LRP QC-3 DIGITAL Brushed Speed-Control User Guide

1. INSTALLATION

The LRP QC-3 DIGITAL is supplied with 2.6mm² power-wires without connectors for maximum performance. Be very careful with the correct wire sequence/colors, as an incorrect connection may damage the speed-control. Avoid creating solder bridges on the solder-tabs and isolate all connections carefully. The motor power wires can be soldered directly to the motor. For the battery power wires, reverse polarity protected plugs are recommended.

Caution: Avoid soldering longer than 5 seconds per soldering joint when replacing power wires on the speed-control and motor to prevent possible damage due to overheating of the components!

• Mount the speedo using the supplied thick/black double-sided tape.
• Connect the receiver connecting wire of the speed-control to the receiver (position: Channel 2).
• Connect the speed-control to the motor:
  • Red wire → Connect to motor "Plus"
  • Blue wire → Connect to motor "Minus"

CAUTION: Be careful with the correct polarity!

• Solder suitable plugs to the battery power wires (refer to section 2 "Connections" for further reference). Plugs are not included. Reverse polarity protected plugs are recommended.
  • Red wire → Connect to battery "Plus"
  • Black wire → Connect to battery "Minus"

• Double-check all connections before connecting the speed-control to a battery.

CAUTION: If a battery is connected with reversed polarity, it will destroy your speed-control!

• You can now switch on the speed-control using the On/Off switch.
• The speed-control is now ready to be set up (refer to section 5 "Radio/speed-control set-up").

Note: If your servo has an external FET connection, you must connect it to the blue FET servo wire of the speed-control.

2. CONNECTIONS

Receiver Connecting Wire: This LRP speed-control is equipped with an LRP Multicon receiver wire, which fits easily into all ordinary receivers.

Power Wires: For maximum performance, 2.6mm² power wires without connectors are used. The unique split solder-tabs allow easy and convenient replacement of power wires, though some soldering skills are required. Avoid soldering longer than 5 seconds per joint to prevent overheating damage. A full 2.6mm² replacement power wire set is available (Order#: #82825).

Diagram Description:

• Motor connections: Blue wire (Motor -) to motor negative, Red wire (Motor +) to motor positive.
• Battery connections: Red wire (Battery +) to battery positive, Black wire (Battery -) to battery negative.
• Receiver connection: Connect the receiver connecting wire to the receiver.
• FET-Servo Wire: The blue FET-servo wire is for external servo connections.
• On/Off Switch: The speed-control has an integrated On/Off switch.

3. INSTALLATION TIPS

• Mount the speedo using the supplied thick/black double-sided tape.
• Position the speed-control where it is protected in the event of a crash.
• Install the speed-control for easy access to connectors and buttons.
• Ensure at least 3cm clearance between the speed-control, power wires, antenna, and receiver. Avoid direct contact between power components, the receiver, or the antenna to prevent interference. If interference occurs, reposition components.
• Run the aerial vertically upwards, away from the receiver. Avoid contact with carbon fibre or metal parts. If the aerial is too long, do not coil the excess length; it is better to cut it down to approximately 35 cm (refer to your radio control system's instructions).
• Ensure the model's body has sufficient cooling slits to increase the performance and lifespan of electronic components.

HEATSINK:

The supplied heatsink is not mandatory but improves and safeguards the performance capacity of your LRP QC-3 DIGITAL speed-control when used near its specified limits. Use only the genuine LRP QC-3 DIGITAL heatsink.

4. SPECIFICATION

* Transistors rating at 25°C junction temperature

** @ 6 cells (7.2V)

Specifications subject to change without notice.

5. RADIO / SPEED-CONTROL SET-UP

The LRP QC-3 DIGITAL stores every step when you press the SET button. All settings are saved in the speed-control's memory, even when disconnected from the battery.

TRANSMITTER SETTINGS

Set the following basic functions on your transmitter (if available):

• Throttle travel: High ATV, EPA
• Brake travel: Low ATV, EPA, ATL
• Throttle exponential: EXP, EXPO
• Neutral trim: SUB Trim
• Servo reverse: Throttle reverse
• Note: Set throttle reverse to 'any setting' and do not change it after the set-up procedure. If your transmitter lacks these functions, it is already in "basic setup" mode.

Setup Procedure:

• Ensure the speed-control is not connected to the drive battery and is switched off.
• Remove the motor pinion or ensure the model's wheels can rotate freely.
• Switch on the transmitter and set the throttle stick to neutral.
• Connect the speed-control to the battery and switch the unit on.
• Hold the SET button pressed for at least 3 seconds using the supplied plastic screwdriver. The SET LED will flash blue, indicating setup mode has been entered.
• Leave the transmitter in neutral position and press the SET button once. The neutral setting is stored, the MODE LED flashes yellow, and the motor beeps.
• Hold full throttle on the transmitter and press the SET button once. The full-throttle setting is stored, the MODE LED flashes red.
• Hold full brake on the transmitter and press the SET button once. The brake setting is stored, the LEDs glow red (MODE) and blue (SET).

This completes the setup procedure. Your LRP QC-3 DIGITAL is now ready to use.

If you make a mistake during setup, disconnect the battery for about 10 seconds and restart from the first step.

Operation Sequence:

• At the end of each run, switch off the car, then switch off the transmitter.
• At the start of each run, switch on the transmitter first, then switch on the car.
• For storage, disconnect the drive battery at any time.

CHECKING THE FUNCTIONS:

Check the LEDs when moving the throttle stick to confirm everything is set up correctly.

6. SUPPRESSION

Motors with no capacitors or insufficient capacitors may interfere with the speed-control. To avoid this, solder the supplied capacitors to your motor, as shown in the diagram.

The Schottky diode improves the efficiency of the speed-control/motor combination and provides extra protection to the brake FETs. Solder the diode in place as illustrated: the white ring must always face the positive motor terminal.

Diagram Description:

• Mabuchi motor / Racing motor: Motors may require capacitors to prevent interference.
• Capacitor: Solder one capacitor to each motor terminal.
• Schottky Diode: Solder the diode across the motor terminals. The white ring on the diode indicates the cathode (negative side) and should be connected to the positive motor terminal.

7. MODE PROGRAMMING

The LRP QC-3 DIGITAL features 4 modes to adjust it to your specific requirements. Factory settings are shown in grey.

• How to get into "programming the modes": Press the MODE button for 3 or more seconds.
• How to check the stored values: Count the number of flashes of the blue SET-LED (1 flash = Value 1, 2 flashes = Value 2, etc.).
• How to change the value: Press the SET button to increase the value by one step.
• How to get to the next Mode: Press the MODE button once.
• How to leave the programming mode: If you are in MODE.4, press the MODE button one more time.

Table of settings, values, and modes (grey-shaded values show "works default settings"):

MODE.1 (AutoCell System)

In LiPo/NiMH Automatic mode, LiPo batteries can be used without worrying about deep discharging. The speed-control automatically detects a LiPo battery and shuts off motor function before critical low voltage is reached, indicated by a blinking SET LED (blue). This protects your LiPo battery from harmful deep discharge.

Tip: We recommend the 4-7cell NiMH Racing Mode for competition use, which deactivates automatic LiPo detection.

MODE.2 (D.E.M.S.-3 Brushed Power Profile)

Higher values provide more overall power and more aggressive throttle response.

Team Tips for D.E.M.S.-3 Settings:

• Touring Car: Brushed: 3-5
• 1/12: Brushed: 2-3
• 19/27T motors: Brushed: 5-6
• Off-Road 2WD + Truck: Brushed: 1-2
• Off-Road 4WD: Brushed: 1-4

MODE.3 (Initial Brake)

Allows you to set a certain level of "hand-brake-effect".

MODE.4 (Automatic Brake)

Allows you to set a slight braking action in the neutral range.

8. SPECIAL FEATURES

• Digital-Active Launch Control: Provides a starting advantage by shortening response time for immediate power at the start. This feature is automatically switched off after the first throttle lift and is recommended for touring cars on high-traction surfaces. To activate: Hold the transmitter trigger at full brake for 5 seconds before starting.
• AutoCell System: Ready for LiPo batteries. This system safely allows LiPo battery use without accidental deep discharging. Motor function shuts off, and the SET LED flashes if very low battery voltage is detected. Tip: Use value 2 for 4-6 cell NiMH racing to disable LiPo protection.
• D.E.M.S.-3 Brushed Power Profiles: Refined versions of the world-winning D.E.M.S. Brushed Quantum power programs. Higher values increase overall power and aggressive response.
• Changing Mode Settings Without Transmitter: At race events, you can change MODE settings by disconnecting the receiver lead from the receiver and following the procedure in Section 7 "Mode Programming".
• Works-Default-Settings: All LRP speed-controls are factory-adjusted. To restore default settings: With the transmitter on, hold the SET button while switching on the speed-control.
• IceDrive Design: LRP's proprietary design results in lower speedo temperatures under all racing conditions, offering a competitive edge.
• Forward/Brake: Designed for top-level competition, this is a pure forward/brake speed-control without a reverse function, offering uncompromising performance.
• Multi-Protection System (3-way protection): Protects against short-circuits (motor), overload, and overheating. If overloaded, motor function shuts off (SET LED flashes), while steering remains functional. Allow the speed-control to cool down. If frequent shutdowns occur, check:
  • Correct gear ratio (refer to motor manual).
  • D.E.M.S.-3 setting is too high (can overheat motor/speed-control).
  • Motor is too strong or damaged.
• QC-3 Worlds Option Kit (optional): Order#83830. This kit supports the battery and provides more punch during acceleration. It is not mandatory; the QC-3 DIGITAL works perfectly without it.

9. TROUBLESHOOTING GUIDE

REPAIR PROCEDURES / LIMITED WARRANTY

All products from LRP electronic GmbH ("LRP") are manufactured to the highest quality standards. LRP guarantees this product to be free from defects in materials or workmanship for 90 days from the original date of purchase (verified by sales receipt). This limited warranty does not cover defects resulting from misuse, improper maintenance, outside interference, or mechanical damage. This includes:

• Cutting off original power plugs or not using reverse polarity protected plugs.
• Damaged receiver wire and/or switch wire.
• Mechanical damage to the case.
• Humidity/Water inside the speed control.
• Mechanical damage to electronic components/PCB.
• Soldering on the PCB (except on external solder-tabs).
• Connecting the speed-control with reversed polarity.

Before sending a product for repair, check all other components in your model and consult the troubleshooting guide. If products are sent in for repair that are operating perfectly, a service fee will be charged according to LRP's pricelist.

When sending a product for repair, the customer must advise LRP whether the product should be repaired regardless of warranty status. If there is no warranty or guarantee claim, inspection and repair fees will be charged at the customer's expense. A proof of purchase including the date of purchase must be included; otherwise, no warranty can be granted. For quick repair and return service, include your address and a detailed description of the malfunction.

If LRP no longer manufactures a returned defective product and cannot service it, LRP will provide a product of at least the same value from a successor series.

Specifications like weight and size are guide values. Due to ongoing technical improvements, LRP is not responsible for the accuracy of these specifications.

For LRP 25-Years Warranty products, the warranty terms on the LRP 25-Years Warranty card also apply. Legal warranty claims from the original purchase remain unaffected.

LRP-Distributor-Service:

• Package your product carefully, including the sales receipt and a detailed description of the malfunction.
• Send the parcel to your national LRP distributor.
• The distributor will repair or exchange the product.
• Shipment back to you is usually via COD (cash on delivery), subject to your national LRP distributor's general policy.