Siemens
Siemens SIMODRIVE 611 Module Repair — Mail-In
Component-level repair for Siemens SIMODRIVE 611 axis (LT) modules and 6SN1118 control cards running legacy Siemens CNC machines. Free evaluation, typical repairs $500–$1,400. Large infeed/NE modules (36kW+) require test capacity we do not claim — we say so instead of overselling.
Coverage: 6SN1123 LT axis modules · 6SN1118 control cards · small infeeds evaluated case-by-case
✓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
- ✓Axis module faults and dead modules
- ✓Control-card failures (the frequent separate failure on 611 racks)
- ✓Trips after motor/cable events
Honest limits
- ✕Large NE/infeed modules 36kW+ — full validation needs three-phase load capacity; we decline these at launch rather than ship an under-tested repair
What you get
- ▸Free evaluation and firm quote
- ▸IGBT/power-stage replacement on axis modules
- ▸Control-card component repair
- ▸Full recap as standard
- ▸24-month warranty
Common part numbers we see
Part-number pages for this service
How SIMODRIVE 611 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.
Bus capacitor degradation
- What you see
- Undervoltage or bus alarms, or faults appearing across more than one axis.
- Why it happens
- These systems share an infeed and bus, so degraded capacitors in the supply section produce alarms that appear to come from several axis modules at once.
- What we do
- The capacitor bank is assessed and replaced and bus stability verified under load.
Power module failure
- What you see
- Overcurrent alarms or an axis that trips as soon as it is enabled.
- Why it happens
- Power stage failure on an axis module, usually driven by a motor or cable fault downstream.
- What we do
- Power devices are tested cold and replaced, gate drive verified, and the module run under load.
Control board and connector faults
- What you see
- Intermittent faults, or a module that will not initialise reliably.
- Why it happens
- Control daughterboards and their connectors degrade over long service lives, producing faults that move when the module is handled.
- What we do
- Control boards and connectors are inspected and repaired, and reliable repeated initialisation confirmed.
Cooling failure
- What you see
- Thermal alarms during sustained machining.
- Why it happens
- Failed fans and obstructed heatsinks in a system that runs continuously.
- What we do
- Cooling is restored and thermal behaviour verified under sustained load.
What happens on the bench
The same sequence on every 6-stage repair, so nothing gets skipped because a fault looked obvious.
- 1
Safe intake and bus discharge
Drives arrive holding charge in the DC bus capacitors. The unit is discharged and verified at zero before anything is opened — this is a genuine hazard on any drive with a large capacitor bank, not a formality.
- 2
Power stage integrity check
The IGBT or power module is checked device by device for shorted and open junctions before power is ever applied. Energising a drive with a shorted power module simply destroys more of it, so this is done cold, first, every time.
- 3
DC bus and pre-charge inspection
Bus capacitors are assessed for capacitance loss and elevated ESR, and the soft-charge circuit — inrush resistor and its bypass relay or contactor — is checked. A drive that reports undervoltage or trips on power-up very often has a failed pre-charge path rather than a failed power stage.
- 4
Gate drive and feedback circuitry
Gate driver stages and their isolation are tested, because a partially degraded driver produces asymmetric switching that reads as an intermittent overcurrent fault under load and as a perfectly healthy drive at idle. Encoder and feedback interfaces are checked for the damage a shorted motor cable pushes back into the drive.
- 5
Thermal path and cooling
Fans, heatsink airflow and thermal interfaces are serviced. A large share of "failed" drives are thermal alarms caused by a seized fan or a heatsink packed with production dust.
- 6
Powered test under load
The repaired drive is brought up through a controlled power-on and run against a load so the power stage, current regulation and thermal behaviour are proven in operation — not merely confirmed to power up without alarming.
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.
- □Megger the motor and its cable before condemning the drive. A shorted winding or a cable chafed against the machine frame will destroy a replacement drive exactly as fast as it destroyed the first one.
- □Record the alarm code and what the machine was doing when it tripped — during acceleration, at speed, on a hard stop, or only when warm. That distinction separates a power-stage fault from a thermal or feedback fault.
- □Check whether the cooling fan still spins freely and whether the heatsink is clogged. If the only fault is a thermal trip, cleaning and a fan may fix it on your bench.
- □Confirm incoming line voltage and phase balance. Repeated drive failures on one axis are often a supply or wiring problem the drive is simply reporting.
- □Note your parameter set if you have it recorded. Drive parameters normally live in the CNC or the drive's protected storage and our physical repairs do not touch them, but a record is worth having.
Repair or replace?
Servo and spindle drives are where repair economics are most favourable: the hardware is expensive, frequently obsolete, and often tied to a specific machine and parameter set. New replacements for older platforms are commonly quoted at multi-week lead times when they are available at all, and a like-for-like replacement still has to be parameterised and commissioned against the machine. Because a drive failure usually stops the machine outright, the number that matters is rarely the invoice — it is how many production days pass before the axis turns again.
What to ship
- ▸The module (control card installed if it has one)
- ▸Fault/LED state + machine details
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
Why won't you take my big 611 infeed module?
Proving a 36kW+ infeed repair requires three-phase source and load capacity that our launch bench doesn't have — and shipping you an unproven repair on the module that feeds your whole rack isn't a risk we'll sell. We'll point you to options and take the axis modules and control cards, which we can fully verify.
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