Corsair VS550 PSU Schematic: OEM Variants, Block Diagram, Common Faults

User question

esquema da fonte Corsair VS550

Artificial Intelligence Response

Direct answer to the question

• Corsair does not publish a complete electrical schematic of the VS-550 ATX power-supply unit (PSU).
• What Corsair makes public are only pin-out diagrams of the modular cables; service schematics are proprietary.
• To work at component level you must reverse-engineer the board in your possession or rely on reference designs from the same OEM platform (usually CWT or, in older lots, HEC).

Detailed problem analysis

1. Product genealogy and OEM variants
   • VS-550 “V1/V2” (≈2013-2017, HEC): group-regulated forward converter, no DC-to-DC modules, passive PFC.
   • VS-550 “V3” (≈2018-2020, CWT GPA platform): active boost PFC, double-forward topology, group regulation.
   • VS-550 “V4” / current retail part-number CP-9020171-xx (CWT GPB platform): active PFC + synchronous rectification on +12 V, DC-to-DC daughter-cards for +5 V / +3.3 V.

   Different revisions use different controller ICs, so always identify the PCB code silkscreen and IC part numbers before assuming a circuit.

2. Typical functional blocks (current GPB revision, 80 PLUS White)

   Primary (HOT side)
   • EMI/­RF filter → fuse → NTC inrush limiter
   • Bridge rectifier (GBU808 or similar)
   • Active PFC boost stage
   – Controller: Champion CM6500 or OnSemi NCP1653D
   – MOSFET: 600 V Super-Junction (e.g., IPA60R190P6)
   • PFC boost diode & 450 V bulk capacitor (~2 × 220 µF)
   • Main power stage: double-forward (or half-bridge forward in older boards)
   – PWM combo controller: SG6105D / CM6802
   – 2 × MOSFETs on primary heatsink
   • 5 V SB flyback supply
   – PI TNY278 / TNY280 or Silergy SY50289 (8-pin)

   Secondary (COLD side)
   • +12 V synchronous rectification
   – Vishay SiRA12 or Alpha-Omega AOZ2081 driver
   • +5 V / +3.3 V DC-to-DC buck converters (each on a vertical daughterboard)
   – Controller: APW7159, Anpec APW7073 or equivalent
   • Supervisor IC
   – Weltrend WT7527, Sitronix PS223 or GR8323: OVP/UVP/OCP/SCP, POWER-GOOD timing
   • Common LC filters and differential chokes per rail

   Protection thresholds (typical WT7527)	Rail	UVP	OVP	OCP (per rail)
   +12 V	10.4 V	13.4 V	45–55 A
   +5 V	4.3 V	5.8 V	25–35 A
   +3.3 V	2.9 V	3.9 V	22–30 A

3. Reverse-engineering approach without an official schematic

   a. Identify ICs and download their datasheets – each comes with an “application circuit” that is 80 – 90 % identical to what is on the VS-550.
   b. Mark functional blocks on photos of the PCB; trace high-current paths with a continuity buzzer.
   c. Draw a block diagram first, then add component identifiers only where measurement is required.
   d. Verify static parameters before energising:
   – Bridge diode drop, MOSFET D-S short, bulk-cap ESR, PFC diode reverse leakage.
   e. Power-up sequence checks (with an isolation transformer & bulb limiter):

   1. 5 V SB present (purple wire) → ~5 V under 500 mA dummy load.
   2. Assert PS_ON (short green-to-black).
   3. Look for CM6500 VCC (~12–14 V) and DRIVE waveforms.
   4. Measure boosted PFC bus (≈390–410 V DC).
   5. Confirm +12 V appears, then +5 V / +3.3 V from DC-DC boards.

4. Common field failures
   • Dried 5 V SB VCC electrolytic (4.7 – 10 µF, 50 V) → standby hic-cup.
   • Shorted synchronous-rect MOSFET on +12 V → blown secondary fuse-link, OCP trip.
   • Open PFC start-up resistor (2 × 270 kΩ) → no PFC, low bulk voltage, PSU only runs on 115 V mains.
   • Bad output caps (CapXon / Teapo SC series) → ripple > 120 mV_pp, system instability.

Current information and trends

• Budget ATX PSUs are transitioning from group-regulated forward designs to LLC resonant + full DC-to-DC even in ≤600 W class to meet the ATX v3.0 transient spec (PCIe 5.0).
• Corsair’s new “CX-M 2023” already uses LLC + SR + DC-DC with 105 °C polymer capacitors, replacing some VS models in certain regions.
• ATX12VO (single 12 V rail) is slowly gaining traction for OEM PCs; independent repair will again require fresh reverse-engineering.

Supporting explanations and details

Why no public schematic?

1. Intellectual-property protection between Corsair and its OEMs.
2. Liability: Mains-connected SMPS repair has shock/fire risk; vendors reduce exposure.
3. Constant minor PCB spins would render a single document misleading.

Analogy: Treat the datasheet “typical application” as the sub-assemblies; your job is only to draw the inter-wiring between those blocks on your specific board.

Ethical and legal aspects

• Attempting repair voids any remaining warranty.
• Working on the primary side without isolation is life-threatening; always discharge 400 V caps and use an isolation transformer + differential probe when probing primary waveforms.
• Re-distribution of a full traced schematic may infringe OEM copyright; keep it for personal or educational use.

Practical guidelines

1. Obtain: ESR meter, isolation transformer, 100 W incandescent bulb limiter, oscilloscope with HV differential probe, hot-air for desoldering.
2. Always load the +12 V rail with ≥1 A when testing open-frame (a 12 Ω/25 W resistor suffices).
3. After repair, run a 30-minute soak at 80 % load; verify ripple:
   – +12 V ripple < 120 mV_pp
   – +5 V/+3.3 V ripple < 50 mV_pp
4. If PFC is disabled for bench tests (e.g., by lifting the PFC MOSFET gate), do not exceed 115 V input, or bulk voltage will be too low for main converter stability.

Possible disclaimers or additional notes

• Component values given above are typical for the latest CWT GPB board. Older HEC boards may lack active PFC and use different part numbers.
• Some retail units branded “VS-550” in India and Brazil are still old stock without DC-to-DC; efficiency and hold-up time differ.

Suggestions for further research

• Search EEVblog and Badcaps forums for “CWT GPB schematic” – users have posted partial reverse-engineered plots.
• Study Champion CM6500 + APW7159 reference designs; they mirror the VS-550 GPB.
• Review Intel ATX v3.0 design guide (2022) to see the direction future 500-600 W PSUs are taking.

Brief summary

No official Corsair schematic for the VS-550 exists publicly. The unit’s design depends on revision: early versions are group-regulated forward, the latest GPB revision adds active PFC, synchronous rectification and DC-to-DC modules. For repair, locate the PCB revision, download all controller datasheets and rebuild a block-level diagram; that, plus safe bench techniques, provides everything necessary to diagnose or refurbish the PSU without violating Corsair’s intellectual-property policies.

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