Not reaching operating temperature

You must calibrate it again

Common Causes & Fixes

• Loose Tip Nuts: The copper tip carries high-current low voltage directly from the transformer secondary, acting like a resistance-spot welder. If the two retaining nuts holding the tip are even slightly loose, electrical and mechanical resistance increases, drastically dropping output wattage (e.g., dropping from 140W down to 67W).
  • Fix: Loosen the nuts, clean away any oxidation, and firmly tighten them down using a 3/8-inch or 5/16-inch wrench. As the copper tip heats and cools, it shrinks and can lose tension over time.
• Tip Oxidation and Wear: Heavy corrosion, carbon buildup, or a heavily worn, thinned-out copper tip prevents proper current flow and heat transfer to the work.
  • Fix: Remove the tip, clean the contact studs and the tip loop with sandpaper or a wire brush, or replace the tip entirely.
• Trigger-Switch Issues: The mechanical trigger switch can develop pitted, oxidized, or burned contacts inside the housing, failing to deliver full current to the transformer primary winding.
  • Fix: Inspect the switch contacts for burning or clean them carefully, or replace the switch assembly if it fails continuity under load.
• Transformer Degradation or Burnout: Prolonged use or ignoring the recommended intermittent duty cycle (such as holding the trigger down too long without rest) can overheat and damage the internal transformer.
  • Fix: Test the transformer secondary output with a low-range AC voltmeter or check if the gun hums and vibrates normally when the trigger is pulled. If the transformer winding is burned out, the unit usually requires replacement.

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• Does the gun still hum or vibrate when you pull the trigger?
• Does tightening the tip nuts change the heat or hum level?