Series Overview

There are two types of HAAS servo amplifiers: an older 4015 series, which utilizes the classic gold housing, and a newer smart amplifier series, that is housed in a silver-colored case. While connections and functionality between the two are nearly identical and can be used in place of one another, the newer smart amplifier takes some of the older fault codes and breaks them down to discrete signals in order to allow a larger, more specific pool of fault codes.

These newer discrete signals are detectable by the newer version of the control PCB, 93-32-4123D, powered by a Coldfire processor that allows detection of the discrete signals.

Larger amplifiers, the 60A or 90A option generally, can be used as the spindle drive on occasion. Depending on the revision, certain amplifiers will also require an external power source applied for the control power whereas some other types have an internal power supply and only require the DC bus voltage to be supplied. This can be determined by a 3-pin connector located near the POWER and FAULT LEDs. Based on the configuration, if an external power supply is used to supply DC voltage to the amplifiers then that unit will oversee regeneration for the connected units. If the amplifiers utilize the DC bus from the spindle/vector drive, then that drive is responsible for regeneration. This can help pinpoint potential problems if the situation is diagnosed properly to the configuration.

This newer style processor board works in unison with the vector drives as well. Older drives tend to throw alarm 123 which is a very general alarm code. This newer processing board allows that to break down into those discrete signals and offer more specific alarms, turning the general 123 into multiple codes pointing towards overcurrent conditions, over- and under-voltage, along with a few others.

Common Issues

Depending on the style of the drive being used, common alarms and issues will vary slightly. For older versions of the vector drives, units which are unable to support discrete signals, alarm 123 is the most common alarm we see. Due to the nature of this alarm, there can be a wide range of different factors at fault for it and additional troubleshooting is required to determine if the drive itself is causing the fault or if an external factor is leading to the fault. A second alarm in combination with the 123 code will often help pinpoint more specifically where the fault might be stemming from. A thorough troubleshooting guide on this is available from HAAS and can be found here.

The servo amplifier troubleshooting guide, which is also available directly from HAAS, can be found here for information and areas to check specific to the amplifier. A common problem that is observed generally stems from the DC section of these amplifiers and can cause other types of alarms or issues if a short occurs. Making sure that cooling fans are functioning properly along with verifying the low-voltage side being supplied from the Maincon or Mocon processing PCB should also be looked at if amplifier specific faults are being flagged by the machine control.

When a drive has not been reconditioned or reworked for a while, there are limited life components which start to break down and can lead to rough running conditions, excessive load, or a noisy motor during a basic run. With this case, so long as the motor looks to check out during the troubleshooting, sending the drive for reconditioning should take care of the problems.

At Precision Zone, we guide our clients toward the best decisions that serve their business needs. If you have specific repair or replacement questions, get in touch with our expert customer support team at 800-551-4420 or

Written by:

Marketing & Creative Director at IcarTeam, and supporting afiliated businesses,
including Precision Zone, Precision Education Integrators and Alfra Tools.
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