Nema 34 steppers with DQ860MA on Ramps 1.4 DIR pin issue

hello everyone,

i have recently put together a printer with a build volume of 520mx520mx520mm using Nema 34 motors driving ball screws for all axis and Dual Micron 3DP head.
I used a Ramps 1.4 set up to run 4 Wantai DQ860MA drivers. (one for X axis, two for Y axis and one for Z)

I started a print of a 10mm cube for calibration. everything was working fine except for poor bed adhesion.
i stopped the print and applied a thinned ABS layer to the glass bed for adhesion. When i started the same print again my X axis would only move in one direction.
I checked the pin connections for loose wires and used the lcd screen to test the X axis again and ended up with the DIR pin working intermittently until it now completely fails.

I have swapped out the driver twice now and the same thing eventually happened again. I only have this issue with the X axis.

I do see on the Wantai motor website a diagram that shows resistors between the negative signal pins, but with the Ramps board the signal is controlled on the + side.

any input would be greatly appreciated.

thank you

EDIT: I have Nema 34 motors not 42s...
EDIT: Attached - my wiring setup for the DQ860MA driver to the Ramps 1.4, power supply and motors

Edited 1 time(s). Last edit at 08/01/2014 02:04AM by Nived.

is it possible that i have "burnt" out the optocoupler on the DQ860MA driver DIR signal pin?
or does the Ramps 1.4 have current limiting resistors on the driver signal pins already?
just odd that only my X axis is having issues...

I'd check wether endstops still work. Marlin has this nasty habit to move away from triggered endstops only and also the habit to avoid negative coordinates.

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Generation 7 Electronics	Teacup Firmware	RepRap DIY

I just checked the endstops and they seem to be working just fine. i have mine set up to be normally open. measuring from the leads at the Ramps side i have no continuity unless the switch is pressed...

I will be putting 1k ohms resistors in series between the Ramps signal pins and the DQ860MA tonight. I'm also going to replace the suspected "burnt" optoisolator FairChild HCPL2531 with some scavenged EL817 EverLight on the DQ860MA driver.
hopefully this works for testing until exact matching optoisolators come in...

well, the 1k resistors in line on the signals does not work.

i replaced one of the suspected optoisolators and hooked the driver back up to my X axis. everything seems to be working fine. but, i tried the other driver that was not working and it now works as well... so i am lost as to what went wrong...

just crossing my fingers now that the problem doesn't come back.

Limit switch end stops, best/safer if they were wired normally closed, I'm not sure what is recommended for the optical.

End Stops: Magnetic Hall Sensor, Auto level probe. Would an optical sensor be an improvement? [reprap.org]
Filament detection using an end stop. [forums.reprap.org]
some gotchas.. the steppers will not move in a negative direction if it thinks the min endstop for that axis is triggered. Which is why I like to get the endstops working first thing. Be very careful not to short the + pin to the - pin on the endstop connector. Shorting this kills most boards. [forums.reprap.org]
if you only have 3 endstops, you need to disable the max endstops, //#define DISABLE_MAX_ENDSTOPS
End Stop: Start with the M119 command to check your endstop wiring. If the switches are reading triggered when the carriages are not touching them, the printer will think that it is already homed and not move the carriages [forums.reprap.org]
Connecting end stop [reprap.org]
Wiring Diagram: Sometimes the parallel port's limit switch terminal will be signaled by the noise in the steppers’ wires. [solsylva.com]
Wiring limits and home switches [www.pminmo.com]
Unshielded twisted pair: End stop wiring [www.reprap.org]