The A06B-6087-H126 is the Fanuc Alpha PSM-26 power supply module — the unit that feeds DC power to every servo and spindle amplifier in the cabinet. When a PSM fails, the whole machine stops, not just one axis. And here is the part many maintenance teams learn the hard way: a sick PSM often looks exactly like a dead servo amplifier. This guide covers the specs, the failures we see most in our repair lab, and how to diagnose the real culprit before you spend money.
What Is the A06B-6087-H126?
The A06B-6087-H126 — usually called the PSM-26 — is the 26 kW power supply module in the Fanuc Alpha 6087 series. It takes 3-phase 200 V class mains power and converts it into the DC link voltage that powers the cabinet’s servo amplifier modules (SVM) and spindle amplifier module. It also handles regenerative energy when axes decelerate.
In a typical Fanuc cabinet, the PSM sits on the left, with the amplifiers daisy-chained to its right through the DC link bus bars. Everything downstream depends on it. If you are mapping an unfamiliar machine, our A06B series model number guide explains how the power supply, servo, and spindle modules fit together.
A06B-6087-H126 Specifications
| Item | Specification |
|---|---|
| Model | A06B-6087-H126 |
| Module type | Fanuc Alpha PSM-26 (power supply module) |
| Rated capacity | 26 kW |
| Input | 3-phase, 200 V class mains |
| Output | DC link for connected SVM servo and spindle amplifier modules |
| Regeneration | Regenerative discharge to the line (no external resistor in normal operation) |
| Series family | A06B-6087 (PSM power supply modules in multiple capacities) |
| Status | Legacy series — no longer in active production |
Common A06B-6087-H126 Failures We See in Our Repair Lab
Power supply modules live a harder life than amplifiers — they absorb every spike the plant’s mains delivers. These are the failures that actually arrive on our bench:
- Converter / IGBT section failure. The most serious and most common. Usually triggered by mains spikes, lightning, or a short somewhere downstream. The unit may blow its fuses instantly on power-up — do not just replace fuses and retry; find the short first.
- Precharge / inrush circuit failure. The PSM soft-charges the DC link at power-up. When the inrush resistor or its relay fails, you get blown fuses or a unit that never reaches ready state. Very common on 15–20-year-old modules.
- DC link fuse failure. Often a symptom, not the disease — a failed amplifier or IGBT downstream takes the fuse out. We test the full DC link circuit before returning any repaired PSM.
- Open phase / input detection faults. Sometimes the module, sometimes genuinely bad plant power. We see both. A phase-loss fault that follows the module to a known-good supply is an internal sensing problem — repairable.
- Cooling fan and capacitor aging. Same story as the amplifiers: stalled fans cause overheat faults, and dried-out capacitors cause erratic behavior and reduced ride-through on voltage dips.
Machine dead and not sure if it is the PSM or an amplifier? Send us the LED status on the PSM and each amplifier — that combination usually tells our engineers which module is at fault. Free diagnosis: [email protected]
PSM or Amplifier? A 3-Step Field Check
Because a failed PSM starves every amplifier of DC link power, its symptoms mimic downstream failures. Before ordering parts, run this sequence:
- Read the LEDs in order. Start at the PSM (leftmost module), then each amplifier. A PSM showing an alarm with dark amplifiers points at the PSM. A healthy PSM with one alarming amplifier points at that amplifier.
- Measure the DC link. If the DC link voltage never builds up at power-on, suspect the PSM’s precharge circuit or converter section — not the amplifiers.
- Swap logic, not hardware. If another identical machine is available, a careful module swap confirms the diagnosis in minutes. If not, send us your observations — we will help you interpret them.
Getting this right matters: we regularly receive “failed” servo amplifiers that test perfectly good — the PSM was the problem all along.
Compatibility: H126, H130, and the Alpha i Generation
- A06B-6087-H130 (PSM-30) — the 30 kW sibling on the same platform. In many cabinets a PSM-30 can stand in for a PSM-26 (oversizing the supply is generally acceptable; undersizing is not). Cabinet layout and connector compatibility must be confirmed first.
- A06B-6110 / 6140 series (Alpha i PSMs) — the newer generation, such as the PSM-26i. Not interchangeable with the classic 6087 series despite the similar capacity ratings. Different control interface and pairing.
- Never undersize. Replacing a PSM-26 with a smaller-capacity module risks overload faults and converter damage under peak axis loads.
For a sense of how Fanuc power supply generations compare, see our Fanuc power supply module comparison.
Repair or Replace: What Makes Sense?
| Option | Typical cost | Lead time | Best when |
|---|---|---|---|
| Repair your failed unit | Lowest — save up to 75% | 3–5 days standard | Failure is in the converter, precharge, sensing, or fan circuits |
| Tested replacement from stock | Moderate | Ships in 48 hours | The whole machine is down and every hour costs money |
| Untested surplus | Varies | Varies | Only if you can bench-test before installation |
One PSM-specific note: because the module feeds everything, a failed replacement means another full-machine outage. Bench-testing under load before installation is not optional for this part — it is the whole job. Every PSM we ship is load-tested first.
A06B-6087-H126 In Stock at OUKE
We stock the A06B-6087-H126 PSM-26 power supply module, bench-tested under load before shipping. Orders leave our Dongguan warehouse within 48 hours via DHL, FedEx, or UPS, with a minimum 1-year warranty and no MOQ.
Repair is equally fast: standard turnaround is 3–5 working days, with a 99.5% first-pass success rate across our Fanuc power supply repairs.
FAQ
What does PSM-26 mean on the A06B-6087-H126?
PSM stands for Power Supply Module, and 26 is the rated capacity — 26 kW. The module converts 3-phase 200 V class mains into the DC link power that feeds the cabinet’s servo and spindle amplifier modules.
Is the A06B-6087-H126 discontinued?
Yes. The classic Alpha 6087 series is no longer in active production. Tested used, refurbished, and repaired units from specialist suppliers like OUKE are the standard sourcing route.
Can a PSM-30 (H130) replace a PSM-26 (H126)?
In many installations, yes — the PSM-30 is the higher-capacity sibling on the same platform, and oversizing the supply is generally acceptable. Confirm cabinet layout and connectors first. Never replace with a smaller-capacity module.
My PSM blows fuses immediately at power-on. What is wrong?
Instant fuse failure usually means a shorted converter section or a failed precharge circuit — sometimes triggered by a downstream short. Do not keep replacing fuses; each retry can spread the damage. The unit needs bench diagnosis.
All my servo amplifiers look dead. Is the PSM the problem?
Quite possibly. If the PSM fails, every amplifier loses DC link power and appears dead. Check the PSM’s LED status first and measure whether DC link voltage builds at power-on before condemning any amplifier.
Get Your A06B-6087-H126 Back Running Fast
Need a tested A06B-6087-H126 or a repair quote for your failed PSM? We have 100,000+ SKUs in stock, all tested, shipped within 48 hours — no MOQ. Send us your part number: [email protected] or WhatsApp +86 15107352558.