Orion towers will not home

[Struve]

The three stepper motors used to home the Orion have no power when a G28 command is issued, nor when home on the front panel is clicked in the printer settings menu. I have found small (nano) fuses F3 and kF2 on the board and they check out OK, but am unable to find F1 to check it. Does anyone have an idea about lack of power to the 3 steppers? They worked fine before.

[Eaglezsoar]

The three stepper motors used to home the Orion have no power when a G28 command is issued, nor when home on the front panel is clicked in the printer settings menu. I have found small (nano) fuses F3 and kF2 on the board and they check out OK, but am unable to find F1 to check it. Does anyone have an idea about lack of power to the 3 steppers? They worked fine before.

Did you pull the nanofuses and check them? The other larger fuse is for the heatbed.
About the only thing besides catastrophic failure on the board that would prevent 3 steppers from moving
would be one of the fuses. Please remove them and check them again.

[Polygonhell]

Is the extruder stepper working?
Are the steppers powered and not moving or actually unpowered?
I'd check the endstops are working properly, that can prevent motion.

You mention they were working before, before what?

The stepper drivers can be destroyed by unplugging the motors while the board has power, but even is you did that, it seems unlikely you'd be unlucky enough to blow 3 of them. So I'd lean towards either bad firmware, and if you haven't changed that the fuses, though you mention having tested those.

[Struve]

Thanks for the fast responses! I checked the fuses in place and they read about the same as the leads to the meter (0.2xx ohms). I did set up to extrude metal clay and perhaps the firmware was reset, so I'll take out the fuses and check them out of circuit and reset the printer for ABS.

The extruder I built has a lower current motor (0.4 A instead of the 2.5 on the Orion). I have printed a few things in ABS on the Orion and am very happy with the quality. The reason I bought the Orion is to print on a fixed bed. My previous experience is with the UP! and the bed makes the metal clay slump during printing due to its rapid movements. The syringe drive was built on the UP! and works fine there, but the Orion seems to ignore manual manual extruder commands from Repetier, even after I set the target temperatures to 0 (or 24 which were the current temperatures of the bed and extruder). With the flexibility of the Orion also comes considerable complexity which I understood would be the case, but it still sucks.

After what? After a lot of changes, and replacing F3 which had blown, but F3 makes the printer look dead, so it should be OK. I blew F3 twice by having a ribbon cable to my print head and fan, and the connector on it was off by a little when I pressed it in, causing all wires to become one. I've put on many of these and this is the only time it happened. Cutting off the connector and putting on the new one prevented F3 from blowing again, and the head could be homed and moved with G code or Repetier just fine. The stepper motor on my syringe drive would not move, however. I then did some new settings in the slic3r setup to enable printing with a cold head and bed (and with the cooling fan 100% all the time) to see if that would enable the extruder stepper. Sliced a simple cylinder shape to presumably set the printer to the new setting, attempted to run it, and that is when the homing stopped working. The extruder does not work either. That is when I checked the fuses. I can control the cooling fan speed and shut it off and turn it on from Repetier, however.

[Struve]

So, I did the following as suggested:
1. Set up slicer to the settings used successfully for printing a simple ABS cylinder
2. Mounted the stl cylinder
3. Sliced the cylinder
4. Hit Run - at this point the Orion display said Home, but nothing happened with the xyz steppers
The fan on my metal clay extruder tuned on
The now external Orion head started to heat and reached ABS printing temperature
The bed heated to its target temperature
5. Waited for about 600 "layers" to be displayed on Repetier - no motion on my metal clay extruder stepper motor
6. Changed the fan and stepper connections from my print head to the Orion print head
The fan on the Orion print head started
The stepper on the Orion print head was motionless and turned easily by hand, so I would guess it was not powered
7. Stopped the print, turned off Orion, unplugged Orion
8. Pulled fuse F2 read 0.191 ohms for leads, 0.196 ohms with fuse in line
9. Pulled fuse F3 (even though this could not be bad) with similar results to F2

It seems to me that something in common with all of the stepper motors is open circuit. Could it be in the eeprom data, or other software? I've only had the printer for just over a week, so it should have the latest board. Are there any circuit diagrams available for it?

[Polygonhell]

If it did work originally, it's unlikely to be the firmware unless you flashed it before it stopped working.
Unfortunately things get harder to diagnose from this point.

The fans and heaters are on a completely separate circuit. Just to make sure, you have 12V going to both sets of connectors? There are 3 completely separate circuits on the board.

The first thing I would do is verify the stepper drivers are getting 12V from the board, you'll have to look up the pinouts for the drivers, they are the square chips at the bottom of the board.
My guess is they are not, the next thing is tracing back the 12V line to figure out why.

If they are getting voltage the next thing to check is that the enable line on the driver goes low when you send a movement command and stays that way.

[Eaglezsoar]

Schematics are available at http://reprap.org/wiki/Rambo

[Struve]

Voltage at X33-1, and both sides of F2 were 12 VDC, but both sides of D2 were 0VDC, so the fuse holder is bad.
The fuse holder was probably damaged during my first attempt at removing F2, before making a tool to do this.

[Eaglezsoar]

Rambo1.2gF2F3.JPG

Voltage at X33-1, and both sides of F2 were 12 VDC, but both sides of D2 were 0VDC, so the fuse holder is bad.
The fuse holder was probably damaged during my first attempt at removing F2, before making a tool to do this.

Inspect the fuse holder under a magnifying lens, there are tiny metal contacts that hold the fuse in place.
It is very possible to gently bend those contacts in a small amount to make contact with the fuse again.
I would do this only under magnification because these things are so small.
Ultimachine also offers board repair for a reasonable cost.

[Struve]

Oh what fun! Since SeeMeCNC was out of RAMBO replacement boards, one was ordered from UlitiMachine. It came yesterday, but the 10 pin connector on the top edge was not screw terminals, but pins in a holder. Happened to have a mating connector with screw terminals and sockets that fit. Unfortunately, this combination was too big for the space allotted for the board. Cut off the connector and replaced with a 10 position screw terminal (half a day's work). The connector for the board fan was missing from the new board, so put a screw terminal there. Got everything back together and turned it on - no smoke! Only 2 white lines on the Orion display!!

More FUN, More research, upload and unzip arduino-1.0.5-r2-windows, printout the SeeMeCNC instructions for use - most important part was loading SeeMeCNC's Repetier.INO file into arduino-1.0.5-r2-windows (which causes a new copy of arduino-1.0.5-r2-windows to start). Clicked verify - errors?? Set target to mega 2560, clicked verify - no errors. Download to RAMBO - success, all worked. Original stepper worked, but not the NEMA 17 on my metal clay extruder. Another 1/2 day shot, but I learned a LOT!

More fun and research on the Forums. Too much current for a NEMA 17 (mine takes 0.4 amps). Saved a copy of Configuration.h as Configuration.horiginal MOTOR_CURRENT {175,175,175,200,0} // Values 0-255 (RAMBO 135 = ~0.75A, 185 = ~1A) changed to MOTOR_CURRENT {175,175,175,90,0} // Values 0-255 (RAMBO 74 = ~0.4A, 135 = ~0.75A, 185 = ~1A). Metal clay extruder motor now turns fine, but it is a getting little too much current, so I'll probably change 90 to the 74 that I calculated (185*0.4). Now for the metal clay printing...

[Eaglezsoar]

A tremendous amount of work and money expended but it sounds like you got it. You have great fortitude and an I won't give up attitude.
Congratulations on what you accomplished! You should consider sending the old board to Ultimachine for repair at least then you will have a spare.