Fanuc A50L-0001-0434 | IGBT Power Module 6MBP50VCA120-51 | New Sealed

Fanuc P/N: A50L-0001-0434 | Module P/N: 6MBP50VCA120-51 | Manufacturer: Fuji Electric (for Fanuc) | Condition: New, Factory Sealed

Two Part Numbers — One Module

If you have been searching for either A50L-0001-0434 or 6MBP50VCA120-51, you are looking for the same component. The A50L-0001-0434 is the Fanuc ordering reference; 6MBP50VCA120-51 is the Fuji Electric module part number printed on the component itself. Both are in common use depending on whether the engineer is working from a Fanuc service manual or a component datasheet.

What This Module Is — Plain Language First

The A50L-0001-0434 is an Intelligent Power Module (IPM) — a self-contained power semiconductor assembly that combines six IGBT switches and a freewheeling diode bridge with built-in gate drivers, overcurrent protection, short-circuit protection, and thermal monitoring, all in a single package.

In a Fanuc CNC servo drive or spindle amplifier, this module is the power stage — the component that converts DC bus voltage into the three-phase AC output that actually drives the motor. When this module fails, the drive loses the ability to control motor current. The amplifier typically faults with an overcurrent or power stage error alarm and cannot restart until the module is replaced.

Technical Specifications

Parameter	Value
Fanuc Part Number	A50L-0001-0434
Module Part Number	6MBP50VCA120-51
Module Type	IPM (Intelligent Power Module) — 6-pack IGBT bridge
Manufacturer	Fuji Electric
Collector Current (Ic)	50 A
Collector-Emitter Voltage (Vces)	1200 V
Topology	3-phase inverter bridge (6 IGBTs + 6 freewheeling diodes)
Gate Drive	Built-in isolated gate drivers (per phase)
Protection Functions	Overcurrent (OC), short-circuit (SC), undervoltage lockout (UVLO), overtemperature (OT)
Fault Output	Open-collector fault signal output
Control Supply Voltage	15 V DC (gate drive supply, per phase group)
Package	Transfer-moulded plastic module with base plate
Mounting	Heatsink mounting via screws (thermal interface compound required)
Operating Junction Temperature	−20 °C to +150 °C
Storage Temperature	−40 °C to +125 °C
Typical Applications	Fanuc αi / αiF / βi series servo amplifiers, spindle amplifiers
Condition	New, factory sealed

The Role of This Module in a Fanuc Drive — A Visual Breakdown

Understanding where the A50L-0001-0434 sits in the drive architecture helps clarify why it is the component most frequently replaced after a drive failure:

AC Mains Input
│
▼
[Rectifier / PSM] ──→ DC Bus (typically 300–600 V DC)
│
▼
[A50L-0001-0434] ──→ 3-Phase PWM Output ──→ Motor (spindle or servo axis)
(IGBT IPM)
│
▼
[Gate Drive Signals from Drive PCB]

The drive control PCB generates PWM gate signals. The A50L-0001-0434 amplifies those signals to switch 50 A of motor current at up to 1200 V, translating the control signal into actual motor torque. The built-in protection circuits monitor every switching event and pull the fault output low if any abnormal condition is detected, preventing catastrophic failure of the drive or motor.

Common Failure Symptoms

How do you know the A50L-0001-0434 has failed?

Fanuc servo and spindle amplifiers equipped with this module typically show one or more of these conditions when the IPM has failed:

Alarm 9 / SV401 / SV409 (servo drive overcurrent / IPM alarm) on Fanuc 0i, 10/11/12, 15, 16/18/21, 30i/31i/32i series
SP740 / SP741 (spindle amplifier overcurrent) on αi spindle drives
Drive ready LED fails to illuminate; module fault output line pulled low at power-up
Visible damage to the module: burned or cracked body, discolouration of heatsink mounting area
One or more IGBT phases conducting in all states (short-circuit failure), causing immediate overcurrent trip

In most cases, the drive control PCB is undamaged when the IPM fails due to overcurrent or thermal overstress — only the power module requires replacement.

Which Fanuc Drives Use the A50L-0001-0434?

The 6MBP50VCA120-51 module is used across a range of Fanuc servo and spindle amplifier units. Common host amplifiers include:

Fanuc Amplifier Model	Axis / Function
αiSV 40/80 (A06B-6117 series)	Servo axis amplifier
αiSVSP (combined servo/spindle)	Servo or spindle section
αiSP 15/22/30 (A06B-6121 series)	Spindle amplifier
βiSV (selected models)	Servo axis amplifier
SVM2-series (A06B-6096 series)	Dual-axis servo module

Verification recommended: Always confirm the module part number on the installed component before ordering. Open the drive amplifier, locate the power module (mounted to the main heatsink), and read the part number printed on the module body. The presence of "6MBP50VCA120-51" on the module confirms this is the correct replacement.

Genuine vs Non-OEM — What the Difference Means in Practice

IGBT power modules for CNC drives are sometimes offered as generic substitutes using electrically equivalent modules from other manufacturers. The risks of non-OEM substitution in Fanuc drives are real and documented:

Factor	Fanuc A50L-0001-0434 (OEM/Fuji)	Generic / Substitute Module
Pin and footprint compatibility	✅ Exact OEM specification	⚠️ Often slightly different pinout or mounting pattern
Gate threshold voltage matching	✅ Matched to Fanuc PCB gate drive output	❌ May require different gate resistor values
Fault output logic level	✅ Compatible with Fanuc drive PCB fault input	❌ May use different logic levels
Thermal characteristics	✅ Characterised for Fanuc heatsink design	❌ Thermal resistance may differ
Risk of repeat failure	Low — root cause addressed	Higher — mismatch may stress drive PCB
Warranty / traceability	✅ Full OEM traceability	❌ None

For Fanuc CNC equipment, using the OEM-specified Fuji module eliminates these variables and ensures the replacement performs identically to the original.

Before You Replace the Module — A Practical Checklist

Replacing an IPM in a Fanuc drive is a straightforward procedure, but the following steps reduce the risk of repeat failure:

Identify the root cause. A healthy IPM does not normally fail in service. Common root causes include: motor insulation breakdown (causing sustained overcurrent), blocked heatsink airflow (thermal overstress), incorrect DC bus voltage, and PCB gate driver faults. Address the root cause before fitting the new module.
Check the motor winding resistance and insulation. A phase-to-phase winding resistance imbalance or low insulation resistance (< 1 MΩ phase-to-earth) indicates motor damage that will destroy the new module on first energisation.
Inspect the drive PCB gate driver section. If the gate drivers on the control PCB have been damaged by the IPM failure event (common in short-circuit failure modes), fitting a new IPM without repairing the PCB will result in immediate re-failure.
Apply fresh thermal interface compound. Remove all old thermal compound from the module base plate and heatsink mating surface. Apply a thin, even layer of new high-performance thermal paste (e.g. Shin-Etsu X-23 or equivalent).
Torque mounting screws to specification. Uneven clamping pressure causes hot spots on the module base plate. Follow Fuji's recommended mounting torque for M5 screws.

Ordering & Availability

✅ New, factory-sealed unit — never installed or powered
✅ In Stock — dispatches within 1–3 working days
✅ Global Shipping — DHL / FedEx / UPS express options available
✅ Anti-static ESD packaging — safe transit for power semiconductor modules
✅ Volume pricing available — for maintenance spares programmes and machine fleets
✅ Expert support — pre-order compatibility checks available on request

Frequently Asked Questions

Q1: Are A50L-0001-0434 and 6MBP50VCA120-51 the same component?

Yes. A50L-0001-0434 is the Fanuc service parts ordering number for this module. 6MBP50VCA120-51 is the Fuji Electric manufacturer part number for the same physical component. Fanuc sources this module from Fuji Electric for use in its servo and spindle amplifier products. When ordering, either reference can be used to identify the correct part — but always verify by reading the part number physically printed on the installed module before placing your order.

Q2: What type of module is this — IGBT or MOSFET?

This is an IGBT-based Intelligent Power Module (IPM). It contains six IGBTs arranged in a three-phase full-bridge (inverter) topology, along with six freewheeling diodes and integrated gate driver circuitry. IGBTs are the standard switching technology for industrial motor drive applications at this voltage and current level (50 A, 1200 V) because they combine low conduction losses with adequate switching speed for PWM motor control.

Q3: What is the rated current and voltage of this module?

The 6MBP50VCA120-51 is rated at 50 A collector current (Ic) and 1200 V collector-emitter voltage (Vces). In the context of a Fanuc servo or spindle amplifier, the 1200 V rating provides the necessary derating margin above the DC bus voltage (typically 300–600 V DC), and the 50 A rating supports the peak current demands of the motor during acceleration and cutting load cycles.

Q4: Which Fanuc alarm codes indicate a failed A50L-0001-0434?

On Fanuc CNC systems, IPM failure typically triggers alarms including SV401, SV409 (servo amplifier IPM fault), or SP740/SP741 (spindle amplifier overcurrent). On older Series 0 / Series 10/11/12 systems, the alarm may appear as an axis amplifier alarm 9 or a drive-not-ready fault. In all cases, the amplifier module's LED indicators should be checked — most αi and SVM series amplifiers have a red LED that illuminates to indicate an IPM or overcurrent fault condition.

Q5: Can I use a generic IGBT module with the same electrical ratings instead of the OEM Fuji module?

Electrically equivalent modules from other manufacturers (e.g. Mitsubishi, Semikron, Infineon) may have the same nominal Ic and Vces ratings but differ in pin layout, gate threshold voltage, fault output logic, and package dimensions. Using a non-OEM module in a Fanuc drive without verifying these parameters against the Fanuc PCB design is risky and may result in immediate or premature failure. For production-critical CNC equipment, the OEM Fuji module is the safe and recommended choice.

Q6: Do I need to replace the drive PCB as well when replacing this module?

Not necessarily. In many cases — particularly where the IPM failed due to motor insulation breakdown or thermal overstress rather than a gate driver fault — the drive PCB is undamaged and only the power module requires replacement. However, if the IPM failed catastrophically (e.g. internal short circuit that may have back-driven voltage spikes into the gate driver section), the PCB should be inspected carefully before the drive is returned to service. If gate driver ICs or optocouplers show signs of damage, the PCB should be repaired or replaced simultaneously.

Q7: How do I safely handle and install an IGBT power module?

IGBT modules are sensitive to electrostatic discharge (ESD). Always handle in an ESD-controlled environment, wearing a wrist strap bonded to earth ground. Do not touch the module terminals with bare hands. When mounting to the heatsink, ensure the mating surface is clean and flat, apply fresh thermal interface compound, and tighten mounting screws evenly in a cross pattern to the manufacturer's specified torque. Avoid bending the module terminals during soldering or connector installation.

Q8: Is this module new or refurbished?

This is a 100% new, factory-sealed module supplied in original OEM anti-static packaging. It has never been installed in a drive, never been powered, and has not been refurbished or remanufactured. We do not sell used or reconditioned power modules.

Q9: What is the typical cause of failure for this module in Fanuc drives?

The most common root causes of A50L-0001-0434 failure in service are: motor winding insulation breakdown causing sustained phase-to-phase or phase-to-earth overcurrent; inadequate heatsink airflow leading to junction temperature overstress; incorrect DC bus voltage due to power supply module (PSM) issues; and, less commonly, drive PCB gate driver malfunction causing abnormal gate signals. A module that has failed without an obvious external cause (e.g. new machine, short service life) warrants a thorough investigation of the motor and power supply before the replacement module is commissioned.

Q10: How long does shipping take, and do you offer express options?

Standard international shipping via DHL, FedEx, or UPS typically takes 5–10 working days to most destinations. Express next-day or 2-day delivery options are available for urgent production-down situations — contact us with your location and required delivery date and we will advise on available options and costs.

A50L-0001-0434 Fanuc Professional Power Module 6MBP50VCA12051 New Sealed