Pork Barrel - pulverized a pad!

[Bret608]

Hi all,

I'm hoping someone can point me in the right direction on what to do when a solder pad gets pulled up.

Here's how it happened:

I was working on my Pork Barrel (current version fabbed board), on which I've only gotten about twenty resistors soldered in so far. I was just about to do R25, when I noticed I couldn't get the lead through the bottom pad. It looked like it had a little solder in it, but not enough to completely close the hole. I wonder if it made its way there when I did R24?

Anyway, instead of taking a step back and just thinking it through, I decided to be smart and use desoldering braid to try and clean it out. It got only a tiny bit of solder out, but also kind of fused to the surface of the PCB and started to pull up the surface. Not so smart I guess!

I'm not sure if the pad is completely wrecked or not, so I guess as a starting point I'll ask: 1) how to get the rest of the solder out of the hole? 2) if the pad is trashed, is this the type of PCB where I could re-build the pad by exposing some of the trace and using some spare component lead to create a new pad? What would be the best way to go about that?

This is a bummer of course, but I'm sure this was bound to happen to me at some point! Thanks for any advice you can provide. I can always post a pic or two if needed, but I'm not sure it's necessary at this point.

Cheers,

Bret

[9Lives]

I'm no master by any means but I have ran into this similar issue so many times... I've almost figured out that desolder braid either sucks or I just don't use it right.. That being said I'm not all that great with the pump either. Usually what I do is try and heat with the iron and remove carefully. Seems wreckless but I save it that way more ofter than with the tools.. And to be honest the easiest way I've found to cope with these issues is to see what component comes directly before the messed upp pad and manually connect the 2 leads if possible and try to insulate some how. It leaves me very dissatisfied bc it's so ugly but if you think about it, you just wanna get the damn thing to work. (thats how we do everything in Georgia lol) if I can't do it that way I then try and scratch the trace very gently and solder to it but I feel like I get a better connection when just connecting the 2 leads.. Hope that's helpful. Just step back from it man and think about it. When I get frustrated with these pcbs I usually make it worse.

[pickdropper]

A couple of things that help solder braid:

1.)  Put a little extra solder on the tip of your iron before applying it to the brain.  I know this seems counter-intuitive, but it can help.  Just don't put too much.

2.)  Some braid is impregnated with flux and other braid isn't.  I apply a bit of flux to the area where I want to remove the solder and sometimes to the braid itself.  For this purpose, the flux pens can be really handy.

[Bret608]

Thanks to both of you for the help! I totally thought about either a) heating the pad gently and removing the extra solder with a bamboo skewer or b) just connecting to the lead of next component as you suggest.

However, I took a step back as well, which was a good idea. I work at a technical/community college with a really good electronics faculty. I got in touch with one of the instructors and long story short, we're supposed to meet up this afternoon so he can have a look at the damage. He said they could lend me a desoldering pump to try, or if I really did damage the pad, he will help me fix it. I am loving that I am about to get a tutorial from a pro!

[DutchMF]

Keep it up, Bret! The Porkbarrel is well worth it, it sounds gorgeous! (Even with an MN3207 @ +9V,  !) It's the build I get the most compliments for from my guitar playing, non-soldering buddies! Let me know when you get it working.

Paul

[Bret608]

Thanks Paul! I will hopefully get this fixed and wrap it up in a couple of weeks.

I posted a question about the differences between MN3007, MN3207 and V3207 in General Questions a while back before I bought parts. Scruffie, Jacob, LaceSensor and others gave me a real schooling. Long story short, I was worried about voltage, clipping, and all that, and they usefully pointed out that even the chorus boxed\s that used the MN3007 back in the day did so at 9 volts for the most part.

What's more, I found out that the Ibanez CS9 used the MN3207. This is actually one of my all-time favorites, slightly preferable to the CE2. So I think a Pork Barrel with 3207s brings together some of the best!

[madbean]

De-soldering braid is not too great at removing solder between pads, although it works pretty well on the surface face of them. You really need some vaccum action to get to the through-hole.

One other trick: if you have some solder stuck in a pad, heat the bottom pad up with your iron then gently push the lead of the component through the top side. The solder heats up from the iron and sticks to the lead as it is pushed through the hole.

[DutchMF]

De-soldering braid is not too great at removing solder between pads, although it works pretty well on the surface face of them. You really need some vaccum action to get to the through-hole.

One other trick: if you have some solder stuck in a pad, heat the bottom pad up with your iron then gently push the lead of the component through the top side. The solder heats up from the iron and sticks to the lead as it is pushed through the hole.

another reason to hang on to your resistor clippings, provided by the Bean himself: Even if there's no component left, you could still use a clipped-off lead to get the solder out. It works, used it myself. Save those clippings!!!

Paul

[Bret608]

Thanks a lot to you both, Brian and Paul! That thought had occurred to me about getting the lead through while heating the pad. One of the electronics faculty where I work invited me to bring my board down to their lab tomorrow so he can help see how bad the pad is (they have really nice equipment!). I'll report back on what method we end up using to fix it.

[Bret608]

Hey guys,

Just wanted to follow up on this! The electronics instructor I mentioned invited down to their department yesterday. I brought my board and parts. We looked at the solder pad in question under this massive magnifying glass that probably cost several thousand dollars! He said I hadn't destroyed the pad too badly, but that I had wrecked the connection between R25 (the bottom pad) and C15 (the right pad, if looking at the solder side of the board). We checked the schematic to make sure these should in fact be connected, and it does look to be the case. Could Brian or someone who's built it confirm for me too?

Anyway, we got the extra solder out of the pad with no problem using a pump. He showed me a good fix--scratch to expose a bit of trace between the bottom pad of R25 and the right pad of C15, and allow some extra lead from each of those components to meet on top of that exposed trace. Then solder the whole thing to re-establish the connection. Does that make sense to folks here as well?

I feel I participated in a "master class" or something! He let me hang around and use their equipment to finish most of the board. He also loaned me a pump and some other tools to take home and use to finish the project. And you should see the collection of components they have!

Cheers,

Bret

[DutchMF]

When looking at the solderside of the board, the pads you mentioned should indeed be connected. You can see it in the schematic as well. Good luck fixing it, and what a cool dude, that electronics instructor!

Paul

[Bret608]

You bet! My natural tendency to over-network has paid off in spades!   

Thanks for confirming Paul--the guy's knowledge is tremendous but I thought it'd be good to double-check with someone who's built it. He told me a couple of the other instructors are musicians whose interest is audio electronics. I never thought working at a tech college would have such implications for my personal interests!

[Bret608]

Hey 9Lives,

Turns out what you suggested and what the electronics instructor where I work suggested was the same. I basically scratched to expose some trace between R25 and C15 and manually got the leads of those two parts to touch. I did get them to solder together. It looks a bit blobby so I wonder if it was too much or not hot enough.

Anyway, the hole for R25 (the one with the damaged pad) didn't fill up with solder, but then I didn't expect it to. There is still some of the pad on the side of the hole that corresponds to the other trace, which I believe goes to Q3. If the resistor lead that is bent over toward C15 isn't touching this part of the pad that remains, do I need to worry about continuity going to Q3? The instructor who checked it out with me didn't think it would be a problem, but he hasn't yet seen it post-fix!

Thanks again,

Bret

[Bret608]

Hi everyone,

I hate to bump this thread again! Does anyone have any insight on whether my "R25 lead soldered to C15 lead" fix should work, at least theoretically? As mentioned, there is still some of the metal pad left to corresponds to the trace going to Q3, but it's not in contact with the R25 lead and its solder (there's a gap where the pad was damaged).

I think if this pad didn't have traces going off of it in more than one direction, I'd be in good shape already! Also, I don't have a good sense of how deep in the boards the traces are, how they meet up with the pads, etc...

Thanks everyone! Just trying to make sure I have this fixed up as well as I can before I try to fire it up.

[jkokura]

That pad needs to connect to three parts: C15, C17 and Q3. Essentially, if those 4 component leads are not connected you need to make a manual connection via wire or part leads. Whatever you need to do to make that happen, do it.

Jacob