Solved motor phase A may be disconnected reported by driver(s) 1

[dc42]

Please post a link to the specification for your stepper motors you were using when you had the warning messages, and tell us what motor current you had set.

The "motor open circuit" warning is new in recent firmware versions. We are aware that it is unreliable in some situations, which is why it is disabled at low motor current settings.

[HarveyS]

@dc42

I had the same problem with the e3d stepper motor supplied with my Titan Aero (Genuine) extruder and the stepper motor I ordered to use with the new Zesty Nimble.

Titan Aero supplied stepper motor - P/N MT1703HSM168RE Current set to 1000ma.

Ordered for the Zesty Nimble:
Stepperonline - P/N 70HS10-0704S Current (set to various values) up to 700ma. "phase A" errors at all values.

0_1567974400991_Stepper-Motor_MT1703HSM168RE.pdf
0_1567974463817_StepperMotor_70HS10-0704S.pdf

(Made many successful prints with the Titan Aero on RRF version 1.19.2 before starting the updates.)

[keith]

@dc42
NEMA 17.
1.8° Step Angle.
200 Steps Per Revolution.
1A Phase.
0.48Nm Holding Torque.
40mm Body.
19mm Output Shaft (5mm diameter)
750mm wire lead with Molex connector

Motor current set to .8 amp.

I think I have it sorted out. One of the wires in the cable has a short. I cut the connectors off and checked the wires without any connectors which is surprising considering the Y axis motor and motor wires never move. I might expect a wire to wear down on something like the direct drive motor over time but not the Y axis. Seems to be working now with a new cable. What Molex connectors are these? I want to order some backup connectors.

[Phaedrux]

@keith said in motor phase A may be disconnected reported by driver(s) 1:

What Molex connectors are these?

https://duet3d.dozuki.com/Wiki/Connector_and_spare_part_numbers

[keith]

@phaedrux
Thanks phaedrux. BTW it is cartesian I designed for IDEX, I only have one X head setup on it for now though.

[dc42]

@keith, I'm glad you solved it.

@HarveyS, do you get the error reports only when loading or retracting filament at high speed? Or at low speed?

[HarveyS]

@dc42
I think its related to speed also. Manual extrusion / retraction with DWC > ~15 mm/s or greater and > 5~ 10 mm length with a Zesty Nimble, e3dv6 hot end with a 0.4 mm nozzle and a 30 W heating element. PLA @ 200 C. Tried Both stepper motors and had basically the same results. The inductance on the 17HS10-704S. is a little higher ~ 5.5 mH and the current rating a little lower, but the e3d stepper motor yields about the same results. (And yes prior to testing I had completed a PID tune and a measured 100m extrusion to set the steps/mm correctly.)

When trying to print a real gcode file I get multiple errors and the filament basically retracts right up out of the nimble even though retractions were set to 1 mm. Now the strangeness. After aborting a print I sometimes had something strange occur. It looks / acts like the direction of the stepper was reversed afterwards(!) and I had to cycle power on the printer to recover... (Weird right?)

Just for the heck of it I have a 17HS08-1004 (~$8) on order that others have reported to work correctly ( 4 mH, 1000 ma rating, and lower inertia) when set to 500 ma with the Duet WiFi.

[HarveyS]

@HarveyS
@dc42
Just a quick reply to myself for anyone reading further on this thread.
Replaced the stepper motor with a 17HS08-1004S, set the current to 500 ma as others have used and low and behold - no phase A disconnect errors with Reprap version 2.04RC1. Even when over driving the extruder to the point where it chews filament, so problem solved. Now I can go on and start tuning / tweaking my slicer settings for best prints.
Thanks everyone.....

[dc42]

Thanks for the update. I think the issue is that fast retractions using a highly-geared extruder such as the Nimble require high motor speeds. I see that Trinamic says on one of their recent datasheets that open load detection shouldn't be relied on at high speeds. So in the next firmware version I'll set an upper speed limit for open load detection, in addition to the existing lower speed limit.

[HarveyS]

@dc42
Good to know. I also think that the detection is also sensitive to the resistance & inductance of the stepper motor. There was nothing really wrong with the wiring or the original stepper motor I tried(Or the e3d one from my Titan Aero.). With a nimble we wind up with ~2700 steps/mm or ~40K steps/sec at 15 mm/sec which I've been told is about the max. theoretical for an e3dv6 with a 0.4 mm nozzle. (And I don't think with the nimble we can do that for more than short bursts.) Continuous or long duration extrusion on my rig the max is more in the ~10 mm/sec range(Maybe ~12 mm.sec). Can you post a link to the latest documentation for the Trinamic driver?

[T3P3Tony]

@HarveyS https://www.trinamic.com/products/integrated-circuits/details/tmc2660-pa/