Burnt resistor on zprobe

Hi! I had a problem with my printer yesterday. One of the resistors on the motherboard thst connects to the bltouch burnt out.
Does anyone know what kind of resistor I should use to replace it?
It’s a wanhao duplicator i3 plus, monoprice version. Here is a pic of the burnt part.


Judging by the burnt areas around that connector, it looks like you’ve burnt out more than just the resistor. The tracks around that connector going to the micro look burnt too and the connector looks like it got very hot. The bltouch doesn’t pull the sort of current that imho would cause that amount of damage, max 300ma when activating the probe, I’d be surprised if the bltouch caused this. Either way that board looks quite charred. Maybe give it a clean up with some isopropyl alcohol and post the cleaned up pics and people can make a better guess as to if it’s repairable.

I’ve measured continuity on several different points and everything seems to be fine except for the missing resistor. I think you are right about not being caused by the bltouch itself. It’s probably due to a bad soldering job (done by me) when adding the missing pins for the bltouch that caused this. I still think that the board might be salvable if I replace the resistor and clean up the rest of the board. Thanks for your answer!

I will keep my fingers crossed for you :slight_smile: Good luck!



Which resistor is missing? There is one resistor on your photo marked “0”. It is this one? From your photo, the burn is very near the 24v (pin 1 of the connector). You probably made a shortcut with another pin.

And I think it is dangerous to use this burned motherboard.

Especially as charred PCB can become conductive…


Shouldn’t there be another resistor next to that one?
If not, then there is a different problem than I thought.

Any chance I can replace the motherboard with an Arduino or raspberry pi? I can’t get a replacement in my country

No. It is to select 5v or 24v for the first pin. No resistor.

Yes but with a lot of effort. You have to recreate the motherboard yourself.


See Z-probe in my post:

Thank you for all your help! I’m going to work on it over the weekend and see if there is anyway to fix it or replace the board with an Arduino. Otherwise I’ll have to import the board or something.
Thanks again!

Turns out that the problem was that pins 2 and 3 from the z probe connector were shorted out and pin 2 was always grounded.
I was able to fix this by changing the Z_STOP_PIN number in pins_i3_PLUS.h in the source code to PIN 36 and then using pin 3 from the EXT connector instead of pin 2 from the z probe connector.

Thanks for the support!