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| Place of Origin | JAPAN |
| Brand Name | FANUC |
| Certification | CE ROHS |
| Model Number | A06B-6058-H334 |
The Fanuc A06B-6058-H334 is a three-channel AC digital servo amplifier unit from Fanuc's S-series drive platform — a tri-axis module that simultaneously controls three servo axes, designated L, M, and N, each capable of driving Fanuc AC servo motors in the 0S, 5S, and 10S range.
As a third-generation S-series amplifier, the H334 carries the later A16B-1100-0330 PWM servo control card, an update from earlier S-series generations that improved digital signal processing and drive reliability in the field.
Three-axis integration in a single enclosure was Fanuc's design philosophy for this drive generation: instead of three individual single-axis drive units consuming separate rail space and requiring three separate sets of bus connections and fault wiring, the A06B-6058-H334 consolidates all three axes into one physical unit.
This integration reduced control cabinet footprint, simplified machine wiring, and standardised the servo drive assembly for the three-axis milling machines and machining centres that were the primary application.
The H334 fits directly into machines running FANUC 0-B, 0-C, and Series 15 control systems — the generation of Fanuc CNC hardware dominant in machine tools built during the late 1980s and through the 1990s.
A large installed base of these machines continues operating in production worldwide, making the A06B-6058-H334 a consistently demanded spare part for maintenance and repair operations rather than a historical curiosity.
| Parameter | Value |
|---|---|
| Axes | 3 (L, M, N channels) |
| Supported Motor Models | 0S, 5S, 10S |
| Series | S-series (3rd generation) |
| Compatible Controls | FANUC 0-B, 0-C, Series 15 |
| PWM Control Card | A16B-1100-0330 |
| Power Board | A20B-1003-0864 |
| Interface | PWM digital communication to CNC |
| Housing | Yellow framed mount |
| Weight | Approx. 21.21 lbs |
| Status | Discontinued |
The S-series amplifiers communicate with the CNC control via PWM (pulse-width modulation) interface — a digital protocol that transmits velocity commands and position feedback between the CNC and each drive channel.
This digital communication path distinguishes S-series amplifiers from the earlier analogue command drives that preceded them in Fanuc's product history.
On the A06B-6058-H334, the A16B-1100-0330 control card sits at the top of the unit and manages the digital PWM communication, the current control loop for all three axis channels, and the fault monitoring circuits.
Below it, the A20B-1003-0864 power board handles the high-voltage switching stages, DC bus, and regenerative discharge circuitry for the three-axis assembly.
When a fault develops in a working drive — common causes include failed power transistors, degraded electrolytic capacitors, relay contact wear, and corrosion on PCB traces — the fault is usually isolatable to one of these two boards or the power semiconductors in the output stage.
Repair facilities familiar with the H334 architecture can typically restore the drive to working condition by addressing these specific failure points, which is why repair and remanufacturing services for the A06B-6058-H334 remain commercially viable decades after the unit's production end.
The H334 designation identifies the specific motor size combination the drive is configured for: three channels, each sized for the 0S/5S/10S motor range. In Fanuc's S-series motor nomenclature, the number identifies the continuous torque rating — the 5S produces a higher output than the 0S, and the 10S higher again.
For a three-axis vertical machining centre where the X, Y, and Z axes each drive through leadscrew mechanisms of different sizes and friction characteristics, having all three channels in one enclosure while using the same motor family simplifies the maintenance inventory significantly.
The L, M, and N channel designations correspond to the three axis connections on the drive.
In a standard machining centre, L typically drives one axis, M a second, and N the third — the specific mapping to machine axes (X, Y, Z) depends on the machine builder's wiring configuration and parameter settings in the CNC.
The FANUC 0-B, 0-C, and Series 15 controls that the H334 supports were Fanuc's primary CNC platforms for industrial machine tools during their production era.
The 0-series provided a cost-effective control for smaller and mid-range machines; the Series 15 offered the higher-performance solution for complex multi-axis and high-speed applications.
Both families used the same PWM servo drive interface that the H334 implements, which is why a single drive unit covers all three control generations.
Machines running these control generations include vertical and horizontal machining centres, turning centres with live tooling, grinding machines, and dedicated CNC production equipment from machine builders including Mori Seiki, Mazak, Okuma, and Makino among others.
The continued operational status of these machines in production environments worldwide is what sustains the secondary market for the A06B-6058-H334.
Q1: What does "3rd generation S-series" mean, and how does it differ from earlier S-series drives?
Fanuc's S-series digital servo amplifiers evolved through several hardware generations, each updating the PWM control card, power board design, and signal processing.
The 3rd generation carries the A16B-1100-0330 control card, which features improved digital current control compared to the earlier A16B-1100-0310 and A16B-1100-0320 variants. The later control card provides better harmonic rejection and tighter velocity loop bandwidth.
For maintenance purposes, the generation matters when sourcing replacement boards — the A16B-1100-0330 is not interchangeable with earlier S-series control cards.
Q2: Can the A06B-6058-H334 be used with motors outside the 0S/5S/10S range?
The H334 is configured for 0S, 5S, and 10S motor models. Using motors outside this range — such as 20S or 30S — requires a different drive unit sized for the higher current output those motors demand.
Operating an undersized drive with an oversized motor will trigger overcurrent protection on motor start or under load. Always verify the motor model designation on the motor nameplate before selecting a replacement drive.
Q3: The unit is discontinued — where are replacement units sourced?
Refurbished and surplus A06B-6058-H334 units circulate through the industrial spare parts market from machine decommissioning, overstock inventories, and specialised repair suppliers.
Fanuc-certified repair centres and third-party electronics refurbishers offer both exchange units (where the customer's failed unit is rebuilt and returned or a refurbished unit is supplied in exchange) and outright surplus units. All reputable suppliers test units on Fanuc S-series test rigs with actual AC servo motors before shipment.
Q4: What are the most common failure modes of the A06B-6058-H334?
The most commonly encountered failures are: failed power transistors in one or more of the three output channels (presenting as axis overcurrent or drive fault alarms), degraded or open electrolytic capacitors on the power board (presenting as erratic axis behaviour or DC bus voltage faults), worn magnetic contactor contacts (presenting as intermittent drive ready faults), and corrosion on PCB trace connections in harsh environments.
The A16B-1100-0330 control card's DAC outputs and fibre-optic interface circuits also fail over time in environments with high vibration or temperature cycling.
Q5: What alarm codes on the CNC indicate a problem with the A06B-6058-H334?
On FANUC 0-B/0-C and Series 15 controls, servo alarms pointing to the S-series drive typically appear as AL-400 series errors (servo alarms) on the CNC operator panel. Specific codes identify the fault type — overcurrent (typically AL-401 or AL-411 depending on axis), overvoltage, DC link faults, and communication errors between the CNC and drive.
The alarm code pinpoints which axis channel is affected.
Before replacing the drive, confirm the fault is in the drive rather than the motor, feedback cable, or CNC interface card by following Fanuc's diagnostic procedure: check motor insulation, verify encoder feedback continuity, and swap axis assignments if possible to determine whether the fault moves with the drive or stays with the axis wiring.
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