Carpc: Please help me locate the thermocouple on this circuit board

[nobb123]

Hi.
I have a carpc with a motorized LCD touchscreen monitor (MTSVO-SC). The problem is that I live in Canada and when the temperature is too low, the monitor will refuse to open. It makes a beeping noise and does not open until the temperature is above -5C. I would like to override this protection circuitry so that I can use the monitor in cold conditions. I opened up the monitor today to try to locate the device that senses the temperature. My guess is that the monitor uses a thermocouple, and if true, I am guessing that I can make the monitor always think that the temperature is over -5C by removing the thermocouple and soldering on a resistor with the appropriate resistance (since thermocouples measure temperature with resistance).

The problem is that locating the thermocouple is easier said than done. I have googled up pictures of thermocouples and I also have general knowledge of what a thermocouple looks like. I was wondering if anyone could please take a look at these circuit board pictures and help me find the thermocouple (if any).

http://img67.imageshack.us/img67/9933/img7794pg5.th.jpg

http://img67.imageshack.us/img67/4028/img7797jw2.th.jpg

In one of the pictures, I did a close up macro shot of some weird round plastic device which I suspect has the potential to be a thermocouple (since it only has 2 leads soldered onto the back of the circuit board). I am not sure. Is there some way I can test to see if this device is in fact a thermocouple? I thought about using my multimeter to measure the resistance across the leads at different temperatures, but I'm playing it safe and don't want the slight electrical current from my multimeter damaging anything.

Advice would be appreciated. Thanks!

 

[triden]

It doesn't necessarily have to be a thermocouple, and I would actually guess against it. It could have an IC temp sensor like an lm35 or even a thermistor on it. Thermocouples are usually used in high temperature enviroments and cost more than a simple IC temp sensor would. If you want to figure out what the dives you are looking at are, read the number off the top of the device and type it into google. It should show up with a datasheet or some information pertaining to the device.

Also, if you take the "th" out of the end of the picture filenames, you get the fullsize image.

 

[ravenprp]

Hi there,

After looking at the pictures, I believe the round plastic device you mentioned is indeed the thermocouple. It looks like it is connected to the circuit board through the two leads, which is typical for a thermocouple.

To test if it is a thermocouple, you can use a multimeter to measure the resistance across the leads at different temperatures. You can also try heating up the device with a hair dryer and see if the resistance changes. Just make sure to use the appropriate settings on your multimeter to avoid any damage.

If you do confirm that it is a thermocouple, you can try replacing it with a resistor as you mentioned. However, I would recommend consulting with a professional or doing further research before making any modifications to the circuit board.

I hope this helps and good luck with your carpc!