LCD ringing  

Re: LCD ringing

Just finished building my printer last night

Whenever I power it up the LCD backlight lights up, and the unit emits a loud ringing noise. The smaller fan also powers up.

When I hold the X button on the the LCD unit the noise stops until release. I have double checked the direction and order the LCD cables are installed and also swapped them and the same thing continues. Anyone seen this or have any ideas of the cause? I have not seen a similar post on this.

sounds for me as if something is wrong with your rambo board.

disconnect every connector/cable at your rambo board, except the 12V power supply from the psu.
then power it up and connect the rambo through USB to your computer and check if it responds properly at pronterface. pronterface is a control program, with terminal capabilities, that comes with the driver package that you can download at prusa's website.
make sure you've set the communication speed to 115200 baud.

if you can successfully connect and get responses from the printer through the USB (it's an RS232 interface), then at least the "brain" (rambo) is working and we can proceed to do further tests (next would be to connect just the LCD module with the ribbon cable to connector P1).
if you can't connect, then it's very likely that your rambo is either defective from the hardware point of view (board) or at its software (firmware flashed unsuccessfully); you then have to contact the prusa support through the chat option of the shop.

Re: LCD ringing

I have the excact same problem as Anders. I will try to remove everything except for the power cables.

Re: LCD ringing

i did what you said and in pronterface it looks like i have a succesfull connection with the printer board.

what do you think my next step should be?

Re: LCD ringing

i have made progress, i started connection 1 wire at a time and checking to see when the problem start. When i connect the nozzle thermistor cable my board lights red and the ringing sound starts. At the moment i have everything connected except for the cable from the nozzle thermistor and everything works fine. This also explains why the fans start up thinking the nozzle is too hot im thinking.

Re: LCD ringing

@espen:
hmmm... I guess that there is a shortcut between the thermistor and the heater cartridge, check the wires at the hotend. maybe there's a shortcut between one of the thermistor wires and the whole hotend body ? the standard thermistor is a very tiny little glass bead, which sits inside a hole at the heater block and should be fixed very tentative with a grub screw. if this screw is tightened to much, the thermistor cracks and at least one of its leads will have a shortcut to the hotend body.

...This also explains why the fans start up thinking the nozzle is too hot im thinking.

yes, definitely.

Re: LCD ringing

Okay so i have contacted support and togheter we managed to figure out the problem.

The issue is with the nozzle thermistor.

We connected the nozzle thermistor to the heatbed thermistor and what we saw is that the nozzle thermistor says that the heatbed is 368 degrees.

After verifying the result, prusa support will send me a new nozzle extruder.

See picture for details.

If anything is unclear contact Shane in support.

Re: LCD ringing

and let me not forget to thank you JeffJordan for leading me along the way. If it wasnt for your first message i wouldnt now if it was my nozzle or my motherboard 🙂