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  1. #1
    RC poster
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    Jul 2017
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    16

    Exclamation Xmaxx electronic advice needed.

    Hi Guys
    Im relatively new to RC and this is my first post on this forum.

    I recently bought an xmaxx 6s version and decided to re-gear it to 17/50 to get a bit more out of it.
    Im running 2x 11.1v 6s 45c 6200mah lipos.
    To keep the system running cool i purchased a castle 2028 cooling fan for the motor and two 30x30mm YR racing tornado fans mounted either side of the stock ESC.

    I was having an issue where i had no steering but throttle response was fine. (no fans were connected to receiver at this time).
    I checked the output voltage from the ESC and was reading 6v.
    I also had a 11.1v 1500mah 30c pack which went to an external BEC board and that would output 5v to both YR fans in parallel with a j connector for the receiver also wired in parallel.

    After unplugging the ESC connector from the receiver, I then plugged in the J connector from the external BEC board into the receiver and success i now had steering back.

    (sorry i don't have any pictures to demonstrate this)

    After a few changes in wiring i ended up running both the ESC plug to the receiver and the external BEC board into a spare channel of the receiver.
    I then also connected the 2028 fan to the remaining channel on the receiver.

    I connected the 2 lipos the car needs to run and turned on the ESC.

    So now i had steering, all fans running and everything was looking good.
    I figured by powering 4 additional 5v fans that nothing should cook and worst case scenario the weakest link would be the receiver.

    Oh how wrong i was....


    I took the xmaxx out for a test run and about 10 mins into my first pack offully charged batteries my power dropped by about 70% and had a slow flashing red LED on the ESC, i thought huhh must be low voltage cutoff.

    I put my second set of fully charged batteries in and the same thing happened about 10 mins later of light usage, only about 80% throttle used at the very most occasionally.

    i go over to the car to turn the esc off and notice a electrical burning smell. i quickly remove the shell and smoke starts to come out of the car. i quickly disconnect all 3 batteries but couldnt tell where the smoke was coming from.

    i took the car home to inspect and after pulling a few electronic components apart i found that i cooked the receiver, the external BEC board, all 4 fans and i think i also destroyed the ESC as i cannot get an led indication and when i tested the voltage on the plug that goes to the receiver it read 23v... so i think its probably at the end of its innings.


    And here is where the irony lies, by trying to keep the system cool i accidentally created a short circuit that basically Kentucky fried my Xmaxx


    So i was wondering if there is a way to test if the steering servo would also be shorted and the 1600kv motor.
    If the motor isnt destroyed then ill be buying a hobbywing MAX6 (which ive heard run much cooler :P) and a new receiver

    But if the motors damaged then ill be selling it as a rolling chassis cheap.

    Is there a way to check if the motor is still working and the steering servo without the ESC or receiver?



    Cheers Guys

  2. #2
    RC Turnbuckle Jr. ReglarGuy's Avatar
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    Feb 2012
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    Yes, they make a stand alone motor tester $60ish, and a stand alone servo tester $10ish. I have them, and they both work really well. You might not want to spend the money, though, if you're wanting to sell your truck as a roller rather than upgrading to a Leopard/Max6 setup that will handle a re-gearing.

    With you originally having a re-gearing of 17/50 with a stock system it's no wonder you had problems. In the owners manual it shows that a stock Xmaxx can't really be re-geared, because it's on the very edge of just barely being able to handle the stock gearing. If you do ever do decide to go with a new motor and ESC upgrade, though, you will be glad you didn't sell your truck as a roller. It's a great truck once you beef up the electronics. Good luck with what ever you decide.

    The ReglarGuy is kid tested and father approved.

  3. #3
    RC poster
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    Jul 2017
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    Great, Thanks for the feedback!
    Awesome truck BTW!

    I checked for shorts in my motor with a DMM and all was fine, spun the end of the motor carefully with a drill and read the AC voltage across all the different combinations of motor wires and they all checked out as the same voltage.
    I also shorted two of the motor wires and the pinion was much harder to turn so hopefully everything is ok with the motor.
    I decided to keep the xmaxx and just purchased a Max 6 ESC and a 2085x steering servo and new TQi 6533 receiver .

    Should have everything up and running in about 3 weeks as it's being shipped from US and I'm in AUS

    Also a few other question
    As I plan on using my CC Blower 2028 fan, do I simply just plug this into a spare channel on the receiver?
    Will the max 6 ESC need any additional fans or should it be fine? I'll be running 6s with 17/50 gearing but from what I have heard they run much cooler than the stock ESC.


    Cheers

  4. #4
    RC Racer
    Join Date
    Oct 2013
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    246
    The Max 6 has a way nice ESC fan all ready on it so you dont need to buy one!! As for your motor fan yes you can plug it into a spare channel on the receiver!! I bet your motor is OK but Id be tempted in to buying the 1200kv x-maxx motor to go with the Max 6 ESC but then you would have to buy some of the power up parts traxxas sells for the 6s X-Maxx conversion but you would have a 8s X-Maxx and you would really love it.Geared 17/50 it would be a 50+ mph Truck??

  5. #5
    RC poster
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    Jul 2017
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    Sweet that's great!
    Cheers for the input

    Yeh down the line when i have some spare cash ill most likely upgrade to the new 1200kv motor and new 8s batteries as i only have 6s at the moment.
    Jeez i cant imagine this 10kg truck going 50mph, i got it up to about 40mph and thought that was pretty darn quick for such a large RC!

    Does the max 6 need any configuration or programming to get it going, such as thermal shutdown protection and low voltage cutoff?


    Cheers

  6. #6
    RC Qualifier
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    The Max 6 out of the box will be fine with the defaults. I think 37-40 is a great speed on 6s but I guess it depends on how much room you have to run. I would not bother with the 1200Kv until the 1600kv fails. It's faster and should run fine with your setup. (I run the same Max 6 / 1600Kv on 6s geared 18/54 for 37mph)

    Get a temp gun though that way you can be sure it is running OK. Also if you wreck a V1 ring or pinion then the V2's drop right in. Note you would need to do front/rear at the same time as they are a diff ratio from stock V1.

  7. #7
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    Jul 2017
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    Cool i cant wait to get it up and running, just have to play the waiting game now.
    Good idea, ill leave the stock motor until it dies or i have issues with it as i was pretty happy with the way it was running stock.
    I did have issues with throttle lag (felt like the slipper clutch was loose but i tightened the slipper right down until the spring was compressed fully and then backed it off 1/8th and that didn't resolve the issue) im hoping that was ESC related, i guess we will see.

    Also i read somewhere about the type of battery connectors you should be using. What would be the best type of plug for me to use with 6s batteries? TRX plug, EC3 plug?


    Cheers

  8. #8
    RC Qualifier
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    I think a lot of folk like the XT90 connectors. I use Deans still as they are on all my rigs and bats and it's too much effort to swap em all out! Haha.

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