14D681K Varistor Replacement for Avalon PSU3300-03 Power Supply

14D681K Metal Oxide Varistor | 680V Clamp Surge Suppressor for Avalon PSU3300-03

The 14D681K is a 14mm radial-lead metal oxide varistor (MOV) rated for 420V AC continuous with a 680V clamping voltage and 4500A peak surge current — the AC-line surge suppressor used on the Avalon PSU3300-03 power supply. Sits across the AC mains lines after the fuse and clamps transient overvoltages before they reach the bridge rectifier and primary-side switching circuitry.

14mm disc in the standard MOV form factor — drop-in replacement when the original sacrifices itself absorbing a surge (its job) or degrades from years of mains transients. A fresh 14D681K restores the PSU's first line of input protection on Avalon A1066 / A1166 / A1246 hardware running PSU3300-03.

When to Replace the 14D681K

• PSU dead after a known voltage event — surge, lightning, utility transient — varistor often sacrifices itself and shorts to protect downstream circuitry.
• Input fuse blown with no other visible damage — varistor shorted, took out the fuse on the next surge.
• Visible cracking, blackening, or charring on the disc body or epoxy coating.
• Burn marks on the PCB around the varistor footprint after a fault event.
• Preventive replacement on Avalon PSUs returning from sites with poor mains quality.

14D681K Varistor Specifications

FAQ — 14D681K Varistor

Q: Why does the varistor short when it absorbs a surge?
A: That's its design behaviour — a MOV clamps overvoltage by conducting the surge to neutral. Big surges fuse the internal granular structure into a low-impedance path, sacrificing the part to save the rest of the PSU. Always replace a sacrificed varistor along with the input fuse.

Q: Can I substitute a different MOV size or voltage?
A: No — match exact part number. Smaller disc = lower energy capacity = won't survive the next surge. Different clamp voltage = wrong protection threshold. Stick with 14D681K for the PSU3300-03 footprint.

Q: How do I test if the existing varistor is still healthy?
A: Power off and isolated, measure resistance across the leads with a high-range DMM. Healthy MOV reads OL (megohms+). Shorted or partially-conducting reading = degraded varistor, replace.

Q: Bulk pricing for Avalon PSU3300 repair benches?
A: Yes — email contact@lys-sz.com for volume pricing on 14D681K plus matched input fuses for PSU3300 repair kits.

Related products

• Avalon PSU3300-03 Plus (A1066 / A1166 / A1246)
• Avalon PSU Flyback Small Board (PSU3300 / PSU3400)
• S14K300 Varistor (Bitmain APW9)
• TVR 14511 Varistor (Bitmain APW12)

Avalon PSU3300 repair benches stocking 14D681K varistors by the strip? Email contact@lys-sz.com for bulk pricing. Worldwide shipping from our Shenzhen warehouse.