X and Z not returning home!

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SmakDaddy
Posts: 4
Joined: Mon Jul 22, 2013 3:25 am

X and Z not returning home!

Post by SmakDaddy »

I am not sure why, but when I am attempting to home the x and z axis (repetierhost 0.90), the X axis moves about 10mm away from the sensor, and the Z axis moves about 10mm down.

I have tested all the opti-sensors, they all seem ok. If I remove the signal (Yellow) wire from the opti-sensors, the onboard led lights up, and goes off when the sensor path is 'broken'. When I connect the signal wire back up, the leds on the mainboard light up and behave the same way and go off when the sensor is tripped.

The odd thing here is that the Y axis is working perfectly, and the opti-sensor behaves the exact same way, but as the led trips as expected, I dont think this these are the issue anyway.

Does anyone have any ideas what could be wrong? I have attempted to adjust the power going to the stepper in case thats the issue, but no luck there either.

Perhaps I'm suffering from the issue where the opti sensors arent getting enough power and are constantly tripping, Is there a way to calibrate the sensors themselves?


Update:
I have tried the auto-home using the control module (not connected via USB) with the exact same result. Y homes, X and Z move about a cm away from home.

I've also measured some characteristics to see if anythings wrong there.
X Opti
---------------
Vcc-Gnd: 3.14V
Sig(open)-Gnd: 2.86V
Sig(triggered)-Gnd: 3.96V

Y Opti
---------------
Vcc-Gnd: 3.16V
Sig(open)-Gnd: 1.98V
Sig(triggered)-Gnd: 2.61V

Z Opti
---------------
Vcc-Gnd: 3.13V
Sig(open)-Gnd: 2.87V
Sig(triggered)-Gnd: 3.95V



So.., what I'm seeing is way too much going through the signal on X and Z so the open state is the same as Y's closed state.

I've checked for shorts - none
I've checked resistance between opti sensor boards and the mainboard, and getting about 1 ohm between on all points of all sensors (also I dont think this multimeter is really build to measure fractions of an ohm..)

Ideas?


Update 2: The updatening
I figured putting a trimpot in line with the signal would probably just pull more voltage across the signal, which is exactly what it did :\


Update 3: Son of update
I took that trimpot and put it between signal and ground (on the X axis) at its highest resistance, then slowly lowered it until i found a point where it was low enough to allow the X to find home, but still stop when it broke the sensor. I measured the resistance afterwards, 998 ohm. That close to 1k cant be a coincidence. The only thing I'm worried about is that the 2 open and closed values are so frightfully close, that a little drift, say from nearby components heating up, could throw it off again.

At this point I'm just playing with it, if anyone has any good ideas, or at least ones less awful than mine, let me know :D :D

dsarmiento
Posts: 6
Joined: Fri Jun 21, 2013 3:59 pm

Post by dsarmiento »

I had the same problems in several opto sensors. My recommendations are the following:

- The opto sensors need 5V estable.
- Don't use the fan ports because of possible excesive current drain.
- Connect the red cables from the opto sensors (VCC) to the 5V port from the mainboard. This port is the one where the Purple cable from the power supply is connected (it is labeled as 5V and I think is the Standby power).

After making these changes, using a multimeter in DC mode, measure the voltage in opto sensors between GND and VCC, it have to be nearly 5V. Then measure the voltage between GND and SIG when the optosensor is not activated (when the vane is not touching it). It have to measure less than 2.3V. This voltage (2.3V) is the limit between logic 0 and 1 that the Arduino circuits (ATMEGA) recognize. If it measures more than 2.3V, the opto sensor will not work properly and I recommend to change it.

johndesmet65
Posts: 6
Joined: Wed Oct 30, 2013 6:48 pm

Post by johndesmet65 »

Finished ( almost ) upgrade 2.0 to dual head. Worked out ( almost ) fine. Now X-home pushes heads 10 mm away from home each time home button is pushed in repetier manual control. Y and Z are OK. Opto sensors seam to work Ok . Any help ? Anything to do with upgrade ?

Legion 2.3
Posts: 84
Joined: Sun Apr 20, 2014 6:23 pm

Post by Legion 2.3 »

Have a look at the voltage of the sensors:
Vcc, Sig (open), Sig (closed).

If the Voltage "Sig (open)" is higher than 2,3 V, you can try to put a trimpot between sig and Gnd, this will pull the voltage down. That´s a bit dangerous because if you pull it down too much, the board won´t detect the endstop which will result in a crash (it´s not really dangerous, the X-axis will run against the mechanic endstop and the stepper motor will start to click as hell (it skips steps), just leave your finger on the power button when you´re experimenting ;) )

I don´t know which kind of endstop you´ve got. If you have the new version (not the pcb-version), don´t give them 5 V, it could kill them and they´ll end up in smoke :?

Do you have a new board for the dual head upgrade ? It could be a defective one.

johndesmet65
Posts: 6
Joined: Wed Oct 30, 2013 6:48 pm

Post by johndesmet65 »

Thanks. I have still the old board. I also kept the old opto sensors . In fact I am only intereted in the dual head. The x -sensor works and the head can be positioned as should be. However with every push on the x-home button the head advances about 10 mm to a new home x-position and the head can not be brought back to the original home position. Should I put the new sensors ( without little printed circuit ) on ? Or did I something wrong by istalling the new extruder carriage on the x-axxis ?

Dreide
Posts: 176
Joined: Sun Sep 29, 2013 12:32 am
Location: Lausanne, Switzerland

Post by Dreide »

Hard to believe - you neither did switch the board nor did you change the wiring of the opto sensor, and now it just does not work anymore??? Maybe it is just that some wires became loose in the process of upgrading.
The problem is that there are several versions of opto sensors out there. Do you have the PCB-type sensors with additional electronics on it (resistors, LED, ...)? If so, connecting the red wire to 5V instead of VCC at the opto sensor port might solve the problem, but connecting other types to 5V will kill them, as Legion 2.3 pointed out already.
When you say "Opto sensors seem to work", do you mean that both LEDs for the X sensor (the one on the small opto PCB (if there is one) and the one on the main board) blink as you close and open the opto path? - If so, weird!
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

johndesmet65
Posts: 6
Joined: Wed Oct 30, 2013 6:48 pm

Post by johndesmet65 »

Looks like problems are related to software. I loaded the " old " 2.0 firmware and the printer works perfect ( one extruder of course ) . This indicates sensors are working OK. Then again loaded 3.0 dual head firmware and the problems were there again : no homing on x and z. ???

Dreide
Posts: 176
Joined: Sun Sep 29, 2013 12:32 am
Location: Lausanne, Switzerland

Post by Dreide »

Although I think that the end stop polarity is not an EEPROM setting, maybe resetting the EEPROM to the factory settings helps (an upgrade from Marlin to Repetier could fail to do so by some mishap). Just execute the commands
M502
M500
to reset the settings and save them to the EEPROM.

If that does not help, check if a wrong polarity is the problem. You can do so by just closing and opening the opto manually while trying to home. But I cannot see why polarity should be the issue here.
Given other posts in the forum, the Repetier firmware is somewhat less robust when it comes to spurious end stop signals, so the signal of your X sensor might be just too close to the brink, in which case the 5V trick would probably work (assuming you have those PCB-type optos with additional electronics on it).
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

johndesmet65
Posts: 6
Joined: Wed Oct 30, 2013 6:48 pm

Post by johndesmet65 »

No results after M502 and M500 . Problems remain unchanged. "Old" firmware had Marlin file while new firmware has Repetier file.... . I am reluctant to play the 5V thing...
Checking now if board is compatible with firmware indicated.
Thanks for your cooperation.

seaton
Posts: 291
Joined: Tue May 14, 2013 9:04 am
Location: Bunbury, Western Australia
Contact:

Post by seaton »

I've had similar issues with repeiter and Felix 2 opto boards. It looks like Repeiter is too sensitive to noise on the endstops. Why I have no idea. the problem I think it has something to do with the Opto Boards used in the Felix 2 as Felix 3 doesn't use these boards any more.

Measure the signal going back, I found that there appears to be an offset voltage on all of the sensor signal, but my problem endstop was slightly higher than the rest, this higher offset voltage and taking into account for noise would trigger a home signal even when it wasn't there. My solution was to reroute the signals away from the hotbed and extruder cables, this seemed to work for a while, then started getting problems again, luckily I had a spare opto board, replaced it and all working well since. the offset voltage is now the same across all boards.

I'm not sure why there is an offset voltage as my thought are it's either on or off, but the opto boards are definitely creating this offset. I did post it in a previous post somewhere of what the readings were.
Stephen...

Felix 2.0 -> Felix 3.0 dual
Simplify3D Slicer, Kisslicer
Have you added your Felix to the Map? http://goo.gl/maps/HajnZ

http://blog.strobotics.com.au

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