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DESCRIPTION: Power Supply Circuit Board


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2 Year warranty
Part NumberA20B-2101-0390
Model #A20B21010390
TypePower Supplies
Warranty2 Year
Display 7- segment LED
Noise filterOn board
Series typeAlpha I
Board typePrinted circuit (power supply)

Our Repair Services

MRO Electric repairs CNCs, PLCs, Servo/Spindle Drives, Motors, Amplifiers, VFDs, HMIs, and more, most of which can be repaired in only 3-5 days.

Repair Benefits

MRO can restore your failed A20B-2101-0390 to remanufactured condition and save you up to 75% compared to buying new. We offer standard repair pricing to ensure you the best value for your repair.

Our certified technicians use rigorous testing procedures to ensure your parts are restored to fully functioning condition. Our team proudly stands behind all repairs by providing a minimum 2 year warranty.

Our technicians have vast experience with most manufacturers and models. In addition to this A20B-2101-0390 we also repair drives, motors, PLCs and more, so if you don’t see the model you need, please contact us.

Core Exchange

If you are interested in getting credit for your faulty A20B-2101-0390, just let us know and we can issue you an RMA to send it in as an exchange. Our exchange program provides you with savings and keeps us stocked for the next time you need anything.

  • Shipping Weight : 1lb

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Ask about exchanging your faulty A20B-2101-0390 for credit when ordering from MRO Electric

MRO Electric provides a 2-year warranty on every item we sell and repair. We stand behind all of our products and guarantee them for the full 2 years. If there is an issue with any of our products within the warranty period, we will evaluate the unit and repair or replace it under warranty.

Additional Information

Fanuc A20B21010390 Overview

The A20B21010390 is a printed circuit board, or a power supply board, for the Alpha I series spindle amplifier. This power supply board module is manufactured by Fanuc. The Alpha I series consists of several modules working together to bring power and control to your system. The ai series consists of servo motors, spindle motors, and servo amps. These modules administer high-speed control with great efficiency. The spindle and servo units are able to achieve this with sharp precision. The control and precision benefit you in a couple of areas. One benefit is the monetary savings, which is a result of the second benefit, which is energy savings. Keeping energy costs down not only saves money but is good for the environment.


The basic units that comprise the Fanuc ai series or Alpha I series, are the power supply (PS), the servo amp (SV), the spindle amp (SP), the AC reactor, connectors, fuses, and a power transformer. The A20B21010390 power supply board features a noise filter. It also features a seven-segment LED status display which is located on the front panel of the A20B21010390 ai power supply unit. The connectors directly beneath the LED are the CX1A input connection and the CX1B output connection. Beneath the input and output connections is the CXA2A connection. The bottom half of the Fanuc A20B21010390 has the JX1B, CX37, CX3 MCC, and CX4 ESP connections.

How to use the A20B21010390

The Fanuc A20B21010390 works within the whole ai series and is for use with the Fanuc servo amp. This is a basic overview of connecting the system. The CNC, servo motors, servo amps, and other modules in the Fanuc ai series must have specifications checked to ensure the units are the correct ones for your stipulations and the wiring is correct. If the connections are properly connected, power on is the next step and set the initial parameters on the CNC. After measuring the AC power voltage, connect the power. Next check that the protective ground line is correctly connected and select the ground fault interrupter that complements the leakage current. After you check the Phase sequence of the fan motor supply to ensure the motor rotates in the desired direction to avoid a decrease in cooling efficiency. Now you are ready to initialize the parameters.

The Fanuc printed circuit board A20B21010390 comes with a two-year warranty.

Product Description

The A20B-2101-0390 is a Power Supply Circuit Board that is manufactured by FANUC. These products are manufactured in Japan and are designed for Commodity production, advanced machining, and CNC milling usage. All of the products come with a 2 year warranty from MRO Electric. We also carry Power Supplies from other manufacturers such as Siemens and Control Techniques.

Related Products

Check out the rest of our FANUC product line. Whether it's using our online instant quote feature, giving us a call at (800) 691-8511, or sending us an email at, we strive for customer satisfaction first. This means lower prices and better service for you. For more products like A20B-2101-0390, take a look at more from our Power Supplies line. If your current unit has gone bad, take advantage of our Core Exchange program for the most inexpensive route. You can learn more about this program on our FAQ page here. We offer a repair service on all of our A20B-2101-0390 products that keep your downtime to a minimum. To stay up to date on manufacturer news, as well as access any of our datasheets, manuals, or other documentation, we suggest you take a look at our blog.

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