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FANUC 16 and 18 A, B, and C series controls from the late 1980s and 1990s are still running in plants across the country. Tri Star has the expertise to diagnose and repair all three variants.
Get Expert Help NowTri Star CNC Services
4146 W. Orleans Street McHenry, IL USA 60050
815-578-9145
The FANUC 16A, 16B, 16C, 18A, 18B, and 18C use Alpha series servo drives, not the Alphai hardware found in the later i series. This distinction matters for diagnosis and parts sourcing. A technician who works daily on i series hardware may not know the difference until they have already ordered the wrong components.
The A, B, and C variants of the 16 and 18 predate much of what is available online. Alarm code references for these specific sub-variants can be incomplete, and technicians without factory-level experience on these controls may be working from a reference that does not fully apply to your machine.
Alpha series drives are out of production. Replacement and exchange units exist but are not unlimited. Getting to a solid diagnosis quickly matters, because the longer the repair drags out, the harder sourcing becomes and the higher the risk of extended downtime.
Compatible Drives and Motors: FANUC 16 & 18 A/B/C Series
The following alarm codes appear frequently on FANUC 16 and 18 Alarm Codes systems. Each has a known set of root causes. The section below explains what each code means and what typically drives it.
Servo ready signal off. The servo amplifier is not in a ready state. Can be caused by a hardware fault in the Alpha series amplifier, a power supply issue, or an E-stop that has not fully reset.
Servo error too large on one or more axes. The axis is not following commanded position. Inspect the Alpha series amplifier, encoder feedback, and the mechanical load on the axis.
Encoder signal fault. The pulse coder on the servo motor is sending an invalid or missing signal. Check the encoder and its cable for damage or degraded connections before condemning the motor itself.
Spindle overheat. Check the spindle motor cooling system and the Alpha series spindle amplifier condition. Thermal sensor faults can trigger this alarm without the spindle actually being at an unsafe temperature.
Spindle position coder alarm. The coder or its wiring is not delivering a valid feedback signal. Inspect the coder coupling and signal cable before assuming the coder itself has failed.
Hardware overtravel in the positive or negative direction. Verify limit switch operation and confirm no mechanical obstruction exists. Also verify the overtravel parameter settings have not shifted.
The 16 and 18 A, B, and C series use Alpha series drive hardware that requires specific knowledge and sourcing connections most general CNC shops no longer maintain. Tri Star works on all three variants. Common repairs include Alpha series servo amplifier rebuild or exchange, spindle amplifier repair, encoder and pulse coder replacement, feedback cable repair, and parameter restoration.
Exchange units for Alpha series amplifiers are still available through Tri Star's parts network, though availability is more limited than for i series hardware. Tri Star assesses cost and timeline after a full diagnosis. No work begins without your authorization.
Our team is made up of former engineers and technicians from FANUC, Yamazen, Mori Seiki, Giddings & Lewis, and Kearney & Trecker. You get the people who built and serviced these systems, not technicians working from a manual.
20-plus years of FANUC-specific repair experience since 2005.
Most repair shops warranty parts and labor. Tri Star warrants the complete assembly repair. If something related to the repair fails within a year, you are covered without a debate about what is and is not included.
Full 1-year warranty on every complete assembly repair. See our repair services page for details.
We come to your facility. No need to pull and ship servo drives that may sustain additional damage in transit. Our technicians travel nationally to diagnose and repair your FANUC control where it sits.
National on-site service for manufacturing facilities of all sizes, based out of Illinois.
We move fast because your production cannot wait. After diagnosis, we focus on getting your control repaired and back online as quickly as possible. No being pushed to the back of a 6-week service queue.
5.0 Google rating from customers who needed fast, accurate support.
If your servo drive or amplifier is beyond repair, we offer a parts exchange program with tested, verified units ready to ship. No waiting weeks for new hardware to arrive from overseas.
Exchange units available for a wide range of FANUC control generations and drive types.
We do not reset the alarm and hand the machine back. We find out why the fault occurred and fix the underlying problem. That is the difference between a repair that holds and one that fails again within weeks.
Backed by factory-level FANUC training and decades of hands-on drive and control experience.
Call 815-578-9145 or use the contact form at tristarcnc.com/Contact. Tell us the alarm code, the control model, and your machine type. The more detail you share upfront, the faster we can help.
Our team reviews the fault and identifies the root cause, not just the alarm number. We have seen these codes hundreds of times and know what they actually mean for your specific control generation and drive configuration.
We travel to your facility for on-site service, or you can ship the unit in for depot repair. Either way, we work fast and keep you updated throughout the process so there are no surprises.
Every complete assembly repair comes with a full 1-year warranty covering the complete assembly, not just individual components. You get back to production knowing the repair is covered.
What does a FANUC 16 and 18 Alarm Codes servo alarm actually indicate?
A servo alarm indicates a fault in the servo drive, motor, or feedback system on one or more axes. The specific alarm number narrows the cause. Tri Star diagnoses the exact failure point rather than replacing parts based on the alarm code alone.
Can you repair FANUC 16 and 18 Alarm Codes controls on-site at our facility?
Yes. Tri Star provides on-site repair nationwide. Our technicians travel to your facility to diagnose and repair the control in place, which avoids additional damage from shipping and gets the machine back online faster.
How long does a FANUC 16 and 18 Alarm Codes repair typically take?
Turnaround time depends on the fault type and parts availability. After diagnosis, Tri Star provides a clear timeline. We prioritize fast completion because every hour of downtime carries a real production cost.
What warranty does Tri Star provide on CNC control repairs?
Tri Star warrants the complete assembly repair for one full year. This covers the full repair scope, not just individual parts or labor hours. Most shops only warranty parts and labor. Tri Star warranties the work.
What if the drive or amplifier on my FANUC 16 and 18 Alarm Codes is beyond repair?
Tri Star maintains a parts exchange program with tested, verified units for a wide range of FANUC control generations. If your unit is not repairable in-house, an exchange unit can often get you back online without waiting weeks for new hardware.
Do you work on both older and current FANUC control generations?
Yes. Tri Star services FANUC controls from the earliest DC servo generations through current production platforms. Our team includes former engineers and technicians from FANUC, Yamazen, Mori Seiki, Giddings and Lewis, and Kearney and Trecker, giving us coverage across the full range of FANUC hardware.
Tri Star CNC Services is based in Illinois and provides on-site repair and depot service to manufacturing facilities across the United States. We travel to your location when on-site diagnosis is the right approach.
Your FANUC 16 and 18 Alarm Codes does not have to stay down. Tri Star CNC Services has the factory-level expertise to diagnose the fault correctly and repair it right the first time, backed by a 1-year complete assembly warranty.
No obligation. We diagnose first, quote second. You approve before we start.
815-578-9145
815-578-9145