Although the steup I had was working OK, I decided some tweaking was in order. The pot that came with the servo turned to easily and was hard to dial in perfectly. Although it was protected by the body I was also concerned I may hit it accidentally when I had the body off and have to deal with reseting it. I also experienced a little "Servo Creep" ... meaning that no matter how well I adjusted the pot, the servo would creep now and again as if it was just off center. Lastly, I knew that if I didn't make a backup servo, mine would fail 5 minutes before a comp and leave me frustrated. So I did a little research and found 6 options to fix some of these problems.
PARTS & SUPPLIES USED
Towerpro MG945 or comparable servo
Assorted servo horns
18-22awg insulated wire
2x 2.2k resistors
Assorted Potentiometes & trimmers
10k 15 turn Cerment Potentiometer
Servo Neutralizer
TOOLS
Dremel with cutoff disks
Drill with assorted bits
Soldering Iron
Screwdrivers
UPDATE:Part 2
Option 1: Replace the pot with some resistors.
A. I read in a few places that people would simply replace the servo pot with a 2.2k to 3.3k resistor. This way, once it is adjusted by the radio it should never change.
B. I purchased some 2.2k resistors for $1 from Radio Shack (# 271-1605). Installing the resistors was pretty easy. You take 2 resistors and make yourself a "W" with them soldering them in place of the pot. I just wanted to test to see how they worked, so I left them full length in my laziness.
C. Although this got rid of the pot, it meant the only way I could adjust the servo was via radio. Although I got pretty close to a perfect adjustment, it still moved slightly, so I scrapped the idea.
Option 2: Replace the pot with a different pot
A. I had also seen where a few people replaced the with assorted different pots both larger & smaller. Once again Radio Shack had what I needed with their assorted pots & trimmers pack(#271-1605). Of the bag of pots this was the smallest and hardest to turn so I gave it a try.
B. I noticed no big difference between this pot and the stock pot other than it was a little harder to turn. Althoug that solved part of my problem, I moved on to the next idea.
Option 3:Put in a 15 turn pot
A. In theory this should allow for a finer dial in which would allow me to find the dead zone a little easier. I picked up a Radio Shack 15 turn Cermet Potentiometer (Part #271-343) and soldered it in.
B. With this pot I felt like I could get a better dial in on the dead zone, just like I wanted. I decided to completely install this in the servo and do some field testing with it. The first part of the installation is obviously to cut off the old pot and solder this in, the next part is to drill out a little hole where the adjustment screw can poke through.
C. I did a few test fits and had to scrape a little bit off the back of the pot to get it to fit in snugly, but it fits perfectly now.
D. Here it is going into the case. I added a drop of CA glue on each end to hold it in tight. I was also able to put in a longer set screw in place of the stock one to make sure it doesn't go anywhere(visible in step C).
E. Here is the servo all neat and still adjustable from the outside. Not only does it look better but it's easier to adjust and less prone to get thrown off. Just what I wanted!
For those of you that are wondering what happened to options 4 - 6.
Option 4: Install a Servo Neutralizer
A. So WTF is a Servo Neutralizer? A Neutralizer expands the "dead zone" of the servo by 12hz so that the servo does not "creep". This should put an end to any issues I am having and allow me to slap in cheap resistors or pots, with no creeping. It can also be easily transfered from one servo to another easily because it just plugs inline. The downfall is that the cheapest I could find it was at E-clec-tech.com. Unfortunatly, the vendor never sent me my unit. After a few months of unanswered emails I disputed it with my credit card company and ordered one from bpesolutions.com. It was more expensive but it got here in 3 days.
B. The install on this was easy. As far as results ... it does EXACTLY what I wanted it to do. I pulled out the original servo setup and played around with the pot, with and without the Neutralizer. With the neutralizer I was able to adjust my end points and make it so that the thing just doesn't creep! Perfect! Although this is not the cheapest solution, it is probably the best for modded servos.
Option 5: Install an actual "Servo Winch"
A. Hell no I'm not paying for a Futaba S5801 $130 servo sail winch! However, because I only need about 1.5 rotations out of my winch, the Hitec HS-785HB servo looked promising. There is just one problem. It's a 1/4 scale servo so it's HUGE. Unfortunatly I failed to notice this when I ordered it from Servo City. Anyway, since I had it I decided to test it out.
B. It does exactly what I wish I could do with my smaller servos. I can adjust the end points on my TX to give me 1.5ish turns which is perfect for my setup ... but again, it's just too big for my rig. SO it will either get returned or head to ebay...
Option 6: Install a servo relay
A. This will not work for most people because they don't have a spare channel, but I wanted to try it anyway. I'd use one servo channel to power a relay that would kill the power to the winch, so it can't creep unless I turn the relay on.
B. So I knew I wanted a servo relay, but my searching revealed that they run about $80 from most suppliers. WTF? Then I rememberd I had a spare servo board lying around and started thinking. I decided to try to use the old servo board to control my relay. Instead of having a motor connected to the servo board, I'd attach a small relay that would in turn control the positive juice to another servo. From looking at the servo relays available for sale out there, that's what it looks like they do.
C. So I cut up some parts and started making my setup. It seemed like ti was boign to work but apparently I didn;t have any good spare boards lying around. Unfortuantly I was also never able to find the right relay to make this work. I tried a few from Radio Shack and even started looking through some manuals but I'm still thinking about how I can get this to work. Maybe one day I can update this section.
Long story short is that the hidden pot and Neutralizer work the way I want them to. I could do with less wires but that is something I can fix.
Here is a little video of it in action:
