Problems updating Tevo Flash firmware

Hello,

I am new to 3d printing, and recently purchased a Tevo Flash. Everything was fine till after several weeks of use I tried to update the firmware. After flashing though, the LCD (while turning on) remains blank. Being my first try, it is entirely possible I didn't flash the correct marlin or something, but after many different tries I downloaded the original Tevo Flash firmware, and flashed that. Unfortunately the LCD is still not functioning.

When connecting the printer via USB and opening Cura, I can preheat the nozzle just fine, the tempteture reading is stuck on 111 degrees though, and the bed temp is not displayed. I've tried lots of fixes, from trying to change the LCD contrast to enabling different LCDs in the configuration.h file in Arduino. Any help with this issue would be greatly appreciated.

Post a link to your Marlin Firmware.

or try this
https://github.com/JimBrown/MarlinTa...onfiguration.h

and learn the lesson: if it works - don't bugger about with it :-)

One thing to check. Make sure the configuration.h file actually has your screen selected.
Sounds like maybe it's choosing the wrong screen.

Haha yes, lesson learnt. And I'm not sure if there is a different way. But what I did was go into the configuration.h to the LCD controller section and enable the display most similar to mine. I have the MKS Mini. Is that the correct way to do that?

Thank you, I'll try that one. Unfortunately I don't have enough posts to send links yet.

You were right!! I tried another config program and managed to find my LCD specifically! The LCD is working now, thank you two for your help! Unfortunately I still have one more problem, the temperatures are still stuck. I'm thinking it is a problem with the hotend thermistor, as when I tighten it it changes from 111 degrees to -14. But what confuses me is that the bed temperature stays at around 108 degrees, which is strange because I never touched it. After replacing the nozzle the temps just jumped there and stayed there.

There are two temperatures that you should memorize.

-14 C -- Open Circuit
358 C -- Short Circuit

This is on my 3D Printers anyway. You can test this yourself.

Okay yes. So I measured the resistance of the thermistor. Its about 50k ohms at room temperature. But no matter what I do the temp is still displayed at 111 for the hotend and 108 for the bed. Even plugging out the cables going to the hotend makes no difference. Do you think its a problem with the board?

Glad we got your screen working again :-)
For some screens you even have to add extra libraries to ide.

how warm is the room ?
could just be measuring ambient temps. (I don't do farenheits)
But sounds more like bad wiring somewhere.

Ah sorry, I forgot to mention this is indeed in degrees Celsius. So not room temperature. And could be. Like I mentioned I might have damaged the hotend thermistor by accident, but I haven't touched the bed. Are the two linked in any way? If not, what could cause both temperatures to be stuck on a high temp? Just for information's sake, both the hotend and the bed start heating properly, they naturally just shut down because of the safety features not detecting a temperature change. The steppers are also functioning just fine.

You say the thermister is 50K at room temp.


I hate to be the bearer of bad news but a NTC 3950 is suppose to measure 100k at room tempature
According to this web page that is what a Tevo uses https://3dprinterupgrades.wordpress....rantula-parts/

Now if you really have a 50K thermister then you need to change the thermister settings in your configuration.h
I do not see a 50K thermister listed in Marlin firmware.

*** Special note ***
Why is it that every time my FREE Cen-Tech Digital multi-meters need batteries replaced the meters stop working correctly,
Measured a 100k thermister as 1.5 ohms!!!!!. With new battery.

That's OK. Used my Fluke meter Digital Multi-Meter now it measures 99.9K ohms at room temp.

Thank you for checking that, I finally found the problem, it seems both the bed and hotend thermistors somehow burnt out. I ended up connecting a varible resistor in place of the thermisor and checking that the change in "temperature" was detected, this tells me that the board is at least fine (whew). I still have no idea what might have caused this but am taking it up with the place I bought it from. I really appreciate your help with this issue.

You are Welcome!