I just finished assembling my first K8400.
When trying to zero the axis, all motors continue to run despite having reached the end-of-travel switches. That is not what I expected, and I pulled the plug before the Z axis touch the printing head.
The red LEDs on the sensors are all on. I measured the voltage on the phototransistors, and I am not very happy - I see 4V when not illuminated, but 0.6, 1.2 and 2.2 V (X,Y and Z) when illuminated. That is far from a logic zero, and I am concerned that the end-of travel sensors could be defective. What type is the photocoupler? Is the current on the LED enough to get a good logic zero?
I stopped testing and will await your answer.
[quote=“Wrong Way”]Make sure each end stop has the correct cable plugged in to it.
Check it on the control board as well[/quote]
That’s the first thing I have checked. Otherwise the LED would not power on
Be sure, all wiring is ok, each plugged in the proper socket. I question the correctness of voltages on the phototransistors.
[quote=“Wrong Way”]Still waiting to get one
I didn’t mean to offend but that is the best place to start.[/quote]
Agreed - sorry, I had to present myself, I built my first radio receiver half a century ago, and spent a life in computers, electronics and test equipment - I have an idea on how to troubleshoot it.
Only, there are no schematics and no specifications on the photocouplers; possibly the voltages are right, but again I expect the motors to reach the end-of-travel point and then stop, not to continue stepping until a time-out expires. I feared to see the assembly plate crushing against the nozzle.
Can you measure the signal wire when the endstop is inactive and active?
Sincerly[/quote]
Thanks for the schematic. After some more testing, only the X axis endstop is not working, the other two are fine. When I herad the motors “buzzing” at end of travel I pulled the plug, but it is only one doing that.
I will test it and report the voltages.
Everything works fine. The culprit was one of the pulleys that prevented the x-axis to reach the ened of travel. The sensors are good.
All fixed, thanks for your help - I just printed the Vertex logo
So Pin1 is signal, pin2 Ub, pin3<GND (do not get confused by the pins of the sensor itself). Well my voltmeter does not measure 15 V on pin 2 to 3 but 3 V. The Schematics of the main circuit show that the resistors R52,R56,R60 limit the voltage, so 3V may be ok here so 15V is wrong.
Just to make it complete I measure 2,12 V on pin1 to pin3 standby and 4,2V when triggered.
The add-on could possibly made by using a transistor BC848 with some 1k resistor between signal on pin 1 and base. In emitter/collector pin 2 with its 3V could power the extra LED (green or yellow ?) of the endstop circuit when the photsensor is triggered. With SMD-components everything may fit on the board without changing its appearance and function.
To make it clear: These are just some thoughts, nothing was tested so far! So be careful when you try it.
I_go_3D, I agree with you. The current LEDs are of little value, to have an end-of-travel indication would help in setting up the printer.
15V on pin 2 is clerly wrong, 3V is reasonable. A different circuit on the small PCB would fit, by sure. But requires four new PCBs.
It’s a bit of a hassle, but you can solder 1206 or 0805-size SMD components connecting each other without any pcb. In 0805 this means < 3 mm all toghether.
And as far as I see you only need one transistor, one LED, a resistor in front of the transistor-base and perhaps some pre-resistor if 3V is too much for the extra SMD-LED.
Well it’s a challange but you can do it !
And if you are a really cool guy you’ll do it in 0603 or even 0402 … (that’s sandgrain size)
[quote=“I_go_3D”]No - extra pcbs are not really needed.
…or even 0402 … (that’s sandgrain size) :D[/quote]
Well, I design and work on microwave equipment, I already hand-soldered some 0402, and assembled a circuit with 220 parts in 0805 - I know the tricks only don’t want to spend much time on the K8400 to modify it. Well, may be, a day.
Though I share with you all. I fixed a new PCB to the end sensors - the provided ones give no value for users than that the power is on to the sensors.
The new PCB have two LED’s, one green (power on) and one red LED (lights up when end stop engaged).
I ordered a small test batch of PCB:s (10 pieces) and it tested out well. No modifications needed. I have tested these one month now. The cost per complete PCB where $17 for my test batch.
If there is interest from the community I guess the cost would be $10-$12/end stop if 50+ made.
Shout out if you are interested, I can administrate - but it requires we are enough to get the cost down per piece.
Is it really so that no one is interested in the improved end stop PCB’s.
I have had a lot of use with the end stop LED triggered when adjusting Z stop level for example.
With the improved end stop you can see immediately when it is triggered when adjusting
the Z-level adjustment screw.
I am more than willing to hand over the schematic and board files for your next version of Vertex.
This is according to me a very good upgrade to the already good design of Vertex.
Touch base with me if there is any interest for this.
- sorry, I had to present myself, I built my first radio receiver half a century ago, and spent a life in computers, electronics and test equipment - I have an idea on how to troubleshoot it.
