Re: Clean and Lubricate Pots in Tek 475

Tom Phillips

I was able to free up a frozen intensity pot in my 465B. The 465B intensity pot is located near the rear of the interface circuit board. A long thin epoxy extension shaft connects the pot shaft to the front panel control knob. The pot shaft was so stiff that the long shaft just flexed rotationally when I turned the front panel knob as the pot refused to move. After removing the case, I set the scope vertically on the rear feet and removed the high voltage shield to access the intensity pot. I put a couple of drops of Deoxit D5 on the metal pot shaft and left it to soak. Over a day’s time I periodically added another drop of D5 when the previous drop had evaporated/penetrated down the shaft. The long epoxy shaft continued to flex and the pot shaft didn’t budge. I then used pliers applied to the metal coupling at the pot shaft to gently get rotation started. Once the pot shaft started to move things improved quickly over the next few hours because, I believe, the D5 could now better penetrate down the pot shaft.

This process took a day but it didn’t require much of my hands-on time. Eventually, I’d still like to disassemble the pot for complete internal cleaning because the intensity adjustment is a little jumpy. However, the process I described solved the main problem of a totally unusable intensity control.


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