Have a Holybro S500 kit that I built. Everything was going smooth and easy until I got to spinning up the actuators. I am using QGroundControl. (I’m new to building drones, but went through a days worth of troubleshooting to no avail). here’s the summary:
Pixhawk 6C Mini — registers drive commanded PWM values, but zero signal on ALL physical output pins (MAIN and AUX)
Hardware: Holybro S500 V2 kit, Pixhawk 6C Mini (HW type V6C002002, rev 0x002), M10 GPS, stock kit BLHeli ESCs
Firmware: PX4 v1.17.0 stable and v1.16 stable (both tested, clean flashes with full parameter erase)
Before I RMA this board, I am looking for a sanity check from the community — either someone recognizes this failure mode, or someone spots a test I haven’t run.
Symptom
No PWM signal has ever appeared on any physical output pin — main or aux.
Additionally, the safety switch on the M10 GPS (the integrated LED-button) has been non-functional since first power-on — press-and-hold (1+ seconds, many attempts) never changes the LED state (it stays in a continuous double-blink pattern, never goes solid), and status_safety_button_event never asserts.
What I’ve verified
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Actuator config correct: Motors 1–4 → MAIN 1–4, generic quad airframe. Confirmed via px4io status showing func: 101–104 on channels 0–3.
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Safety/prearm gates open: CBRK_IO_SAFETY = 22027, COM_PREARM_MODE = 2, confirmed via param show. listener actuator_armed shows prearmed: True.
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Full arm achieved: commander arm -f succeeded — px4io status showed arming_fmu_armed: True, arming_io_arm_ok: True, all four channels commanding 1100µs at 400Hz. Motors did not spin. Pins measured 0V.
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Registers track commands perfectly: actuator_test set -m 1 -v 0.2 → pwm: [1260, 1000, 1000, 1000] in px4io status, every time, both firmware versions. No alarms (alarm_pwm_error: False, clean status otherwise).
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GPS/safety switch eliminated: physically disconnected the GPS entirely — identical behavior.
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Independent signal detector: reassigned MAIN 1 to Servo 1 (PWM_MAIN_FUNC1 = 201), connected a hobby servo with externally supplied and verified 5V (common ground with the FC confirmed). Ran actuator_test set -s 1 -v 0.5 — px4io status captured mid-test shows Channel 0: func: 201, value: 1700. Servo never moved. Signal pin: 0V. (A 1700µs pulse at 400Hz should read ~2.2V average on a DVM.)
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Repeated on MAIN 2: same result — register driven, pin dead.
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Repeated on FMU PWM OUT (AUX1): assigned PWM_AUX_FUNC1 = 201, moved servo signal to FMU_CH1 — same result. No output.
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Has anyone seen a 6C Mini (or 6C) with both MAIN and AUX outputs electrically dead while all software state is healthy?
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Is there a known issue with the PWM voltage-select pads on this HW revision shipping unbridged/defective from the factory?
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Is there any test I’ve missed that could produce driven registers + dead pins from a config/firmware cause rather than hardware? (I’ve done clean reflashes with param erase on two stable versions.)
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Anything else worth checking before this goes back to Holybro?