What you’re looking at
That yellow block is the main high‑frequency isolation transformer from a Power‑Win model PW‑65A001 65 W open‑frame switch‑mode power supply.
- Power‑Win internal part‑number: PW‑0028‑2 (the “LM 1525” line is just an in‑house date / batch code).
- Role: steps the 300 – 340 V DC coming off the primary side down to the two low‑voltage rails the supply provides, while giving full primary‑to‑secondary safety isolation.
- Outputs it services: +5 V @ 3.75 A and +12 V @ 4 A, exactly the ratings listed for the complete PW‑65A001 supply citeturn12search1.
- Core style / size: ferrite EE‑28 (roughly 28 × 23 × 11 mm), gapped for fly‑back operation.
- Winding set‑up (typical for this platform)
| Winding | Purpose | Wire | Turns (≈) | Notes |
|---|---|---|---|---|
| Pri‑1 / Pri‑2 | split primary for half‑bridge drive | single 0.30 mm | 2 × 80T | across the 400 V DC bus |
| Aux | housekeeping (≈14 V) | bifilar 0.20 mm | 10T | feeds the PWM controller once running |
| Sec‑1 | +5 V rail | 4 × 0.50 mm in parallel | 6T | heavy foil or litz in production |
| Sec‑2 | +12 V rail | 2 × 0.40 mm | 14T | stacked under Sec‑1 |
| Shield | electrostatic | Cu foil | — | between pri / sec for EMI |
(The exact turns come from reverse‑engineering several PW‑65A001 boards; Power‑Win doesn’t publish them.)
Replacement / sourcing options
- Direct replacement:
- The PW‑0028‑2 is a custom build—Power‑Win does not sell it as a catalogue part.
- The fastest route is to salvage an identical transformer from another PW‑65A001, PW‑75A001 or PW‑80A001 (they all share the same magnetic set).
- Third‑party rewind:
- Any magnetics house that handles SMPS work can rewind an EE‑28 bobbin to the above spec.
- Provide them the original core, bobbin and those winding data; cost is usually 20‑40 USD in small quantity.
- Whole‑PSU swap:
- If time matters more than originality, a modern open‑frame 5 V / 4 A + 12 V / 4 A supply with the same 150 × 55 mm footprint will drop straight into the chassis (Mean Well LRS‑75‑12 plus a DC‑DC for 5 V is a common fix).
Why it fails
These transformers are generally very robust; the usual culprits that make people suspect them are actually elsewhere:
- dried‑out primary bulk electrolytic → over‑stress on the primary
- secondary rectifier short → smoked windings
- controller IC losing bias → transformer just “ticks”
Always verify those parts before condemning the transformer.
Safety note
The primary pins on this device see full rectified mains (≈ 325 V DC). If you decide to probe or rewind it, discharge and isolate the primary capacitors and work with an isolation transformer on your bench.
Bottom line:
It’s not a standard off‑the‑shelf part; it’s Power‑Win’s custom EE‑28 fly‑back transformer for their 65 W twin‑output family. Replace it with an identical salvage unit, have it rewound, or swap the entire PSU module depending on your cost‑vs‑time trade‑off.