dtg84 Posted June 29, 2011 Report Share Posted June 29, 2011 Hello, I am new to MIDIbox and have minimal experience soldering. Everything has been going swimmingly (even got ICs on without much trouble). However, I noticed that I soldered the incorrect resistor in one part of the PCB. I desoldered it and removed the resistor, but in doing so ended up stripping the contact points for the two sides of the through-hole resistor. My question: am I SOL??? I hope I didn't ruin the board... Thanks, Dylan Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted June 29, 2011 Report Share Posted June 29, 2011 (edited) To estimate the damage, we need hi-res pics from front and backside. You can most likely use a short wire from another solder point to fix the problem. If you need to desolder components again, first cut every pin at the top of the PCB, remove the component, then use a vacuum pump from the backside and your iron from the frontside for every pin to "clean" the holes. Edited June 29, 2011 by Hawkeye Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 29, 2011 Author Report Share Posted June 29, 2011 Sorry, I am not quite sure what you mean by using a "short wire from another solder point". Can you please explain in detail? Unfortunately I don't have a decent camera to get a close-up shot. All I can say is that on the top of the PCB on one contact point of the resistor seems to be completely stripped of metal. The other contact point seems to be stripped of metal on the backside. Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 29, 2011 Report Share Posted June 29, 2011 That description is unfortunately not very helpful without pictures - if you can provide at least the resistor number from the board you might be able to get better help. That said, what Hawkeye is talking about is to follow the track where the resistor goes and to use a wire to solder the resistor somewhere else. This could involve scraping the solder mask (the red coloring) off the top of the trace enough to see copper and solder the wire to it, or you can often solder the wire directly from the component the preceded the pad you lifted, thereby bypassing the area. It won't look exactly pretty but it works and you can probably solder the wire and resistor on the bottom-side of the board so that top still looks relatively nice (other than the lifted pads). Hope that wasn't too vague but well, you asked a vague question :) Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 29, 2011 Author Report Share Posted June 29, 2011 That description is unfortunately not very helpful without pictures - if you can provide at least the resistor number from the board you might be able to get better help. That said, what Hawkeye is talking about is to follow the track where the resistor goes and to use a wire to solder the resistor somewhere else. This could involve scraping the solder mask (the red coloring) off the top of the trace enough to see copper and solder the wire to it, or you can often solder the wire directly from the component the preceded the pad you lifted, thereby bypassing the area. For what it's worth, the resistor is R65. Can't seem to find a track for the top end of the resistor (front surface), but I can see one on the bottom end of the resistor (front surface). Not sure what you meant following the first comma of the last sentence above "or you can [...]". Quote Link to comment Share on other sites More sharing options...
Hawkeye Posted June 29, 2011 Report Share Posted June 29, 2011 Just follow the trace where your solder pad came off to the next pad. Solder one end of a short wire there and the other end to your corrected resistor, where the pad came off. Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 29, 2011 Author Report Share Posted June 29, 2011 Just follow the trace where your solder pad came off to the next pad. Solder one end of a short wire there and the other end to your corrected resistor, where the pad came off. ahhh, i incorrectly traced the top of R65 to the small hole just to the right of R58 (face palm). I removed the wire again (second mistake), but can't get the solder out of the small hole next to R58, since R58 is already soldered in there, making it hard to remove. Is this a big deal? What will happen otherwise? Also, the top of R65, if you look at the PCB, doesn't appear to trace anywhere. suggestions? (sorry for all of the careless mistakes; I am really mad at myself right now). thanks, dylan Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 29, 2011 Report Share Posted June 29, 2011 R65 looks to be going into the ground plane which is why you don't see a trace. That's what it looks like according to the schematic. R58 does not, however. The solder in the small hole is not a problem - it's a via so it's basically bridging a trace from the top of the board to the bottom. In other words, it was already connected anyway so adding solder won't hurt anything as long as the solder isn't causing a short (touching another hole or component). Because R65 appears to go to ground, if that's the lifted pad, you can use a wire on anything that is part of the same ground plane. The other pad connects to R69 so if that pad is good, you could solder the wire to the leg of R69 on the same side. Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 30, 2011 Author Report Share Posted June 30, 2011 Because R65 appears to go to ground, if that's the lifted pad, you can use a wire on anything that is part of the same ground plane. The other pad connects to R69 so if that pad is good, you could solder the wire to the leg of R69 on the same side. Thanks, it appears that the bottom leg of R65 has the same trace as R69. Should I connect the two bottom legs(I managed to strip the pad on the bottom joint of R65 too)? Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 30, 2011 Report Share Posted June 30, 2011 Yes you can do that. Also pulling pads shouldn't be a common occurrence - you might want to consider turning down your iron to see if that helps. Also, I find solder wicks far less useful than a solder sucker. You can pick one up from Radio Shack for $5-10. Your mileage may vary but I have found them wildly useful, particularly if you cut out a small notch on the plastic tip to fit the iron in. You could also try to solder on the side of the trace if that side doesn't have the lifted pad (or the pad isn't being used to connect a top trace with a bottom one). Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 30, 2011 Author Report Share Posted June 30, 2011 Yes you can do that. Also pulling pads shouldn't be a common occurrence - you might want to consider turning down your iron to see if that helps. Also, I find solder wicks far less useful than a solder sucker. In both cases, I ended up pulling the pads after trying to get the solder off with the soldering pen and the solder sucker. I think maybe I worked to aggressively with the iron, or held it on the contact for too long(?). My soldering pen doesn't have a potentiometer on it - the heat is fixed. Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 30, 2011 Report Share Posted June 30, 2011 You'll definitely want a temperature controlled soldering iron and station. There are high dollar ones out there but I found a decent Weller at Fry's. It couldn't have been over $60, though I've had it for a while so I don't remember how much it cost exactly. It is not temperature calibrated (as in my dial has numbers 0-5 instead of actual temperatures) but it's /wildly/ better than the Radio Shack one I was using. Here's the thing - how much are those OPL3 chips worth to you? To me, they are damn near priceless so there's some serious justification for purchasing a good soldering iron and some of the other essentials (a good flat tip, a pointy tip for SMD work, etc.). Soldering became easily 10x easier with a temperature controlled iron so, again, I HIGHLY recommend one. Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 30, 2011 Author Report Share Posted June 30, 2011 I have a Weller soldering pen, which I got for 40 dollars. I am bummed that I already managed to mess up the board by stripping a couple pads, but I certainly don't want to overheat the OPL3 chips due to overheating... I am kicking myself in the shins for making such stupid mistakes. I will heed your advice and take a trip to Fry's. Thanks for your help! Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 30, 2011 Report Share Posted June 30, 2011 Yep I think you'll be happier for it. Even with a variable iron you can do bad things though :) You'll have to figure out what works best, but I keep mine midway (at 3) most of the time. I crank it up to about 3 1/2 when I'm desoldering. As far as the board goes, my sammichSID has some uglies on it - I had to end up cutting tracks to figure out where a short was. I had to fix it using one of the end legs I cut off of a part and soldered between the cuts. It looks a bit ugly but it works. And my first attempt at the MB-6582 resulted in a huge headache I still have yet to fix with hooking up the control surface with the mainboard. I opted to just start over and make my own control surface (not just because of those issues but more because I wanted a rackmount version that had room for SSM's and fun stuff like that). *shrug* You live, you learn! Quote Link to comment Share on other sites More sharing options...
dtg84 Posted June 30, 2011 Author Report Share Posted June 30, 2011 overheat the OPL3 chips due to overheating... Derp! "Destroy due to overheating" is what I meant. In any event, glad to know I am not alone in my mistakery. I guess we all start out as newbies anyhow... Best, Dylan Quote Link to comment Share on other sites More sharing options...
m00dawg Posted June 30, 2011 Report Share Posted June 30, 2011 In any event, glad to know I am not alone in my mistakery. I guess we all start out as newbies anyhow... Yup! Quote Link to comment Share on other sites More sharing options...
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