Home Forums Everything about everything else Tricopter Tail Servos Keep Burning Out

Tagged: , , ,

Viewing 12 posts - 1 through 12 (of 12 total)
  • Author
    Posts
  • #38199
    Ben Brown
    Participant

    I have recently run into an issue where my servo doesn’t move and gets really hot really fast then just smokes. I have only had it up in the air a few times in the last few years as it never really works for me turns out my motors weren’t powerful enough so fixed that then wanted to take it out got caught with issues on cleanflight 2.0 had to find a way to get the old configuration to run along side the new got that setup and it worked the tail servo moved perfectly then finally I took it out and it instantly started to smell of burning I tested it before going out and it all worked took it home and plugged it in again and smoke started to come out the servo unpluged it and checked my config and it was all right then took my spare servo and tested it with the servo tester and it worked plugged it into the FC and it got hot and didn’t move unplugged it again and tested again with the servo tester and it worked then tried again and the same thing happend I have checked voltages coming from the FC and they are at 5v but something is causing my servo to burn out when conected to the FC and I can’t work out what. Has anyone had this issue before or have any idea how to solve it, I am using Savox SH0262MG servos.

    #38201
    LitterBug
    Participant

    Sounds like you are trying to use analog servos. Make sure you have digital servos which can handle faster update rates. You can reduce the servo update rate to 50, but you will be much better off in the long run with a good digital servo.

    Cheers!
    LitterBug

    #38203
    Ben Brown
    Participant

    I did think that to start with but they are digital servos. Savox SH0262MG

    #38208
    Ben Brown
    Participant

    It might have been a firmware thing I can’t remember which cleanflight I was on but it forced an upgrade to v2.0 which didn’t work so reverted to v1.14 and that initially seemed to work but looking further I thought I would check out triflight and found v0.6 was based of that version of cleanflight but there was a warning against using it as it was based on v1.14. I have just ordered 2 more servos and flashed triflight as it now has a version for my FC lets see if that makes a difference and does not burnout my servos.

    #38209
    Ben Brown
    Participant

    Out of curiosity more than anything I took the two servos appart and found that each one burnt out in a different place (Image attached) I am not an electrical engineer so don’t really get what I am looking at but I am assuming it’s some sort of driver chip that burnt out as there are two on each servo I assume one for left and one for right. When moving them by hand they don’t seem to bind they have a smooth motion.

    #38216
    LitterBug
    Participant

    Interesting. Those look like the motor drivers. What was the servo angle when they burned up and how long did it take before it happened? What voltage are you running to the servo?

    I was looking at the specs for the servo at http://www.savoxusa.com/Savox_SH0262MG_Micro_Digital_Servo_p/savsh0262mg.htm
    The recommended servo update speed is 200-250 which is a tad lower than what I’m used to for a digital servo. The current version of TriFlight defaults to 300hz which may be too fast for your servos. You can check the update rate by looking at this parameter: servo_pwm_rate = 300

    Cheers!
    LitterBug

    EDIT: Older versions of Triflight (ie 0.5) also defaulted to 300 servo update rate.

    #38231
    Ben Brown
    Participant

    I centered the servos before installing them using the 5v from my PDB on my servo tester. The first servo was working then on around the third power up I smelt burning it took about 30 seconds to get to smoking level then I unpluged but it was dead. The second servo just got real hot really quick and smoked after about 20 seconds. The servos are running at 5v and I did check this to see if they were getting to much power and it was 5v.

    When the servos failed I was running cleanflight and I checked the pwm rate and it was around 50 which I think is default.

    The servo speed can go higher A lot of the heli guys are running them at 270hz or 333hz with no reported issues I will change triflight when my new servos arrive though and hopefully not burn them up.

    #38240
    donnyb
    Participant

    Hold on! It looks like everything you’ve connected together is good. Servos do get hot if they jitter. I looked at the specs and it seems the servo should handle anything you throw at it. But the 5 volts you think your getting from the fc may have voltage drops below the lowest rating of 4.8 volts.

    Thats when you can run into current problems. Say the max current of the servo is 600mha @ 5 volts max.

    If you get it in the air and say your 5 volts drop to 4.5 volts your servo will pull more than the max current say 650mha and its possible the magic smoke appears.

    Once you cooked it it will always smoke if you try to use it.

    A easy way to check it out before you hook up a shiny new servo.

    Is remove the props hook up your voltage tester to the 5 volt output. Wind it up to full speed and see if your still getting 5 volts.

    If not get a separate bec and power the servo with that. Do not let the separate bec power run back to the fc. Just hook it up to the red wire on the servo. By default all the grounds are usally connected together.

    Otherwise your fc could loose the magic smoke. Lol

    #38264
    Ben Brown
    Participant

    That makes sense although when they fried they were plugged in but not under load, just sat on the ground. I will attempt a test tomorrow and see what happens to the voltage. If I were to power the servo separately could I split out the servo and fc from the same bec, I am using a PDB with built in 5v 2Amp output that goes directly into the servo pins on my FC (Spracing Evo) currently.

    #38296
    Ben Brown
    Participant

    I have just tested the voltages and I have a constant 4.95v under multiple loads from low to high. My new servos have also arrived and I have tested them and they both work using a servo tested I then plugged them into the FC and got no response but they didn’t get hot either which was a good sign. I think that it is some kind or resource mapping issue but I have been unable to to map correctly yet using triflight 7.0 beta 2.

    #38298
    Ben Brown
    Participant

    The servo is now working the only thing I changed was to use triflight and the servo works perfectly not getting hot or anything, not sure what caused the issue in the first place the only thing I can think of is a configuration error or a firmware issue.

    #57571
    CoraDias
    Participant

    Hi…i am a new user here. As per my knowledge you should make sure the digital servos must be there which can handle faster update rates. Also here it can reduce the servo update rate to 50, but you will be much better off in the long run with a better digital servo.

    https://www.7pcb.ca/pcb-fabrication/

Viewing 12 posts - 1 through 12 (of 12 total)
  • The forum ‘Everything about everything else’ is closed to new topics and replies.