Nozzle and bed thermistors "defective"?

[Apotheoun]

I had an issue the other day where my F3 fuse popped while I was doing my PEEK fan print. Now that I replaced that fuse my thermistors (displayed on the LCD) are saying 'def'. When I first start up the printer it says the nozzle is around 20 degrees and the bed is around -22 degrees then switches over to 'def' after about 10 seconds. I've gone through all my wiring and there's nothing wrong with it as far as I can tell. Any idea what's going on?

[Mac The Knife]

Double check where it plugs into the board,,,

[Brian]

I had an issue the other day where my F3 fuse popped while I was doing my PEEK fan print. Now that I replaced that fuse my thermistors (displayed on the LCD) are saying 'def'. When I first start up the printer it says the nozzle is around 20 degrees and the bed is around -22 degrees then switches over to 'def' after about 10 seconds. I've gone through all my wiring and there's nothing wrong with it as far as I can tell. Any idea what's going on?

If one thermistor is disconnected or shorted out, they will both read "def".

[nitewatchman]

I had an issue the other day where my F3 fuse popped while I was doing my PEEK fan print. Now that I replaced that fuse my thermistors (displayed on the LCD) are saying 'def'. When I first start up the printer it says the nozzle is around 20 degrees and the bed is around -22 degrees then switches over to 'def' after about 10 seconds. I've gone through all my wiring and there's nothing wrong with it as far as I can tell. Any idea what's going on?

This indicates a definite problem with the bed Thermistor. Most likely the Thermistor circuit is open. This could be anything from an open Thermistor to a loose connection. Start by removing and replugging the connection to the board. There is a chance that the plug was disturbed when the fuse was replaced.

If this does not solve the problem remove the plug and test the resistance between the two sockets on the plug itself. The resistance should be about 100K ohms. If this is less or open trace back to the Thermistor until you find a broken wire, bad solder connection, or open or shorted Thernistor. Rehabilite as required.

If all of this checks okay, there is likely a problem with the Rambo input circuit. There are other inputs on the Rambo that can be utilized but this is outside my experience. There are others here that can walk you through this.

Edit: Additionally, while some fuses just get touched by the "finger of God" and fail there is usually a reason for the event. Check you wiring very carefully to be sure that there are no shorts that could leak bed heater current into the Thermistor input on the Rambo card.


nitewatchman

[RegB]

As an insult to the English language....

I will say that I heartily concur - with the notion that the thermistor circuit is "open".
Almost certainly the one that is showing very low temps (negative (or -'ve) value).

My experience of a similar symptom stemmed from my lack of skill at crimping pins onto little wires.

The heck with it, if I ever do this again I'll use WIRE NUTS for temporary connections (-:

I think I hear someone physically CRINGING at the thought.

[geneb]

That would be me.

g.