RAMBo Problems?

[DLS3141]

I have noticed some erratic behavior from my Max V1 and I'm concerned that it may be the RAMBo, but I'm not 100% certain.

• It has powered up seemingly OK, but been non-responsive to commands from the dial/button on the LCD. Re-bootoing the printer by switching it off, then on has fixed the problem (sometmes it has taken more than one power cycle). I cannot connect to it via USB.
• It has powered up and responded to the dial, I've connected to it via USB and it responds to motion commands, but not commands to heat. The G code terminal shows nothing and heating commands entered there simply disappear when I hit enter.
• Most problematic: It's powered up, I've started a print and made some random amount of progress, then one or both of the heaters have seemingly switched off while the head keeps moving and the extruder keeps trying to push filament. Eventually the filament solidifies and the extruder can't push it through the nozzle and just grinds away. After some time, the heater switches back on and it starts to extrude again, only since the machine has continued to move, it's extruding layers into thin air and when I come to check, there's a bird's nest on top of a partially finished part.

It's not the power supply since that would totally kill the print. I've run the part files through NetFab and eliminated the possibility of an "open solid" or other geometry problems. I have tried the same part with different slicers and thought I had it fixed, but it did the same thing again.

Any ideas?

[Mac The Knife]

I would check the hotend's thermistor for a loose connection.

[DLS3141]

https://imgur.com/gallery/9UzFr

Typical results.

[geneb]

It actually could be the power supply. Start it heating the hot end and bed and then check the 12v rail to see what the voltage is. I'd also recommend checking and tightening all the screw terminal connections on the RAMBo board.

g.

[DLS3141]

It actually could be the power supply. Start it heating the hot end and bed and then check the 12v rail to see what the voltage is. I'd also recommend checking and tightening all the screw terminal connections on the RAMBo board.

g.

I will check, but I don't understand how the power supply would fail such that the hot end and bed would lose power, but the machine would keep moving. I fully admit to being fairly ignorant about the inner workings of power supplies though.

Thanks

[geneb]

The RAMBo controller uses 5V to run. Both the hot end and heated bed use 12V. If the power supply is sagging under load, it's not going to be providing the full 12V that those two elements require. The sag won't have any effect on the RAMBo because there's a voltage regulator on the board that converts the incoming 12v to 5V. They'll continue to work even if the input voltage falls as low as 7-8 volts.

g.

[Khayrisill]

Hi guys,

Have a similar problem, but I never found why. Sometimes When I start the printer the bed and hotend temperature that is display on the LCD screen is not constant even without the heat powered on. I need to restart it several times before seeing stable temperatures.

[DLS3141]

I measured the voltage at the power in terminals on the Rambo while the hot end and the bed were heating up and read 11.52V - 11.68V, the extruder and X,Y,Z servos were off the entire time. I don't know if that constitutes "sagging", but it was less than 12V.

[Mac The Knife]

What is the voltage before you power up the heaters?

[Khayrisill]

What is the voltage before you power up the heaters?

Personally, in my case I have always 12.3 V

[DLS3141]

I measure 12.2V with the Rambo powered on but no heaters or servos.

[geneb]

To ME that constitutes a sagging condition. If it was my printer, I'd replace the power supply.

g.

[DLS3141]

To ME that constitutes a sagging condition. If it was my printer, I'd replace the power supply.

g.

Thanks, it will be here Saturday.

[geneb]

Good luck!

g.

[DLS3141]

I'm sure I'll need luck in no small portion.

Replacing the power supply is pretty much the first step in a major overhaul. Once I replace the power supply, I'll be able to print the parts I need for the other steps.

• Power Supply replacement
• Upgrade to Duet/Panel Due
• Rewiring (clean up my messy wiring)
• Relocate Extruder to the top of the machine
• Acrylic enclosure

[frminio]

Hi Geneb,

I was reading this thread as I am experiencing mid printing extrusions stops. I first thought that it could be related to thea temperature setting so I slightly raised the nozzle temperature. No success. Your comment on the power supply is intriguing since I lately experienced big print (>5h) showing a sudden change in extrusion quality, clearly shown by a wither plastic (under-extrusion) ( I will post a picture to illustrate this. This same print ended up with a proper extrusion by the end of the print. I did notice that but did not inquire much as the part was ok with me.

I will follow your suggestion on tightening wires and check voltage.
thanks
Francesco

[geneb]

If the extruder is flat stopping for a short period of time, that sounds like the stepper driver is overheating and resetting - especially if the printer continues to move normally.

g.

[frminio]

Hi Geneb,

The extruder seems to work properly. In any case, it is not resetting. Lately, I replaced the hobbed drive roller, thinking the old one was degraded. It seems that this was not the fixing.

What happens is that I have two extruders. The original one EZStruder that is giving this problem and the new one an EZRStruder that seems to work better (stronger in keeping the filament in the hot end).
The part in the picture was printed in PETG using the new EZRStruder. It was printed the way you see it, with the whiter part near the end of print.
It looks like the filament was extruded at a lower temperature, but then everything came back to normal to finish the print.
Now, with the old extruder it looks like the filament gets clogged and /or the extruder is not capable to push and keep the filament down in the hot end.

Since this phenomenon (filament tend to clog) happens with both extruders in a similar manner, I tend to exclude the extruders themselves them from the troubleshooting path.

So, today I was looking at temperatures.
I print with ColorFabb NXGen, a good quality sort of ABS. I usually print at 225 degrees Celcius. Since last two prints stopped at mid print, using the old extruder, I raised the temperature from 225 to 230. What I noticed is that nozzle temperature fluctuates between 225.8 and 230.9 degrees Celcius. I find it strange that the temperature drops so much, all the time.
When I upgraded my V2 with the HE280 I did not recalibrate the temperature probe law inside the firmware. Maybe it is a good idea to do this.
Ok, before raising the temperature that seems again not be the fixing, I checked the voltage and the wiring as you were suggesting. I found them somehow loose and tightened them back firmly. The voltage was looking low, around 10V when heating up the bed and the nozzle, with very similar values. But I measure the voltage on the screw side of the plugs.

Francesco

[geneb]

10v under load is WAY too little. It looks like you may have a failing power supply.

g.

[frminio]

Thanks geneb,

I will follow this path.

Francesco

[rootboy]

When my power supply failed, I replaced it with an Astron RS-35M that I had for my Icom 735 ham radio. It works perfect.

The Astron is a bit pricey, but this should do the trick:

https://www.amazon.com/TekPower-Analog- ... wer+supply

[geneb]

rootboy, if he's got a v1, he needs an ATX power supply. I'm not saying the monster above won't work, but you can get a good ATX supply for less than that, and it'll fit in the printer.

g.

[frminio]

hi geneb,

Before moving to purchasing another power supply I was able to better troubleshoot.
The actual voltage output was 11.25V and I was able to raise it up to 12.35 acting on the little orange screw show in the picture, nearby the green led.
When the nozzle is heating up the voltage fluctuates between 12.10V and 12.35V. Are these fluctuations sing of degradation?
For the moment I consider this is fixing one part of my problem. I am turnings my attention to the "old" extruder, as "new" extruder is printing fine

[geneb]

That little amount of bounce isn't anything to worry about - it could be your meter or how well the probes were connecting to the test points. Congrats on the troubleshooting!

g.

[rootboy]

@frmino: No, that's just loading that you are seeing.

@geneb: Oh yeah, the monster does indeed work. And it's not like I was using it for anything else... And yeah, it doesn't even come close to fitting anywhere other than under the table.