Makita 638739-1 — Genuine Makita noise suppressor / interference filter
Short description
- A genuine Makita potted noise‑suppressor module (part number 638739-1) used in a number of corded Makita tools. It’s a small, black, moulded capacitor/filter assembly with insulated leads that sits inside the tool’s handle/switch cavity and is wired across the switch to damp brush arcing and suppress EMI/RFI from the motor.
Why you’d replace it
- If your corded Makita is causing radio/TV interference, or is tripping or behaving intermittently due to brush‑spark noise, replacing a failed suppressor restores the original electrical noise suppression and stable operation without changing the tool’s mechanical fit or balance.
Fitment / example models
- Documented fitment includes: GA4030, GA4030R, GA4530, GA4530R, GA5030, GA5030R, JS1601, JS1602, PJ7000 (and related corded Makita grinders and shears that use the same switch/handle assembly). Check your tool’s parts diagram for the same part number to confirm fit.
Key details (what to expect)
- Function: EMI/RFI suppression and damping of switching spikes from carbon brushes.
- Construction: potted (moulded) module with insulated leads designed to resist vibration and workshop conditions.
- Location: installs inside the handle/switch cavity and is typically wired directly across the switch terminals.
- Voltage/use: used in Makita’s corded tools across mains variants (documented on both 110 V and 240 V corded models).
Installation notes
- The part is a direct, like‑for‑like replacement for the original unit; replacement normally requires access to the switch/handle cavity and basic hand tools (and basic wiring/soldering skills if the leads are soldered). Reassemble the tool exactly as shown in the parts diagram to preserve safety and insulation.
Part number and identification
- Makita part no.: 638739-1 (sometimes listed without the dash as 6387391). Keep this number handy when matching to your tool’s parts list.
If you need the part to restore a noisy or intermittent corded Makita, this genuine Makita suppressor is the direct replacement used in the grinders and shears listed above.
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