The 24V DC switch mode power supply (SMPS) is one of the most common failure points in CNC machines. When it fails, the entire machine loses control power — no controller, no drivers, no I/O. This guide shows you how to diagnose the fault and get the right replacement in UAE same-day.
SMPS units have a limited lifespan. Capacitor degradation over 3-5 years of continuous use causes output voltage to drop or fail completely.
UAE mains power can have voltage spikes, especially during grid switching. Unprotected SMPS units fail on high voltage transients.
Drawing more current than the PSU rating (e.g. 24V 6.5A supplying 10A load) causes thermal shutdown or permanent failure.
A wiring fault downstream — shorted sensor, solenoid, or terminal — causes the PSU to trip on short circuit protection or burn out.
UAE ambient temperatures plus poor panel ventilation cause SMPS internal temperatures to exceed limits, accelerating component failure.
Workshop environments with dust or moisture ingress into the control panel cause tracking, short circuits, and component corrosion.
Use a multimeter on AC voltage setting. Check the SMPS input terminals — should read 220V AC. If no mains, the issue is upstream (circuit breaker, contactor, or wiring). Fix mains first.
Switch multimeter to DC voltage. Measure the output terminals (+V and -V or COM). Should read 23.5-24.5V DC. Zero voltage or fluctuating voltage = PSU failure.
Disconnect all load wiring from the PSU output. Measure output voltage again. If voltage is now correct, a downstream component is shorting. Reconnect loads one by one to find the fault.
Most SMPS units have a green LED for normal operation. LED off with mains present = internal failure. Some units have a separate fault LED.
Inspect the PSU for bulging capacitors, burn marks, or the smell of burnt components. These confirm internal failure. Do not attempt repair — replace the unit.
Match voltage (24V), current (minimum equal to original rating), and wattage. The ANDELI S-150-24 (24V 6.5A 150W) is the standard UAE replacement for most CNC machines. Available same-day in UAE.
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AACNC stocks ANDELI S-150-24 (24V DC 150W) industrial power supplies in UAE — the standard replacement for most CNC machine control panels. Same-day dispatch from Dubai. Cash on Delivery available across all UAE emirates.
Common questions about CNC machine power supply faults
Test the output terminals with a multimeter on DC voltage setting. A healthy 24V PSU reads 23.5-24.5V DC. Zero, very low, or fluctuating voltage confirms failure. Also check if the green indicator LED on the PSU is off.
We do not recommend attempting repair. SMPS failures usually involve failed capacitors or protection circuits. Replacement cost is low (AED 129 for ANDELI S-150-24) and a repaired unit may fail again soon. Replace for reliability.
You need to match: output voltage (most CNC machines use 24V DC), output current (must be equal to or greater than the original), and physical mounting (DIN rail). Check the original PSU label for voltage and amperage rating.
A sudden power supply failure rarely damages the controller. However, low or fluctuating voltage can corrupt controller parameters or cause memory issues. After replacing the PSU, verify all controller parameters are intact.
Yes — AACNC stocks ANDELI S-150-24 power supplies in UAE. Same-day dispatch on orders before 2pm. Delivery to Dubai in 1 business day. Cash on Delivery available.