Samsung DWB50 Dryer Drum Turns Backwards During Dry Cycle

Understanding the Problem

A Samsung DWB50 dryer that suddenly turns its drum in the opposite direction during a dry cycle can feel like a scene from a sci‑fi malfunction.
In most cases the appliance is still safe to use, but the unexpected reverse rotation can lead to uneven drying, excessive wear on the motor and belt, and, in some rare situations, a safety hazard if the drum’s internal components become misaligned.

The first step is to determine whether the reverse motion is a temporary glitch, a sign of a deeper mechanical fault, or an indication that the dryer’s internal control board is acting up.
By following a systematic approach—checking power, examining the motor and its drive belt, inspecting the control panel, and evaluating the dryer’s sensor readings—you can pinpoint the cause and decide on the best remedy.

Why the Drum Might Spin Backwards

Motor‑Drive Complex

The dryer’s motor is typically a universal motor paired with a timing belt or direct‑drive pulley.
If the belt is worn or the pulley’s teeth are damaged, the motor can slip and cause the drum to reverse.
In some models the motor has an electronic commutation system that can switch the polarity of the current, inadvertently driving the motor in the wrong direction.

Control Board and Relays

Samsung dryers use a microcontroller that sends pulses to relays that drive the motor.
A fault in the control board can send a wrong sequence of signals.
When the board fails to shut off the relay that controls the motor’s direction, the drum will continue turning or reverse mid‑cycle.

Sensors and Feedback Loops

The dryer has several sensors: a door‑switch, a temperature sensor, a moisture sensor, and a drum‑position sensor.
If the drum‑position sensor misreads the drum’s location, the control board might think the drum is stalled and reverse it in an attempt to “free” the load.
A short or loose wiring connection can trigger such misreads.

Physical Damage

Mechanical damage to the motor shaft or the pulley shaft—caused by a foreign object, a dropped weight, or a manufacturing defect—can break the normal direction of rotation.
The motor may lock or lock up, and the control board will attempt to compensate by driving the motor the other way.

Safety First

Before performing any troubleshooting:

• Unplug the dryer from the mains outlet.
• Wait at least ten minutes to let any stored static discharge dissipate.
• Ensure the dryer is on a stable, level surface and that the floor around it is clear of obstructions.
• Keep a fire extinguisher nearby in case of electrical fault.

If you are unsure about any step or feel uncomfortable with electrical work, contact a qualified appliance repair technician.

Step‑by‑Step Troubleshooting Guide

1. Verify the Symptom

• Start a short dry cycle with a small load.
• Observe the drum’s rotation: does it reverse after a set number of turns, or does it keep turning in the same direction?
• Note the timing: is the reversal triggered after a specific temperature or after the moisture sensor signals “dry”?

2. Inspect the Motor and Belt

• Remove the dryer’s rear panel according to the user manual.
• Look at the motor’s pulley: is the belt still taut? Are the belt’s teeth intact, or do they show signs of wear or damage?
• Check for any foreign objects caught in the belt or pulley.

If the belt is worn, replace it with the correct model belt for the DWB50.
If the pulley is damaged, it may need to be replaced or repaired.

3. Test the Motor’s Polarity

• While the dryer remains unplugged, use a multimeter to test the motor terminals for continuity.
• Connect the multimeter probes to the motor’s input terminals and observe the reading as the dryer is briefly powered on (only for a second or two, and only if you know what you are doing).
• If the motor runs in reverse when powered, it confirms a polarity issue.

In most cases, reversing the motor’s electrical connections (i.e., swapping the two input wires) will correct the direction.
If you are unfamiliar with electrical polarity, seek professional help.

4. Check the Control Board

• Look for any visible signs of damage on the control board: scorch marks, bulging capacitors, or loose solder joints.
• Remove the board from the dryer housing (if your model allows) and inspect for shorts or open circuits.
• If the board shows any signs of damage, it may need to be replaced.

Samsung’s DWB50 often uses a board that can be sourced from the manufacturer’s parts catalog or from reputable third‑party suppliers.

5. Test the Relays and Switches

• Identify the relay that powers the motor. This relay should be located on the control board or a separate relay board.
• Using a multimeter, test the relay’s coil for continuity when the dryer is supposed to be in the drying phase.
• Check the relay’s contacts for arcing or burn marks. A bad relay can cause the motor to receive power in the wrong direction.

Replacing a faulty relay is usually inexpensive and can be done with a simple soldering or solderless technique, depending on the relay type.

6. Inspect the Drum‑Position Sensor

• Locate the drum‑position sensor on the dryer’s drum housing or motor housing.
• Verify that the sensor’s cable is intact and that the connector is firmly seated.
• Use a multimeter to test the sensor’s resistance values against the manufacturer’s specifications.
• If the sensor fails or its resistance is out of range, replace it.

Because the sensor informs the control board of the drum’s rotation, a faulty sensor can cause the control board to misinterpret the drum’s state and reverse it inadvertently.

7. Examine the Door Switch

• The door switch must be fully closed and engaged for the dryer to run.
• Open and close the dryer door several times, feeling for any resistance.
• If the switch is stuck or fails to close, the dryer may try to restart the motor in an attempt to continue operation, leading to reverse motion.

Clean the door switch contacts with a mild electrical contact cleaner and ensure the switch arm moves freely.
If cleaning does not help, replace the door switch.

8. Evaluate the Moisture Sensor

• The moisture sensor sits inside the dryer drum or behind the door.
• Remove the sensor housing and clean the sensor elements with a dry cloth.
• Check the sensor’s wiring for kinks or damage.

A failing moisture sensor may cause the dryer to believe the load is still wet and attempt to restart the motor, sometimes in the opposite direction.

9. Look for Shorted Wires

• Inspect all wiring harnesses for signs of insulation wear, fraying, or cuts.
• Pay special attention to the wires leading to the motor and control board.
• Use a continuity test to confirm each wire runs uninterrupted from one terminal to another.

A shorted wire can send an errant signal to the motor’s relay, causing the reverse rotation.

10. Perform a Test Run

• After replacing any defective component, reassemble the dryer.
• Plug it in, start a dry cycle, and watch the drum’s behavior.
• If the drum no longer reverses, you have identified and fixed the issue.

If the problem persists, re‑inspect the previously checked components, as the issue may be intermittent.

Preventive Maintenance Tips

Keep the Drum Belt Clean and Tight

Dust and lint accumulate on the belt and can cause slipping.
Clean the belt with a damp cloth and tighten it if you feel it’s loose.

Regularly Inspect the Motor and Pulleys

Periodically check the motor for noise or vibration.
If you notice any humming or unusual sounds, consider having the motor inspected by a professional.

Maintain the Door Seal

A worn door seal can let air in and reduce drying efficiency, prompting the control board to restart the motor.
Replace the seal if it’s cracked, torn, or compressed.

Clean the Lint Filter

A clogged lint filter increases resistance and can cause the dryer to overheat or restart.
Clean it after every use.

Avoid Overloading

Excessive load can overload the motor and cause reverse rotation as a safety measure.
Follow the manufacturer’s recommended load capacity.

Schedule Periodic Professional Servicing

At least once a year, have a licensed technician inspect the dryer’s electronic and mechanical components.
Early detection of sensor drift or relay wear can prevent major failures.

When to Call a Professional

• You find a short in the motor wiring and are uncomfortable repairing it.
• The control board shows burn marks or severe damage.
• The dryer continues to reverse despite replacing all inspected components.
• The dryer’s safety interlocks (door switch, temperature sensor) fail to function properly.

Professional technicians have specialized tools to diagnose and repair high‑frequency control board faults, replace relays, and test motor commutation with precision.

Warranty and Replacement Options

If your Samsung DWB50 dryer is still under warranty, document the reverse drum issue with photos and a video of the malfunction.
Contact Samsung’s customer support and request a service call.
Most warranty terms cover both mechanical and electronic components.

If the dryer is out of warranty and the repair costs approach the price of a new unit, consider:

• Replacing the entire motor assembly.
• Upgrading to a newer Samsung model with improved reliability.
• Purchasing a refurbished or certified pre‑owned dryer.

Always weigh the repair costs against the expected remaining lifespan of the appliance.

Final Thoughts

A dryer drum that turns backwards is a clear sign that something in the motor drive or control system is out of sync.
By following a systematic troubleshooting procedure—starting with a simple inspection of the belt and motor, moving through electrical checks of relays and sensors, and ending with a test run—you can often locate the root cause and fix it without professional help.

When in doubt, lean on a qualified technician.
And remember: regular maintenance, quick fixes for small wear items, and staying within load limits can keep your dryer running smoothly and safely for many years.