Fans are turning on and off

Thoughts about Raise3D, 3D printing and making in general.
gizmo91
Posts: 65
Joined: Fri Jul 15, 2016 9:44 pm

Fans are turning on and off

Postby gizmo91 » Wed Aug 30, 2017 2:03 am

The hotend cooling fan runs for a few seconds, then stops for less than a second, then spins back up. I've replaced the fan, plugged fans into the other ports on the control board and they are all doing this. Seems the 12v is dropping out.

Anyone see this before or had a similar situation? Hoping to make it through the current print (fingers crossed)

Jetguy
Posts: 1790
Joined: Tue Mar 22, 2016 1:40 am

Re: Fans are turning on and off

Postby Jetguy » Wed Aug 30, 2017 5:13 am

You should probably check your ribbon cable to the extruder breakoout and STOP PRINTING!!!
Let me make this very clear to you, you have a SERIOUS FAULT and continuing to print you have NO IDEA the danger you are potentially facing.
The same cable that carries the power for those fans carries the temperature signal back to the motion controller board.
IF that cable breaks connection there is a potential that the firmware will NOT detect this disconnect and ASSUMES the extruder temp being read is valid and CAN turn on the extruder heaters FULL BLAST with no control. This can cause a fire due to thermal runaway.

If your fans stop- STOP PRINTING. This is the few times you get a warning signal that a potential fault exists.

Jetguy
Posts: 1790
Joined: Tue Mar 22, 2016 1:40 am

Re: Fans are turning on and off

Postby Jetguy » Wed Aug 30, 2017 5:16 am

You likely are seeing this result from a loose or failing ribbon cable to the extruder breakout board- Again, we discovered a fault condition that IS NOT detected by safety code in the firmware. This specific case can lead to an uncontrolled heater- hot enough to cause serious damage.
viewtopic.php?f=4&t=2594&p=17372&hilit=runaway#p17372
If you see your fans stop - stop printing- don't hope you make it through it.

Jetguy
Posts: 1790
Joined: Tue Mar 22, 2016 1:40 am

Re: Fans are turning on and off

Postby Jetguy » Wed Aug 30, 2017 5:46 am

Again, just some facts about the system.
#1The motion control board in the base of the printer has the regulator that reduces the main 24V to 12V. That same 12V is powering the LED strips, the motion controller cooling blower, and then via this ribbon cable, supplies the 12V to the extruder fans via the ribbon cable.
If the 12V regulator were failing at the mainboard- then the LED strips would flicker or fail off, and the motion controller blower would slow down or stop. Again, a 12V failure at the source is obvious because the LEDs lighting the build area would flicker or fail off and that should be a huge warning sign. If that's not happening, then the mainboard and the 12V regulator is working and not the cause of the fault.

#2 The fans at the extruder breakout are plugged into the direct constant on connection of the 12V source and not software or controlled in any way. Again, if you see a loss of 12V power at the extruder breakout and NOT a matching outage of the LED strips and motion controller cooling blower- then the ribbon cable is the suspect failure. Again, that ribbon cable is what provides the 12V to the breakout from the main motion controller board.

#3 If the ribbon cable fails or becomes unplugged at either end during printing- this fault may not be detected by firmware but also means that the heaters for the extruders can go into thermal runaway. Again, the same cable and connectors that carry the 12V to the extruder fans also carries the return signal back of the extruder temp. If that cable fails or becomes unplugged, there is absolutely a situation where the motion board and firmware do not know this happened and that if that temp is even 1 degree below the setpoint- the heater is on in an uncontrolled state.

#4 On the N2 series of printers (N2 and N2Plus) the ribbon cable makes a sharp bend out of the cable chain to plug into the extruder head breakout board. That can pull or loosen the cable from the mating socket on the breakout board over time. Again there is no lock on this cable and only friction holds it in place.


Here is a picture of the N2 at the local makerspace with a zip tie around the entire board and connector to attempt to secure it and prevent this failure. Note, this is not without risk as you can see how this one was installed in the lower right corner it crosses over one of the 12V fan ports and if pulled too tight, could bend the pins in that connector and even worst case cause a short.
Ribbon cable.jpg

User avatar
Brandon
Posts: 100
Joined: Fri May 05, 2017 1:22 pm

Re: Fans are turning on and off

Postby Brandon » Thu Aug 31, 2017 3:06 pm

If this is a continuing issue shoot us a ticket here:

http://help.raise3d.com/support/tickets/new

gizmo91
Posts: 65
Joined: Fri Jul 15, 2016 9:44 pm

Re: Fans are turning on and off

Postby gizmo91 » Fri Sep 01, 2017 1:26 am

Thanks Jetguy! It was the ribbon cable, its not loose on the connector but the cables are loose going into the connector, exactly at that 'sharp turn' you mentioned. I did start to have thermal runaway too, luckily I shut it down as the temp was reading 274C when it was set at 215C.

Ticket submitted

gizmo91
Posts: 65
Joined: Fri Jul 15, 2016 9:44 pm

Re: Fans are turning on and off

Postby gizmo91 » Sun Sep 03, 2017 6:37 pm

IMG_9024.JPG
When you start wigging out because your printer isn't printing something, and you are waiting on Sales to get back with you on how to order a replacement ribbon cable since the machine is out of warranty, you have to take matters in your own handles and get it back up and running. Its not pretty but its working. I don't trust it to print without me being close, but at least I can get some printing done. Replacing the ribbon cable is going to be a pain. First, its wrapped in a tape, assuming to reduce heat and wire fatigue (wish the connector had that as its where mine failed), second the ribbon cable is then combined with the extruder wires and other connectors in another 'wrap', and lastly the troublesome IDC 14 pin connector won't fit through the cable train so may have to fish the new wire through and then crimp it :( --- so its not going to be an easy job!

BTW - this should be a warning to everyone with a N2, if your fans start acting weird, your ribbon cable IDC connector at the breakout board may be failing from fatigue. The use of IDC connectors isn't recommend for high vibration/movement as the wire is pierced by the blades and it will eventually fail from fatigue. The print assemblies main task is to move and jerk around as it prints --- so you will get a failure, just a matter of time. I've seen some posts about a cable tie holding it in place, this may help but its an awfully sharp angle that the cable comes out of the chain.

My printer was going practically non-stop for 9+ months, so not complaining about replacing the cable, just hope R3D improves that connection on the next printer or on new N2s. Especially since thermal runaway is a real possibility which could lead to potential fire hazard.


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