Invt vfd bord all tasting and madule Replace

---Invt vfd bord all tasting and madule Replace

🔧 INVT VFD Board All Testing and Module Replacement Description

Description:
This process explains the complete method of checking, testing, and replacing all major modules and components of an INVT Variable Frequency Drive (VFD) board. The purpose is to ensure proper operation, detect faulty parts, and restore full functionality of the drive.


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⚙️ 1. Safety Precautions

Before starting any work:

Disconnect AC input power completely.

Wait 5–10 minutes to discharge DC bus capacitors.

Use ESD protection to avoid damage to control circuits.

Always verify “Power OFF” using a multimeter before touching any part.



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🧩 2. Visual Inspection

Check the board for:

Burn marks, broken tracks, or damaged components.

Bulged or leaking capacitors.

Loose or corroded connectors.

Clean the board with IPA if dust or carbon is visible.



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⚡ 3. Power Section Testing

(a) Rectifier Circuit

Test diode bridge using multimeter diode mode.

Forward drop should be 0.4V–0.6V and reverse side should show OL.

If short circuit appears, replace the rectifier module.


(b) DC Bus Capacitors

Measure capacitance and ESR (Equivalent Series Resistance).

Replace if value is low or leakage current is high.


(c) IGBT Module

Test between Collector–Emitter (C–E) → should be open both sides.

Gate–Emitter (G–E) → should not show leakage.

If short or low resistance found → replace IGBT module.



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⚙️ 4. Control Power Supply Section

Check the low-voltage supply outputs:

+15V, -15V, +5V, +12V


Missing or unstable voltage indicates faulty regulator IC, zener diode, or switching supply components.



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🔌 5. Gate Driver Section

Verify driver ICs (e.g., HCPL-3120, IR2110, TLP250).

Apply small test pulse to input → output must switch accordingly.

Replace driver ICs or optocouplers if no switching output.



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🧠 6. Control & Logic Board Testing

Check oscillator crystal frequency (8–12 MHz).

Test microcontroller (MCU) power pins for correct voltage.

Verify EEPROM, keypad, and display connector continuity.

Ensure RS485 communication port is working.



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🌡️ 7. Fan and Temperature Section

Test cooling fan on 12V or 24V supply.

Measure NTC sensor resistance (normally 10kΩ or 50kΩ).

Replace if open or out of range.



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🔄 8. Module Replacement Process

(a) IGBT Module Replacement

1. Remove old IGBT module carefully.


2. Clean the heatsink surface.


3. Apply new thermal paste evenly.


4. Install new module and tighten screws with equal torque.


5. Check continuity again before powering up.



(b) Driver or Control Board Replacement

1. Disconnect all connectors carefully and mark their positions.


2. Fit new board properly aligned.


3. Recheck wiring before power ON.


4. Test with no load first, then connect the motor.




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🧪 9. Final Testing Procedure

1. Power ON the VFD without motor connection.


2. Check display and ensure no fault code appears.


3. Measure DC bus voltage:

~310V for 220V input

~540V for 380V input



4. Connect the motor and run at low frequency (5–10 Hz).


5. Check output voltage, current balance, and temperature.


6. If operation is stable → VFD is OK.




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🔍 10. Common Replaceable Modules in INVT VFD

Module Type Function Common IC / Part No.

Rectifier AC to DC conversion KBPC3510, MDS100A
IGBT Module Power switching FGA25N120, CM50DY-12H
Driver IC Gate signal HCPL-3120, IR2110
Power Supply Low voltage supply LM7815, LM7915, LM2576
Optocoupler Isolation PC817, TLP250
MCU / DSP Control logic STM32, TMS320
Display Board User interf؟