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Comprehensive Repair Guide for Votol EM Series Controllers

Comprehensive Repair Guide for Votol EM Series Controllers

  • Product Code: Votol
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Warning: Repairing power electronics requires advanced skills and understanding of serious risks, including electric shock and fire. Always disconnect the high-voltage battery. Large capacitors retain a dangerous charge—discharge them through a resistor (~100 Ohm / 5W) before touching any part of the board.

1. Key Symptoms and Quick Diagnostics

Before disassembly, always perform these basic checks:

 
 
Symptom Most Likely Cause Where to Look First
Controller completely dead (no power, no comms) 1. Blown main fuse.
2. Failed DC-DC converter (no 12V/5V for logic).
3. Blown input diode bridge.		 1. Check the main fuse (F1 on PCB).
2. Check input diodes (D1, D2) for shorts.
3. Verify input voltage is present at terminals and after the fuse.
Error "09" on display Critical fault. Typically a short circuit in the power stage or a fault with hall sensors/ drivers. 1. Check MOSFETs for short circuits (phase to negative).
2. Check current shunt resistors.
3. Inspect the motor hall sensor cable and connector.
Motor jerks, lacks power, loud humming 1. Failed/degraded MOSFET in one phase.
2. Failed gate driver IC (IR2184/2184S).
3. Incorrect angle settings.		 1. Check all MOSFETs for shorts.
2. Visually inspect gate drivers (IR2184) for damage.
3. Check gate resistors (often burn out with a short).
Controller overheats quickly 1. Poor contact with heatsink.
2. Dried-out thermal paste.
3. Motor bearing issue (increased load).
4. Phase current limits set too high.		 1. Disassemble, check MOSFETs are flat on the heatsink, reapply thermal paste.
2. Check "Current Limiting Phase" parameter in software.
No regeneration (EBS) 1. Blown regeneration diode (near BAT- terminal).
2. Fault in the feedback circuit.		 1. Visually inspect and test the large regeneration diode (D7, often in a metal case).
2. Check any fuse in the regeneration circuit.

2. Step-by-Step Repair Procedure

Step 1: Visual Inspection and Basic Checks

  • DISCONNECT THE BATTERY.

  • Discharge the main capacitors.

  • Visual Inspection: Look for burnt components, bulged capacitors, darkened PCB areas, cracked solder joints.

  • Multimeter in Diode Mode:

    • Check the main fuse (F1) for continuity.

    • Check for a short circuit between the main B+ and B- terminals. If shorted, the problem is almost certainly in the MOSFETs.

    • Check the input diodes (D1, D2) and the regeneration diode (D7).

Step 2: MOSFET Diagnostics (The Most Common Failure)

  • MOSFETs are arranged in groups on heatsinks (usually 12 for an EM-150).

  • How to test:

    1. Set multimeter to Diode Test mode.

    2. Place black probe on the Drain (D) (this is the common negative/ground plane).

    3. Touch the red probe to the Source (S) of each MOSFET. A good MOSFET will show a ~0.4-0.6V drop from its body diode.

    4. Now, briefly touch the red probe to the Gate (G) to charge it, then immediately go back to the Source (S). The MOSFET should turn on, and the reading should drop near 0Ω.

    5. If there is a short (0.000V) between Drain (D) and Source (S) in either direction, the MOSFET is shorted and must be replaced.

  • Crucial: Desolder and check all MOSFETs in a parallel group. A short in one often destroys others in the same phase.

Step 3: Gate Driver (IR2184/IR2184S) Diagnostics

  • Always check the gate drivers if MOSFETs are shorted.

  • A failed driver is often visibly damaged (cracked, chipped, darkened).

  • Testing:

    1. Check for driver supply voltage (~12V) between VCC (Pin 1) and VSS (Pin 4).

    2. Check for a short circuit between the driver outputs HO (Pin 7), LO (Pin 5) and ground (VSS).

    3. Check the small resistors around the driver (gate resistors, etc.); they frequently burn out.

Step 4: DC-DC Converter Check

  • If the controller is dead but has no main short and the fuse is good.

  • Locate the power management IC (often a VIPer22A or similar). Check for output voltages +12V and +5V.

  • Check the output diode and electrolytic capacitor of this converter.

Step 5: Soldering and Replacement

  • MOSFETs: Use only original or verified equivalents with correct voltage (Vds) and current rating (e.g., IRFB4110, IRFB4115). Do not use weaker substitutes.

  • Soldering: Power MOSFETs and thick PCB traces require a high-power soldering iron (60-80W minimum) and/or a hot air station. Use high-quality solder and flux.

  • Thermal Paste: Upon reassembly, you must apply new thermal paste to the MOSFETs before mounting them to the heatsink.

3. Common Replacement Parts

 
 
Component Type / Equivalent Note
Power MOSFET IRFB4110, IRFB4115, IRFB3207 Key specs: Vds >= 100V, Low Rds(on). Replace all in a parallel group.
Gate Driver IC IR2184, IR2184S Interchangeable. Check surrounding components.
Regeneration Diode (D7) MUR1560, MUR1620CT Must be an Ultra Fast Recovery diode.
Input Diodes (D1, D2) 1N5408 or similar  
Main Fuse (F1) Model-dependent (30A-80A) Never bypass the fuse with a wire! It protects the entire system from catastrophic failure.

4. Post-Repair Validation Procedure

  1. Without connecting the motor, apply +12V to the controller's logic power wire. LEDs should light up, and the COM port should be detected.

  2. Connect with the Votol software and read the configuration. Ensure settings were not corrupted.

  3. Test phase outputs: With an oscilloscope, check the phase output connectors (A, B, C) for clean PWM signals when gently throttling. If no scope is available, proceed with extreme caution.

  4. Only after successful "bench tests" connect the motor and battery for a test run with very low current limits initially.

Final Summary: The primary cause of failure (~80% of cases) is shorted power MOSFETs. Replacing them is a well-documented and often successful repair. However, it is critical to find and address the root cause of the failure (overloading, water damage, poor cooling, manufacturing defect) to prevent a repeat failure

Tags: Votol, EM-100, EM-150, EM-200 controller, repair, diagnostics, electric scooter, e-bike, motor driver

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