Gen6 working but no Temp registering

Hello. This is my first RepRap and I am in desperate need of assistance.

I have a fully constructed and operational Prusa printer with Gen6 Electronics and RepRap for my printing platform. The Gen6 board is running Marlin 0.9.3 firmware and I am using Audrino 0018 to modify the settings. X, Y and Z axis are all fully functional and have been calibrated. E works but is not yet calibrated. End stops work as well. With a modified start temperature setting, my Hot End does heat up.

The issue I am stuck at is that the RepRap software does not register any temperature - shows 0 the entire time.

I bought the Hot End kit with a 100k termistor (unknown make and model) and I was unable to get it or the spare to register a temperature although both do show the correct behavior when connected to a multimeter and heated up. I have since replaced them with the EPCOS 100k thermistor listed in this forum and have modified the thermistor.h table with the correct settings from the thermistor web page (http://reprap.org/wiki/Thermistor). I have even tried to simply attach the above thermistor directly to the pins on the Gen6 board (to rule out any wiring issues) but I am still getting 0 for the current temperature.

I do get an error when I start the RepRap software - listed below. It starts correctly, gives teh RXTX Version mismatch, then displays the GUI and the last 4 lines appear. Again, even with these errors, I have full functionality of the X, Y, Z and E axis and I can heat up my Hot End. I just have no way of maintaining a stable temperature.

WARNING: RXTX Version mismatch
Jar version = RXTX-2.2pre1
native lib Version = RXTX-2.2pre2
ERROR: GCodeWriter.waitForOK(): Serial Error: Line Number is not Last Line Numbe
r+1, Last Line:0 [0.000s/-1333306330804ms]
ERROR: Requested to resend line 1 [0.000s/0ms]
ERROR: ringGet: line 1 not stored [0.000s/0ms]
ERROR: Resent: N1 *127 [0.015s/15ms]

I attached the current thermistor table - I am using value 1 from the config page.

If anyone can take a look at this and point me in the right direction, I would greatly appreciate it!

Clayton

Check for shorts from the thermistor connection to 5V.

I will verify there is 5V from the board and re-test. Thank you.

I get 4.95 Volts at the pins on the board and 4.95 Volts at the thermistor connection.

Would it be helpful to try and run something other than RepRap software to test this?

If that was with the thermistor connected it does suggest a short to 5V (I'd expect about 4.75V at room temperature: R25 and the thermistor form a voltage divider to convert its variable resistance into a variable voltage for the ATmega's A/D converter to measure), but what I really meant was to measure the resistance from the 5V rail to the thermistor connection: it should be R25's 4.7kOhm, if it's zero then that's your problem.

I will test this tonight. Thank you for clarifying and helping me out!

I get 4.89 V. When I hold the thermistor between my fingers, the voltage increases to 4.91.

So it has more voltage than you thought but it is showing a voltage change with temperature changes. It seems like the voltage is going the wrong way when warmed up - shouldn't it be dropping in voltage as it gets warmer?

That small change is probably noise, as it makes no sense for it to increase with temperature.

rebecca.palmer Wrote:
-------------------------------------------------------
> but what I really meant was
> to measure the resistance from the 5V rail to the
> thermistor connection: it should be R25's 4.7kOhm,
> if it's zero then that's your problem.

I purchased a new pre-assembled Hot End and the same issue is occurring - it will heat up (with the modified settings in Marlin) but it does not register any tempertature - always zero.

I am going to try a new power supply (cheaper solution) and if that does not work, I will have to assume the main board is bad.