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So, I am helping my son get his mini kossel together. He is using a Rambo 1.1 (my spare board that has worked in the past). When he connects he gets the temp defect. We've verified the thermistor is working properly all the way back to the connector on the board. We've also checked the little fuses and they are both good (I even switched them to double check).

There is a possibility that he wired the heater/thermistor incorrectly since I gave him a prebuilt hot end (E3D) with a 4 conductor connector already attached. If he inadvertently crossed a wire from the heater and thermistor could he have blown the thermistor port? Oh, we reconfigured and checked T0, T1 and T2 ports also and they all fail the same.

Any ideas?

cheers,
Michael

I assume when you say you reconfigured the ports, that you changed the pin assignments in Repetier firmware pins.h in the Rambo section of the header file? My first temp input went bad and I reconfigured here and it worked using another input.

Note that if the bed thermistor is enabled in the firmware and not connected you'll get the def condition as well, so you need to disable the heated bed in the firmware.
To check the thermistor input, connect a 100KOhm resistor to the thermistor port and see if you get a reasonable temperature reading, if you don't the port is dead or the pins are configured incorrectly.

FWIW unless you have actual voltage running into the thermistor pins, it's unlikely you damaged them, just connecting the heater resistor probably wouldn't hurt it.

Thanks guys. Yes, the bed was disabled in firmware as there is no heated bed yet. I ended up pulling RAMBo #1 out of my Rostock. And it works fine. However, we discovered that the heat cartridge appears to be dead (which is odd also). He's replacing the cartridge now and we'll see.

Broose, yes, I did all the right things to test t0, t1 and t2 and they all failed. Didn't test t3 since by default pins.h does not have it configured and I didn't think I needed to muck with it given that the other 3 didn't work.

It is possible that he had a thermistor wire and the + from the hot end wired to the thermistor. But that would only blow one thermistor port I would think.

Most likely blew the ADC on the board and you will have to send it in for repairs but knowing you, you can probably replace SMD components yourself.

mhackney wrote:It is possible that he had a thermistor wire and the + from the hot end wired to the thermistor. But that would only blow one thermistor port I would think.

You can blow them all through just one pin if your unlucky.
There is really only 1 ADC on the chip and it's multiplexed across the pins, if you're lucky you blow just enough of the logic to kill only one pin, but if your unlucky you can kill the ADC and none of them will work.

and that's what it looks like happened. The swapped RAMBo works fine. I'll send this one back for repair. Kids...

cheers,
Michael