Problem with megatronics 2 electronics

I don't know where to start with this request for knowledge for a problem I have, if this is the wrong area, I am sorry.

I have a 300mm machine from a company that folded during start up. It is off the shelf parts and I can do great printing work on it. It was made by Indimension3d it was a prototype of the failed Ideator12.

I have many hundreds of things printed on it. Recently I started having problems with it. It was skipping steps on the Z axis, after going thru all the mechanical possibilities, I found that one of the pololu stepper drivers on the megatronics 2 board was bad. I switched it out and was back in business with no more z skipping. However, I now think that was a symptom of the actual problem (that I do not understand).

Here is the symptom of the problem that I see while it is running: randomly, the interior lights dim slightly and the steppers change noise when printing. It seems to be running out of power, or has a loose connection. In the spirit of trying something even if it is wrong, I installed a new power supply. That did nothing.

I have checked every connection I can and found nothing loose or causing a change. So because it seems dirt simple, I am looking at the Megatronics board and replacing it, still in the spirit of throwing parts at it until something sticks.

It looks like I could get one for under $40 bucks. I should be able to swap it out mechanically and get the jumpers and connections done, but my knowledge flat spot includes where the software to let it know that it is a printer and not a toaster lives. I am thinking I need to get it off the current board, and load it onto the new board.

I may be jumping ahead, is it something simple?

If anyone has suggestions on how I can stop the flickering and stepper noise changes, it would help me out a lot. Thanks for reading this, Ken

I would start by posting a video on you-tube and attaching a link here.
It will be a lot easier to determine whats wrong if we can see and hear whats going on.

Roberts clif,

I will get a shot on youtube as soon as the issue returns. Usually when printing ABS with a hot enclosure and bed, after a few things. I am using PLA right now, and it seems fine. I was thinking about it possibly being heat related so I got out my thermal imager, scanned the enclosure and found a couple of hot spots.

One hot spot is the Z axis pololu drive. It has been as hot as 280° f. and there is another component on the mega board running at about 135°f that seems to be related to the hot driver. I am attaching photos of them and a shot of the board with a conventional camera.

I will try spot cooling the area when the problem returns.

I may try and turn down the pot on the hot driver to the point it still barely functions and re-thermal it, once the current print is done.

They have heat sinks you can buy for the Stepper motor driver chips. I would put a 60mm fan to help cool the controller parts.
The stepper motors drivers have a current adjustment that can be made this may allow for a reduced current to help keep them cooler.

Edited 3 time(s). Last edit at 08/13/2017 08:00PM by Roberts_Clif.

Roberts clif,

I tweaked the current adjustment down until the z axis still ran, just barely, then increased slightly. (seat of the pants adjustment) and the next thing I printed showed a thermal image of 150° f with no dimming, missed steps or other issues. I also spotted another very hot pololu drive on the Y axis and backed that pot off too, while the machine still moved well.

I hope this does the trick.

I will take your advice and add a fan.

Another design flaw of this machine is that the electronics are inside the enclosure without any dedicated cooling. While the prints look pretty because of the stable temp, I think I need to move the electronics out and add fans.

My 3D Printers came with 4 TO220 case stye IC's Mosfet's and 5V Regulator only had a heat sink on the 5V regulator, added to all and included all A4988 Stepper Drivers,
Designed a 3D Printed Snap together Controller case with Fan, the cooler I keep the Controller the longer they should last.

Edited 1 time(s). Last edit at 08/16/2017 09:18AM by Roberts_Clif.