Just puzzling myself with a circuit, first time ever!

Thread Starter

Spyros00

Joined Nov 29, 2019
4
Hello friends!

Just before telling you my problem, I need to tell you that I haven't any knowledge of the electronics field. I'm just curious if I can find a way to fix it.
I 've bought some lights for the bicycle the other day, one white and one red (front & back). My problem is that one of them, the front one, has appeared to be problematic about 5 days after I bought it. There are 2 light sources where one of them just keeps being turned on a little bit, and gives a small light emission, even when I've turned it off.

As these days were rainy and the bicycle was outside, I supposed that its electronics might have gotten exposed to the water, as the product is cheap probably not well designed to be out with that weather.

I opened it up, and the batteries and the circuit were all wet inside. I let the components to dry out and tested it, but still the same problem. After I started scratching one of the components attached on the circuit surface with a "U1" sign, which seemed to be dirty/rusty and tested again. At that time, that circuit worked fine, so did both of its light sources.

Then, I made the mistake to scratch the other side of that U1 component, which had also one rusty/blue-colored spot, but the material of that spot (which probably connected the U1 with another component) didn't stand the pressure of the pin that I 've been using on my "GoWildOnTheCheapLight" educational operation.

Please, if it's possible, I would like to know what exactly I've destroyed. And if there is any way of fixing it!?

Currently available: microscope, pin, puzzling mood73409293_1637066413101846_2236679604657979392_n.jpg78497210_797460490690076_5906638427905851392_n.jpg

Admin, I'm sorry but if this post isn't supposed to be here, please delete or move it where it should be! Thank you! :)
 

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dl324

Joined Mar 30, 2015
9,575
Welcome to AAC!

Carefully clean the leads with isopropyl alcohol and maybe use some delicate abrasion to clean up the leads. Then try to apply flux and solder. If the lead near C1 is broken completely, a piece of wire to bridge the gap might be necessary.

With that much corrosion, I'd be worried that it had migrated up the lead and into the package.

If you can remove and install surface mounts, you could try to look for a replacement part. I searched and nothing came up...

Or buy another one.
 

Thread Starter

Spyros00

Joined Nov 29, 2019
4
Welcome to AAC!

Carefully clean the leads with isopropyl alcohol and maybe use some delicate abrasion to clean up the leads. Then try to apply flux and solder. If the lead near C1 is broken completely, a piece of wire to bridge the gap might be necessary.

With that much corrosion, I'd be worried that it had migrated up the lead and into the package.

If you can remove and install surface mounts, you could try to look for a replacement part. I searched and nothing came up...

Or buy another one.
Thank you, friend! Yes, I also searched but some hoover parts came up :)

I think I'll give it a try with the flux and solder surgery method you suggested. Just to be sure, flux is a paste and solder is a wire, is it right?
 

dl324

Joined Mar 30, 2015
9,575
Just to be sure, flux is a paste and solder is a wire, is it right?
You can use liquid or paste flux. Just make sure it's for electronics and not plumbing.

Solder wire usually has a core (rosin flux), but you need more than that.
Something like this:
1575074648271.png
Unleaded, 63/37, 60/40, doesn't matter as long as it's for electronics.
 

Thread Starter

Spyros00

Joined Nov 29, 2019
4
You can use liquid or paste flux. Just make sure it's for electronics and not plumbing.

Solder wire usually has a core (rosin flux), but you need more than that.
Something like this:
View attachment 193443
Unleaded, 63/37, 60/40, doesn't matter as long as it's for electronics.
Thank you, Dennis, I understand the terms now!

One more question I have, please....
Will I need a heating source, like a soldering pen, that I checked in some soldering wires videos?

Thanks in advance! :)
 

dl324

Joined Mar 30, 2015
9,575
Will I need a heating source, like a soldering pen, that I checked in some soldering wires videos?
Yes, you'll need a soldering iron. Unless you plan to be doing a lot of soldering, a hobbyist iron is all you need.

From a 2013 Jameco catalog (they don't have PDF's for the newer ones):
1575157231972.png
If you need to remove solder, soldering wick or a solder sucker will be needed.
1575157335008.png
1575157385701.png
 

Thread Starter

Spyros00

Joined Nov 29, 2019
4
Yes, you'll need a soldering iron. Unless you plan to be doing a lot of soldering, a hobbyist iron is all you need.

From a 2013 Jameco catalog (they don't have PDF's for the newer ones):
View attachment 193498
If you need to remove solder, soldering wick or a solder sucker will be needed.
View attachment 193499
View attachment 193500
Dennis, thank you very much for the info and advice!
Keep sharing the good stuff!

I think I 'm ready to take some investigation for it in the local market.
I'll try coming back with results :))
 
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