# Possible to repair fried circuit board component?



## ETPOF (Mar 1, 2016)

Hi. I'm new here, hopefully I can get some good help and I'll probably stay around .
I'm gonna try and keep this background brief and short, but it still may be a bit long for some. Sry!
I'm an RC hobbyist, and was salvaging electronics from an old model plane to put on a new airframe. Unfortunately, I accidentally tore motor wires off the control board while doing so. No problem right? Just solder it back on? Well, I decided to ask a friend to solder it back on while I painted the frame. It should've been fine, but later as I was testing the electronics, I noticed the motor (the one that had the broken wires) still wasn't working. Then I noticed a small, what looked to be a flame under one of the components. It was sort of an orange/red glow. After disconnecting the battery (which I ruined while frantically yanking it out) and putting out the flame, I noticed that the component had been burnt and blackened. I also noticed the crappy soldering job my friend had done (wish I had noticed it before the test! ).
So yeah. Now there's a blob of solder (Yes, the crappy soldering job cause the wires to fall out again) and a fried component on the board. Is there anyway to repair these? If so, what tools will I need? I have no idea what part this is, and it's very small, but I can provide more details if needed. Only to the extent of what I know about the board though. (Photos attached)
Ty
-ETPOF


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## m4gicfour (Mar 1, 2016)

Quite probably yes, you can just replace the fried component, after cleaning up the soldering job. Looks to me like the solder is bridging contacts between two or more pads on your output for sure, and quite possibly elsewhere.

The issue is going to be whether or not that guy took anything with him when he went... That, and your own skill with an iron but if it's broke, there's no harm in trying (I suppose beyond possibly damaging a motor or battery you hook up to test it).

Look around the whole circuit board for other damage or melty/scorched bits, and blobby solder; especially any that looks like it might be bridging adjacent pads. You'll want to make sure there's no remaining short circuits anywhere or other damaged components, delaminated traces, etc before attempting a repair. If you've burned through or delaminated any traces you may need to solder in jumper wires to replace the broken trace but I doubt you'll have that much damage, that all looks to be power supply circuitry and pretty beefy traces as far as the part of the circuit that was involved in the incident but I can't say for sure.

Next, you're going to need to get the numbers off that guy and look up the datasheet online to be absolutely sure of what it is, then you can order them from any number of electronics suppliers. To actually get it off the board you can heat up each lead one at a time and use the solder sucker to get the majority of the solder away, then gently (_Very_ gently) pry up on that lead you've melted and sucked away the solder on,  and allow it to cool while you're holding it away from the board. Hopefully enough distance that there's no remaining solder connecting the lead to the board when you're done, but it makes more sense to go around the chip a few times slowly working it up than to try to pry it up all at once and pull a trace off the board. Really, *lift* is what you're trying to do, more than pry.

As for tools, a solder sucker and a soldering iron with some fine gauge electronics solder; perhaps a magnifying glass (one mounted on a helping hand is usually easiest), a pair of tweezers and a steady hand can get it done. Soldering picks are helpful for many things, including lifting and prying on things to get them apart. If you can get your hands on a temperature controlled soldering iron it will make your life a lot easier. A hot-air desoldering station would probably be easiest but I sort of doubt you have one lying around 

I know there's guys on the forum with more experience in PCB repair than myself, so I'm sure one of them will be along sooner or later to give some tips.


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## ETPOF (Mar 1, 2016)

Wow! Thank you for such a quick reply.
What I got from that (in simplest form of course) is that I should clean up the solder mess using a solder sucker and iron, remove the fried component with those as well (lifting and not prying), and replace the component. Question though. Is there a difference between a solder sucker and wick? It sounds like your preferred method is the sucker. Here's the only issues I might have:
-I'm gonna have to buy a kit or find a sucker because I've been borrowing the soldering iron from a neighbor. No big deal though.
-I haven't had any experience tinkering with circuit boards. Anyone know of a crash course somewhere? That would be a big help. As a result of this issue, I'm not sure where to start looking to find what the part is.
I could send more pics with the numbers on the board if those specs help at all, though I doubt they will. Apologize if it seems like I'm asking someone to do the work for me. I just don't have much experience with PCBs.
-Finally, I'm not too skilled with an iron, but I can definitely do better than that blobby mess! Maybe I can get a learn-to-solder kit? It would probably come with a board or something I could practice on but if not, I have a spare from a broken nano-quad. And hopefully helping hands? Idk. I might be asking too much of a tutorial kit as those aren't usually too high-end .
But otherwise you're right about there being no harm in trying. I have plenty of batteries to spare anyway. Just small, cheap, 180 mAh lipos. I'm just glad it didn't catch because if there's one thing I've learned though the hobby, it's that lipo fires are BAD. I hear that they should be or out with sand, and I didn't have any of that nearby! I'll bring some for the next test I guess. Just in case...

And I did inspect the board for any other damage. I didn't see anything except for a small burnt spot directly above (or to the top right of in the photo) the burnt component. This spot looks to be on a small blob from soldering other wires, so should it be fine? Here's another photo for clarity (actually it's just zoomed in on the original )


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## keakar (Mar 1, 2016)

I would say go for it what do you have to lose?

just take your time and make neat solder joints that melt together and don't blob it on top like he did.


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## ETPOF (Mar 1, 2016)

keakar said:


> that might also only be the "end result" of the real problem and after you repair the "visible" damage, something else will have a melt down or blow and that could take out anything on or connected to the board at the same time.
> 
> if it were just a burnt trace from something that you caused shorting something out then I would say go for it but other then just for fun I don't see much chance for saving that board unless you know absolutely 100% the cause and corrected that first.



Well, I'm 99% sure of the cause.
The board wasn't built by me. It has worked fine in the past. The only damage done to it was the wires being ripped out and then the bad soldering job as a result. Come to think of it however, could this have also damaged other parts of the board or even the motor? Even the battery felt hotter than usual during the failed test, so that is a possibility. I guess I'll see what happens. Thanks!



keakar said:


> I would say go for it what do you have to lose?
> 
> just take your time and make neat solder joints that melt together and don't blob it on top like he did.


What the heck. Let's do it lol. Bad soldering got me here. Good soldering is all I'll need to fix it.


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## m4gicfour (Mar 1, 2016)

ETPOF said:


> Wow! Thank you for such a quick reply.
> What I got from that (in simplest form of course) is that I should clean up the solder mess using a solder sucker and iron, remove the fried component with those as well (lifting and not prying), and replace the component. Question though. Is there a difference between a solder sucker and wick? It sounds like your preferred method is the sucker. Here's the only issues I might have:
> -I'm gonna have to buy a kit or find a sucker because I've been borrowing the soldering iron from a neighbor. No big deal though.
> -I haven't had any experience tinkering with circuit boards. Anyone know of a crash course somewhere? That would be a big help. As a result of this issue, I'm not sure where to start looking to find what the part is.
> ...


Yep, there's a difference. A solder sucker (of which there are two common varieties - the spring-loaded type I linked last time, and a bulb type where you squeeze the bulb to push the air out of it then let it expand again to create a vacuum which sucks the solder away). The spring-loaded type you push down the plunger which locks in place, then just push a button and the spring fires the plunger upwards, creating a vacuum which sucks solder away. Solder-suckers (especially the spring-loaded type) are generally better for getting relatively larger amounts of solder away, and are reusable. Wick is braided copper which naturally draws the solder into it when heated. Wick is generally used for much smaller amounts of solder, like the leads on a microcontroller or IC for instance. It might work better in this case for the chip you'll have to remove, but I've not personally had much luck with wick.

This kit has good reviews. Comes with an adjustable wattage (but not temp controlled AFAICT - you can set how much heat it's putting out, but it won't automatically maintain a temperature.) iron, a few tips, a basic stand, a sucker and some solder. I've not used that kit myself, and there are probably better options out there, but as a starting point.

You'll need the numbers on the chip itself. If the scorchyness has obscured it, rubbing alcohol on a q-tip may clean it up. A decent digital camera may help you read them. If you can get the numbers/letters off the chip itself I can look it up for you, or point you in the right direction.

Helping hands are usually pretty cheap and ubiquitous (and usually frustratingly cheaply made as well). You can usually find them at any place that sells soldering irons.

Sorry I don't know of any learn-to-solder kits or anything of that sort. Practicing surface-mount soldering on some dead electronics that you aren't unhappy to see stay dead would probably be your best bet.

Unfortunately that's not really clear enough to show anything. However, if you look at the first image, you'll notice that below your scorchy chip that the big blob of solder is bridging two pads (look to the right, and see how two wires are soldered to two pads on an identically-marked space). This is the kind of stuff you need to look for. If it were me, I'd redo the solder either way, as that's going to be a fairly poor connection.





keakar said:


> that might also only be the "end result" of the real problem and after you repair the "visible" damage, something else will have a melt down or blow and that could take out anything on or connected to the board at the same time.
> 
> if it were just a burnt trace from something that you caused shorting something out then I would say go for it but other then just for fun I don't see much chance for saving that board unless you know absolutely 100% the cause and corrected that first.


The cause is almost certainly the short circuit caused by the gigantic blob of solder on the output...



ETPOF said:


> Well, I'm 99% sure of the cause.
> The board wasn't built by me. It has worked fine in the past. The only damage done to it was the wires being ripped out and then the bad soldering job as a result. Come to think of it however, could this have also damaged other parts of the board or even the motor? Even the battery felt hotter than usual during the failed test, so that is a possibility. I guess I'll see what happens. Thanks!
> 
> 
> What the heck. Let's do it lol. Bad soldering got me here. Good soldering is all I'll need to fix it.


Yeah, unfortunately this could have fried your motor and battery. It could have taken out other components on the board, too, but there's usually visual signs.

Chances are, however, if I'm correct about the cause - then that chip was likely the only thing short-circuited, and it probably destroyed itself cutting the circuit and saving everything else. (that, or it could have destroyed itself in such a manner as to dead short the circuit, which would be bad, but it's far less likely in my admittedly limited experience.)

Your battery would have seen a high, but probably not catastrophic load. Check it carefully for melty looking areas. Especially the wires. If the insulation is melted, you probably don't want to be hooking it back up to a charger or load. You'd have to cut off the melted section and re-wire the pack, at least, if that was the case. Chances are the cells themselves are alright  (LiPo cells for RC use are both high-current capable and generally protected - They can handle fairly high current and - if protected - they'll break the circuit themselves if catastrophically-high current is experienced - which may render them unusable, or they may be able to be reset by either time or applying a charge for a few seconds, depending on which protection mechanism was tripped, if any)


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## keakar (Mar 1, 2016)

simple way is hold it upside down while you liquefy the solder, gravity will pull all the excess solder away as you pull the soldering tip away from the board, "carefully" wipe off excess while still hot and repeat until the "blob" is gone.

that will clean up the mess so you can see what you are working on.

off hand the problem I see you may have is if that small black chip may be fried and if it is, I doubt you can find a correct replacement. if you are lucky it was just the wire touching it and no permanent damage was done

good luck and take your time, don't rush it


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## m4gicfour (Mar 1, 2016)

keakar said:


> simple way is hold it upside down while you liquefy the solder, gravity will pull all the excess solder away as you pull the soldering tip away from the board, "carefully" wipe off excess while still hot and repeat until the "blob" is gone.
> 
> that will clean up the mess so you can see what you are working on.


That works too, as long as you're real careful 

I still prefer the sucker, but there's more than one way to skin a cat, as they say.



keakar said:


> off hand the problem I see you may have is if that small black chip may be fried and if it is, I doubt you can find a correct replacement.


I would say 98% chance that guy's toast. You don't generally get smoke and flame out of an IC and have it still survive. EDIT - I re-read the OP. He said it appeared to be a flame. My bad. Still, incandescence is not a great sign.

Digikey, Mouser, and Newark disagree with you. 99.9% of these ICs are off-the-shelf parts, and a few cents to a few dollars apiece. Shipping usually costs more than the part itself.


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## ETPOF (Mar 1, 2016)

m4gicfour said:


> Yep, there's a difference. A solder sucker (of which there are two common varieties - the spring-loaded type I linked last time, and a bulb type where you squeeze the bulb to push the air out of it then let it expand again to create a vacuum which sucks the solder away). The spring-loaded type you push down the plunger which locks in place, then just push a button and the spring fires the plunger upwards, creating a vacuum which sucks solder away. Solder-suckers (especially the spring-loaded type) are generally better for getting relatively larger amounts of solder away, and are reusable. Wick is braided copper which naturally draws the solder into it when heated. Wick is generally used for much smaller amounts of solder, like the leads on a microcontroller or IC for instance. It might work better in this case for the chip you'll have to remove, but I've not personally had much luck with wick.
> 
> This kit has good reviews. Comes with an adjustable wattage (but not temp controlled AFAICT - you can set how much heat it's putting out, but it won't automatically maintain a temperature.) iron, a few tips, a basic stand, a sucker and some solder. I've not used that kit myself, and there are probably better options out there, but as a starting point.
> 
> ...


I guessed as far as the difference between the wick and sucker, just was wondering which was more efficient. My bad wording. Sry! It looks like the sucker is probably easier, quicker, and more versatile so I'm gonna go with that. Plus, even with a small board, that still is a large amount of solder.

Otherwise, this was another very helpful reply! In the morning (at least, the morning here) I can get some better pictures. Fortunately, the board isn't too small (I can read the words and numbers) so those should be pretty easy to get.

And as for the lipo, I'm gonna take the safe route and not use it for now. Besides the heating, frantically trying to disconnect it caused the plug (there's a more technical term. I'm just blanking right now) to bend. It's a bit puffed from the test, and of course, puffy lipos are also bad.

So in the meantime, I'll be researching soldering kits and techniques.



keakar said:


> simple way is hold it upside down while you liquefy the solder, gravity will pull all the excess solder away as you pull the soldering tip away from the board, "carefully" wipe off excess while still hot and repeat until the "blob" is gone.
> 
> that will clean up the mess so you can see what you are working on.
> 
> good luck and take your time, don't rush it



I did see this method, but I don't like to find ways around things like that, especially if I'll be buying a kit with a sucker or wick anyway.


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## ETPOF (Mar 1, 2016)

Alright. Hopefully this doesn't count as bumping but here are the pics as promised.

I have both back and front here with the back in two orientations if it assists with reading the numbers. The white stuff is foam that has been on the board since I got it from the company. It was where the board was glued into the original airframe. Hopefully there are no numbers under it?

What's on the front is "2013 Horizon Hobby" (the company) and a CE marking with the number 1434.

On the back, the letters/numbers are DU410V1.

How would I search for the components for this board?


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## m4gicfour (Mar 2, 2016)

ETPOF said:


> I guessed as far as the difference between the wick and sucker, just was wondering which was more efficient. My bad wording. Sry! It looks like the sucker is probably easier, quicker, and more versatile so I'm gonna go with that. Plus, even with a small board, that still is a large amount of solder.
> 
> And as for the lipo, I'm gonna take the safe route and not use it for now. Besides the heating, frantically trying to disconnect it caused the plug (there's a more technical term. I'm just blanking right now) to bend. It's a bit puffed from the test, and of course, puffy lipos are also bad.


Each method has its strengths, and is most efficient in a different situation.

A sucker is best for large amounts of solder; it won't get that very last bit off unless you're some kind of ninja. With a sucker the main downside is that you have to melt the solder with the iron, then quickly pull the iron away while moving the sucker in and activate the plunger before the solder cools. It takes a bit of technique, but it's pretty easy. There's also the potential to suck up small components with it if they're not soldered on but I can't say I've ever actually done that. 

With a wick, you touch the wick to the solder and then heat the wick with the iron which seems easier, but the wick saturates quickly and you're forever cutting the end off and doing it again so it's only good for very small amounts and it's an expendable so it gets real expensive if you try to use it to remove large amounts of solder. You use it up then buy more where as the sucker effectively lasts until it breaks.

The *proper* method is to remove the bulk with a sucker, and then the remaining with wick but I rarely use wick myself. I also only rarely do any desoldering on SMD components (like what you'll be doing here, and where it makes the most sense to use). So it's up to you how you want to do it.

Yeah if your lipo is puffy I'd probably not use it. That said, I'm just a hobbyist like yourself, and far from an expert on battery chemistry and safety.



ETPOF said:


> Alright. Hopefully this doesn't count as bumping but here are the pics as promised.
> 
> I have both back and front here with the back in two orientations if it assists with reading the numbers. The white stuff is foam that has been on the board since I got it from the company. It was where the board was glued into the original airframe. Hopefully there are no numbers under it?
> 
> ...


Here's an example of the kind of image you're going to need.


Spoiler: Example images



In this example, I've picked a small component to identify. In this case, Q6. I know it's probably a transistor of some variety because it's marked "Q" on the PCB, and I can then begin the detective work of finding out just exactly what it is. Unfortunately, while the packaging types are standard, just what's inside and which pins do what are not, so there's some work involved. We need to know what it is you have, and then find a suitable replacement.

In the example, for the packaging type (SOT-23-3, determined by size, number of leads, and lead position mainly) with marking 431, after a bunch of googlin' it appears to be a Texas Instruments TL431 Precision Adjustable Shunt Regulator. The PCB reference mark (if present), package type, and marking are all important for finding this out.






...and the same component, from another angle.





I took both these photos (of a laptop power supply, not that it's relevant) with a smartphone camera. The component in question is less than 3mm (or slightly less than 1/8") long! If you don't have access to a high quality DSLR with a decent lens and proper macro settings, a smartphone can still do an adequate job as shown here but due to the nature of smartphone cameras (and cheap point & shoot cameras to a lesser extent) the optics suck. Bright, even lighting is very important in all cases when trying to take detail photos close up (macro), and especially in the case of a smartphone with no optical zoom you want to be as close as you can get - right at the point where the camera cannot physically get any closer without being unable to focus. In this case I had the lens at 2.5" from the board, any closer and it wouldn't focus but any farther and the markings were too tiny and blurry to read. You'll probably need to play around with angles, lighting, and distance to get a decent picture.

Most Point & Shoot digital cameras have some limited amount of optical zoom (by moving the physical lenses) before they start with digital zoom (which is simply blowing up the image, and loses quality). If you decide to use zoom in that case, you have to make sure that you're not hitting the digital zoom for the best resulting detail in the image. Typically, with a smartphone you've got a fixed lens. You absolutely do not want to zoom in, in this case, as doing so is purely digital and will lower the quality of the image, for reasons I'm not going to get into here.

If the markings on your crispy component are obscured by scorching you can't clean off or is melted off, and both the connection points I've circled in yellow serve the same purpose (for example, two channels to control two of the same type of motor) then you'd probably be safe to look at the intact component in the same place on the other channel (red circles)







The other option you have is to contact Horizon Hobby with your board number (probably the DU410V1) and a photo showing the entire board and the component in question circled and see if they'll just tell you what the component is. Most of the time I would say that the majority of companies would tell you that it's 100% irreparably destroyed, to throw it out and buy a new one rather than giving you any useful information (for liability reasons. What if you do something stupid and then burn your house down and try to sue? It's a ridiculous idea, but it's the kind of things companies have to deal with.) but being that they're a *hobby* company they might be a bit more open to helping you work on it yourself.


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## erocker (Mar 2, 2016)

Looks like there's an identical chip next to the burnt one. Grab the writing off of it and you should be able to find one.


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## m4gicfour (Mar 2, 2016)

Yeah, I know I'm dreadfully verbose, but I did already suggest that 

It's good advice as long as the two side-by-side what-appear-to-be-outputs serve the same function. Identical only goes as far as the semiconductor packaging, after all.


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## keakar (Mar 2, 2016)

m4gicfour said:


> Digikey, Mouser, and Newark disagree with you. 99.9% of these ICs are off-the-shelf parts, and a few cents to a few dollars apiece. Shipping usually costs more than the part itself.



ah but its not just the getting another one that looks like it, its to know WHAT to get.

you never want to just "assume" its the exact same as the one next to it (which it most likely is) but that's the rub, being able to properly identify what it used to be to get another replacement that wont fry stuff.

but at this point that's about all you can do, just not an ideal situation to be in.


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## keakar (Mar 2, 2016)

ETPOF said:


> I did see this method, but I don't like to find ways around things like that, especially if I'll be buying a kit with a sucker or wick anyway.


well a sucker is great for removing "all" of the solder for unsoldering things, but for removing "excess" solder (blobs) without removing all of the solder, holding it upside down and using gravity to remove all but the correct amount of solder is the best way.

I solder things every day so im good at it but even still on a few occasions in need to "clean up" a few solder joints.

a good tip is to use a wet sponge in a saucer to wipe off the flux buildup on the hot solder tip if it gets dirty, but then your not doing 100 solder joints on ever board like I do.

what is the part number on the board? i couldnt find it by lookingfor a 1434 Receiver Board so there must be another number that identifies it. have you looked into the cost of getting another board? just curious what those things cost, im thinking these are generic boards used in most stuff that cant be more the $10 I would think


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## m4gicfour (Mar 2, 2016)

keakar said:


> ah but its not just the getting another one that looks like it, its to know WHAT to get.
> 
> you never want to just "assume" its the exact same as the one next to it (which it most likely is) but that's the rub, being able to properly identify what it used to be to get another replacement that wont fry stuff.
> 
> but at this point that's about all you can do, just not an ideal situation to be in.


You're absolutely right about that; blind assumption based on nothing but visual similarity of the semiconductor package is a bad idea.

I'm hoping, though, that op will be able to get some clearer macro photos and that he'll be able to tell us whether those two sets of two solder pads serve the exact same function (I.E. controlling two separate servos/motors of the same type from separate control signals from the transmitter, such as e.g. rudder and elevator controls. )

Knowing that, being able to inspect the traces to see how both components are wired in, being able to see and verify identical package type, and hopefully getting at least a partial off the burnt component to match against its neighbor would give us a much better amount of confidence, or inform us that they are indeed different.

That is to say: We don't know what we know until we know it, y'know?


keakar said:


> well a sucker is great for removing "all" of the solder for unsoldering things, but for removing "excess" solder (blobs) without removing all of the solder, holding it upside down and using gravity to remove all but the correct amount of solder is the best way.
> 
> I solder things every day so im good at it but even still on a few occasions in need to "clean up" a few solder joints.
> 
> ...


He has all the numbers he could read off the board listed in his... second? post with pictures. I couldn't find anything based on them on google or horizon hobby's site, but maybe you'll have better luck.

The only thing I was able to find was what looked like a newer version of the same board, and it was listed at $49.99 or $59.99 iirc.

Flux was the other thing I meant to mention but forgot. You think a Flux pen would be worth it for a single smd ic? What kind would be the other thing.


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## keakar (Mar 3, 2016)

m4gicfour said:


> The only thing I was able to find was what looked like a newer version of the same board, and it was listed at $49.99 or $59.99 iirc.
> 
> Flux was the other thing I meant to mention but forgot. You think a Flux pen would be worth it for a single smd ic? What kind would be the other thing.



yikes !!! I was hoping that little thing was $5-$10 so no harm in destroying that one but that's a little chunk of gas money at $50

I don't bother with flux, I just always use electronics grade flux core solder but after a few dozen solder joints you need to wipe off the excess that builds up and starts to burn and turn into carbon buildup on the tip


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## ETPOF (Mar 3, 2016)

Apologize for the late response.

This all seems to be related to the same problem of finding the part numbers, so I won't bother quoting.
I've been experimenting for quite a while (broke another motor wire off while doing so :/. Oh well. More soldering practice, I guess, right?) trying to take photos of the piece, but iPhones clearly aren't the best method. I'll be trying a Samsung next. My iPhone close-ups are either blurred, or too far away from the piece, making the top look flat. m4gicfour, may I ask what smartphone you used? It appears that you have an attached lens, or just a really good macro camera.

Besides that, what I _can_ tell you is that you're correct about the component functions. The two components seem to correspond with the two side-by-side motor outputs below them, where the wires broke off. The board controls a small, twin engine plane that uses differential thrust. The Duet to be exact. It was my first plane and the airframe is now garbage, so that's why I decided to salvage the electronics. Don't tell me to buy another only because the board is nearly as expensive as the plane because I think fixing it myself will be a more fun and interesting solution! (Unless of course it becomes aggravating and not fun) .
Besides having to deal with the motors being placed on separate sides of the airplane (and therefore they might be programmed slightly different to account for the differential thrust), the outputs and their components should be identical. I could try to call Horizon Hobby and see if they can tell me the part in the meantime.


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## m4gicfour (Mar 3, 2016)

keakar said:


> yikes !!! I was hoping that little thing was $5-$10 so no harm in destroying that one but that's a little chunk of gas money at $50
> 
> I don't bother with flux, I just always use electronics grade flux core solder but after a few dozen solder joints you need to wipe off the excess that builds up and starts to burn and turn into carbon buildup on the tip


...and about $2 of PCB or less in bulk, with $1.50 of parts on it . 

That's about what I thought, but I don't do a whole lot of SMD soldering myself so I don't bother with flux either and figured you might either confirm my thoughts, or tell me about how fantastic flux is and why would anyone ever not use a flux pen. Good to know I'm not crazy.



ETPOF said:


> Besides that, what I _can_ tell you is that you're correct about the component functions. The two components seem to correspond with the two side-by-side motor outputs below them, where the wires broke off. The board controls a small, twin engine plane that uses differential thrust. The Duet to be exact. It was my first plane and the airframe is now garbage, so that's why I decided to salvage the electronics. Don't tell me to buy another only because the board is nearly as expensive as the plane because I think fixing it myself will be a more fun and interesting solution! (Unless of course it becomes aggravating and not fun) .
> Besides having to deal with the motors being placed on separate sides of the airplane (and therefore they might be programmed slightly different to account for the differential thrust), the outputs and their components should be identical. I could try to call Horizon Hobby and see if they can tell me the part in the meantime.


Well, that's promising. The fact that they're identical outputs means that so long as each of those semiconductors is wired identically into each channel, there's a very good chance that they are, in fact, exactly the same part.

Contacting HH might be a dead end, but it can't hurt to try.



ETPOF said:


> trying to take photos of the piece, but iPhones clearly aren't the best method. I'll be trying a Samsung next. My iPhone close-ups are either blurred, or too far away from the piece, making the top look flat. m4gicfour, may I ask what smartphone you used? It appears that you have an attached lens, or just a really good macro camera.


Samsung Galaxy S6, stock camera. Even using Samsung's camera app. Heck, I even shot that through a Lifeproof FRE (which is junk, unfortunately, but it's "waterproof" so it has a clear plastic window over the camera, which should theoretically lower quality).

I mean it when I say lighting is critical. The samsung camera goes fruitloops and fuzzy as all heck if the lighting isn't perfect. 
You'll probably want manual focus if you have the option. The samsung app will autofocus on whatever you tap on, on screen, which is a nice feature.


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## keakar (Mar 3, 2016)

[QUOTE="m4gicfour, post: 3425309, member: 53599
That's about what I thought, but I don't do a whole lot of SMD soldering myself so I don't bother with flux either and figured you might either confirm my thoughts, or tell me about how fantastic flux is and why would anyone ever not use a flux pen. Good to know I'm not crazy.[/QUOTE]

yep, I only use flux if im soldering copper plumbing pipes because there you definitely "have to" use it and sand the crap out of the copper first to remove all oxidation so its shiny new


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