speed control dial doesn't seem to change anything, it's just stuck on one speed.

Diagnosis

The Ryobi ONE+ HP Compact Router (PSBCR01B) utilizes an Electronic Speed Control (ESC) module that regulates the voltage delivered to the brushless motor based on the position of the potentiometer dial. When the speed remains constant regardless of the dial position, it indicates a failure in the feedback loop between the dial and the control board. Most commonly, the potentiometer—the variable resistor behind the plastic knob—has either suffered a mechanical failure (the shaft has snapped or stripped) or an electrical failure (the carbon track inside the potentiometer has worn out or shorted).

You can confirm this by listening to the motor's pitch. If the router immediately jumps to maximum RPM (approx. 20,000 RPM) the moment you pull the trigger, the ESC is likely failing to "clamp" the voltage. If it stays at a low, sluggish speed regardless of the dial, the circuit is likely stuck in a low-voltage state. To verify if the issue is mechanical, feel for any "play" or looseness in the dial; if the knob spins freely without the typical tactile resistance of a potentiometer, the plastic D-shaft has stripped away from the metal stem.

How to Fix It

Because the ESC and the speed dial are integrated into a single proprietary electronics module housed within the upper casing, you cannot simply "clean" the dial. You must replace the switch and control assembly to restore variable speed functionality. Follow these steps for a full replacement:

1. Remove the 18V/36V ONE+ battery and ensure the tool is completely powered down.
2. Using a T10 Torx driver, remove the four housing screws located on the perimeter of the upper motor housing.
3. Carefully lift the top plastic cap. Be mindful of the tension spring that manages the trigger mechanism; do not let it snap outward.
4. Locate the speed control module. Disconnect the wiring harness connecting the ESC board to the brushless motor leads. Note the color coding of the wires (usually Red, Black, and Blue/Yellow) to ensure correct polarity during reassembly.
5. Unscrew the mounting bracket holding the potentiometer dial to the outer shell.
6. Install the replacement ESC/Switch module (Part # varies by production run, typically sourced as a complete upper-switch assembly).
7. Route the wires through the internal guides to avoid pinching them when the housing is closed.
8. Reinstall the housing screws and tighten them in a cross-pattern to ensure an even seal against the motor housing.

If That Didn't Work

• Check the Battery Communication: The HP (High Performance) line uses a communication chip between the battery and the tool. If you are using an older, non-HP battery, the tool may default to a "safe mode" or a single speed to prevent overheating. Try a high-capacity 4Ah or 6Ah HP battery to see if the variable speed is restored.
• Inspect for Carbon Dust Infiltration: Open the housing and check for fine sawdust or carbon buildup around the potentiometer. Use a can of compressed air to blow out the ESC board. If conductive dust has bridged the solder joints on the board, it can create a "short" that bypasses the speed control.
• Verify Trigger Switch Continuity: If the trigger switch itself is failing or partially melted from heavy use, it may be sending a constant "full power" signal to the ESC, overriding the dial. Test the trigger for a crisp "click" and consistent spring return.
• Inspect Motor Brushes (if applicable): While this is a brushless model, check the internal wiring for any charred insulation. A partial short in the motor windings can occasionally trick the ESC into staying at one speed to maintain torque.

Heads Up

• Avoid "Max Speed" Long-Term: Running the router at the absolute maximum setting for extended periods increases heat buildup in the ESC, which is the primary cause of potentiometer failure.
• Dust Management: Always use the dust shield. Fine sawdust is an insulator; if it packs into the vents, the ESC board will overheat, causing the speed to fluctuate or lock up.
• Battery Heat: If the battery is overheating, the tool's internal thermal protection may limit the RPMs regardless of the dial setting. Let the battery cool for 15 minutes before diagnosing a speed failure.
• Tighten Collets Properly: Ensure your bit is seated fully. An unbalanced bit causes vibration that can loosen the potentiometer nut over time, leading to the "stuck speed" sensation.