How to determine if mk3 Rambo and/or Display board/cable is bad?
I have a mk3 that has printed very well for 1.5 years. My failure occurred when removing a completed print and the display showed garbage. Now, after every power cycle or press of the reset button, I see the initial "Original Prusa i3" display, but it is immediately replaced with either random garbage or a blank screen.
I tried both Factory Reset and Full Factory Reset.
I can connect via Pronterface, but none of the remote controls (to move axis or change temps) responded.
I have worked with Prusa support twice. Power supply measures 24V. After disconnecting all connections except the two power supply inputs and the two display cables, I was able to reflash the firmware successfully (however the screen never showed any valid content).
Does anyone have any additional troubleshooting ideas in order to determine if the Rambo board, the display unit, or something else needs to be replaced?
Thank you
Jim
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
Given that Pronterface is not using the display, but is not able to control the printer,
I would guess it is the Einsy (Rambo) board. But that is all it is - just a guess.
$79 from AliExpress or $133 from Newegg. Both of those are free shipping. I did not check Prusa...
Display board should be even cheaper.
This article may give you some ideas:
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
The ribbon cables will not fail like that, and typically nor the Einsy.
Most likely, an ESD event sent garbage data to the printer and display. A power off may fix the issue. If after a power cycle the display is still hosed, some EEPROM data was corrupted by the ESD event. Do a full factory reset with data clear, and run through the calibration wizard again.
https://help.prusa3d.com/article/SYvbQ66IXF-factory-reset
- All data - resets everything including all calibration data, meaning the whole EEPROM is erased. After this reset, the user is expected to go through the calibration flow again, with the exception of the probe height setting.
Why ESD? In winter, humidity drops and static builds up quite easily. Touching the printer without anti-static gear can cause a small spark that creates an EM field that hammers all the exposed wires, the ribbon cables, too. The cable drivers are hardened against ESD, but can yank voltages around that cause the CPU at both ends to do bad things, like write garbage to EEPROM when they shouldn't.
If this happens more than once, start using a anti-stat grounding strap clipped to the power supply case.
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
Thanks Tim and Rob for the replies.
I have attempted the Full Reset, but the screen immediately goes to garbage after the "Prusa..." splash text, so I don't know if I was successful or not. The beep patterns do not match up exactly, so I doubt it.
I also tried sending, "M502" and "M500" via Pronterface. The message was sent, but I don't see a reply in the log -- it keeps repeating "echo:busy: paused for user" every second or so.
My issue appears to be the same as the comment from Jon Mason on Rob's recommended article "LCD screen not working". His answer was to replace the LCD.
At least that is cheaper than the Rambo.
jim
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
If you checked every obvious reason then my replacement path would be.
1. Screen with cables (usually they are sold as bundle)
2. Einsy board
Before buying a new board I would tear it apart, inspect for any visual damage. Then attach everything back loosely and see if it's still same issue. If yes, then getting a new board.
Often linked posts:
Going small with MMU2
Real Multi Material
My prints on Instagram
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
On the Mk2 the REPRAP screen assembly had the plastic hoods over the ribbon cable pins, on back to front... I suspect the Mk3 may be the same.
if you get your LCD assembly from Prusa it should be a direct swap. if you buy from the internet, you may need to turn the hoods round,
the hods are a tight push fit on the pins.
regards Joan
I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
I do ask you to report back and let us know what fixes it for you. Every data point helps!
RE: How to determine if mk3 Rambo and/or Display board/cable is bad?
Update: A replacement display correctly shows the language selection after the splash text upon power on.
I'm in the US and ordered from Printed Solid. (Free shipping over $30, so I threw in a couple more items with the $18.25 display)
https://www.printedsolid.com/products/ldo-prusa-mk2-mk2-5-mk3-lcd-display-replacement
Thanks for the advice everyone...now I think I'll do a full tear down and lubrication before reassembly...
jim