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View Full Version : EX-5UR trigger fix & folding antenna


gctkaz
2012.02.06, 05:59 PM
I recently bought a 2nd-hand EX-5UR which had some trouble in the throttle pot, I don't know if any of you have encountered this, but forward throttle and brake work fine, but the car will not go in reverse unless the trigger is side-loaded towards the left side of the unit. I think what happens is the pot wiper gets worn down and no longer makes contact unless the pot is squeezed.

So, I came up with a cheap (free) and easy fix, just wedge something in between the pot and casing to compress the pot. I used a folded piece of plastic cut from a blister pack, easy to tune the thickness with folds, and nice low friction too, doesn't affect the trigger action at all.

Remove the trigger assembly and slip a wad of plastic inside:
http://img703.imageshack.us/img703/5521/trigger01.th.jpg (http://img703.imageshack.us/img703/5521/trigger01.jpg) http://img580.imageshack.us/img580/9640/trigger02.th.jpg (http://img580.imageshack.us/img580/9640/trigger02.jpg)
Unnoticeable when reassembled, and now I have a perfectly working EX-5UR!

Next, I read that lots of people were annoyed about the fixed antenna, but I didn't find any mods except one which shortened it to about an inch. Anyway, I went and added a RP-SMA connector and a folding antenna from a WiFi adapter. I still need to use this antenna so eventually it will be replaced with one from dealextreme.

Sizing up a panel. I used a piece of circuit board which is just the right thickness, and very rigid:
http://img855.imageshack.us/img855/4509/ant01.th.jpg (http://img855.imageshack.us/img855/4509/ant01.jpg)
After cutting & filing to size, I etched the board clean and drilled the holes:
http://img7.imageshack.us/img7/1870/ant02.th.jpg (http://img7.imageshack.us/img7/1870/ant02.jpg)
I didn't have any small screws, so I used zip ties and pulled them real tight:
http://img221.imageshack.us/img221/765/ant03.th.jpg (http://img221.imageshack.us/img221/765/ant03.jpg)
Stripped the end of the stock antenna and soldered it to the RP-SMA connector:
http://img267.imageshack.us/img267/5153/ant04.th.jpg (http://img267.imageshack.us/img267/5153/ant04.jpg)
Antenna detached:
http://img832.imageshack.us/img832/2784/ant05.th.jpg (http://img832.imageshack.us/img832/2784/ant05.jpg)
Folded:
http://img641.imageshack.us/img641/1364/ant06.th.jpg (http://img641.imageshack.us/img641/1364/ant06.jpg)

The RP-SMA connector cost me $2.24 after taxes, and I just had the circuit board lying around. Now I won't have to worry about breaking my antenna if I just have the radio in tossed in my backpack or trunk.

edit: I should add, if I still wanted to poke Steve in the eye just for fun, I still can :p
http://img109.imageshack.us/img109/8020/ex5poke.th.jpg (http://img109.imageshack.us/img109/8020/ex5poke.jpg)

herman
2012.02.06, 08:28 PM
pretty cool mod... thanks for sharing... :D

RFick73
2013.02.12, 12:55 AM
Hey Gctkaz,

Thanx for letting us know our radio was plagued with the same issue as yours!

Dave W. was unable to replicate the issue, but it was evident after this GTG.
I lent it to a newbie & we were seeing 90% of the times you went to go into reverse the car didn't move.

I just finished tearing the radio apart & following your guide.
Works 100% of the time now!

The only thing I would add is to make sure you let people know to remove the large plastic loop/radio rest at the top of the radio as there are two hidden screws under it!

Took me some prying & wondering why it wasn't moving.
The I kinda just tugged on it and wow, look.. Two more screws! =/

The Club thanx you for the guide!

gctkaz
2013.02.15, 03:49 PM
Whoops, you're right about the plastic loop. I'm not quite sure what it's there for...

Since the thread got bumped, I think I will take the opportunity to ask some of the other experts here about the antenna.

Is that antenna any kind of special coaxial antenna? I'm just a bit concerned that stripping the end off and soldering it to an RP-SMA connector as if it were just a normal stranded wire isn't exactly proper.

Personally I have not noticed any negative effect and I don't even use the external antenna any more, but in the interest of doing things right, I'd like to know if it's safe to treat the antenna like that.

TheSteve
2013.02.15, 05:16 PM
Generally speaking just adding additional length to an antenna as you have done is not a good thing, however 2.4ghz RC gear is quite tolerant to such things. Also the range needed for a MiniZ is pretty short. So if its working for you then its all good(but don't try it with a transmitter that puts out real power)