Project Start Prompt

flux

A 10 mA sensor should not pull a healthy 9–12 V supply down to 1.2 V. This indicates either a short/pinout error or a very high-impedance VDD source.
The observed drop corresponds roughly to:
Rsource≈12−1.210 mA=1.08 kΩR_{source}\approx\frac{12-1.2}{10\,mA}=1.08\,k\Omega
Check in this order
  1. Replace the sensor with a resistor load
    • For 12 V at 10 mA: use 1.2 kΩ, ≥0.25 W.
    • Connect it between sensor VDD and GND.
    • If VDD also collapses, the auxiliary VDD supply cannot provide 10 mA.
    • If VDD remains near 9–12 V, the sensor wiring, pinout, or output connection is wrong.
  2. Connect only sensor power
    Disconnect the sensor signal/output pin. Connect only VCC and GND.
    • Voltage stable: the signal interface is clamping or back-powering VDD.
    • Voltage still collapses: supply capacity, polarity, or sensor fault.
  3. Verify connector orientation and pinout
    Measure resistance from the sensor VCC pin to GND while unpowered. Also confirm PCB connector numbering against the sensor datasheet—connector numbering is often mirrored.
  4. Measure across D10 and any series resistor
    If most of the voltage appears across one component, that component or the upstream supply is limiting current.
Likely correction
The sensor should have a regulated auxiliary supply capable of at least 30–50 mA, allowing startup margin—not a high-value resistor/Zener-derived VDD rail intended only for the driver IC. Add local 100 nF + 47 µF capacitors at the sensor connector. If the sensor signal uses a different voltage domain, interface it through a transistor or optocoupler rather than connecting it directly to the driver IC.
Do not increase or bypass a series resistor until the resistor-load test rules out reversed wiring or a short. No schematic changes were made, and execution remains unavailable because your ACUs ran out.
J

junc

is the circuit diagram is okay ??

flux

No—the circuit is not okay for the present sensor load, even if the LED driver works without the sensor.
From the screenshot, the sensor appears to be powered from the LED-controller’s VDD/auxiliary supply through D10 and filtering. That rail may be intended only for the controller IC and therefore collapses when another ~10 mA is added. The measured 1.2 V strongly supports overload/current limiting, excessive series impedance, or incorrect sensor pinout.
Also verify:
  • Connect a 1.2 kΩ, 0.25 W resistor instead of the sensor. If VDD collapses, the auxiliary supply design is inadequate.
  • Connect only sensor VCC and GND. If stable until the signal pin is connected, the signal interface is clamping VDD.
  • Confirm D10 polarity, connector numbering/orientation, sensor voltage rating, and sensor VCC-to-GND resistance.
  • Ensure the sensor ground is truly isolated from rectified mains. An isolated LED output does not automatically make the controller-side VDD safe to touch.
The likely redesign is a dedicated isolated sensor supply rated for at least 30–50 mA, with 100 nF + 47 µF at the connector, followed by an optocoupler or properly rated transistor interface to the LED controller. I cannot approve component values or isolation from the screenshot alone; the full KiCad schematic needs a net-by-net review. No design changes were made, and execution stopped because your ACUs ran out.
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