Thermocouple Issues

[JasonParallel]

Finished my build recently and just got a thermocouple in the mail (http://www.amazon.com/exec/obidos/ASIN/B0142SKL0Y/tvwb-20). With it connected I'm still getting the no pit probe message. The config for probe 0 is set to Type:thermocouple mv/c:5 offset:0. When checking the voltage across the legs of the thermocouple connector I see 0 volts. Any idea what to check next?

 

[Steve_M]

Without any pics, my guess is that you've got a solder bridge across some of the legs of the TC amp. Use a magnifying glass or take some steady pics you can zoom in on to check the soldering.

Refer to the picture in the TC Amp Testing wiki page.

Run a continuity check to make sure that 1,2,4,5,6 are not shorted out to each other.

 

[JasonParallel]

I got a board with the surface mount amp pre soldered and tested from Bryan. So I'm guessing that is not the issue.
pics: https://goo.gl/photos/rgNVmuS5TfDAXHtD7

Heating up the TC with a lighter I can see the voltage on it go up from 0 to ~2mv. I see no change on the probe pin.

 

[JasonParallel]

It does look a little shiny between 2 of the legs. Maybe I got something in there. Time to find a magnifying glass.

 

[JasonParallel]

Never mind. The top middle 2 pins (marked 2 and 2 in your linked page) are supposed to be connected, right?

 

[Steve_M]

Yah. It really looks like you're missing the 10k resistor here.

 

[JasonParallel]

Hmm. That sure is. I wonder what happened there. I guess I'm going to have to learn how to solder surface mounted.

Thanks Steve

 

[Steve_M]

If you can't find the surface mount one, you'll have a spare 10k resistor that you didn't solder in because of the TC build. You could clip the legs nice and short and try and solder it in place.

You also need to solder in the copper clip for the thermocouple jack, so that you don't accidentally pry it up from the PCB.

 

[JasonParallel]

Good call. It's ugly but it works now. There will be ribs this weekend!

 

[Dean A]

G'day guys - a quick comment about this thread; the exact same thing was going on with my 4.3 board - except I had both surface mount 10k resistors missing from my TC amp.

I've mounted the 10k resistor and borrowed another from the 3rd probe, something I'll remedy when next in the electronics purchasing mood. Looks crap but who's going to see when in the case...

Being this thread saved me I'll use words like stuck thermocouple reading and probe 0 temperature wrong with first build so first timers like me can can find this.

Cook on peeps and a big thanks to the developers, contributors & community for a nice little project, cheers !!!!