After reassembling my hex with a 2.5 apm and new hex pdb, I tried a test flight or two and after flipping a few times and busting a prop, i reduced my expectations to just a hand test or two so i could validate my wiring etc. However, as i would arm and then throttle up, the copter would suddenly stop and disarm requireing me to re-arm. Id throttle up again and same cycle over again after maybe 20 seconds of run-up.
I had re-soldered the whole pdb and had specifically re-soldered the APM power leads with a heavier guage wire than the stock ( Is it me or is the stock cabling unnecessarily flimsy?) but logic says that maybe theres a cold solder joint that disconnects power to the APM. Problem is whenever i check continuuity and futz with cables, it tests good. Anyone have a suggestion?
Thanks in advance
Bart, It would help if you could explain the setup in more detail, particularly for people that has not seen your PDB!
What is the supply voltage and current capability?
Where is the supply being connected?
Are there any Servos connected?
What current is being taken with the motors not running?
For a voltage drop to occur on throttle up suggests that the battery is shot, batt connections are making poor contact, very thin supply leads etc...
my apologies- I thought i had specified that the PDB was stock issue DIY drones, hence my complaints regarding the flimsy signal leads. When i first assembled the board, i had done so with cheap solder, and then reconsidered and redid it all with known good quality stuff. THat's why im dumbfounded that im having problems now. It's also why you can see so much heat distress in the attached photo. FWIW ive also soldered ( with the good stuff) the esc leads to the motors. Im considering 2 things, and please speak up if anyone thinks this is foolish.
1. resolder all signal leads to the esc signal pins instead of the board and
2. doing likewise with the APM power leads.
I should also add that the battery is a new 4400 3S ( yes, yes i know eflight sucks on ice but its what i got). I should also add that there are no servos and that the esc signal outputs have a 3" extension so as to make reattaching escs simpler without needing to field strip the copter just to re-plug/ re-seat.
I'm not sure how to say lightly this but uh... that's really pretty bad. Bart, are you soldering with open flame? There's really no telling what is going on with that thing.
I think you're going to need to get new electronics and see if there's somebody who can help you. You can't fly with that.
loolol well kinda. Thanks for not mincing words, because if it sucks, then it sucks. Dontcha hate when some pansy-ass gets their feelings hurt over legit criticism? The deal is I had bought a butane bernzomatic soldering iron that's been very spotty- not getting hot enough etc..and id used the open torch to do the main pads quickly and then had desoldered with it as well. Just to salve my own pride, it looked great when id first done it. :P And yes, i know i need a real solder station too, but that'll have to wait till there's some extra green.
Is there any benefit to the board aside from the weight? I mean as opposed to just using wire- at least for the main power leads? -because eventually, id like to integrate everything in a fiberglass shell if that will prove light enough. Maybe that's stupid as it could create EM fields if the runs are too long, right?
Thanks guys, and may all your brown-outs be non-pants related.
Bart, Stating that it's a stock pdb is not much help to anyone who isn't familiar with said board!
Also as already realised here, a photo can go a long way in helping diagnose problems. Although in this case (as L has said) from the picture, it's hard to see whats going on in that board!
Ok, we can still try to make some progress! The chances are that your battery is fine, your soldering capabilities have already taken a hit but from what can be seen, the leads does seem to be soldered to the board, different types of solder would not cause the problems your experiencing, at least not immediately!
As you have noticed, a pdb is not vital, it's just a very convenient way to solder several wires together! For instance, you have at least two heavy wires coming in from the battery, then several medium wires going out to the ESC's. It would be hard to do this neatly without some kind of PDB, nothing fancy, a piece of PCB would do just as well!
From your description, Your problem appears to be a voltage drop somewhere on the supply side!
1) Looking at you photo, I can't see any heavy wires coming in from your battery?
2) You really need access to a cheapo meter, measure for resistance/ voltage drop across the supply leads
3) ESC signal wires only need light wires, no current flows in these as such, just signal and signal ground.
4) Brownout seems to be the current (generally misused) buzz word, adopted for any problem that crops up, forget it! Your problem is in the main supply wiring, connectors etc.
Bart, you don't have to spend a lot of money on a soldering station. I started out with a $20 40W iron and it worked for years.
Mind you... a 40W iron will have trouble doing those bigger joints. But I got a lot done with it.
Thanks! All good suggestions / criticisms. It seems this is a tool issue that i should have addressed sooner, I actually do have a multi meter and had tested continuity of all of those cables before reassembling it. And correct me if Im wrong but the APM is actually separated from the main circuit by the ESC such that the power is regulated, right? Is it a bad thing to just pull direct from the battery to power the APM? Further, whats to stop me from wiring all of the esc's directly without removing the power leads? Stupid question but I dont really know if its a bad thing to have all six leads into the apm directly-err in parallel. I mean,connecting them in this way wont effectively make the connection in series would it? Further, would this create a ground loop? Knuckleheaded questions, but I know just enough to be dangerous and im trying to resolve that.
Thanks to everyone for their help and interest
I actually do have a multi meter and had tested continuity of all of those cables before reassembling it. And correct me if Im wrong but the APM is actually separated from the main circuit by the ESC such that the power is regulated, right?
Well yes it is but if the supply to the esc's drop below about 1.5v above the bec voltage then the bec output will start dropping! So it's worth measuring for voltage drop on the main supply wires! switch the multimeter to low volts, connect the multimeter leads one to the +v cable (near to battery as possible), and the other lead near to ESC as possible, increasing load (higher rpm) should show hardly any voltage drop. If it does then the leads are not thick enough or you have a poor connection somewhere.
If that sounds a bit difficult to do then at least monitor the bec voltage at the apm while increasing rpm on the motors. Any voltage drop there will mean the supply voltage is dropping substantially somewhere! Please lash the multi down and be careful, the props are needed to be on so that the motors are running under load and drawing current, always respect the spinning props!
Is it a bad thing to just pull direct from the battery to power the APM?
Don't do this, it will blow the APM board! v supply is 5v -+ 0.5v
Further, whats to stop me from wiring all of the esc's directly without removing the power leads? Stupid question but I dont really know if its a bad thing to have all six leads into the apm directly-err in parallel. I mean,connecting them in this way wont effectively make the connection in series would it?
If you mean the ESC signal leads then yes they would be effectively in parallel
If the ESC's use a 'Linear' bec, then it should be ok. (You should be able to find this out in the ESC data sheet!) If they are not Linear then its not recommended to use them in parallel, just connect one bec, so one esc signal lead will have its three wires, all the rest will have the white pin pulled out of their plug and taped up.
would this create a ground loop?
Yes but there probably won't be any observable problems with that.
Awesome Peter- those questions have been plagueing me for a while. Thanks also for explaining a practical test for loading. As you may have guessed, the nuts and bolts of circuitry are a little out of my bailiwick. But not for too much longer, thanks to everyone's generosity