Weird Crash

[Planehazza]

Yup, mini vBar with a single servo connector providing power, my bet is you'll find that's the problem. Your battery should be fine, and the deans from the battery is also good, and while it could be soldering the known vBar issue is a more likely bet imo.

Mikado have a FAQ about power issues with some servos on the Mini vBar:
https://www.vstabi.info/en/node/1422

And RC Heli Nation recommend wiring your system to provide servo power externally to the Mini vBar:
Mini VBar Power Bus - RC Heli Nation

If you can, see if you can reproduce the issue on the bench. Holding the head to load the servos while moving the sticks as fast as you can may be enough, and if you can reproduce the issue on the bench it will give you much more confident in any fixes you make.

Your power wiring layout isn't ideal, although you're doing the right thing by splitting the deans into two plugs with a Y connector, only one of those connectors is providing power to the vBar and servos, the other is only powering the receiver. That means all your current is being pulled through a single plug that isn't really designed for high currents. Ideally you want two servo connectors providing power to the Mini VBar.

You can wire that yourself easily enough, although there is a Spartan Power Bus which provides two pass through servo plugs, allowing you to provide power to the vBar through two ports while still being able to use them:
Spartan Micro Power Bus SRC-MPB

If I were you I would look to make two changes here:

• Add a capacitor as recommended by Mikado (The R2 Prototyping Buffer Pack is worth a look, it's more expensive, but also provides you with a backup power supply)
• Ensure you have two leads providing power into the Mini vBar

Very interesting read, thanks. I wasn't aware there was such an issue with the Vbar mini, but I have always know that (generally) it is imperative to have redundant power inputs to the 'system'. I thought that by having a power input directly to the Vmini and the Rx would suffice, espcially as there is power going from the Rx to the FBL via the patch lead (RX B connector). It's interesting to see how it's come together. I wonder if the addition of the larger, heavier A123 pack (despite being a much better discharge rating) simply just put that added load onto the servos.

I don't understand that RC Heli Nation diagram. I don't get how having three servos getting power from a single output would alleviate the issue. I'll have a think as to how I could get two power leads to the Vbar directly.

I haven't decided yet what I'm going to do. I can't decide if investing another £100+ into a Fusion is a good idea or not. I'm on the fence as to whether I should just cut my losses now and sell the electronics and frames as spares and get myself £250.

EDIT: Grumpy, I just saw your reply after writing this post.

As I read it it's not a single plug, it's two.

One wire connects direct to the Vbar, the other wire in the Y-lead connects to the receiver then to the Vbar via the connections between receiver and Vbar?.. On the other hand if there aren't any power (+ and -) connections between receiver and Vbar then I'd agree, another connection to the Vbar is needed. But in that case you need to have some other wire powering the receiver.

You are correct. I've got a Y lead from the Deans providing power to Vbar and Rx, and as you and I have both said, the patch lead between them should also reroute power. Just double checked my photos and manuals, and yes, power to Vbar and Rx, as well as Pitch patch lead connecting signal and power between the two units.

[Grumpy]

I thought that by having a power input directly to the Vmini and the Rx would suffice, especially as there is power going from the Rx to the FBL via the patch leads (RX connectors). It's interesting to see how it's come together. I wonder if the addition of the larger, heavier A123 pack (despite being a much better discharge rating) simply just put that added load onto the servos.

Yep, that's what I'd say too. As long as the power has two feeds to the Vbar it 'should' be ok. Accepted that one feed will have a little higher voltage drop due to multiple connections, so the other will take preferentially more current, but that shouldn't be a big issue unless pushing to the absolute limit.

[Planehazza]

Yep, that's what I'd say too. As long as the power has two feeds to the Vbar it 'should' be ok. Accepted that one feed will have a little higher voltage drop due to multiple connections, so the other will take preferentially more current, but that shouldn't be a big issue unless pushing to the absolute limit.

Yup, and I wish we were wrong as it would mean we'd got to the bottom of it. It's clear there's a power problem somwhere but I'm struggling to see where. I had all the wiring out recently and I saw no damage or shorts etc.

[myxiplx]

Your current patch lead is only sending signal data though, unless you have another +ve and -ve lead from the RX to the FBL it's not providing another source of power.

[myxiplx]

And bear in mind that it's not necessarily just a question of raw current capacity. The Mikado article shows a more subtle electronic effect is also a factor, and just adding a capacitor to smooth the delivery can make a huge difference.

Of course, if it's been flying find like this for a while without problems, it could also be a servo on the way out, or some damage to a servo gear causing it to pull more power than it has been previously.

[Planehazza]

Your current patch lead is only sending signal data though, unless you have another +ve and -ve lead from the RX to the FBL it's not providing another source of power.

It is mate One of them uses all three leads as aileron, elevator, and rudder signals leads, but no power. The final one (collective IIRC) is a standard patch lead - it sends just one channel's signal and +/- power. I'll try to get a photo tonight.

And bear in mind that it's not necessarily just a question of raw current capacity. The Mikado article shows a more subtle electronic effect is also a factor, and just adding a capacitor to smooth the delivery can make a huge difference.

Of course, if it's been flying find like this for a while without problems, it could also be a servo on the way out, or some damage to a servo gear causing it to pull more power than it has been previously.

Yeah, it's just typical (and foolish of me) that this model does not have an OptiGuard. I did noticed that one of the bell crank was jammed the wrong way, which could explain a crash and current demand, but it's more like that it happened during the crash. It was only the left bell crank but the model did not roll; instead it flipped straight into the ground...

[myxiplx]

Aaah, ok, so you've a standard receiver connection in addition to the wire direct from the battery? From your picture I thought you were using just that one single signal wire from the receiver to vBar.

[Planehazza]

Aaah, ok, so you've a standard receiver connection in addition to the wire direct from the battery? From your picture I thought you were using just that one single signal wire from the receiver to vBar.

Ah no, that's just a picture to show the Y lead so I left everything else unplugged so it could be seen clearly.