Troubleshooting ESC (Solved)

[Wr4ptr]

Hey folks, so here's the scenario. I went out and flew 2 batteries on a 5" quad that I built. I've flown it a number of times with no issues and this night was no exception. Two great flights. Landed softly. When I put the 3 battery on, the ESC makes the first 3 tones, but doesn't make the last two and the quad won't arm. When I hook up to betaflight and put a battery on, the little battery indicator at the top of the screen with sometimes flicker. When it's solid, it's only reading like 4.2 V (like a 1s battery even though it's a 4S), so it seems like a low power condition. This happens when I connect ANY of my 4S batteries to that quad. Then batteries check out fine and on the battery checker and when I hook these batteries up to my other quad when it is connected to betaflight, it shows 16.2 V. So, I'm comfortable that the problem is with this quad and not with the batteries. When a battery is plugged in and I jiggle the XT60, it does not seem to have any effect and there is no visible damage to the XT60 on the quad or to the wires. The power wires are firmly soldered and I am using a capacitor soldered on with the power wires. Stack is the LDARC 30.5 x 30 5 mm KK Superfly Tower with a 4-in-1 ESC. Also, the quad will not link to my transmitter. However, I THINK this is because the frsky receiver is not receiving power.

I was thinking of just flashing the firmware in case it's just a gremlin, but it really seems like the quad isn't seeing the right amount of power coming in.

I'd be interested in any troubleshooting ideas or thoughts on what might be going on. Please let me know what additional info you need for a diagnosis. Thanks in advance.

 

[tevek]

Fairly sure the first couple of beeps on start up are the esc’s initialising and the last couple are the FC doing the same. Had that happen to me in similar circumstances to you last week and it turned out the FC is cooked. No reason for it other than some sort of possible voltage spike when powering up the quad when mine expired. Also in betaflight, I had a warning pop up regarding gyro and another that I can’t remember having failed and that was that. When I stripped mine down, I found what i think was the voltage regulator charred and the smell of death. Waiting on feedback from the supplier regarding warranty as the quad was only ten packs old and certainly not damaged or thrashed.

 

[Acronaught101]

I wonder if it could be the capacitor on your power lead. I’d try to desolder that one and replace with new one. Try that out.

 

[Wr4ptr]

Good thought, Acronaught101. We wondered the same thing and tested that out. I think a dead/damaged capacitor COULD cause this type of issue. But we actually got it solved. I got some help from a guy I know who is into RC cars and knows a lot, in general, about electronics. This was a nice bit of Quad troubleshooting and problem solving.

Through voltemeter testing, we found that power is getting all the way through the ESC with appropriate continuity. This stack has a ribbon cable that connects the ESC to the FC. So, then we tested the output pins on the ESC side of the ribbon cable. We figured out that two of them weren't passing their signal through to the FC. It was a full power pin (16 V) and a ground. So, we backed those two wires out of the ESC side of the ribbon. We used the voltemeter to find two pads on the top of the ESC that were correct (one that had 16 V and one ground) and we soldered the appropriate wires to them. Plugged in the quad and, Voila!. . .we're back in business!

I thought my ESC was fried, but it was really just a couple of pins supplying the ribbon cable. Looking around, this is not terribly uncommon. So, add it to your troubleshooting algorithm.

Cheers!