I'm having trouble with my latest 5" miniquad build powered by an iFlight Succex brain. Under full throttle, the quad tumbles as if a single motor failed. All components are new with no hard crashes that would have hurt the motor. Seems like the ESC is to blame.

Before I scrap this build and buy new components, I'm looking for any troubleshooting tips you may have! 

I kind of regret going with the iFlight hardware while minimizing my budget, but it seemed to get good reviews. Should I try a new ESC first, or is the FC not worth my confidence either?

I'm also considering swapping the stack into my Flywoo Explorer V1 which has had some unsettling failsafe type crashes, even though the Crossfire link showed no indication of going down. Could be a GPS setup error, but I've developed some mistrust over the GOKU F411 setup on that original BNF. Worst case, maybe the iFlight stack is safer for that lightweight 1404 2750kV setup? It would be bulkier than the 16x16 Goku though.

Build specs are as follows:

Firmware: Betaflight 4.2.4 - Target: FPVM/BETAFLIGHTF4(STM32F405)
FC: IFLIGHT SUCCEX-E MINI F4 2-6S FLIGHT CONTROLLER - 20X20MM
ESC: iFlight Succex 4-in-one 35A 2-6S , 40A burst (should be plenty right?)
   -DSHOT600
   -BLHeli G-H-30, 16.7
Motors: Emax Eco II 2306 1900 KV
Battery: 6S 1300mah 120C
Capacitor: 470uF 35V
VTX/Camera: DJI Air Unit
RX: Crossfire Nano RX
Frame: QAV-S JohnnyFPV Edition
TX: Taranis X9D - OpenTx 2.3.11

I assume the FC is soft mounted.

I would thoroughly check for cracks in the carbon arm.

Could be a tuning issue.

It sounds like you are getting a motor desync. A blackbox log would likely reveal if that was the cause of your issue.

You have quite a low capacity capacitor installed. At least 1000uF is recommended, especially on a 6S build so you could try swapping that out. Make sure you use a decent known brand. There is no guarantee doing that will fix your issue but you have nothing to lose by trying.

If that doesn't work then some other things to try are increasing the demag compensation in BLHeliSuite and changing the motor timing.

Thanks guys. 

The frame is in solid shape and the FC is soft mounted. I am on stock PIDs, however, so maybe some tuning is needed. I just didn't think stock settings would cause a desync.

I will work on demag compensation and motor timing. These are things I haven't messed with before.

A blackbox review is probably a good idea. What are the tell-tale signs of desync?

(04-Jun-2021, 05:35 AM)hexvortex Wrote: What are the tell-tale signs of desync?

At the point where your quad falls put of the sky you would see the motor command value suddenly shoot up 100% on any motors that had a desync.