FANUC
FANUC PCB Repair — A16B & A20B Control Boards — Mail-In
Board-level repair for FANUC A16B and A20B printed circuit boards: control power supplies, I/O boards, memory boards, and interface cards from Series 0 through current controls. Free evaluation; typical repairs $300–$800.
Coverage: A16B- and A20B- series PCBs — power, I/O, memory, interface, display boards
✓Fixed — or it's free
Unrepairable units are refunded; evaluations cost $0
✓24-month warranty
Every repair covered, parts and labor
✓3–5 business days bench time
Rush (1–2 day) and emergency service available
✓Program preserved
Your application and settings stay in the unit
Symptoms this repair fixes
- ✓Dead control power supply boards
- ✓Alarm conditions traced to a specific board
- ✓Battery-leak corrosion damage
- ✓Cracked solder joints and connector wear
Honest limits
- ✕Boards with lost proprietary firmware where no dump exists (we tell you before any charge)
- ✕Severe multi-layer trace destruction (evaluated honestly)
What you get
- ▸Free evaluation and firm quote
- ▸Component-level repair: capacitors, regulators, logic, connectors
- ▸Corrosion and battery-leak damage remediation where viable
- ▸Functional verification appropriate to the board class
- ▸24-month warranty
Your program is safe
Machine parameters live in the CNC memory — tell us if this board carries battery-backed memory and we will handle it accordingly. Always back up your CNC parameters before removing boards.
Examples we see regularly
Part-number pages for this service
How FANUC Board Repair (A16B / A20B) units actually fail
Most units we receive fail in one of a handful of well-understood ways. Here is what each fault looks like from the machine, what is happening electronically, and what we do about it at the bench.
Supply rail and capacitor faults
- What you see
- Random alarms, resets that clear on a power cycle, or a control that becomes unreliable once warm.
- Why it happens
- Aging capacitors on the board supply produce marginal rails. On a machine control this presents as exactly the intermittent, wandering faults that are hardest to place on the machine itself.
- What we do
- Capacitors are replaced and rails verified under load with ripple measured, then the board is soak-tested warm.
Battery-backed memory loss
- What you see
- Lost parameters, alarms about memory or battery, or a control that has forgotten its configuration.
- Why it happens
- Battery-backed memory relies on a battery and its retention circuitry, both of which have finite life. Loss of stored parameters on a machine tool is a serious event.
- What we do
- Batteries and retention circuitry are addressed, and we flag anything we find at risk rather than leaving you to discover it later.
Connector and interface damage
- What you see
- Intermittent faults that change when cables are moved, or a specific interface that has stopped working.
- Why it happens
- Connectors take mechanical and thermal abuse in machine-tool environments and are a genuine failure point — not a detail to overlook while looking for a failed component.
- What we do
- Connectors and interface circuitry are inspected, repaired or replaced, and the interface proven functional.
Component failure from supply disturbance
- What you see
- A board that fails outright, often after a power event at the machine or in the plant.
- Why it happens
- Surges and supply disturbances damage interface and power circuitry on control boards.
- What we do
- Failed components are replaced at board level and the board is tested and thermally soaked before return.
What happens on the bench
The same sequence on every 5-stage repair, so nothing gets skipped because a fault looked obvious.
- 1
Intake and fault reproduction
The board or display is logged against your RMA and, where it can be safely powered, the reported fault is reproduced. Machine-tool electronics are frequently reported as "the machine will not run", so the first job is establishing what this specific board is actually doing wrong.
- 2
Power and supply verification
Supply rails are measured under load and checked for ripple. Aged capacitors on a supply produce exactly the intermittent, hard-to-place faults that machine-tool controls are notorious for — random resets, alarms that clear on a power cycle, and displays that fail only when warm.
- 3
Memory and battery-backed data
Where a board carries battery-backed memory we treat its contents as the customer's. Loss of backed-up parameters is a serious event on a machine tool, so batteries and retention circuitry are handled carefully and we flag anything we find at risk rather than discovering it for you later.
- 4
Board-level repair
Failed components are replaced at board level — capacitors, driver circuitry, backlight and inverter assemblies on displays, and connectors, which take mechanical and thermal abuse in machine environments and are a genuine failure point rather than an afterthought.
- 5
Test and thermal soak
Repaired boards and displays are tested and left running warm, because a machine-tool fault that only appears after twenty minutes of operation is worthless to fix if it is only proven for two.
Check these before you ship
Some of these will tell you the unit is fine and the fault is elsewhere. We would rather you find that out now than pay to ship a good unit.
- □Record the full alarm text and number from the control. Machine-tool alarms are specific, and the exact code often identifies the board before it arrives.
- □Note whether the fault is present from cold or only appears once the machine has been running — thermal faults and hard failures are found differently.
- □On a display fault, check for a faint image under a bright light. A visible image means the LCD and video path are alive and the backlight circuit is the fault.
- □If parameters are still readable on the control, record them. Our physical repairs do not erase machine parameters, but a machine tool is not the place to have no record.
- □Check the machine's supply and grounding if boards have failed repeatedly. Recurrent electronics failures on one machine usually have an electrical cause upstream.
Repair or replace?
Machine-tool electronics are the strongest case for repair anywhere in a plant. Control hardware is expensive, frequently long out of production, and tied to a specific machine by its parameters and configuration — replacing a board can mean a retrofit project rather than a swap. Meanwhile the machine is a large fixed asset producing nothing while it waits. Repair keeps the original control intact and the machine in its known-good, proven state.
What to ship
- ▸The board in anti-static packaging (a clean bag + firm padding minimum)
- ▸The machine's control model and the symptom/alarm
Full packing guidance: mail-in instructions.
Ship your unit to
USPS
Control Board Lab
PO Box 120241
Arlington, TX 76012
UPS / FedEx
Control Board Lab
1009 Oakwood Ln # 120241
Arlington, TX 76012
Write your RMA number on the outside of the box and include it on a note inside. Units over 50 lb (large VFDs, spindle drives, industrial PCs in enclosures) ship by freight — contact us before ordering and we will arrange dock-to-dock shipping.
Frequently asked questions
Should I worry about losing machine parameters?
Back up your CNC parameters before pulling any board — that is best practice regardless of repair. If your board carries battery-backed memory, note it on the intake form; we maintain memory power during service wherever the hardware allows.
Start with a free evaluation
Ship it in, get a firm quote, approve before any work — pay nothing if it can't be repaired.
The Fixed-or-Free Guarantee: if we can't repair it, you don't pay for the repair.
Call (817) 799-7332 · 📱 Text us a photo of your unit · Email repairs@controlboardlab.com