Hi, we're uh, still in the old lab today. Bit of an impromptu uh video thanks Phil Phil's behind the brother and Phil is behind the camera. he's my brother-in-law and uh Here Comes r r you're on the blog mate. Hey everyone R is uh my buddy and we're building up our RG copter SL Canyon copter which we're going to modify and fly through a canyon and it's going to be really cool.

Once we actually finish it, we're hoping to get it. Airborne Today we're hoping to get it off the ground and uh and we've run into a little snag. It was working fine. This morning our Motors were spinning and everything was fine and then we decided to and then we wanted to hook it up to the PC to uh uh, you know to get the conss and calibrate it and do all that sort of stuff and no, it, um, itches would not D all of our Um leads on our um aru uh pilot Mega that's an Ru pilot Mega board and that's the IMU board which sits on top.

It's got all the sensors and stuff like that. It's a standard um Ru copter uh RG copter uh sensor platform and uh, and control platform for the copter and um, none of the lights. None of the LEDs on it would come on crazy when we hooked it up, uh, it seemed to have just completely died so uh, we've had to do some impromptu troubleshooting and uh, what we've narrowed it down to is um, a complete five or short on the 5 Vol rail on this IMU board? go figure. So um, if you have a look at the schematic here and it overfill, and let's take a look at the schematic here.

We've got uh, 5 volts, 5 volts coming in here on the USB cuz you can actually power this board up through the USB We narrowed it down. we disconnected it um, from all of our uh circuitry cuz we wasn't weren't sure what was causing the problem. So 5 volts coming in from the USB it goes through a poly switch here, one of these resetable Uh fuses and that sure enough was getting really darn hot. So and that's the 5V Rail and the 5vt rail goes off to various Uh chips and devices.

One of the primary ones is the um uh Rs232 Ftdi uh chipset which can, which uh, which converts the USB into the RS 232 so you can talk to your Aru uh Mega uh board and it runs from a uh it runs from the 5vt rail so it's a primary device, but there's other devices on here. There's this, um, analog to digital conver chip here it. it also runs directly uh from 5 Vs and a couple of 3.3 Vol uh Parts up here. but uh, and there's two uh, 3.3 volt voltage Regulators on there I'm not sure why they need uh two 3.3 volt voltage Regulators on there I don't know.

noise isolation or uh, something like that. I'm not actually sure maybe to share the current between them I Got no idea, but um, basically any one of those devices um, could be shorted out uh, or one of the other culprits. um, could be uh, one of the bypass caps cuz bypass caps can also short outters as well. They're fairly notorious for that.

It can happen. so one of the devices on here is shorted out. Either that or we through, you know, cutting wise and soldering stuff and everything. We could have actually got a little solder dag on there.

or we could have, uh, got a little bit of a wire dag that's shorting something out, but that looks pretty clean so it looks like it's uh, almost certainly one of the components on the board. and let's actually measure it. and uh, have a look. and I've shorted out my probes here I've only got a Am probe Am 220 left.

Everything else is over in the new Uh lab, but uh, we'll compensate for the Uh probe resistance there. so we've shorted out that. It's a little bit dodgy. but there we go.

and uh, if we have a look at the output, the rail here and there it is, it's 0.2 0.1 Ohms, It's practically a dead short. There you go. so it's a really serious short directly on the 5V Rail and uh, the way you troubleshoot, um, these is either the brute force method of sucking uh parts off until you find the culprit and your short suddenly, uh, vanishes, You can do that. It's a Brute Force approach.

Uh, it's not bad to start with your bypass Caps or something like that instead of you know, desoldering like a um, you know, an so uh package device or something like that. which is you can ruin your chip really annoying and you can ruin your day. Or you can get a high res um ohm meter and actually, uh, trace it down and uh, you can actually follow it through. If your multimeter has got enough uh resolution which this one doesn't.

this one's only 0.1 You'd need at least a 4 and 1/2 digit meter to do that. Probably a 5 and 1/2 digit and you can actually Trace down. Uh, the short or an LCR meter or something like that that has good low res. ohm um, low res.

ohm uh functionality and you can actually trace it down on the board until you find that it gets a bit lower in that direction and you see it increase in another part of the board and you can narrow it down to one individual uh part. So we're probably going to have to do that. Haven't done it yet. I Have no idea your guess is as good as mine, but probably smart money might be on that f um, that uh, Rs232 ftdi chip because well, it's connected directly on there.

maybe um, maybe some ESD um from the Rs232 lines has shorted the rail internally or something like that Scr latch up I've done a whole video on that I should link in my Scr latch up uh video that can easily cause the chip to short out and well I don't know, but it could be one of the other devices regulator or something or a bypass. C I don't know. it's going to be a pain in the ass I was hoping just to get this thing airborne and flying and jeez. impromptu troubleshooting.

Well I found a decent uh fluke and uh, the wife was using it to measure the baby bath water temperature. go figure. So this one didn't make it to the lab. So I've got a 4 and half digit meter.

so let's actually Probe on this board and have a look. So if you want to get in here R and we will, uh basically what? I'm um what I'm considering is that these are tanms. There's a couple of tanms and anytime you see tanms there, um, always suspect a tanum cuz they're a real bastard they are. Now if we measure, let's say this tanum here.

these are on the 5V rail. Okay, what we're getting is there we go? Can you get the meter? Yep, Yep. 0 One2 Ohms Okay, I've shorted out my I've compensated for my probe resistance. Oh let's do it again.

Okay, there we go. Okay I shorted out my probes and measure across that tanum we getting .14 Ohms. Okay, that's not too bad. Let's measure across the Ftdi chip for example, which is that pin there and one of these pins over here? 0.53 Ohms.

Okay, so that's much higher. so you know it's not going to be this chip if this measurement here is, uh, smaller in value than this one over here. So you keep tracking around the board like this. But look at this big tanum down here.

He's got guilty written all over him I reckon. so let's probe him. and bingo. 0.08 Ohms.

So that's smaller than lower in value than this tanm over here. So it's most likely that that tanm is the culprit. Um, the schematic does show uh, three tantalums across the 5V rail. But these other two tantalums here, which are the only other two on the board that I can see anyway unless I'm blind, are, um, uh, obviously on the 3.3 volt rail.

So my money is on that bastard tanum there. So I'm going to lift uh, one end of that sucker and I still got one iron left here the two other irons. but we do have an iron left. So going to lift that, think we might have a winner? Let's go.

All right. So there we go. We've lifted that, uh, lifted one end of that tanum there. and uh, let's measure that and see what we get.

Okay, here we go. Let's Pro the rail. Oh no, what? okay, no I uh. called him guilty before, uh, finding he was innocent.

so going to have to lift another one. So let's uh, get back here and hopefully it's one of the Tanons, but that that's weird I uh could have sworn that would the CU it had the lowest resistance, but maybe it's one of the devices. who knows. Um, although it was closest to that chip bang There We go.

Tanum is lifted and a still shorted bastard. All right. Well, what fail? Um, yeah, there you go. I was hoping it would be Tanum cuz that would have been an easy fix.

and if it is one of the chips, it could be screwed at least for today. And I forgot to mention, sometimes a way to actually, uh, well, get rid of the short is you can actually blast the short right out. You get a really high current, uh, power supply, not high voltage. It's the same, um, voltage.

stick it across there and hopefully you can actually blow out the short. If it's an Scr, latch up in a chip or something, you can blow it open. So at least, uh, that will actually get your board back operational, semi operational again. so not sure if that's going to be any good for us.

but anyway, that's one of the methods as well For getting rid of a short doesn't help you fix it, but uh, it might get you out of trouble anyway. Just another tip we've got uh oh. We started out using uh, cheap ass uh probes. like, until we found some good flute probes.

When you're doing stuff like this trying to measure right down in the uh noise on the Ohms range. Really? Ultra sharp professional probes. can't beat them. Don't buy the one.

Don't use the one hung low ones. It'll ruin your day. Your regions will fluctuate all over the place. You got to penetrate any oxide coding on the solder joints and things like that.

Really sharp probes. Trust me. All right, tracing this down wasn't the tanum. Caps I've lifted up both of those on the 5 rail.

Bummer. So I'm tracing it down here and uh, it looks like my lowest point so far is this cap here I Find that the, um, uh, the board layout doesn't quite match, uh, precisely. There's a few, uh, minor differences, but this cap here seems to be my lowest value at 80 milliohms. So and if I go if you trace that F this is the 5 V rail, the brown one there.

If you go up to say these pins up here I'm measuring like 0. 22 ohms. but this cap down here I'm measuring 0.08 ohms. And then if you go to this cap the big Tanum down here which I thought was the C and I lifted, it was like11 ohms or there about.

So this is my lowest culprit and there's nothing else there. So I think I'm going to suck out that uh, bypass Cap there and see what we get. Looks like we might have tracked it down. Murphy's Law again I've sucked off a few of the tanms I've sucked off a couple of the Ceramics as well.

Well Thought: I nailed it down. but it turns out, check this out. Here's our lowest point: I didn't check the actual uh I think it's the magnetometer board or something. It's little add-on board bang.

The lowest resistance point is actually smack on that board. So our short is either happening on that connector itself or more likely on that board because this board actually, um, it's You know, it can actually short out. so maybe during operation we've shorted it out somehow and it's caused a permanent short on that, um, on that uh, secondary daughter board there. So I don't know.

anyway. um, it looks like it's either on that board or part of the connector or something like that. so we have to suck that off. and uh, good thing is I think it works.

Without this, it's just an optional uh board you can put on so hopefully. um, that won't stop us getting now. Copter flying today and sometimes you're lucky. I Just so happened to have a found a little bit of soda w left on the bench.

It's all the rest of it all Gone to the lab and I've got a little off cut of solder that I had left on the bench. so sometimes you win, don't have to go there. So anyway going to suck this uh thing off and uh, see what's roll with that board ground and VCC I got the board off. It turns out I couldn't use my solder Wick I had to heat up all four pins at once and lift it off.

Um, wasn't doing that well and should be no, no, no, no you bastard. this is a the short remains. Are you kidding me? Look at that that's across that uh tanum that I thought was the culprit before1 o 09 Directly across these pins. Here it's see, it's it's lower, It's 004.

So the short is not up here because this is a lower value. It's got to be almost across these two pins here. like there's something on the solder end down in there or something within the board itself. Often if this is a brand new board, um, the first thing you would expect first thing would you would Su suspect.

and if you've never powered it up before, you would suspect that it was a board manufacturing or or an etching era and you get a little etch uh, fault between you know, two two tracks. That's fairly common, but because this is a no one working board that we're trying to, uh, troubleshoot here and those two pins definitely straight across there. Are you kidding me? Unbelievable. Murphy's uh, killing us at every every turn here.

And if we take a look at the here's the uh. you take a look over here on the board. here's our two pins on there. There's a GPS it goes through there.

there's well, maybe it's that. Maybe it's that cap there, that's what's left and it's um, I don't know. Well, there's one cap I think yeah, that looks like a cap there and it's uh, well, maybe it's not. Maybe it's no.

I Think that's a pull-up resistor perhaps. and there's something. Well, that's it. it's got to be.

This is my lowest resistance point between these two pins here, so there's got to be something around that area. This, uh, by the way, they've actually taken out all of the ground plane so you can't see the flood field ground plane which goes all the way in between those pins. but going to have to probe some more. Oh man, this is getting bloody painful.

Let me tell you. Unbelievable. Murphy gets you every time. son of a you want to know what it is.

Nothing to Murphy Again, nothing to do with the components. nothing to do with this magnetometer board won't be able to get the this CA inside the bloody connect. You know it's not that uncommon actually, and we probably should have guessed at that cuz we were disconnecting and doing all sorts of things and then it stopped working and this is the connector that we didn't even plug stuff into. It specifically has no GPS written on there.

It's some sort of telemetry connector. we don't have anything on our copter that plugs into it. and if I can get a photo of the actual pins in here it it shows that it's almost like something is really like a you know, like a you've got a screwdriver in there and just slammed it in and bent two of the damn pins in there. So I don't know.

Just freaky shits happen here where I know something has gone in there and poked these two pins and shorted them together. Unbelievable. Man, got to get the correct tongue angle here. It's important and let this be a lesson to you.

Don't start sucking out components until you're absolutely 100% sure you've traced out every path and you've nailed it. cuz if I did, uh, maybe if I had a slightly better meter I could have done it. But yeah, I'm blaming my tools all right. What can I do? But yeah, let that be a lesson to you.

Don't start uh, desoldering components willy-nilly? All right. Pretty darn confident that it's going to light up now. No props attached and let's power it from our USB Woohoo Hey, we have lights. It's working.

There you go. it's like Christmas just like Christmas time. there you go. That's a absolute textbook classic example of uh, being led up the Garden Path In troubleshooting, we started out found our 5V rail was shorter than we uh, thought it might have been the uh Ftdi up here.

that was the first. Cate We worked our way across the board and down. Then we noticed the Tums aha classic culprit not wasn't them. We narrowed our resistance down even further.

it looked like that board the IMU uh, the sorry, the little um magnetometer board and we thought we had a classic fire mode with that magnetometer board where it pushed down and shorted something out while we were mucking around around with it. and it turns out that happened to be just next to the least possible thing I would have suspected because my mind was shut off from it was the connector that we weren't using. Who would have suspected a connector that we don't plug into would have shorted pins, especially when the board was working. Unbelievable Man, that's classic Murphy 101 So there you go.

Keep your mind a bit more open next time. but jeez, what a classic. see you! First flight test. We have no idea we haven't even spun the motors up with props on yet.

All right. First flight test. We've finally got it armed and uh, go for it. R give it a bit of throttle to be twisting.

Yeah, it is. It's off. it's off the ground. Well, we got somewhere.

Okay, it seems to be moving to the which way is it actually facing? Uh, yeah. where's the front? The front is here. Front is here. So I'm standing in front of it.

so it's moving to the left. I Don't even know what mode we're in at the moment. No. Okay, I'm pretty sure it's the right one.

It's just going left though. so it's unbalanced. Is that that mean it's unbalanced? Or it? Yeah, you're getting a bit close there. R Chut my feet off.

All right. We're running out of gas. I Don't know how we landed now. Well, so we can't actually switch them off even at minimum throttle.

That's weird. Try and reach the battery, but wait until it dies. Well, it's slowing down. Yeah, not quite as loud as I thought it would be.

These seem to be going a lot faster than these. Well, we probably don't want to drain it. We probably should, uh. attempt to.

Uh oh. okay. Some have just stopped. Yep, not in the garden.

Oh, in the garden. that's going to stop us. Hang on. that one's definitely spinning.

Funny. Number one, that's just bizarre. I Mean, well give it some more throttle. but a very fine line between taking off and hovering.

And yeah, and it moves pretty quickly. And and then you can't just drop the throttle cuz the thing will just fall. Yeah, it's a good lawnmower. Very fine line.

almost half half that's You can see how with some practice you can absolutely cane in this. Very touchy I can't get over how tou it. It keeps going away from number One y So yep, it's uh. well.

actually that that was going backwards. Yeah, it's been doing it the whole time. More unless you want to. The battery.

Uh, fall off. fall off. It's really stable now. Yeah I know it's excellent.

It's very stay. It's really hard just to get it. It seems to want to face a particular direction right? High here? Yeah. got minimum throttle full left and it ain't shutting down.

At least it does. Oh, have a fly, might as well use our battery up. It's always fun having to dangle down. Okay, if people see this video and it's like 2 feet away from a wall, there they're going to they're going to, that's not the place to test it.

Oh, in that mode, it's doing its ownt control. Oh okay, right. so you can steer it. Yep.

I think it's trying to maintain it Altitude zero right? Whoa. Nice work. All right. We really should be down the park then we don't have to worry.

There we go. I Think we're running out of battery? Are we? Yep, we're out. You can just drop that stick anytime.