Repairing Shorted Servos

I was setting up dual servos on the ailerons of a 4 star 40. I plugged a Y connector into a Berg reciever then I plugged brand new Futaba
3004 servos into the Y using extensions. I turned on the transmitter and plugged the battery in the receiver. Nothing happened when I moved the aileron sticks. I pulled the servos and tested them on a servo tester. Still nothing. I thought perhaps bad servos. I had two more new 3004 servos so I tried them first on the tester, then seperatly on the reciever. They worked as intended. Then I plugged the servos back into the Y and plugged everything back in. I then moved the aileron stick again and still nothing. I pulled the servos again and tried them on the tester. Nothing. Then I replaced the Y connector and leads and installed some servos that I had on the bench and the ailerons worked fine. There must have been a short in either the leads or Y connector, Since I paid 8 bucks for the Y connector and leads, I cut the cords on them and threw them away. (I understand this was a knee jerk reaction, but I didn't have a receipt and I doubt the place I purchased the seros and wires from would have replaced the servos and and I was not in a happy frame of mind ) I have had a shorted servo before, and it looked like a capacitor had burned where the leads come into the servo. Is it possible to replace the capacitor (or whatever the component is) and have working servos again. And if I could repair the servo myself, would it be trustworthy assuming I did the repair correctly. I would send them in to get repaired but I'm sure the cost of repair is equal or more than the servo cost new.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
goodfella wrote:

Since servos generate no power, its hard to see how shorting their leads could damage them at all.
You are more likely to have damaged the receiver, as the power comes via that.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Perhaps I should have said that the leads were possibly reversed in the Y or the leads. The connectors had Futaba ends and were commecially made so they could only fit one way.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
They can be repaired if you are into working on microelectronics with surface mounted parts. A good soldering iron for this application is far more expensive than the servos. Then you will need a good magnifying glass, preferably illuminated. Also not free.
wrote:

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
goodfella wrote:

Well they usually survive being reversed..since the positive is in the middle that always ends up in the right place, and you generally end up with the -ve on the signal line instead of the earth, which usually does nothing at all.
If you got your wiring so messed up that you put the voltage on backwards that would probably not be a Good Thing tho, but that would require two miswires.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Simply plugging in a servo backwards will not cause harm to the servo. The problem comes in if the Y harness was designed for old style Airtronics which has Plus and Minus leads reversed from that of Futaba, JR and Hitec. Hooking up a Futaba servo to this kind of harness, or to a harness misassembled witht he plus and minus leads crossed, will definitely let all the smoke out, just as it would if you hooked an old style Airtronics servo to a JR or Futaba harness. To make matters worse, Airtronics did not use standard color coding on their leads, so it would not be obvious when you had a reversed polarity situation.
Keep the smoked servos for their plastic parts and buy replacements. Consider this a $50 training exercise. Every time you need a gear set or a case part, you get $10 of the $50 back......
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I tie a knot in the lead or mark the dead servo with masking tape and a pen. mk
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Is it worth it? to save a few bucks your risking your plane. Sure you may do a great job, but to me I'd just throuw them and buy more servo's
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.