Anyone want help me to reverse engineering a person scale?

Hi, I would to "hack" my bathroom scale in order to log weight using arduino, i disassemble it and I've noticed a TEST connection with 2 pin. In the back of the PCB the pin are called K- and K+. Also there are another 4 pin that I think are for read the weight data, named E- E+ S- S+ I have not idea how to proced, anyone can help me? Thanks :)

Edit: This is what I've found on other PCB side |500x281

open the scale and create a schematic of the electronical bits. take photos of the boards can close up's of the chips used.

use your scope and test the output of those pins.

google arduino bathroom scale to see what others have done.

I've googled a bit but not found usefull info. I don't have a oscilloscope so can't test it! I would to know what are TEST and SW pin

"Test" and "Sw" - no particular idea.

"E-", "E+", "S-", "S+" are the "Energise" and "Sense" connections to the strain gauge bridge. I suspect it is driven by a constant-current source to compensate for battery run-down. The LM324 (the machine obviously operates from a 9V battery) amplifies the strain gauge output for the display chip (voltmeter) in the "blob". If you fully trace out the LM324 part of the circuit, you could derive an analog voltage to measure and know how the calibration/ compensation circuits work.

simply put, you have one of hundreds of designs. there is no common circuit and no compelling reason for anyone to spend the hours to figure out what this particular circuit does or how it works and then create an interface.

this is especially hard due to the lack of information.

google digital scale and find out what someone has done, then get that specific make and model scale and follow their instructions.

what makes this a very difficult project is that it is not for a beginner and it will be a one-off. that means spending hours for the end product of one.

there is tons of information about hacking scales. best thing you can do is read it all, read about the circuits, familiarize yourself with the technology, and attempt to measure things. in the end, you will not be a novice.