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| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A20B-1006-0482 |
Part Number: A20B-1006-0482
Manufacturer: FANUC Corporation (Japan)
Product Type: Spindle Drive Base Wiring Board (Power Section PCB)
Board Series: A20B-1006
Drive Family: A06B-6088 Alpha Series Spindle Amplifier Modules
Compatible Drive Units: A06B-6088-H226 (SPM-26), A06B-6088-H230 (SPM-30)
Associated Control PCB: A16B-2202-0432 (control card)
Associated ROM: A20B-2902-0390
Input Voltage: 283–325V DC bus
Status: Discontinued by Manufacturer
The A20B-1006-0482 is the base wiring board — the power section PCB — for FANUC's 6088 series Alpha spindle amplifier modules.
In the Alpha spindle drive architecture, each module contains two functionally distinct printed circuit boards: the control board, which handles the signal-level intelligence of the drive, and the wiring board (also called the power board or base board), which carries the power stage components — the high-current transistors, current sensing circuits, gate drivers, and the heavy power bus connections to the motor and DC bus.
The A20B-1006-0482 is the wiring board fitted in the A06B-6088-H226 (SPM-26, 26kW class) and A06B-6088-H230 (SPM-30, 30kW class) Alpha spindle modules.
These are the larger modules in the 6088 series, driving the high-torque spindle motors used in demanding machining applications — heavy-duty machining centres with powerful spindle motors, grinding centres, and large turning centres where the spindle needs to maintain constant speed and torque under substantial cutting loads.
The "base wiring board" designation reflects this board's physical position at the bottom of the drive module's board stack.
The control board (A16B-2202-0432) mounts above it, communicating through connectors that pass control signals down to the power stage.
The wiring board receives the gate drive signals from the control board and uses them to switch the power transistors, generating the variable-frequency, variable-voltage output that drives the spindle motor.
| Parameter | Value |
|---|---|
| Part Number | A20B-1006-0482 |
| Manufacturer | FANUC Corporation |
| Product Type | Spindle Drive Base Wiring Board |
| Board Series | A20B-1006 |
| Compatible Drives | A06B-6088-H226 (SPM-26), A06B-6088-H230 (SPM-30) |
| Associated Control Board | A16B-2202-0432 |
| DC Bus Input | 283–325V |
| Spindle Motor Class | Alpha 26, Alpha 30, Alpha P40 (model dependent) |
| Origin | Japan |
| Operating Temperature | 0 – 55°C |
| Status | Discontinued by Manufacturer |
| Condition Available | New (surplus) / Refurbished / Repaired / Exchange |
The 6088 series modules operate within FANUC's Alpha shared-bus drive architecture. A PSM (Power Supply Module) converts the incoming three-phase AC to a regulated DC bus. The spindle amplifier module draws from this bus and generates the three-phase AC output to the spindle motor. Within the SPM module, the power conversion happens on the wiring board.
The wiring board's power stage uses IGBT (Insulated Gate Bipolar Transistor) devices. IGBTs combine the high current capacity and low saturation voltage of bipolar transistors with the voltage-driven gate control of MOSFETs.
For spindle drive applications — where the transistors must switch multi-hundred-ampere currents at hundreds of volts, thousands of times per second — IGBTs are the appropriate technology.
The gate drive circuits on the A20B-1006-0482 generate the precise drive signals these IGBTs require.
Current sensing is another key function of the wiring board.
The actual motor current on each phase is measured and reported back to the control board. The control board's current loop compares the commanded current (from the speed loop) to the measured current and adjusts the PWM duty cycle to close the error.
Without accurate current sensing, the closed-loop current control cannot function, and the motor will not produce the correct torque.
The SPM-26 and SPM-30 designations indicate the spindle module's power class.
These modules serve the most demanding spindle applications in the Alpha series — large machining centres where high material removal rates require sustained high-power spindle operation, and precision grinding applications where constant spindle speed under variable load is critical to part quality.
The spindle motors driven by these modules — Alpha 26, Alpha 30, Alpha P40, and similar high-frame motors — require the current and power capacity that only the larger 6088 variants can provide.
The wiring board's component selection and thermal management are matched to these current levels.
Running a lower-rated wiring board in a higher-power drive application would result in component thermal overload.
The separation of control electronics from power electronics in the 6088 series has a practical maintenance benefit. When the spindle drive fails, identifying which board is the fault source determines the replacement component.
This saves cost compared to replacing the complete drive module.
A fault in the control board (A16B-2202-0432) typically produces control-related alarms — communication errors, parameter faults, feedback processing errors — without necessarily overloading or damaging the power stage.
A fault in the wiring board (A20B-1006-0482) typically produces power-related alarms — overcurrent, overvoltage, IGBT faults, gate drive faults — or results in incorrect or absent motor output without control-side symptoms.
Distinguishing which board is at fault guides the replacement decision.
Replacing only the faulty board avoids spending on a functional board that is merely sharing the drive module with the failed one.
Q1: The spindle drive shows an IGBT alarm (often displayed as a single-character alarm code). The control board has been tested and confirmed good. Is the A20B-1006-0482 the likely fault location?
IGBT alarms that persist with a confirmed-good control board point to the wiring board's IGBT module or gate drive circuit.
The IGBT alarm can arise from a failed IGBT (short circuit or open circuit), from a gate drive circuit that is no longer providing correct switching signals, or from a current sensing fault that causes the drive to misread motor current as exceeding the overcurrent threshold.
All of these faults are located on the wiring board. Board replacement or IGBT module replacement is the appropriate response.
Q2: The spindle motor produces unusual noise at certain speeds but no alarm is generated. The motor and motor cable are confirmed undamaged. Could this be the wiring board?
Unusual audible noise at specific speeds without alarm suggests current irregularity in the motor's output.
If one phase of the wiring board's power stage is producing asymmetric current — due to a degraded IGBT or gate drive issue — the motor will receive unbalanced current and produce torque ripple that manifests as noise or vibration.
This noise is speed-dependent because it is related to the switching frequency harmonics.
Scope the motor output currents on all three phases while reproducing the noise condition; asymmetric phase currents confirm a wiring board fault.
Q3: A replacement A20B-1006-0482 was obtained. Are there any differences between the -0482 and the -0483 that would affect interchangeability?
The A20B-1006-0482 and A20B-1006-0483 are close variants within the same wiring board family for the 6088 series. They are associated with different drive models and current ratings within the SPM range.
The -0482 is documented for use in the SPM-26 and SPM-30 drives.
The -0483 is associated with other SPM ratings in the series.
These are not necessarily interchangeable — the current handling capacity and thermal design may differ.
Always match the board to the specific drive model it was designed for.
Q4: The drive has been in service for over ten years. What components on the A20B-1006-0482 are most likely to show age-related degradation?
The electrolytic capacitors on the wiring board's gate drive power supply section are the primary aging concern. These capacitors maintain the stable DC voltages that the gate drive circuits need to switch the IGBTs correctly.
As they age, their capacitance decreases and ESR increases, degrading the gate drive supply regulation.
This can produce intermittent IGBT switching errors that appear as occasional, hard-to-reproduce alarms.
The IGBT modules themselves also have finite service lives — their thermal cycling over a decade of use gradually stresses the bond wires and solder connections inside the module.
Q5: Is this board specific to the A06B-6088 series only, or can it be used in other FANUC spindle drive families?
The A20B-1006-0482 is specifically designed for the A06B-6088 Alpha spindle module series.
The connector layout, component placement, thermal interface, and electrical ratings are matched to the 6088 module mechanical and electrical architecture.
It is not interchangeable with wiring boards from other FANUC spindle drive families (such as the 6064, 6078, or later 6096-series drives), which use different wiring board specifications matched to their respective drive architectures.
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