Help! Flickering Screen, power shuts off
I bought my Prusa I3 MK3 kit earlier this year, and just finished assembly. I was feeling very proud of myself, and got to the point of plugging it in to watch it load up.... the LCD screen turned on, the fan turned on, inside the motherboard I can see a green light turn on and a red light turn on. After about 3-4 seconds, however, the LCD display starts flickering and then shuts off. The red light and fan also turn off at the same time - the green light remains on.
I have checked my cable connections no less than 10 times, and have unplugged all of them and put them back in. I have checked everywhere for any pinched cables - I was very careful, as per instructions, not to pinch anything and on inspection the wires seem physically in good shape.
This seems like something is shorting out? Why oh why is this happening? This is incredibly frustrating after all these painstaking hours of building this thing... does anybody have any suggestions as to how I can troubleshoot this?
I am a high school teacher, and was given this kit as a gift for my robotics classroom. I have been working on setting this up for my classroom. My students were really excited today to see me connect the last cables... and then this. I feel like I could cry right now. I was very meticulous when building this thing, triple checking myself along the way to be sure that I didn't make any mistakes. Right now, this feels like a super expensive mistake. Please help!
Re: Help! Flickering Screen, power shuts off
Ouch - I feel your pain. Troubleshooting new product tun-ons is always tricky.
I use the minimalist approach with a bit of logic.
Unplug about half the power consumers. In this case unplug all of the motors. If the issue persists, plug those back in and then unplug / disconnect the heaters. If the problem persists plug /reconnect those.
Now you are left with the low power items.
Unplug the fans, if the problem persists plug the fans back in and unplug the temp sensors (it probably isn't the sensors unless they are plugged into the wrong slot - I had problems identifying where to plug them in). Last thing to check is the LCD cables - but if you unplug them you'll be running blind.
If at any time you see a change in self test - then add items back one at a time until you see the failure again. Once you've identified what connector is the problem, you can dig deeper from there.
Let me know if this gets you any farther along.
ps: a photo of the wired control board would be helpful.
Re: Help! Flickering Screen, power shuts off
Thank you so much for your response. I've gone through all the steps exactly as you suggested, and I've seen no change. It continues to flicker and turn off
I unplugged all of the motors, and turned it on - it flickered and stopped. I plugged the motors back in.
I then disconnected the heaters. Same thing - powered on, LCD and fan came on briefly, flickered, then turned off.
I unplugged the fans, same as above, followed by the temp sensors with same result... turn on briefly, flicker, and then turn off.
I uplugged the LCD cables, it seemed to do the same thing as before but without the visual cue of the LCD screen. That is, I could hear the fan turn on and then turn off at about the same time.
It's difficult to get clear pictures with all the wires, but I've done my best!
Re: Help! Flickering Screen, power shuts off
The filament sensor is plugged in backwards ... Red should be to the outside of the board, the blank pin to the inside.
And verify the extruder end of the cable is correct.
Re: Help! Flickering Screen, power shuts off
The odds are the filament sensor is damaged, so plugging it back in isn't a good idea. Reading other threads in the help forums, they are catching fire and melting the extruder housing.
You can try unplugging it at the CPU side, turn on the printer to see if it begins powering up. If the printer does come on, then you turn things off and try plugging it back in; then try powering on again. But even if that worked, the filament sensor is questionable, and last thing you want is a fire. I'd just leave it unplugged until I got a new one.
Re: Help! Flickering Screen, power shuts off
Okay, I have an update: I see in the one photo that i had my filament sensor cable in the wrong way... I had originally had it in correctly, but when replugging everything had turned it around. I've put it back correctly again, but that did not solve the problem.
I went through all the above steps again and this time when I removed the heat plate connections it powered on and stayed on! However, nothing appears on the LCD screen - there is no text but the back light stays on.
Very excited at this progress, I turned it off, plugged the heat bed back in including power and .... some success. The machine turns on, the fan turns off after a moment but I suppose that is expected when it's not printing? The LCD screen turns on, but no text.
I put the memory card in, and the LCD screen turns off.
I feel like I'm missing something simple but crucial here. Any suggestions?
Re: Help! Flickering Screen, power shuts off
Make sure you reconnected the two LCD cables in the right order. Mine had I and II marked in red Sharpie. One stripe goes on the outside, two stripes inside.
LCD cable with ONE stripe (Connector P1)
LCD cable with TWO stripes (Connector P2)
The pink stripe on the LCD cables should be facing upwards.
Re: Help! Flickering Screen, power shuts off
Fans are off when not printing, and the only indication of power is LCD glow and info on screen.
Not sure why disconnecting the heatbed would cause it to start up. Maybe a coincidence with the filament sensor. But you may want to recheck the heatbed end of the connection under the plastic strain relief. Verify it matches the instructions. Red wire to VCC, black wire to GND. And that the two wire ends don't touch anywhere.
And, here's one of the filament sensor threads... again, I'd leave it unplugged. You can still print without it.
Re: Help! Flickering Screen, power shuts off
Yikes about the filament sensor. I'll unplug it.
So, to recap my progress: I now have power and and LCD screen that lights up. Weirdly, though, when I put the SD card in the LCD screen won't turn on? I am putting it in correctly, I think, with the pins facing me.
I've put the SD card in my computer, and it recognizes that there are files on it.
Re: Help! Flickering Screen, power shuts off
OMG it works. I don't know what I did, but it works now. I will just proceed through the setup, fingers crossed all goes well from here. I am so happy I could cry.
oh shoot... spoke too soon. So the SD card loads a screen "Hi I am your original Prusa 3D printer would you like me to guide you through the setup process?" I click yes, it does some whirring, very briefly shows the message "sorting files..." then stops whirring and flashes back to the "Hi I am your original Prusa..." screen. I've tried this a few times, it is stuck in a loop and won't load the files. Argh.
Any suggestions for what I can do next to try to move beyond this point? One tiny step at a time... creeping towards success.
Re: Help! Flickering Screen, power shuts off
Leave the SD card out for now... try powering up to do the initial setup. It should guide you through a couple of X-Axis leveling and PINDA calibration tasks.
And yes, SD card does go in "upside down" - gold fingers up.
Progress is good on these sorts of issues 🙂
If all else fails, a hard reset of the controller might help - access hole for button is on top of the controller board, I've never had to press it, so it may help, or not. But with all the false starts so far, I doubt it will hurt.