How can I tell if it receiver problem or the fbl unit?

Id start by doing a range check w your tx and rx. I, and quite a few others, use the ar7700 as well and it works great. I would def either use hit glue or some 3m double sided tape to make sure the servo cables stay plugged it. Its a nitro so its gonna be vibrating quite a bit.

Thank you Sir.
do you have any idea about this?
The weird part is when I got shut out from the receiver, both the lights were on lit solid no blinking. Still no control from radio.
Showed received frame was corrupted in log.

To answer this question accurately, yes, your setup has a ground loop in it.
Whenever there are multiple paths to ground, it is a potential problem.
Your power was fed directly to Spirit Pro and also to AR7700. Primary load is from servos and as that load fluctuates during flight, there are potential differences in ground-level to satisfy those loads. Either most directly from the battery power lead connected to the Spirit Pro, or indirectly from the battery power lead connected to the AR7700 travelling over the single line connection (bad).
https://en.wikipedia.org/wiki/Ground_loop_(electricity)
No way to know if this is the cause of your crash though.
After my recent experiences though, I would recommend all power connections go direct to FBL and let AR7700 get power only from single line connection to Spirit Pro.

What servos were you using?


Also, it is very important that your heli tail is grounded to protect from static discharges. You can verify with a multi-meter. I look for continuity between a motor mount bolt on the frame and the tail shaft. If you don't have continuity between these points, figure out where the problem and bridge it with a wire. Depending on the model of heli, this may mean adding a wire between the boom and frame, or something else.

(For tail BLS-G)
Nominal Voltage*: 6.0 - 7.4VDC
Operating Voltage: 5.5 - 8.4VDC
Torque: 90 - 120 oz-in
Speed: 0.05 - 0.03 sec/60°
Frequency: 760µs/560Hz
Dead band: 2µs
Weight: 73.5g
Wire: JR/265mm

(For cyclic)
Nominal Voltage*: 6.0 - 7.4VDC
Operating Voltage: 5.5 - 8.4VDC
Torque: 180 - 215 oz-in
Speed: 0.11 - 0.09 sec/60°
Frequency: 1520µs/330Hz
Dead band: 2µs
Weight: 73.5g
Wire: JR/265mm

Both are ProModeler
This is what I ran into.

Lost input from radio (JR11x) to the AR7700.
Lights on both sat and 7700 stayed solid orange.
Till I pulled bat wire then I regained control.
This is on a Heli AR7700 srxl to Spirit pro.
Why would the lights stay solid (on), but have no input from radio?
thanks for your help SIR
So you are saying you can have a ground loop with only 1 battery?

For me it looks like the data cable was not holding correctly because problem is getting worse according to log.
Alternatively it was static discharge issue as I said earlier.

Did you verified if you have had a control before you disconnected the battery (after loss of signal)? I
If you can perform range test with your transmitter and it will be OK, then I think that there is no problem with RX/TX.

I also recommend to just start your helicopter and leave it for at least 10 minutes. Then if there will be no issue with connection I guess

_________________
Spirit System developer

yes, had no control until I unplugged the power lead from receiver only.
Do you have any idea why lights stayed on (no blinking) no radio control at all?
As far as static, could of been loose belt but don't no if that happened when it hit the ground.
If I need to ground boom not sure how yet.
Did range check all seems ok tx to rx.
Now that brings us to fbl.
Since it was still countering heil. movement with no radio control could fbl be a problem.
Or just connection between the 2.
Still don't think there is a problem with fbl at all.

Strato

Based on what jmackey said above it could possibly be a ground loop. Remove the BEC connector from the receiver and just use the SRXL cable to power it. Also check for continuity with a multimeter from the tail shaft to the motor mount. It should show very little resistance.

This is nitro no bec.
From mount to tail rotor shaft 0 continuity.

Sorry meant the RX pack