How to check an electrical circuit?

Question

Arduino

Good afternoon, tell me how to check the circuit with a multimeter?
I assembled the circuit according to the drawings on a solderless board, connected it to the arduino and I understand that it (the circuit) does not work, I think that there is a break in the circuit somewhere.
There are 4 main modules in the circuit: an instrumentation amplifier (ina121) and 3 filters (op-amp TL042), is there any way to check their outputs, since all other elements are amplifier windings.
And could it be that the drawing suggests using a tantalum polar capacitor, and I use a ceramic polar of the same rating?
Another difficulty lies in the fact that this whole circuit is an analog sensor that receives a signal from the skin, so I have no idea how to check for performance, is it possible to artificially generate a signal?

Answer 1

What's the scheme? It's just that on solderless boards using noodles from wires, there are such pickups that there is nothing to catch with an instrumental amplifier. Usually, a printed circuit board needs to be soldered with them, and maybe even with a screen.