Modifying a Servo

Modifying a Servo
by Tony van Roon

Project Background Info:
I was in need to modify four expensive JR-DS8231 Ultra Digital servos to rotate 360° instead of the standard 130° or something. The mods were required so they could be used with a tethered blimp. The infra-red and night vision camera equipment is mounted underneath the blimp on a special fabricated aluminum cage and is radio controlled (R/C). I choose a digital 10-channel radio transmitter merely for the needed channels and reliability of JR products.
The project was handed to me by our local "Land Resources" department, for my extensive experience with all sorts of radio control systems and products.

Since modifying the digital servos was not gone work, I opted for four cheapie analog servos, Hobbyco C60 (made by HiTec). The little pot inside the servo is 5K and so has to be replaced with 2.5K resistors each. Since 2.5K is not standard stock, I opted for 2.4K resistors. Worked out fine. (I thought maybe publishing my findings could possibly assist in helping someone else obtain the same goals). Check the pictures at the bottom of the page for the modification sequence. I soldered a couple days later two small ceramic capacitors (0.01uF) over the servo motor power connections to eliminate 'servo-creep' on a Futaba servo. Worked fine. See picture 16-a down below.
Also, remove the notch (or stopper) from the gear with the bearing. Snip it off with a cutting plier and then use an exacto knife to clean up the rest.

Underneath this blimp is a system with 2 infra-red cameras which takes a variety of pictures from the soil at different locations. The different colors of the soil in the pictures are then analyzed in regards to soil looseness, clay, (hot)rock, type, etc. The system which houses these cameras had to extremely safe. The 2 cameras alone are expensive at a cost of $35,000 each and weighing almost 4 pounds each plus the battery packs and R/C equipment and weight of the aluminum frame (cage) itself. Total weight to be carried by the blimp, at one time, was about 15 pounds (Can). Cameras can be switched with Infra-red cameras or night vision, etc.

picture 1 picture 2 picture 3  picture 4 picture 5 picture 6  picture 7 picture 8 picture 9  The micro-pot Wire colors Insert  picture 12 picture 13 picture 14  picture 15 picture 16 picture 17  picture 18 picture 19  picture 20

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Copyright © 2004, Tony van Roon
Last updated May 15, 2008