Probe 0 Issue, Please Help

[KGeier]

I've been troubleshooting this issue for the last several weeks with no success. When I first built my heatermeter I was excited when I turned it on and received text "Pit: 88 F" Yet I was confused because I did not have a probe in yet. This has been the issue I've been working on. In the attached pictures I know the solder joints for Probe 0 are trash, I've resoldered them 4 times with no success. I do not believe them to be the issue.

Here are the conditions the best that I can state them:

• When Powered up, Probe 0 displays a temperature of 88 degrees without a probe connected.
• Probe 1 and Probe 2 work as expected and show temperature correctly - 70 degrees.
• When a probe is connected to Probe 0 sometimes there is no result, other times the display shows "No Probe Connected"

 

[RalphTrimble]

Well, you've got some major confusion there.... 'cause I see a standard probe jack installed at Probe 0 with the pullup resistor for the standard probe installed as well, but on the other side of the board I see the SMD components for the Thermocouple Pit Probe amplifier installed??? So it looks like you have an improper mixture of options for your pit probe.

To fix you've got to decide which way you want to go, thermocouple pit probe or standard pit probe?

If you go TC then you need to remove the standard probe jack from Probe 0 and install the TC jack there instead, and you also need to remove the 10K pullup resistor for that probe (the one that is oriented in the opposite direction as the rest). You also need to select the probe type as Thermocouple for Probe 0 in the HM Configuration.

If you want to go Standard probe then you would need to disconnect the thermocouple amp that you have on the board from the ATMega somehow... I haven't looked into doing that, might be able to remove a resistor or something to do that or might have to cut a trace....

You can't have both a standard pit probe and a thermocouple amplifier connected to the ATMega at the same time, you need to go one way or the other.

 

[JakeBrown]

Where is the jack for Probe 0?

I have jacks 1, 2, 3.

 

[RalphTrimble]

Where is the jack for Probe 0?

I have jacks 1, 2, 3.

Are you and the original poster the same guy?

At any rate, in the pictures posted above (the one of the top view showing the actual jacks) the probe jack all the way on the right (the one with the white outline of a larger box around it) is Probe 0. The larger white box outlines the footprint of the Thermocouple jack that should be there to work with the thermocouple amp that is on the other side of the board. The empty space for the probe jack all the way on the left side of the board would be Food Probe 3 (or Probe 3, with probes being numbered from 0-3, pit probe being 0 and food probes being 1-3). Often times this last probe is used for the ambient temperature thermistor but generally a probe jack still gets installed there, and it can be used for a 3rd food probe if needed.