JR XR3 3rd channel mixture

[topfuel443]

Any body using a JRxr3 for use with a 3rd channel mixture? Im using mine on my rigger but it seems to move so slowly when adjusting it. I am going to try and steal a round dial out of one of my old futaba radios and put it in place of the slide button. that way all I would have to do is crank the knob one way or the other. I love JR radios but this is kind of a pain. Does this function work ok for everyone else on the Xr3? ~ James

 

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Topfuel,

Funny you said that! I'm setting mine up right now and was using a mini servo, same radio as yours. I was thinking wow this servo is so sloooowwwww. I created a new servo tray out of wood for a standard servo thinking this would solve the problem. Now you got me thinking??

How effective if at all is it for adjustments while your running the boat?

 

[TimD]

I'm using an XR3 (not the newest one) with the 3rd channel for mixture. I found the position of the 3rd channel trim on the transmitter to be unsuitable so I swapped it with the one used for steering rates.

To do this I had to unsolder the wires from the board and swap them around - works great now.

You cant replace the stock slide button with a slide pot. The XR3 uses 2 buttons on the underside of the slide button, one for up and one for down. The transmitter is looking for the button to go closed circuit to make the adjustment. A slide pot gives variable resistance depending on position rather than giving a closed circuit for each button press. Put simply the transmitter won't understand a slide pot.

For the movement of the 3rd channel - it is slow but accurate. Set the linkage on the outermost servo horn hole and closer to the pivot on the needle valve - that will make each gradation on the TX move the needle valve further.

Hope this helps.

 

[Altimat]

I'd plug it into steering before changing a TX knob. The servo should keep up unless the needle is tight. I did a ton of work on my needles to free them up (2 on one mini servo), and still had to go to a HS5245 Hi-Tech Digital Min for enough power. Only a mini will fit in my radio box.

http://www.hitecrcd.com/Servos/hs5245.htm

 

[topfuel443]

Hey Tim, thanks for the info, you answered a question that I was about to find out for my self. I pulled a couple rotating potentiometers (three prong) out of one of my old futaba radios today. I was about to open up the JR to see what sort of setup it had and see if they would work. Are you sure there are two normally open switches there? one for up and one for down? makes sense now that you mentioned it, just checking before I ditch the idea. I know of a few guys that moved the the swithces around, putting the 3rd function closer to the wheel. I have not heard of any one actually swapping the function controls though like you mentioned. You said it works much better now, in what way? is it faster? or is it just more convienent to use because of the position. It seems as though the steering rate and 3rd function switches do essentially the same thing. kinda like two switches, one up one down for each slide switch. does the steering rate increase at a faster rate than the 3rd function switch? can you be more specific as to what you did? Im sure it will be more obvious once I get it open, but till then....(not at my house right now to open it.)

Altimat, I am using a hitec Digital Feather Light that I use for all of my throttle servos, its got plenty enough torque to move the needle, it just that the radio function doesnt adjust it fast enough from one end of the travel to the other no matter the speed of the servo. I actually have plugged it in to the steering slot and it works great and really fast.....Any other Ideas ?

Thanks Guys ~ James

 

[rcboatlover]

Hey guys, I just bought a JR XS-3 ! This is the new one that allows you to select any channel you want. I'm not setting it up for a remote needle, but I plugged in a servo just to see how it would work. I see what you are talking about! It takes way too long to move the servo!

The problem is that with each click of the button you only get 0.3 degrees of movement. I'm starting to wonder if digital trims are all that good. I liked the analog ones that moved as fast as you could turn them!

 

[Ron Olson]

I asked this question back about a year ago. I went to one race and tried to adjust it on the fly and it took at least 3 laps to get any change at all on the 3rd channel. I pulled the servo out because it wasn't doing me any good. i'm glad that somebody found a cure for this. Want to work on another radio? I've got some old Futaba's in my basement.

 

[TimD]

Are you sure there are two normally open switches there? one for up and one for down?

Yep, I double checked it with a DMM. One button for up, one for down on the third channel trim.

The 3rd channel buttons are on a separate board to the "main" TX board. On this same board are 2 buttons for the steering rates as well. I just swapped the wires for the 2 3rd channel buttons around with the 2 for the rates. I DID THIS PURELY FOR EASE OF USE - there is no difference to the travel by doing this. I was finding it difficult to reach the original 3rd channel trim when racing - especially with the 67 rigger.

I actually like the needle setup being less sensitive thru less travel per click. It took some getting used to but once you have the needle in the ballpark you don't have to adjust it far to get the right tune (a flow meter is handy too! but not essential) I'm using it with a fuel doctor type valve.

Hope this clears it up a little.

Tim.

 

[topfuel443]

Tim, after re reading your post i realized that was what you were talking about(just switching the location) I realize that the switches are not the resistor type, but wouldnt you agree that once the "switch" is pushed to the left or right and the circuit is closed. There has to be a pot somewhere along the circuit, probably on th board it self thats causes the adjustment to be slow or fast? if there were no resistance (variable or not) other than the small amount in the circuit it self, the rate would go imediatley full up or full down. Now I just gotta figure out what controls that. Ill take a look at the circuit and traces tonight, cant be that complicated of a CCA. Thanks ~ James

 

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well after reading everything today I guess it's not the servos. I did try the standard versus the mini and other than getting more throw you don't get much more speed. On my Futaba PCM and Magnum Senior you can really make it open and close the third needle very fast which has it's advantages.

I'm gonna try it anyway but am a little concerned that Ron didn't have much luck w/it until the race was almost over. I'm gonna use a Fuel Doctor third needle but they don't have a lot of room for error and must be set up exact before you hook up your linkage. Disadvantage is unlike a Bob Violet you can't do an adjustment by hand on the bench.

 

[topfuel443]

OK keep in mind that I am a Biomedical Tech. with five years of college in electronics.

Any body ever hear of ESD? Electro Static Discharge? well it what happens when static electricity builds up in the human body and whatever you touch gets hit by the voltage. it can be anywhere from 20,000 to 60,000 volts (low amperage of course) Its happened to everyone who has touched a door knob on a really dry day.

Well this morning before going to work, walking around in my socks on my freshly vacumed carpet, I built up static electricity...... Shortly thereafter I decided to pull apart my JR Xr3 radio to have a look see as to what could be done to fix our problem. As soon as my hand hit the circuit card.......ZAP! a nice blue arc right next to the small CPU chip. I had an entire course on this in college.......... Radio is now a mantle peice......Yes im stupid.

Actually I just left the hobby shop, I got them to send it in for "warranty" repair and decided to buy another radio while I was at it. I bought a Futaba 4channel stick radio. I have been wanting to try a stick radio just for the heck of it anyway and this will solve the slow moving servo problem. Its pretty cheap too...4 servos (standard), radio, Gigantic 7 channel receiver (probably wont use) switch, servo extension, nicad pack for receiver, nicad pack for radio, charger for both, servo horns, and a servo tray for use with whatever, neck strap . all for 159.99 I put it in the boat, and am using the trim for airleroins for the adjustment, or if I need to make a bigger adjustment, i just pull bak on the rudder stick. the 3rd mixture moves as fast as I can move the stick. ~ James

Maybe this should go in "stupid moments in R/C boating" im not having a good week so far.

 

[Finne]

sounds like a pritty good deal for 159.

I was starting to think I'm the only one left in the world useing a stick radio.

(2 channel HiTec.... yea it's ok to laugh)

But man I have to tell you. You're not the only stupid one out there. I'm a computer sience student. And I know all about the touching the chassi before messing with the hardware and stuff... but do I ever do it? naaaaaaa. "ok. let's pull out this processor.... *ZAP* ouch! hey!"

 

[TimD]

There has to be a pot somewhere along the circuit, probably on th board it self thats causes the adjustment to be slow or fast? if there were no resistance (variable or not) other than the small amount in the circuit it self, the rate would go imediatley full up or full down. Now I just gotta figure out what controls that. Ill take a look at the circuit and traces tonight, cant be that complicated of a CCA. Thanks ~ James

James,

The problem is you are thinking of it in Analogue terms. This radio operates with digital inputs. In other words it has a processor that when told that Button "a" goes closed circuit that it shifts the servo by distance "B". Distance B is determined by the programming in the processor - not by a resistor pot in the circuit. The only way to change distance B relative to servo travel is thru changing the program - not an option to us mere mortals.... To prove my point there is provision on the XR3, thru the menu's to change the 3rd channel settings to work for transmissions on r/c trucks. The Xr3's bigger brother - the R1, has a lot more adjustments including for the 3rd channel travel.

ESD is nasty stuff - we have problems with it in Digital Photocopiers all the time. I guess I'm so used to dealing with that stuff that taking ESD precautions is second nature to me. Sorry for not reminding you earlier..

 

[topfuel443]

Yeah, I see your point, once I got inside of it and saw the CPU, I knew it was more to it than I intitially thought it was. It all makes sense, I just had to see (and touch) for myself. My ESD strap was in my day planner a few feet away..... just a brain fart I guess.

Thanks for the input.

~ James

 

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fuuummmmm fuuuuummmm smells like Chicken!

That sucks. Good thing you weren't standing in a puddle. LOL

 

[Propjockey]

We called that a 'smoke test' in electronics school!

 

[topfuel443]

thats right, once you let it out, you cant get it back in......

 

[TimD]

Ahhh yes, the compressed smoke!

 

[rcboatlover]

Topfuel, Your new radio is a surface use only type right? I would be careful where you use that. People sometimes fly planes at the park I go to.

 

[Ron Olson]

...not to mention illegal!