65R044MFD MOSFET for Avalon 1346 Miner PSU Repair

65R044MFD Super Junction MOSFET | Plug-In Replacement for Avalon 1346 PSU3400-03

The 65R044MFD is a high-performance super junction power MOSFET packaged in the rugged through-hole TO-247 form factor — the main switching MOSFET on the Avalon 1346 miner power supply (PSU3400-03). Built on a super-junction architecture, the 65R044MFD delivers the low on-resistance, low gate charge, and ultra-fast body diode needed to keep PSU switching losses low and overall efficiency high under continuous mining duty.

The part undergoes 100% avalanche testing at the factory, guaranteeing reliable performance under the voltage transients and inductive switching loads typical of ASIC PSU primary-side service. The very low figure of merit (FOM) for RDS(on) × Qg means the device transitions cleanly at high frequency without the conduction-loss penalty of older silicon MOSFETs — exactly what an Avalon-class 3kW PSU needs to stay efficient over 24/7 operation.

When to Replace the 65R044MFD on an Avalon 1346 PSU

• PSU3400-03 fails to start — fans spin briefly, no DC output, no startup tick from the transformer.
• Hiccup mode — PSU pulses on and off repeatedly without ever latching to full operation.
• Burnt or visibly damaged TO-247 on the primary-side heatsink — often a thermal failure marker.
• Multimeter diode-test shows short or open across drain-source — either failure mode.
• Repeated overtemperature shutdowns on the PSU under normal ambient — failing MOSFET with elevated RDS(on).

Specs and Technical Features

• Super junction architecture — low RDS(on), low Qg, fast switching.
• TO-247 through-hole package — heatsink-mounted, rugged for primary-side ASIC PSU duty.
• Ultra-fast body diode — supports the inductive switching loads typical of PSU primary stages.
• Very low FOM RDS(on) × Qg — efficient switching at high frequency.
• 100% avalanche tested — every device validated for transient voltage handling.
• Plug-in design — through-hole leads simplify board-level repair vs SMD parts.
• OEM-spec match for Avalon 1346 PSU3400-03 primary switching stage.

65R044MFD MOSFET Specifications

FAQ — 65R044MFD MOSFET for Avalon 1346 PSU

Q: How do I confirm the 65R044MFD is the failed part?
A: Power off and discharge the PSU bulk caps. Use a multimeter in diode-test mode across drain-source: a healthy super-junction MOSFET shows OL one direction and ~0.5V body-diode drop the other. A shorted MOSFET reads ~0V both ways; an open MOSFET reads OL both ways.

Q: Can I substitute another 650V super-junction MOSFET?
A: Electrically possibly, but verify the RDS(on) rating, Qg, body-diode recovery time, and TO-247 pin assignment all match the 65R044MFD spec. Mismatched parts may pass current but exceed the PSU controller's gate-drive capability, leading to repeated failures.

Q: What's the rework process for a TO-247?
A: Through-hole rework — desolder the three leads with a vacuum desoldering pump, lift the part, clean the holes, install the fresh MOSFET with correct orientation (gate / drain / source pin assignment matches the silk mark on the PCB), apply fresh thermal compound to the tab, torque to the heatsink.

Q: Do I need to replace both primary-side MOSFETs as a pair?
A: If the PSU uses a half-bridge or full-bridge topology with paired MOSFETs, yes — replace both as a matched pair to keep switching characteristics balanced. Single-ended forward / flyback designs typically use one primary MOSFET.

Q: Bulk pricing for repair shops?
A: Yes — email contact@lys-sz.com for tray-quantity pricing.

Related products

• Avalon PSU3400-03 (Canaan A1346 / A1366)
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• 813RN A0231 25MHz Crystal Oscillator (Avalon 1166pro)
• Avalon A3205 Chip Tin Tool Fixture

Avalon 1346 repair benches stocking 65R044MFD MOSFETs in volume? Email contact@lys-sz.com for bulk pricing and matched PSU repair-kit options. Worldwide shipping from our Shenzhen warehouse.