Basic soldering, circuit troubleshooting help.

[th3w01f]

My son did a small soldering project after school and I'm trying to figure out how to help him troubleshoot it.

I took an electronics class about 20 years ago but since then I haven't done anything beyond fixing a lose wire on some headphones. I don't see anything that is obviously shorted and the part that seems strange to me is that the lights on the board that the battery is attached to do not work but the lights on the board that is jumpered do work.

Any advice on troubleshooting, tools required, etc would be appreciated. He wants to do a lot more of these so I need to figure out how to tell what's going wrong.

Attachment 53737 Attachment 53739

[SideShow Bob]

Possibly reversed LEDs on the first board, but correct on the second ?

[buffalobo]

Check polarity of each component from battery outward.

A DVM and patience will be good experience for him.

[def90]

yeah, I would check polarity..

[th3w01f]

Thanks for the advice, would a polarity issue on a single LED cause the entire board to not light but allow the 2nd board to work?

[asmo]

A DVM and patience will be good experience for him.

Electronics 101.. First class.

[brutal]

Ditto on polarity checks.

Also check for solder bridges on adjacent pads.

[SideShow Bob]

Ditto on polarity checks.

Also check for solder bridges on adjacent pads.

Oh pish posh, bigger the glob, better the job.

[th3w01f]

Electronics 101.. First class.

He just turned 8 and I took that class 20 years ago so we're both lost.

[th3w01f]

I've done some more testing but still looking for the problem. I used a 9V battery and some wire to verify polarity on all of the LEDs and they are all installed correctly. What's throwing me off is that power is applied to the first board and that's the one that's not working. The solder on the capacitor on the side that doesn't work isn't done well (cap is loose), working on fixing that now, could that cause an issue like this?