Opto sensors

General discussions regarding hardware
Post Reply
nosomis
Posts: 10
Joined: Fri Aug 30, 2013 3:17 pm

Opto sensors

Post by nosomis »

Hi all,
I have run into some trouble with my printer and run out of ideas.
A couple of weeks ago I had some trouble with Z axis not homing correctly.
I replaced the opto sensor and it was fine until the problem came back.
I replaced the sensor again and it didnt work at all - figuring I had a faulty sensor, starting checking my old (spare) sensors which were a mix of the versions 1 and 2 (3v versus 5v). Anyway I ended up with 3 good sensors and now the printer only homes on the z axis. All the sensor leds switch on/off ok on the mainboard when I activate them with a piece of black plastic or credit card. The printer itself seems to ignore the signals and doesn't stop the stepper motors. Does anyone have any ideas - I tried updating the firmware thinking it was corrupt but no change, I'm not even sure that I have successfully changed to firmware. I've removed the mainboard and checked it visually for damaged tracks or components but it looks ok. I have also tried the latest version of Repetier - horrible and no change. When powered up and connected, all functions work fine - it's just the sensor issue.

HELP ??!!!!

Jaanus
Posts: 6
Joined: Fri Jan 02, 2015 9:43 pm

Post by Jaanus »

Same trouble in here, none of 3 opto sensors does not work anymore, LEDs doesn't light at all. Only X axis goes to home, doesn't matter that opto does not work, it goes anyway, but any other axes (X and Y) moved to home by me :)

nosomis
Posts: 10
Joined: Fri Aug 30, 2013 3:17 pm

Post by nosomis »

So how about some help from the technical team - Guilame ????
I have purchased many opto sensors and many hot ends from Felix printers but each time I get a different version. I received no information with the purchases saying they were different. Because the first opto sensor I received needed in the kit needed a higher voltage to work, they were connected elsewhere so when the new version arrived, two were wired the same but needed the lower voltage - consequently they were damaged. Poor documentation from Felix printers.
Can someone from Felix printers assist as it should be a warranty issue.

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

Post by Dreide »

nosomis wrote:Anyway I ended up with 3 good sensors and now the printer only homes on the z axis. All the sensor leds switch on/off ok on the mainboard when I activate them with a piece of black plastic or credit card. The printer itself seems to ignore the signals and doesn't stop the stepper motors.
At least with the the new Repetier firmware ("new" meaning version 0.92), the endstop signals might only be used during homing (depends on how ALWAYS_CHECK_ENDSTOPS is set in configuration.h). Do you have an LCD unit? If so, the POSITION / X POSITION menu item, for example, not only allows you to change the X position but also shows the endstop status (which is normally OFF). Or you can get the current endstop status with M119 in the host program (in the response to M119, "L" means OFF).
If the firmware shows always OFF, you might get away with somehow making the endstop flags more opaque (putting a piece of black tape or card board on the flags, or painting them). Also make sure that the flags fully cover the endstops (a piece of cardboard can help to make a flag just a bit larger).
If, on the other hand, the firmware always detects an ON state (opto closed), there is not much you can do except changing some resistors on the PCB or getting a new endstop. The problem is that the infrared LED that is on one side of the opto is permanently powered up and will become less efficient as it ages. So at some point it will be not efficient enough to drive the photo transistor (on the other side of the opto) and the connected circuit to the OFF state. Later revisions of the PCB use different resistors in the connected circuit that cause the ON/OFF signal levels to be more pronounced. This also gives a better tolerance margin with respect to electrical noise.

EDIT/disclaimer: The above assumes that the firmware is okay. Moreover, as so often with 3D printers and printing, a given problem can be caused by many things. Regarding the optos, they could also just be dirty, or the the voltage of the 12V power supply (which also feeds the optos) has somewhat dropped. So aging of the optos might be just one possibility and should usually not be "the" problem if the signal levels were not on the brink in the first place.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

nosomis
Posts: 10
Joined: Fri Aug 30, 2013 3:17 pm

Post by nosomis »

Thank you for responding Dreide.

No LCD unit.
All the flags are black and I have checked the optos with a solid object and the led on the mainboard go off. I'm unsure about the firmware - could it somehow be corrupt ?
I did download new firmware but how do I know if it the update was successful and how do I overwrite the old firmware ?
If I am not careful, and select the homing function in Repetier I will risk destroying my hardware.
The opto's are also new so not dirty.

Here is a list of opto voltages;
normal triggered
X 1.38v 3.63v
Y 1.57v 3.11v
Z 1.48v 3.18v

and the Z axis homes correctly but not X or Y.

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

Post by Dreide »

nosomis wrote: Here is a list of opto voltages;
normal triggered
X 1.38v 3.63v
Y 1.57v 3.11v
Z 1.48v 3.18v
That does not look too bad, actually. Before I modified my PCB, I measured something around 1.7/3V and the signal was still correctly interpreted by the µ-controler, even though the datasheet of the controler specifies 0.3·Vcc/0.6·Vcc as min/max voltages below/above which the signal is guaranteed to be correctly detected. Vcc is Vcc of the µControler, 4.85V on my PCB, which gives 1.45/2.9V, so my low voltage of 1.7V was not in the safe range.
Your voltages are in a range where they should be correctly interpreted by the µ-controler, which makes me think that it is rather a firmware problem, maybe not from the beginning when the problem started, but now, after you have tried to update the firmware.
If you updated to Repetier 0.92 (download from http://shop.felixprinters.com/downloads ... =firmware/ - the Felix v3.0 version can also be used for v2.0) and connect the printer from the Repetier host, you should find a line with "FIRMWARE_NAME:Repetier_0.92 ..." in the message log ("Infos" have to be enabled for the line to show up). Then you can check with M119 whether the firmware detects the correct endstop state. The Marlin firmware seems to support M119 as well.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

nosomis
Posts: 10
Joined: Fri Aug 30, 2013 3:17 pm

Post by nosomis »

Thanks Dreide, I'll try that and let you know how it goes.

nosomis
Posts: 10
Joined: Fri Aug 30, 2013 3:17 pm

Post by nosomis »

Hi Deide,

The problem seems to have been definitely related to the firmware.
I have 0.91 installed and upgraded to 0.92 as suggested, I checked the command line on the Repetier software and it showed the version change so I was confident the firmware change was successful.
Unfortunately there was no change in the opto behaviour - still wont stop when sensors were interrupted. So I then decided to reinstall the original firmware Marlin 0.90 and success, everything works !
What does this mean however in terms of ever installing new firmware, am I doing something wrong, using the wrong firmware, or wrong opto-sensors, or some software configuration issues ?

Regards.

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

Post by Dreide »

nosomis wrote:Unfortunately there was no change in the opto behaviour - still wont stop when sensors were interrupted. So I then decided to reinstall the original firmware Marlin 0.90 and success, everything works !
Having the motors not stop (except during homing) is the default behavior with the 0.92 version you can download from Felix - on purpose, I guess (see ALWAYS_CHECK_ENDSTOPS in Configuration.h). The thing is that if the endstop checking is enabled all the time, a spurious endstop signal (false signal due to electrical noise) will stop a print. On the other hand, as the endstops are only mounted on one side of the axis, they don't provide full protection anyway, let alone that running against the endstop while printing is a rare case in the first place. So setting ALWAYS_CHECK_ENDSTOPS=0 is not unreasonable.
That is why I suggested using M119 in order to test, without homing, whether the firmware reads the endstops correctly.
One pitfall when updating the Repetier firmware is that the parameters in the EEPROM might be in an undefined state, obviously causing all kinds of trouble. After updating, use M502 to reset the EEPROM to the factory settings (meaning to the settings specified in Configuration.h). That the EEPROM is not necessarily re-initialized after an update is actually a feature when used correctly. See also "The EEPROM trap " on http://www.repetier.com/documentation/r ... tallation/.
Felix 2.0->3.0dual * Repetier (host+firmware) * KISSlicer Pro, Simplify3D * Cubify Design

Post Reply