Bought a k8400 for a reliable price because it wasn’t working.
The LCD doesn’t work. Tried to replace it with another LCD but didn’t solve the problem. Also, when connecties with repetier, the x- and y-movement isn’t working correct: with a 1mm command the head moves way too far. At least, sometimes the motors aren’t working at all; but there is a command going to the stepperdrivers (the led’s light up). So, is there a problem in the ATMEGA2560? Before resoldering a new chip i would like to be sure
Since you purchased this used and it sounds like you do not know what the previous owner has done maybe you should try to reload the firmware.
You can find the instructions in this link. https://manuals.velleman.eu/article.php?id=31
Make sure you use Arduino software 1.0.6 or lower.
Check all of the connections for the LCD and ensure the cables are plugged in with proper polarity.
Clean the end stops with a soft cloth.
The LCD problem might be cause by the SD reader.
Did you check the voltage reference for the stepper drivers?
Have you checked to voltage coming out of the power supply?
Since I don’t know where you are there is a switch on the power supply that needs to be set for the voltage of the mains, have you checked it?
it is quite interesting to see a lot of “motherboard-problems” in short time. Maybe there is a lifetime problem on it.
However, just for information: how does your LCD not work:
is the background illumination missing?
does it remain in the reset state?
or does it display the wrong characters?
It would be helpful to know a little bit more details.
Furthermore, you can check the core voltage of the CPU. On the diode D5 you should measure 5V and 4.3V respectively. The lower the last voltage is, the more critical is the operation of the CPU (minimum voltage level: 4.5V according to ATMEL datasheet).
Thanks for the advices here, get a few things to check now. The powersupply is working and is delivering 15V. An extended universal powersupply isn’t solving the problem either. The background-illumination is working, but no characters are displayed. Operating from a computer via repetier is working, the printer reacts, so i can’t believe the ATMEGA-chip is damaged…
Couldn’t fix the motherboard. Tested the LCD on an other printer, works fine (including the underlaying print with SD-cardreader). Bought a new motherboard (original) and installed the latest firmware (one nozzle, v1.4 from GitHub). Still no working display, even with a new motherboard and a tested LCD. What am I missing?!
Also try disconnecting all of the cables except the LCD and power to the MB remove the drivers as well and test it.
If it works then put them back one by one and test after each one.
I know it’s a pain but it may give you an indication of where the problem is.
When putting the drivers back make sure the orientation is correct.
Doenn’t work, even with all the cables disconnected. Still got no signs on the display. Tried firmware versions 1.1 and 1.4. Doens’t understand why it won’t work. Checked the LCD and saw it working, and bought a new MB, so there can’t be anything wrong IMHO…
Fixed the problem! I send the printer in to a specialist due to a lack of time on my side. The issues that are fixed were indeed a band cable failure. Also the potentiometer was damaged. At least, one stepper driver had a short (axe was moving in one direction with half the speed). A bit a pitty i bought a new MB what wasn’t really needed after all; before buyong a New one i damaged the old one (can try to fix it though…). Got a spare one than…