also Visibly inspected the solder joints and they look fine. This switch should have a tactile “click” when pressed, just like the adjacent PLAY button, and it does not. It has no spring force to keep it open and has room to move around. Does not looked damaged, just a bad switch.

I have been able to get it to be stable long enough to have the K40 boot and home correctly. LEDs look correct. The GLCD comes up and is functional. Lightburn connects and is ready to run.

But once I have Lightburn start raster gcode, it does not get far before it randomly resets the board due to the k40 case vibration. I can hear the PC dropping/connecting the USB connection, as well, and Lightburn drops the connection to the board.

Attached is a short video. The board is mounted on its frame but not bolted yet. You hear me tapping on the panel and can see the status leds. I also tapped the reset switch and no clicking but you can hear the click of the play switch at about 00:32 point. Hope this helps.

It is for sure this switch. I can send a short video if needed.



I was not able to attach the video

Hi Don,

You can post the video on YouTube or another site, then paste the link into a reply here.

Please let us know the results. Is there continuity even when the reset switch is not pressed? What about for the header directly behind the switch? That will give us a direction to take for next steps.

We are interested in getting your board up and running first, then we can work out whether to swap or have you fix, etc.


How fast are your running the machine? The default settings in the configuration file are set optimistically, so they may need to be lowered to minimize vibration, as well as slowing the speed on the file you are running.

The stock blue USB cable which comes with most K40 lasers is known to cause communication issues due to poor quality and should be replaced. We recommend using a higher quality cable if you aren’t already.

Hi Don,

Any luck with this?

Mini with Bad RESET switch

Here is a video. I put a 2-pin lead on the pins next to the RESET switch and tied to my VOM. You can see the voltage from 3.3V (not in reset mode) to 0.0V (RESET).
The button in the switch is lose and has no tactile feedback.

Have wasted a week on this and need to get this running. If I can remove the switch, that will let me run. I am a 35-yr certified Tech/Engineer. I think I can handle that. I do not want to solder on the board and void a warranty but if not running soon, I will have to put the old board back in the unit and run K40 Whisperer again.

Thank you for providing the link. The YouTube video is set to private.

If there is constant continuity, or you can cause it to be intermittent by jostling the body of the button please read on:

We need the reset button to not have continuity (i.e., it thinks it is pressed, but it needs to not be pressed, at the electrical level inside). You can disconnect or remove the one that is there now. Clip the leads to that and desolder them afterwards, one lead at a time, with no switch body in the way.

There’s a header behind the switch that you can hook an external button to, or simply don’t, since reset is not something that is typically done commonly, and a power cycle by disconnecting the power brick would have the same effect.

If this is acceptable for you, let us know. Otherwise, we can make other arrangements.

I reset the video to public.
The switch is not staying open. it is bad. I will remove it tomorrow.
Since this is a normally open switch, it should run fine and not go into reset when not pressed.
I can add an external NO switch for an E-Stop function, if needed, but for now it will work fine.
Please send me a new switch so I can replace it at some point and put the board back in as-new condition.

I removed the bad switch from board. Switch is still bad but board seems to be working fine now without it, as expected No more random resets and no vibration issues. X/Y travel is working well and can run Lightburn.

NOW Chasing a new problem.
Laser test fires manually, but not under PWM control from L/G signal. I followed another repair process from the board but shorting the L/G lines at the PSU does not fire laser either. So I have ordered a new CloudRay Power supply and will receive it on the 17th and install the new PSU and Mini controller again.

For the short term, since I was running on the old setup just fine, I am removing the Mini board and going back to Nano so I can ship orders this week.

Hi Don,

I will try to find some switches to send you when I am back at HQ - unfortunately it slipped my mind when I was just there. I should be back there within a week.

Thank you.

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I have left these for our shipping person to send out shortly.

If you have any further issues please let us know.

Thank you.