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  1. #1
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    Lightbulb [VISIO DIAGRAM] Cabling diagram RX8 + TX8 + 2x2S + CCBEC + Hitec Servo + Stock RX

    Hello,

    I've drawn some diagram with Visio this evening to summarize lots of different information I've read here are elsewhere. My goal is to ensure that my patterns are accurate, and able to have some illustrated starting point to start soldering and then discuss about programming. I also found that the information was scattered right and left, I had read a lot before assimilating, and I think that one diagram is always better than tons of text to illustrate something.

    So here it is:

    ---> Scenario 1:

    CC BEC attached directly to the Hitec 7950TH Servo
    CC BEC output voltage set @ 7,4V to get maximum servo torque



    ---> Scenario 2:

    CC BEC connected to the RX
    CC BEC output voltage set around 6,4V (please ADVISE ME about maximum voltage that the RX can handle...)
    Capacitor to handle peaks. I have 1000uV but also 4700uV capacitors (both 10V of course)



    ---> Scenario 3:

    No external BEC
    ESC BEC supplies power to RX and to servos via RX
    Capacitor to handle peaks and avoid ESC issues




    So please advise me, please correct what's wrong here, please comment. I hope to be able to get the approval for all three scenarios with all warnings and recommendations. When I'm sure that everything is ok, I'll make a summary and correct the diagrams, then publish the definitive version. It will probably help some people who are in the same situation I was some weeks ago

    Thanks for your support.

  2. #2
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    All 3 scenarios look correct to me. Then again I'm not a total expert on wiring BEC's but they all look correct from what I understand. If it was me I would try running without a BEC first and see how it works. If you start experiencing "brown outs" with the radio then you know that you need an external BEC.

  3. #3
    RC Turnbuckle Jr. 87 GN's Avatar
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    looks good to me too.. I did option 2, kind of thinking of doing option 1.. Good work...
    Would you go flip my truck back over??

  4. #4
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    Hello, i don't know anything about BEC and capacitors, but i agree with b@3, if it's working without all that stuff the 3rd option looks cleaner then the other ones, and i think, that, less stuff it's also less problems. Good visio job.

  5. #5
    RC Turnbuckle Jr. 87 GN's Avatar
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    To get the full Potential from a bigger servo, you kind of need an external BEC. You don't have to, but what a difference..
    Would you go flip my truck back over??

  6. #6
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    option #3 should be adequate. I run (3) 208oz torque servos (plus the 3 mini servos) off of the Tekin with 4s lipos without issues. I am pretty sure the tekin can handle a single hi-torque Hi-tec.
    MAN, Use Common Sense
    Funky Gecko, SumVee HDE

  7. #7
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    I am currently using option 2 with 2 savox 1267sg servos for steering and cc bec set at 6.8v haven't had any problems with the rx handling the voltage I have been told that rx can only handle 6v by some and by others that it can handle up to 7.4v I have kept mine at 6.8v and love the performance, had to do the washer mod to the steering assembly to make the servo saver a bit stronger, next upgrade will be aluminum steering arms, kind of wanted to leave a weak link somewhere so I don't break the servos lol.


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  8. #8
    RC Turnbuckle Jr. 87 GN's Avatar
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    Quote Originally Posted by noir 522 View Post
    option #3 should be adequate. I run (3) 208oz torque servos (plus the 3 mini servos) off of the Tekin with 4s lipos without issues. I am pretty sure the tekin can handle a single hi-torque Hi-tec.
    It can, but it is still not getting the servo to it's full Potential. With the extra voltage....... 2v is alot of extra torque..
    Last edited by 87 GN; 01-21-2012 at 09:36 AM. Reason: spselleling ha
    Would you go flip my truck back over??

  9. #9
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    Of course the 3 diagrams illustrate the 3 main tendencies on this forum and elsewhere, I'm not surprised to see 3 kind of answers about the preferred way to do it But I'm happy to see that I did not make any mistake.

    There are still some open questions:

    - capacitor: 1000uV or 4700uV? IMO the bigger the capacity is, the better the capacitor will handle a peak and the less the ESC / RX will be stressed. But there is maybe a reason not to use a big capacitor. Could you please give your opinion?

    - maximum voltage when connecting the CC BEC to the stock RX?

    In my opinion, the most logical and least risky scenario from a technical point of view, if the scenario 1.
    The easiest way is the scenario 3 but you don't use the servo at its maximum torque (7,4V for the Hitec 7950TH)
    The balanced solution is the scenario 2 but the question is: maximum voltage that can be handled by the stock RX without any problem?

    In any case, I'll have to solder cables, connectors etc.... so solder less or more is not an issue there. I didn't make my choice but tomorrow it's time to decide so... I think I'll go for solution 1, or maybe 2 but... probably 1.

  10. #10
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    Hi I soldered everything this afternoon, I have chosen the scenario 1. But I have a problem with my RX8... Everything works except the motor and no led is working on the Rx8 With Hotwire I can see the config but I can't store it in memory... Did I broke the Esc when soldering? I mean was it too hot?? I don t understand what's wrong. But for the servo... What an incredible torque!!! OMG!!


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  11. #11
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    Hi, you're really unlucky, you should try to take everything out ,all those wires and bec and disconnect the servo from ch 1 and try to run the rx8 alone and try to make a factory set up using the buttons on the esc. Have you already try it before or it was the first time?

  12. #12
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    Hi,

    Yes I tried the RX8 alone, same problem, no LED no SOUND nothing. I replaced the RX8 + T8 by the EVX-2 + Titan, with EXACTLY the same connection scenario (Scenario 1) and it works perfectly fine!

    I tried the RX8 alone because on the manual, it's recommended to setup FIRST the RX8 BEFORE connecting it to the motor. That's what I tried to do, but no way it's not working. The RX is powered, all the servo work fine including the Hitec, but the motor don't move and the ESC seems to be dead. As I said I tried to configure it using the Hotwire, it's working, but the configuration is not stored into the RX8... the red light is blinking, the ESC restarts after the program saving, but when I disconnect the RX8 and connect it again on the Hotwire, the default configuration is again the default one. And when I connect the RX8 to the batteries, nothing happens, it's not possible to configure it, no way, the buttons do not work, no LED, nothing.

    I've been in contact this morning with wheelspinmodels in UK, I'll send the ESC and the Motor back and they will investigate, and maybe send it back to Tekin. It doesn't matter a lot because it's winter and I'll use the EVX-2 + Titan, I've made the cabling a way I can change Motor + ESC very easy, nothing to solder, only quick connections with XT60 and/or bullet connectors. I wanted to make something easy to use and being able to change the motor and ESC within 10 minutes or less. I tried yesterday... it's only a matter of 5 minutes Greaaat I'll make a video later on about that. I have to fine tune or to optimize some connections, cabling, but I found the best way for me to swap motor/esc combo when I want without any complexity I'm also able to disconnect the servo, or the CC BEC in a second to replace it in case of problem without any solder iron. Easy exchange of broken or faulty parts is needed. Serviceability, that was one of my main objective. Can be improved of course but for a first time, I'm happy and also found that it was not as complex as I thought finally! Now I feel comfortable with soldering

    IMO the Scenario 1... is the best one. And... INCREDIBLE how the torque and the reactivity changes between 6v via the stock ESC and 7,4V with direct power feed from the CC BEC! Wow... it make sense to use an external BEC, and it make sense to connect it directly, it is not more complex than connecting the CC BEC to the RX, I'm using a servo extender cable for quick connect/disconnect, soldering, heatshrink and ready to use. Without any risk for the RX or the ESC's BEC

    I think I'm unlucky with the RX8 but it happens, and I'm not disapointed or angry because of that I have another motor + esc so... no problemo I'll just have to wait a little bit more to play with the Tekin combo )

  13. #13
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    I think that I can make a tutorial to explain how I did. I kept some 3 pin connectors, just disassembled 1 cable for example, or I used some extension cable to change the gender of a connector, etc... But I'll wait until I've finished the job, meanwhile I'll make a video to show the first result of a beginner trying to do it for the first time. It's not as bad as I thought before starting ^^ But one tool is very useful: the hot air gun. I have a professional Bosch ''blue'' heat gun (LCD display, I can select temperature between 50C to 660C per 10C increments, also the airflow speed), and this is just so easy for the heatshrinks... perfect solution, in seconds, normally the default temp for the heatshrinks is 350C but @ 150C it's fine. I also love the XT60 connectors, and HATE the Traxxas connectors with 12GA cables... OMG I wasn't able to push the connector until the end of the plastic support because the cable + soldering was too big. So finally I changed ALL the connectors, including the battery connectors, to XT60. Small, secured, perfect. Some bullet 6,5 and 8mm are on the way to home to simplify some connections. I didn't bought Powerpole connectors... but I'll maybe try later.

    Message to the beginners like me: soldering, connectors and cabling is not a nightmare. It's less complex than expected, and finally after the first attempt, you'll feel better and will be able to think about future upgrades with less stress, and more flexibility!!

  14. #14
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    Hello,
    i was thinking about your weird tekin, i know you are very meticulous (i don't really know if this word exists in english) but when you've tried it, you have the sensor cable plugged in the esc and motor? or have you try a second sensor cable also the tekin works with brushed motors i would tried it with the titan 775 to see if it's working before sending him back.

  15. #15
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    Hi Droopy,

    I had 3 different sensor cables, the stock one but two others in other lenght (I bought them separately to optimize wiring depending on how I fix the ESC). I tried the 3 different cables, but as I said, the ESC LED were not working even when ESC was connected or disconnected on RX, Motor, both, etc... I tried all the possible scenarii before making this statement.

    I didn't tried to connect the Titan motor because I didn't want to deal with time consuming troubleshooting. It's not working even when following instructions and even when trying logical troubleshooting? Ok, return to the seller for investigation. That's why I chose to work only with value added sellers, it's because they have an aftersales service. The RX8 + T8 has been shipped today to UK, I'll wait for the feed back end of this week, beginning of next week.

    In my opinion, there is a real problem with the ESC because it is not able to store the configuration made using the Hotwire. So first: memory issue. Then also another issue, maybe a broken voltage regulator, a broken component ... I opened the ESC and had a detailed inspections of components, nothing was burned or was showing signs of overheating, so I can't imagine that the heat during soldering was the reason of that. It's a DOA (Dean on Arrival), it happens, it's not a problem for me.

    And... it was finally a good reason for me to try the Dewalt upgrade Because now I feel confident and confortable with soldering, so I bought yesterday 100nF capacitors, brushes, etc... some very useful threads on this forum about that, it was really easy to find a shopping list and all the details about the installation process

    Useful pictures here: http://traxxas.com/forums/showthread...alt-Conversion
    Useful shopping list and instructions here: http://traxxas.com/forums/showthread...alt-Conversion
    http://traxxas.com/forums/showthread....-LOTS-OF-PICS
    The newest product order code here: http://traxxas.com/forums/showthread...alt-motor-info (useful update!)
    And the Sum Summit from where I found the other links and more: http://traxxas.com/forums/showthread...=1#post4973858
    Also that one: http://traxxas.com/forums/showthread....-LOTS-OF-PICS

    People who say that they do not find any information about Dewalt conversion... are not very motivated because you find all of this in minutes. This forum is really a paradise for Traxxas owners who are looking for tutorials, feed backs, and support.
    Last edited by Scaniris; 01-24-2012 at 01:35 PM.

  16. #16
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    Quote Originally Posted by Scaniris View Post
    Hello,

    I've drawn some diagram with Visio this evening to summarize lots of different information I've read here are elsewhere. My goal is to ensure that my patterns are accurate, and able to have some illustrated starting point to start soldering and then discuss about programming. I also found that the information was scattered right and left, I had read a lot before assimilating, and I think that one diagram is always better than tons of text to illustrate something.

    So here it is:

    ---> Scenario 2:

    CC BEC connected to the RX
    CC BEC output voltage set around 6,4V (please ADVISE ME about maximum voltage that the RX can handle...)
    Capacitor to handle peaks. I have 1000uV but also 4700uV capacitors (both 10V of course)



    So please advise me, please correct what's wrong here, please comment. I hope to be able to get the approval for all three scenarios with all warnings and recommendations. When I'm sure that everything is ok, I'll make a summary and correct the diagrams, then publish the definitive version. It will probably help some people who are in the same situation I was some weeks ago

    Thanks for your support.
    After doing some searching, I found this and wanted to ask a few quick questions to make sure I dont screw something up. First, a BIG THANKS to Scaniris and the rest of the forum folks for input and putting it together, it has been very helpful.

    Basically I want to use Scenario 2 with the stock ESC and keep both stock steering servos for now (eventually I will go to just one). Could someone take a look at this and see if things look ok? The reason I want to go this direction is because I was experiencing some glitching/brown outs using the stock ESC with my 5s A123 batteries. I used this same setup w my E-revo brushed stock ESC and realize that the demand on the ESC with the Summit is much more. Anyway, it was suggested by most on the forums that an external BEC is recommended for battery applications over 2s-3s. The servos work fine and are adjusted properly. I did test my Summit ESC with the NiMh batteries and everything worked ok, but would prefer to use my A123 5s setup if possible without hiccups.

    Can someone please make a suggestion or comment if I need to make an adjustment?


  17. #17
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    @scaniris, I just had this happen with my rx8 esc. For future reference your esc is fine, pit tune mode maybe. I updated my esc several times and hotwire followed by some restarting of programs and then it started saving setting and beeping. Sucks but it beats sending in your power house.

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