I did but it looks like the TH pins work at "+" to make the display digits work. I change the pot resistance that is connected to "-" but it doesn't do anything, the display is blank, because it's connected the right way to work, at "+"
Here's the circuit diagram.
lcd display connect to ground to the right TH pin, but doesn't show characters just blank display.
lcd display connect to "+" the right way to work, to the right TH .
Is this a thermocouple? Try to heat it a little.
Have a look at this - Simple Contactless Thermometer Circuit - Make it at Home
It's a thermistor connect by the red and yellow alligator clips to the lcd display.
Does both thermistor and thermocouple measure resistance?
No, a thermocouple generates a voltage measured in millivolts and requires a special amplifier and special connections which are clearly not present on your module, so clearly it is in no way related to a thermocouple.
Quicker than you can Google for the answer.
Thermister is a resistor that changes resistance when it's temperature changes.
A thermocouple generates a micro voltage that changes value with temperature.
Paul
So how this LCD display works, that cob chip does something same with the components, but I doesn't show temperature, the segments just flashes and stay on.
The circuitry is difficult to figure out, same with the components on it.
The most important part of the circuit is U1, the chip under the black blob.
Do you have some kind of adjustable power supply?
Try to slowly reduce the voltage until it turns off.
I have seen many devices where, if the voltage is too high, the inactive LCD segments become activated too.
Well that is of course, a very pertinent point.
This display was almost certainly not designed to operate on 5 V, but more likely 3 V from two button batteries. LCD displays are quite sensitive to supply voltage, particularly those which are multiplexed.
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