geekhack

geekhack Community => Keyboards => Topic started by: fnurl on Fri, 27 January 2017, 11:09:54

Title: I broke this little thing on my minivan :( what is it?
Post by: fnurl on Fri, 27 January 2017, 11:09:54: I has just soldered the switches and leds to the PCB and everything worked, I was so happy... (first build)

Then while clipping of the led legs I got the clippers snagged on a little component beside the LED legs and it came loose. The switch works (phew), but the LED won't light up.

What is it and is it bad? (besides LED fail)

(https://uploads.tapatalk-cdn.com/20170127/16297b5ef2daf5fc1951aa5e9b5dd221.jpg)

It's one of the small square things (the smallest one). I am guessing it's a resistor and I just broke the connection to the led. Am I right?
Title: I broke this little thing on my minivan :( what is it?
Post by: YoungMichael88 on Fri, 27 January 2017, 11:19:18: Quote from: fnurl on Fri, 27 January 2017, 11:09:54
I has just soldered the switches and leds to the PCB and everything worked, I was so happy... (first build)

Then while clipping of the led legs I got the clippers snagged on a little component beside the LED legs and it came loose. The switch works (phew), but the LED won't light up.

What is it and is it bad? (besides LED fail)

Show Image
(https://uploads.tapatalk-cdn.com/20170127/16297b5ef2daf5fc1951aa5e9b5dd221.jpg)

It's one of the small square things (the smallest one). I am guessing it's a resistor and I just broke the connection to the led. Am I right?
That is indeed a resistor. If the pads are ok you should be able to remove it and replace it with a new one, assuming the resistor is damaged. But if it's still on the board, not damaged and the connection has just been broken, you can try to quickly reflow the solder joint (heat it back up to liquid state quickly) and make that connection again.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: happylacquer on Fri, 27 January 2017, 11:20:21: Did you pull any pads? If so probably easiest to live with it. If you didn't just go get a resistor with a matching value and put it on.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: fnurl on Fri, 27 January 2017, 11:24:26: Ok thanks, I tried soldering it back using solder on the tip of the soldering iron, but it was soo tiny and the surface tension on the solder was to great. I probably fried it during the process too.

I guess I'll try to get a new one and see if I can get a hold of somebody at work with access to a finer iron and magnifying glass to help me fix it. Thanks for the reply!
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: fnurl on Fri, 27 January 2017, 11:25:53: Quote from: happylacquer on Fri, 27 January 2017, 11:20:21
Did you pull any pads? If so probably easiest to live with it. If you didn't just go get a resistor with a matching value and put it on.

Couldn't see really. Will have to get a magnifying glass and inspect the damage. Will post a picture later (on the bus atm).
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: pomk on Fri, 27 January 2017, 11:58:18: The trick is to hold the component to the board with tweezers or a toothpick, so that it stays on the board when you lift your iron.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: fnurl on Fri, 27 January 2017, 13:55:48: Here is the damage. Got very fluxy too. Should I clean that up? The toothpick trick might have worked. The first try went well, then... it went bad. It's so small, just 1mm!

(https://uploads.tapatalk-cdn.com/20170127/715a77ce4b8cf97c60a7fb26b8d5026f.jpg)

(https://uploads.tapatalk-cdn.com/20170127/8b6cb9e4aa32b0a6aa4481254d6ef924.jpg)

(https://uploads.tapatalk-cdn.com/20170127/e03c74bfd4b493027e4b287d394c9895.jpg)

Here is a undamaged one. What should I get and where do I get it?

(https://uploads.tapatalk-cdn.com/20170127/af4268eaecdf6d534e00cef63957f72e.jpg)

I'll probably just live with it for now, but should I desolder it? Remove the LED? Or is it fine to leave it like it is?
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: chuckdee on Fri, 27 January 2017, 14:18:13: Can you plug it in and check it? That's what I do to make sure the PCB is good. Check all of the keys around that, and the leds.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: pomk on Fri, 27 January 2017, 14:37:27: You could clean the location with some ipa and then see if the pad is still fine. Resistors typically can handle being heated quite well and if the pad is still present it should be pretty straightforward to solder the resistor back.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: ghostjuggernaut on Fri, 27 January 2017, 14:41:35: If you have a multimeter, you can find the traces and get an idea if the pads are toast. If you dont have one, you can still locate the traces and solder wire directly to the resistor from the source, and then from the resistor to the anode of the led.

I would also recommend desoldering the resistor to inspect the pads, assuming you have a solder sucker. If not, they are pretty cheap on amazon and I would recommend having one if you plan on soldering more in the future. Just an all around good tool to have.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: bmmcwhirt on Fri, 27 January 2017, 19:29:02: Here is a really crappy video I made about SMD/SMT soldering you may find useful.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: unoab on Sat, 28 January 2017, 21:05:37: Quote from: ghostjuggernaut on Fri, 27 January 2017, 14:41:35
I would also recommend desoldering the resistor to inspect the pads, assuming you have a solder sucker. If not, they are pretty cheap on amazon and I would recommend having one if you plan on soldering more in the future. Just an all around good tool to have.

The solder sucker wont be that great here, all he needs to do is push the resistor off the pads with the iron after putting the tip across both ends to melt both joints, drown it in solder if you are having trouble with that, and then I would recommend cleaning off the pads with a desoldering wick/braid. It works much better at cleaning SMD pads than a sucker would. Like everything though some brands just suck, chem-wik has worked well for me and is what I have on my bench.

I found a video that explains it good enough, do what he does and you should be fine or removing it, cleaning it, replacing it, and making sure everything is fine. (skip to 1:22 in the video for the useful part)
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: tp4tissue on Sat, 28 January 2017, 21:42:00: hahaha

buy a new resistor first. there's no point salvaging that one.. it's not expensive.. don't buy just 1, buy like 20, they're probably a few cents each.

Remove solder from the pad.. you can do this with a cutip as it's heated by the iron, because it's not alot of solder where you need a sucker.

Then tin just 1 side of the pad..

get a firm hold on a resistor using a tweezer, and slide it into position right before the tinned pad, then heat the tinned pad, and push it the rest of the distance inward..

NOW... the other side, you'd want to just tin the tip of the iron, remember it just needs to be a SPECK, an tiny bit of solder.. touch that to the other side of the resistor and you're done.

DON"T hold the iron against it for too long.. design is usually 3 seconds max..
Then
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: ghostjuggernaut on Sat, 28 January 2017, 22:03:51: Quote from: unoab on Sat, 28 January 2017, 21:05:37
Quote from: ghostjuggernaut on Fri, 27 January 2017, 14:41:35
I would also recommend desoldering the resistor to inspect the pads, assuming you have a solder sucker. If not, they are pretty cheap on amazon and I would recommend having one if you plan on soldering more in the future. Just an all around good tool to have.

The solder sucker wont be that great here, all he needs to do is push the resistor off the pads with the iron after putting the tip across both ends to melt both joints, drown it in solder if you are having trouble with that, and then I would recommend cleaning off the pads with a desoldering wick/braid. It works much better at cleaning SMD pads than a sucker would. Like everything though some brands just suck, chem-wik has worked well for me and is what I have on my bench.

I found a video that explains it good enough, do what he does and you should be fine or removing it, cleaning it, replacing it, and making sure everything is fine. (skip to 1:22 in the video for the useful part)

Haha I love his videos, his commentary is great.

Ive never seen that trick, using solder to 'suck up' a component. Good to know.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: unoab on Sat, 28 January 2017, 23:04:00: Quote from: ghostjuggernaut on Sat, 28 January 2017, 22:03:51
Haha I love his videos, his commentary is great.

Ive never seen that trick, using solder to 'suck up' a component. Good to know.

Same here, probably why google seeded that one up on my search results when I went poking around for someone else doing what I mentioned.

And its a pretty good trick if you have spares, especially when you are working with increasingly smaller parts and only have an iron at hand. My brass pubes tip cleaner has a handful of smd parts in it from that.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: pomk on Sun, 29 January 2017, 06:53:54: Rossmann is the boss :thumb:

Anyway, the resistor itself is probably just fine and no new one is needed. Most resistors are specified to withstand ~30 seconds in ~260 degree lead bath and I doubt that you managed to go that far. You can try just holding it down with tweezers/toothpick and repeatedly transfer the iron on both pads until they both are molten long enough for you to be able to press and align the components on the pads. Just note that you should never do that with components other than resistors, and even for them it's not really the preferred method. I describe this method because it's the easiest option if you don't want to start purchasing solder wick, flux and/or new resistors.
Title: Re: I broke this little thing on my minivan :( what is it?
Post by: fnurl on Sun, 29 January 2017, 07:26:21: Thanks for all the tips! I will probably try to clean it up first using your tips. Will get some wick and check the pads. Then do the one side first method holding the resistor with tweezers. Thanks!