RC ESC Repair & Electronics Center

High-current semiconductor switches. In brushed ESCs they form an H-bridge; in brushless ESCs three half-bridges energize motor phases. Symptoms: battery short, hot ESC, dead phase, failure to drive. With power removed and capacitors safely discharged, a qualified technician may compare drain-source resistance/diode-mode readings across phases; in-circuit readings are not conclusive. Replace only with correctly rated, thermally compatible parts and check gate drivers first.

Translate logic-level PWM into fast, correctly timed MOSFET gate signals, sometimes with bootstrap circuitry and dead-time control. Failure may mimic a burned MOSFET. Checking gate waveforms requires isolated, appropriate instruments and board-specific service data; do not attach a grounded scope lead to a switching node.

Reads throttle signals, handles neutral calibration, commutation, timing, brake/reverse modes, protections, and status LEDs. Corrupt settings can resemble hardware damage. Try supported reset/calibration/firmware tools before board repair.

Reduce battery-bus ripple and absorb current pulses. Bulging, leaking, loose solder joints or high ESR can cause resets and excess heat. Verify polarity, capacitance, voltage, ripple-current rating and temperature rating when replacing; do not bypass them.

Supplies receiver and servo voltage, commonly via a switching or linear regulator. A failed BEC can cause receiver brownouts and no steering while motor power circuitry is intact. Measure output only at the specified receiver connector with correct polarity and no short.

Measure load current for limiting and fault detection. Damaged shunts, traces, or sensor circuitry may cause false overcurrent shutdown or uncontrolled operation. Never bridge a damaged shunt.

Set gate resistance, voltage sensing, pull-ups and temperature feedback. Cracked parts can prevent starting or cause temperature faults. Identify component markings and compare against manufacturer schematic or a known-good board.

Clamp voltage transients, protect polarity or support bootstrap supplies. A shorted TVS can resemble a battery short. Verify part identity and ratings; never defeat safety protection.

Carry large pulsed currents. Loose bullets, overheated joints, broken traces, and water corrosion can cause stutter, intermittent drive and overheating. Inspect under magnification with battery removed.

Carries rotor-position information to the ESC. Damaged sensor cables or incorrect phase/sensor combinations cause rough startup and poor low-speed control. Check alignment and use compatible test equipment.

Record manufacturer, model, brushed/brushless, sensored/sensorless, voltage range, BEC output, firmware and motor type. Download the exact model manual. Marine and aircraft ESCs may have no reverse or different braking behavior by design.

Confirm reverse is supported and enabled. Many car ESCs use forward/brake/reverse mode with a second reverse command after neutral and a full stop. Check transmitter throttle trim, endpoint, channel reverse, neutral and calibration. Confirm the motor can reverse using the model-specific test. If these pass, suspect firmware/control faults or a power-stage fault; do not assume a MOSFET is bad solely from this symptom.

Verify channel direction, endpoint and throttle calibration; inspect running mode and error codes. Test receiver output with a compatible servo tester or known-good setup. Inspect motor wiring and ESC output faults only after external causes are ruled out.

Check drag brake vs active brake settings, brake strength, transmitter brake endpoint, neutral range and firmware profile. On some aircraft ESCs brake means propeller stopping, not car-style braking. Inspect drivetrain and battery protections; compare behavior to the manufacturer manual.

Disconnect battery; check battery condition, connector polarity, switch, visible corrosion and shorts. Do not reconnect a battery to a shorted controller. Check receiver BEC separately only if the manual allows. Burnt smell or a hard short is a stop condition for professional evaluation.

Check motor mechanical binding, connectors and solder joints. Sensored units: inspect sensor harness and phase mapping. Test a known-good compatible motor and ESC separately. A damaged MOSFET, driver, motor winding or sensor may cause similar symptoms.

Check gearing, tire size, drivetrain friction, current demand, cooling, voltage, motor timing and ESC current rating. Verify fan function and temperature telemetry. Repeated thermal trips require correction of load or hardware issues, not bypassing protection.

Disconnect power immediately; do not power-test a wet board. Inspect seals, connectors, corrosion and trapped moisture. Waterproof ratings vary and do not imply resistance to saltwater. Severe corrosion under ICs often makes replacement safer.

Photograph and inspect the board; identify battery input, bus capacitors, BEC, logic, gate drivers and MOSFET banks. With battery disconnected and capacitors verified discharged, inspect for shorts, cracked joints and damaged components. Use a current-limited bench supply only where the model and technician procedures permit. Document readings and do not replace components by guesswork.

After manufacturer-approved repair, reassemble insulation and heat sinks, test at low power with drive wheels clear or propellers removed, verify neutral, forward, brake, reverse, receiver failsafe and thermal behavior. Stop on abnormal heat, smoke, smell or erratic motion.