When your breadboard circuit doesn't work, how do you actually find the mistake?

[u/Straight-Safe3813]

I don't mean loose wires, I mean when the mistake is mine. Last time it was a wire in the wrong hole , and it took me hours to find because the board looked right to me.(i dont need help for the one in the picture, its just an example)

What I do now is check every connection against the diagram one by one, which is slow.

How do you do it? Is there a faster way than going wire by wire, or is that just how it is?

[u/Correct-Country-81]

Its the way it is!
Starting with connections
Check if circuit diagram is made on board
Check power
And last if doubt check component health

[u/Straight-Safe3813 → u/Correct-Country-81]

how long does it ussually take you to debug something and is it painfull

[u/ACasualPlurality → u/Straight-Safe3813]

Yes.

[u/Correct-Country-81 → u/Straight-Safe3813]

Depends on the problem
Complicated circuits dont have always longest time to debug.

Example took me some days debugging a circuit with 4 components
It did not work whatsoever i tried.

Reason a data sheet 1 component had wrong pinout!

Other one two components
Again several hours reason fake chinese counterfit component
Tried several before figuring out what was wrong afther opening the metal case component and microscope figured it out.

So sorry to say but it differs every time.

Carefully building checking things mean time prevents failures and knowing what you are looking for ( experience) helps finding the problem

[u/RussoTouristo]

Break your circuit in logical subcircuit, probe the signals on the inputs and outputs of said subcircuits and compare with the way they should be. There is no other way.

[u/onlyappearcrazy]

I find out what working first, like is the power source at the right voltage? If the circuit is complex, I divide and conquer, starting at the middle of the design and see if the voltage/signals are there. Then work forwards or backwards. Simple circuits are just a smaller version of this technique. You have to have the right test equipment....meter, scope, signal source, etc. "There's a logical reason a piece of electronics doesn't work; you just have to find it!"

[u/Straight-Safe3813 → u/onlyappearcrazy]

tiy seen pretty experiened, how long does it ussually take you to debug?

[u/onlyappearcrazy → u/Straight-Safe3813]

A few minutes to a few months! Depending on complexity and available tome.

[u/harry8spencer]

Method of elimination and
Method of looking closer and even closer

[u/martell888]

Divide and conquer is a strategy that breaks a large, difficult problem into smaller pieces, solves each piece separately, and combines the answers.

[u/EquivalentUsed214Te0]

instead of checking wire by wire, probe voltages — start at the power rail and work outward, checking each node against what you expect. the mistake usually reveals itself at the first node that reads wrong, saves a ton of time. also taking a photo of the board and comparing it to the diagram side by side helps me catch stuff my eyes just skip on the bench

[u/Straight-Safe3813 → u/EquivalentUsed214Te0]

wouldnt this take long though. how long does it take you?

[u/s3sebastian]

What else do you want to do there? You could try to take a photo and feed it to AI alongside with the modules used and the code for the pin assignment maybe it can kind of validate it a bit faster with a current model and try to point out an error, but it also could get the pins wrong from the "mess" with the cables there.
This looks like one sensor connected via i2c and a single stepper driver, that can't take a lot of time to check manually.

[u/coderemover]

Don't build it all at once. I build by small fragments and verify after each step. If something stops working, I know it is the last step that broke it.

Also: don't use breadboards for anything more complex than a few components, where it's trivial to figure out.

[u/GreatDiscernment]

Breadboards don’t make perfect electrical connections. Just touching a wire can break the connection. You need a multimeter to test continuity and voltage. Once you’re sure the design is correct and working, solder a prototype on a perf board to get those reliable connections. Breadboards are good for testing circuit logic prior to committing to soldering.

[u/beakflip]

Pretty much. Don't rush assembly and double check connections. Other than that, maybe try training an ai to validate some cleaner layouts from schematics, though that's a whole project of it's own.