# Hitachi M12V Speed Controller Repair



## bigendian (10 mo ago)

Hello! I've recently gotten interested in routing and have learned so much from this site. This is my first post and hope to provide some useful information back to the community.

I've repaired the speed controller on my Hitachi M12V and wanted to share details on safely removing the speed knob to clean the potentiometer contacts. What were the symptoms? In my case, the router would not turn on unless the speed control knob was turned all the way up. Here's steps I followed that worked for me.

Once the top router housing is removed, the speed control module is accessible. I've seen others drill holes or unsuccessfully force the knob off to attempt to clean the contacts, but there's actually a screw underneath a little dot of matching yellow compound right in the center. With a little scraping, there is a Philips screw head can be accessed:










From there, use a push pin to scrape away as much compound as possible from around and in the grooves of the screw head until a little screwdriver can be fully seated to turn the screw. Once unscrewed, the knob will come off to expose the potentiometer underneath with a small plastic dust shield:










From here, the shield lifts to expose the bare potentiometer wiper and contacts:










In my case, I just sprayed a tiny amount of contact cleaner, turned the shaft of the potentiometer to work it in, then soaked up remaining cleaner with a paper tower before reassembling. So far the router is working very well after several tests.


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## old55 (Aug 11, 2013)

Welcome to the forum.


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## ScottyDBQ (Jul 5, 2008)

Thanks for a well done article with excellent photos.


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## roxanne562001 (Feb 5, 2012)

Thank you and Welcome to the forum


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