PCB Advice Requested

Thread Starter


Joined Dec 5, 2015
I need advice on a Sailor Moon Brooch that only plays music when you put the batteries in. The push button doesn't work. I opened it up and noticed some grime and possible flux on the circuit board. I cleaned then grime around circuit under the button with 91% Isopropyl Alchocol and it leaves a white residue. The push button still doesn't work. I was going to finish cleaning the grime off the entire circuit board but noticed that there appears to be a scratch on the path under the button. (At the bottom of the circuit between the two bottom nodes on the left). Do you think that is the problem or if I finish cleaning the grime then the push button will work? Should I continue to use the alcohol or something else? It is a really nice toy. Your advice would be appreciated. See the attached pictures



Joined Mar 24, 2008
Greetings! And welcome to AAC!

The Completed Projects Forum (as opposed to The Projects Forum) is for sharing completed projects.

I've moved your post into The Projects Forum, where it will draw more responses.

Good luck with your project!


Joined Jun 26, 2012
I think the scratches are OK. It does not look like the traces are broken. Sounds like a bad or dirty switch.

The switch looks like a common 6mm tactile switch. Push the button by hand and you should feel a click. It could also be that the mechanical alignments are out of whack and the plunger on the cover is not pressing the switch button. Check that first.

If you have a voltmeter, measure the voltage across the pairs of switch pins and (with your third hand) press the button. The voltage should go from 0Volts to roughly the battery voltage. If it does, the switch is OK and your problem is elsewhere. If the voltage doesn't change the switch is not working. You could try to remove the board from the case and shoot some cleaner carefully into the switch - around the button would be my shot. You might find other issues when the board is removed.

If the switch is bad you might be able to replace it depending on your skills. E-Switch makes them and Mouser stocks them as does DigiKey. You'll need to match up the plunger type and determine whether the switch is normally open or closed (most are normally open).

Since the list price Qty 1 for most of these is pretty cheap, you might just contact E-Switch or one of the distributors and ask for a sample once you get an idea of what you need. OR post a picture of the other side of the switch and a member here might have one to send you.

Good luck!


Joined Nov 29, 2011
These pushbutton switches are notoriously unreliable. To test the device, take a penny and short the contacts on the back of the switch and see if it works. If it does, find a replacement switch, replace it and you are back in business.

The gunk on the back is only flux. Too much flux could have contaminated the switch. I personally like to keep my boards clean, but a quick and dirty manufacturer will leave it in place. It is generally harmless.