Unable to heat Stepstruder MK7 in Thing-O-Matic due to Safety Cutoff (Rev. D) fault light

Unable to heat Stepstruder MK7 in Thing-O-Matic due to Safety Cutoff (Rev. D) fault light

Habstinat 04 Jul 2012 01:14

I have just recently finished assembling my Thing-O-Matic MK7 Makerbot with the Safety Cutoff Revision D board. When turned on and used with ReplicatorG, I am able to move the axes and even run a few Makerbot Music pieces without any hiccups. However, I run into problems when trying to heat the Stepstruder MK7 and the Automated Build Platform (more specifically, just the Stepstruder MK7).

My Safety Cutoff board has two LEDs: A green light and a red "FAULT" light. When I first turned on my Makerbot (directly after completing building it), the green light was on and things were A-OK. I was successfully able to heat both the MK7 and the ABP to 50 degrees celcius. However, after moving a few axes and/or leaving it on for a bit (I couldn't seem to pinpoint the exact spot), the green light switched off and the red fault light switched on. From that point forward, I was only able to heat the ABP; the MK7 was staying at room temperature. After rebooting the machine on separate days, the green light was always on at startup, but after a few minutes the fault light would seemingly randomly switch on, leaving me unable to heat my MK7. I haven't attempted any prints yet.

As of today, however, the fault light turns on and the green light turns off every time I boot the machine right away, under any circumstance. The green light briefly flashes on and off once, then the fault light turns on instead. This is kind of worrying, as it stops me from heating my Stepstruder MK7. What can I do to remedy this?

Thanks for any assistance provided.

Re: Unable to heat Stepstruder MK7 in Thing-O-Matic due to Safety Cutoff (Rev. D) fault light

Jetguy 06 Jul 2012 15:32

The black thermal switch is what shorts out the circuit making the light green. If the black switch wires are not connected or the circuit is open, then the red fault light lights up. The other possibility is your solder joints on the board.

Again, things that cause this in order:
1. Black thermal switch not mounted per directions (it trips a temp that is lower than the normal 225C of the head, so it must be thermally insulated such that it doesn't get that hot under normal conditions per the directions)

2. Bad wiring of thermal switch

3. Bad solder joints on the cutoff board.

Common sense test says to replace the thermal switch with a short wire across those 2 terminals and see if you get a green light (do not print or heat without a thermal safety switch!!!)
Process of elimination after that.
http://wiki.makerbot.com/forum/t-368865

Last edited on 06 Jul 2012 15:36 by Jetguy Show more

Re: Unable to heat Stepstruder MK7 in Thing-O-Matic due to Safety Cutoff (Rev. D) fault light

txoof 23 Jul 2012 07:36

I had a similar issue that I eventually traced back to a faulty thermostat (the black sensor). Here's a link to a step-by-step trouble shooting guide I put together to help track down the exact cause: www[dot]txoof[dot]com/2012/07/building-makerbot-trouble-shooting.html

If it is your thermostat, you can simply short it out as JetGuy suggests, but I used a 10Ohm resistor. I can't print unattended until I get a new sensor.

Re: Unable to heat Stepstruder MK7 in Thing-O-Matic due to Safety Cutoff (Rev. D) fault light

Jetguy 23 Jul 2012 10:58

but I used a 10Ohm resistor.

The black device is a switch or dead short so a piece of wire is even easier to jumper across the terminals. In fact, knowing how the circuit works, a resistor for testing is not a good idea as the whole point is to bypass any current that would go through the relay coil trying to pull it in and thus, a resistor just makes it a voltage divider. The circuit is designed to be dead shorted, that's what the large pink resistor is there for, to limit the current at all times.

I realize you may have had the 10Ohm handy, but a piece of wire is better.