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Help! What did I burn? Again!!!

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Mitglied
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Hi,

I´ve just soldered the PCB extension board. Did some test after asembling the board and everything worked fine, leds flashing.

But once I soldered all the leds and connected.... brief flash and dead with that unmistakeable smell... :x


I think (still to confirm) the shortcut was on the leds because I mounted two rows parallel, togheter, but that does not worry me at the moment


What I don´t see is what did I burn. PCB extension board looks fine, no external damage to any component and power reach the board perfectly, but at the output where leds are connected there´s no power at all when it should.


What´s the component I burnt?

How do I check it?
« Bearbeitet von AndresMtnez am 05.01.2016 22:02. »
Mitglied
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Hello,

look at the circuit diagram ;)

http://wiki.mikrokopter.de/en/ExtensionPCB

best regards,
Stephan
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Thank you, but I´m not electronics engineer and don´t know what´s the function of each part. I guess it could be FET 1 (leds soldered on S2) but it looks ok aparently and I don´t know how to check if it´s ok or not....
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fotos?

edit: But I think, it's better to buy a new one ;)
« Bearbeitet von Stephan Lukas am 30.12.2015 11:49. »
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I can upload some, but they will be of no help. It looks like the one on the wiki page (more or less ;p). It worked before soldering all the leds, I tested it and even tested some different patterns for the leds with MKTools, so the build is ok, and there´s no aparent damage to any component

I guess when there´s a shortcut it must be some specific component wich takes the damage.... or the whole board can be damaged?
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then buy an other one ;)
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AndresMtnez meinte
Thank you, but I´m not electronics engineer and don´t know what´s the function of each part. I guess it could be FET 1 (leds soldered on S2) but it looks ok aparently and I don´t know how to check if it´s ok or not....

From your description I guess there is a short-circuit. Could be in the LED modules, how they are mounted (soldering points touching aluminium?) or on the ExtensionPCB.

1. With no LEDs nor batteries connected does ExtensionPCB have a short-circuit between power and GND on either the supply side (16.8 V for Lipo 4S) or on the output 12 V pad to GND?

2a. Do you use a Traco / Recom 12 V DC-DC or do you use a jumper essentially running the board at 16.8 V?

2b. If jumper pin 1 should connect to pin 3, neither should be connected to pin 2 (GND).

2c. If DC-DC what is the voltage at the 12 V pad?

If you had a short circuit it could be you burnt the DC-DC (max 1 A), the FET1 (continuous drain is 21 A) or you burned a track on the PCB.
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Thanks Foersom for your reply

After testing everything with a tester I finally found the shortcut, it was on a led line, I use small connectors on the led lines because my frame is foldable, and the soldering to one of those connectors got loose and caused the shortcut. Those connectors are hot-glued to avoid this, but on this one there was no hot-glue between the two wires, something I I always do as a safety measure to prevent any shortcut. Not on this one tough

I´ve replaced the whole board as Stephan suggested, since it´s only 15 euros and I can buy it here close to my home I think it was the best option

I tested the second output before de-soldering and it didn´t work either, so it was not (only) the FET


With the new board everything works fine.... at S2 because S1 doesn´t work. Probably my fault because I had some problems soldering one of the FETs and maybe overheated it. Anycase I´ve no plans for a second output so right now it will remain as it is
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AndresMtnez meinte
at S2 because S1 doesn´t work. Probably my fault because I had some problems soldering one of the FETs and maybe overheated it. Anycase I´ve no plans for a second output so right now it will remain as it is

Good that you found the cause of the problem and solved it.

About S1 not working. The S1 is intended for photo shutter, it is not intended for being permanent on. It goes through the internal LED in the opto-coupler (TCMT1106). Does the LED1 flash when you activate shutter?

See ExtensionPCB diagram that Stefan Lukas pointed to.
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Part II

Now I´ve burnt another thing, and this time it may be a lot more serious...

In more than 20 years of RC experience soldering everything I´d never burnt anything, and in two weeks I´ve burnt two things... maybe I should take a rest for some weeks...


For the fpv gear I use a regulator (anyvolt micro) wich is soldered to a line wich comes from the main power input soldered to the okto distribution board (v8b). I´ve been soldering a new vtx, and once everything was finished I was adjusting the output from the regulator (it´s adjustable), and by mistake I did a shortcut between Vout and ground.

It was just an instant, but enough to see some smoke from MK tower... :x :x :x :x


Now there´s no power input or output to the regulator (0,3V or similar when it should be 15,2v), but a different line wich is soldered to the main power input too (for camera gimbal) reads 15,2v.... weird.

I connected MK and it beeps each 2-3 seconds. Connected to MKtools it says error 6: bad compass value, and error 9: no NC comunication. When going to page 19 of NC magnet field percentage is 0 or 1, when at home it usually reads between 80 and 120% (due to the iron of the building)

Error 6 is understandable if there´s no NC comunication, as I´m using the external compass wich is connected to NC, but what´s the reason there´s no NC comunication?


I´m in panic, seriously....

Did I burn the FC or NC?


I find it weird as the shortcut was on the regulator output, not input, but obviously it affected something in MK tower, there was smoke so...


I dismantled the tower but didn´t see any evident damage to any board


Help please! What should I check? What parts will be burnt when a shortcut occur on main power input?
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BTW Foersom, I couldn´t check that as I have no free channels, so I have no shutter activation, I only use the pcb extension board for the leds and also to have a visual alarm for low voltage, as I´ve had problems on noisy environements to hear the alarm and a visual alarm is great in those scenarios
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AndresMtnez meinte
I dismantled the tower but didn´t see any evident damage to any board

Help please! What should I check? What parts will be burnt when a shortcut occur on main power input?

Sorry to hear about your new problems.

Check the FlightCtrl separate, like if you were going to update software on it. Disconnect cables from NaviCtrl and tiny 5 pin cable from octo-power-board. Use MKUSB to connect to serial port. Remember to add jumper for power. Does it run? Communication Ok?

Check similar with NaviCtrl. Remember that it is the debug serial port (opposite side as on FlightCtrl) that you should connect to. Communication Ok?

If I remember correctly you have an octo-XL-power-board with BL Ctrl 2.0. Disconnect / desolder your FPV power thingy from the octo-power-board. Check that there is not a short circuit power to GND. On the edge of each side of the octo-power-board there is 2 power pins which are connected directly to battery power input (16.8 V). Check from battery input cable to these points that power and GND connections are Ok. If all this is Ok, try to power the octo-power-board alone. Does all the BL-Ctrl start up?
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I only use the pcb extension board for the leds and also to have a visual alarm for low voltage, as I´ve had problems on noisy environements to hear the alarm and a visual alarm is great in those scenarios

Visual alarm for voltage? I have voltage displayed on OSD on my pilot video link and as backup in the Mikrokopter OSD screen of Graupner MX-20 transmitter.
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Thank you very much Foersom, I´ll check it that way

I don´t use molex connector between powerboard and FC, I guess I only must desolder power input from powerboard to FC, right?

And yes, that´s my powerboard, your memory is great :)


btw, I guess I could check first disconnecting NC to see if the rest of the tower works or not. If it works the problem is on NC. But since I´m using external compass wich is connected to NC I´d still get error 6

Investigation begins, I´ll keep you updated


btw2, I know a university electronics proffesor with huge experience who have designed and built some things wich are rotating around the planet. He´s not a very close friend but he´s a nice person who will help me if I need it, so I´m not going to disturb him for something absurd, but if I could check the boards with some specific equipment to be sure about the damage all the boards received, I can call him

Some months ago he invited me to his classes in the university, I went to first 3, but unluckily didn´t have the time to assist the whole semester
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First check, with NC disconnected, and MK connected to pc through FC mktools show no error, and all bl-ctrl start up ok

Also, all power pins on power board edges read correctly 15,2v (4s on storage)
« Bearbeitet von AndresMtnez am 06.01.2016 20:49. »
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Foersom meinte
AndresMtnez meinte
I only use the pcb extension board for the leds and also to have a visual alarm for low voltage, as I´ve had problems on noisy environements to hear the alarm and a visual alarm is great in those scenarios

Visual alarm for voltage? I have voltage displayed on OSD on my pilot video link and as backup in the Mikrokopter OSD screen of Graupner MX-20 transmitter.

I don´t have telemetry (futaba tx) or OSD. And I also prefer acoustic and visual alarm so I don´t need to check voltage constantly. This way I can only focus on flying and leds and alarm will do that job for me, once they´re activated you can´t miss it if they´re both acoustic and visual
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First check, with NC disconnected, and MK connected to pc through FC mktools show no error, and all bl-ctrl start up ok

Also, all power pins on power board edges read correctly 15,2v (4s on storage)

That is a good start.

As you probably know, a general rule for technical problem solving, when a complex system does not work, try to simplify the system and re-test until you can pin-point which part is really failing. Also swap parts around if you have multiples of the same part.

This is a general rule, sometimes it can be difficult to test parts individually, if manufacturer has made a non-serviceable system.

For your own micro-copter integration do not solder everything together make parts detachable by connectors.
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Now this is weird... no error with NC connected! :shock:

After first test I searched for the problem on the regulator line, the one I was adjusting when did the shortcut and after the accident only showed 0,13v input, but at the point where those wires are soldered (main battery-powerboard wire) it displayed 15,2v.

There was a soldering in that line wich came lose when trying to remove shrink tube, resoldered both and now not only power reach regulator, but the regulator itself works!! :mrgreen:

After adjusting to 10,5v (it was at only 9,2v, that´s the reason I was adjusting it) connected NC again, and everything works fine, no error on MKtools.


I´m on one of those situations when you don´t know if being pleased, or worried because I don´t find where the problem was. I saw smoke, and it was not a thin line of smoke, it was a lot more than when I burnt the pcb extension board


Do you think it´s posible the soldering wich came loose was almost loose and the shortcut de-solder it, so the smoke was from that point wich came hot and burnt the shrink tube? It´s the only thing wich would make sense I think..... and also the only explanation wich would mean I´ve not burnt any board :P

What about the regulator? If the shortcut was at the output... how´s posible that it went backwards to the input line but didn´t burnt the regulator itself?


I´m trying to look for some explanation, but nothing make sense to me....
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About connectors... I´ve always tried to avoid them as much as posible, they´re points of posible failure. If it´s not something you may want to change in the flying field, I solder it. For anything you want to change at home, you can de-solder it in a moment so I prefer soldering to connectors
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Good that it appear to work again.

AndresMtnez meinte
Do you think it´s posible the soldering wich came loose was almost loose and the shortcut de-solder it, so the smoke was from that point wich came hot and burnt the shrink tube? It´s the only thing wich would make sense I think.....

Perhaps that is the case

AndresMtnez meinte
What about the regulator? If the shortcut was at the output... how´s posible that it went backwards to the input line but didn´t burnt the regulator itself?

If you short circuit the output of the DC-DC regulator it will try to supply as much current as possible. That means it pulls more current from the system that feeds the input (the battery?). The weakest link in that chain burns first. Maybe the battery gives up first, maybe one of the components in the DC-DC gives up when they cannot handle the current.

Seeing how your suffer multiple short circuit errors, I would recommend you to think about how to double isolate soldering points. E.g. if a PCB has to be attached to a aluminium surface, put an adhesive tape on the back of the PCB, then shrink tube the PCB, then attach it to aluminium.
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About connectors... I´ve always tried to avoid them as much as posible, they´re points of posible failure. If it´s not something you may want to change in the flying field, I solder it. For anything you want to change at home, you can de-solder it in a moment so I prefer soldering to connectors

Yes that is correct that connector gives a possible failure point, but bad solder points can also do that. A sensible amount of connectors makes things flexible and easy serviceable.
« Bearbeitet von Foersom am 06.01.2016 22:05. »
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I don´t have telemetry (futaba tx) or OSD. And I also prefer acoustic and visual alarm so I don´t need to check voltage constantly. This way I can only focus on flying and leds and alarm will do that job for me, once they´re activated you can´t miss it if they´re both acoustic and visual

I thought you had bought a Graupner MX-20, I think we discussed that earlier.

You need telemetry, I could not live without it! How can you otherwise really know what is going on on the micro-copter when it is >50 m away from you?

If you have a data radio, you can use the OSD in MK Tool.

Do you have video link? Add an OSD to the video link.
« Bearbeitet von Foersom am 07.01.2016 01:05. »
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Yes that Graupner is one of the first items on my wish list, but couln´t make the investment yet

About that data radio, for the price I prefer investing a bit more on a whole tx with telemetry


I´ve never been interested on OSDs, I´m flying fpv since 2006 and never missed it so I can live without it

Anycase knowing what´s going on on the MK is one of the main excuses to upgrade my tx :P
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Foersom meinte
Good that it appear to work again.

AndresMtnez meinte
Do you think it´s posible the soldering wich came loose was almost loose and the shortcut de-solder it, so the smoke was from that point wich came hot and burnt the shrink tube? It´s the only thing wich would make sense I think.....

Perhaps that is the case

AndresMtnez meinte
What about the regulator? If the shortcut was at the output... how´s posible that it went backwards to the input line but didn´t burnt the regulator itself?

If you short circuit the output of the DC-DC regulator it will try to supply as much current as possible. That means it pulls more current from the system that feeds the input (the battery?). The weakest link in that chain burns first. Maybe the battery gives up first, maybe one of the components in the DC-DC gives up when they cannot handle the current


This makes sense for the loose wire and no power reaching the regulator but....

How does that explain error 9 on MKtools? If it was a bad solder burning shrink tube, then mktower should have received no damage, and no error


btw, something I didn´t mention is when error 9 showed on MKtools, GPS CPU update page showed some "!!" instead of "ok". I can´t remember the values, but that must be some sort of error I guess...

Foersom meinte
Seeing how your suffer multiple short circuit errors, I would recommend you to think about how to double isolate soldering points. E.g. if a PCB has to be attached to a aluminium surface, put an adhesive tape on the back of the PCB, then shrink tube the PCB, then attach it to aluminium.


I´m not that clumsy :P

First shortcut was just a loose wire into a connector, and second was my mistake, true, that´s what happens when you try to hold the regulator, the tester, both tester probes, and at the same time turning regulator screw to adjust it. It´s easy some of the probes slide and cause a shortcut. Simple excess of confidence, will never happen again.
« Bearbeitet von AndresMtnez am 07.01.2016 11:59. »

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