Hardware, firmware and software help - Prusa3D Forum

IR Filament Sensor Resistor R2 and R3 values

lordrafa — Thu, 11 Jun 2026 19:03:36 +0000

Hello,

Installing the IR sensor I destoyed the resistors R2 and R3 can anyone tell me the original values of them?.

I mean the small ones in the red pcb rev0.4. The ones that are just on top of the transistor.

Help with possible short - won't display SD card files

EEason — Wed, 10 Jun 2026 21:56:39 +0000

I accidentally touched a wire (one of the thermistor wires, I believe) with the metal tip of a tool a couple weeks ago when I was removing an extruder blob. There was a spark. Printer now powers on and off normally and the display still works, however when I insert an SD card it looks like it is trying to read it and then it shows the startup screen and then goes back to the basic LCD info screen. No error message about the card, and it does this no matter what SD card I put in. I am sure I shorted something but I don't know what, so I am unsure how to repair. Any guidance?

Nozzle Leaking, may have over tightened

Will Harris — Tue, 02 Jun 2026 08:32:31 +0000

My nozzle and heating unit has been slowly leaking. I think it started because I over tightened the nozzle when I put it back on.

But I lowered it the right amount the manual say and am still getting leaks. The manual mentions that over tightening could do damage to the heat break.

Is that likely what's happened here? Is there a fix for it?

Filament Sensor working in 3.14.1, but not in E3D REVO for 60W Hotend version 3.14.1.

Paul K — Mon, 25 May 2026 19:46:59 +0000

I installed a 60W Hotend in my MK3S+ and had to upgrade firmware to the E3D REVO 3.14.1 version.

Fails Filament Sensor in Self-Test. I checked the Sensor by putting a filament in and saw the state did not change from logic level 0 to 1. Checked output voltage from Sensor board. I get 4.22V - No Filament, .25V - with Filament. Both in range.

I re-flashed to 3.14.1 and Sensor shows 0 and 1, respectively.

Re-flashed to the E3D REVO version and is still stays at logic level 0.

WTF is wrong with my extruder??

RedDawg — Sun, 24 May 2026 19:12:24 +0000

One day, OK, next day, this. Noticed extruding was looking erratic. Did a cold pull, and another, both fine. Set screw on hob gear is tight. Bed is level. Belts are tight. Black PLA filament is dry. Did a first-layer cal that was all over the place. Then did a one-layer thick strip 260 mm long, 30 mm wide, rotated 45 deg. Picture shows what I got: Alternating, hard-edged, open and shut bars (80 each) approximately 3.25 mm wide, and a 50 bar length bookended with a 3-bar wide (9.75 mm) closed section.

Can someone with higher math skills than me figure out where this cyclic hiccup is coming from and how to correct it? Thanks.

7bdc8f6c-mk3-extruder-issue.jpg

Calibration Errors After Printing

RMW5h4 — Sat, 23 May 2026 23:37:03 +0000

Hi,

I have been running my printer for quite a while without errors. I had a failed print the other night and since then my printer was unable to start a new one. It would fail during the home check. I tried to run the calibration but the X-Axis fails instantly when traversing to the left. (after hitting the far left stop it immediately indicates a failed test with an "X-Axis Length Error").

When I manually move the extruder left to right it feels like there might be a little "chop" when it gets close to the far left stop.

Any advice? or would I be better off fully disassembling the whole thing and re-assembling?

Bed adhesion and Z offset calibration concerns.

CasualJay — Fri, 22 May 2026 16:47:46 +0000

I have a Prusa MK3S+R and I am having a difficult time after getting a new print sheet (link below) and after washing it with IPA. On paper when I ran the Z offset first layer calibration (unsuccessfully several times) everything seemed fine until I attempted to print a few layers and I was greeted by this warped output. My Z offset is set to 0.950, in the Z offset calibration that was the best result that stuck to the sheet well and did not create a mess.

https://www.amazon.com/UKIAF-254x241mm-Textured-Printers-Dual-Sided/dp/B0FD8GY6YB/ref=rvi_d_sccl_17/142-0321790-7939369?pd_rd_w=1T2Hv&content-id=amzn1.sym.f5690a4d-f2bb-45d9-9d1b-736fee412437&pf_rd_p=f5690a4d-f2bb-45d9-9d1b-736fee412437&pf_rd_r=KSHBQEC64M12Z5BPJ3A9&pd_rd_wg=NAHBl&pd_rd_r=dfc1fc2b-ea4a-40d9-a809-66d3639559f4&pd_rd_i=B0FD8GY6YB&th=1

The reason I'm on this journey at all is because the first layer on the old sheet and with the old settings was streaky at the print bed and the layers were rough.

I am trying to figure out if it is a component that needs to be replaced or is there a calibration I am missing that I need to undergo to get this operational again.

Below are some pictures that might help.

"GCode Sliced for a different printer" no matter what I do.

Lucas — Wed, 20 May 2026 21:07:49 +0000

So I have an MK3S and MMU2S printer and when I send prints to it via Prusa Slicer via the "Send to Printer" button, I always get the "GCode Sliced for a different printer".

What places are these defined and checked and how can I clear it up?

In PrusaConnect it says "Type: Original Prusa i3 MK3S/+" and perhaps that is the mismatch, but how do I change it in there to get all the settings in sync?

I know it's not the biggest deal, but it's driving me a little bonkers.

MK3S LCD dead pixels

4XS — Mon, 18 May 2026 01:01:35 +0000

Screen begin to show dead pixels after 3 years of operation. Recently it become difficult to read. Anyone had this problem and how should I fix.

MK3S Extruder Rebuild – Advice Needed on Replacement Parts and Suppliers

Fetzke — Fri, 15 May 2026 07:33:27 +0000

Dear Community,

after many years of reliable service, my MK3S extruder has started to show some issues. I’m experiencing recurring filament problems and frequent nozzle clogging. Yesterday, it eventually stopped feeding filament altogether and began clicking.

Because of this, I’ve decided to fully rebuild the extruder. I will replace all necessary components, buy new parts where it makes sense, and reprint all printable parts as well.

My hotend has clearly seen a lot of use over the years, so I would like to replace it completely, including the cables, which also seem to be in rather poor condition.

Since this rebuild will take quite some time and effort for me, I would like to take the opportunity to replace any other parts that are likely to be worn out after so many years of use.

Could anyone advise which additional components are worth replacing during such a rebuild, even if they are not yet completely failing?

I would also be very grateful for any recommendations regarding good-quality (and reasonably priced) replacement parts, as well as trusted places to buy them.

Thank you very much in advance for your help!