Faulty temperature sensor on PCB - lights keep blinking, how to replace this?
If you google "T1C temperature sensor", the first result is the LM61 temp sensor from TI. Under the device markings, you can see they label their SOT-23 packages with "T1C". The cool part about this sensor is it's an analog sensor, meaning we can easily measure the output with a multimeter to see what temperature the chip reads. First, peruse the datasheet for a understanding of the chip. The first test I would conduct is measuring the supply voltage, but let's check the pinout first.



Now that we know the pinout, let's start by seeing if the chip is even receiving power. Measure the voltage between pins 1 &amp; 3. The datasheet (6.3 - Recommended Operating Conditions) says to power the chip with 2-10 volts,



however there are a lot of other places that say 2.7-10V. I'd expect it to be powered with 3.3V or 5V. 

 

If your device isn't being powered, then you need to traceback that issue. Let's assume you're getting a lovely 3.3V to the chip. Let's find how the voltage at the Vout pin corresponds with the temperature. On the first page in section 3, it states that "The output voltage of the LM61 is linearly proportional to temperature (10mV/C) and has a DC offset of 600mV."

 


There are a few other operational curves and tolerances that will come into play, but you should be able to get a good idea if the chip is functioning properly. I'd start with room temperature, and write the voltage output down, then slowly increase temperature by some method, whether that be putting it in your toaster oven on warm or blasting your car's heat. Whatever the method, at different intervals, write both temperature and voltage down. Afterwards, you should be able to compare the values to the previously listed 10mV per C proportion. Remember there is a 600mV offset!
Be sure to try and eliminate as many temperature related unknowns or variables by controlling your test environment as much as possible. 

Good luck with the board, post any progress!