RCMC Lansu 3 channel 2.4 radio problem

[sgl]

Hello, I have the Redcat Sumo 1/24th about 12 months old, with the 3 channel Lansu 2.4 radio, using the PCB Rx/ESC integrated unit. I am having a problem with severe steering jitters. Initially it was right hand turning now it is both and all on 4ws. Problem persists with new batteries in Tx and fully charged Rx batteries. I was wondering how to trouble shoot the problem aside from replacing with new units? As the rx is solid state there are no contacts to clean. Is there potentially anything in the Tx that needs to be cleaned?
Thank You
I imagine it's obvious I am new to this and appreciate the help.

Redcat Sumo Crawler,
stock with Lipos

Losi MRC Pro.
Brushless, Lipos, Flysky GT3b
Stock configuration
Just finnished

 

[braq]

Hi,

stock it comes with battery holders for 4 cells, aka 4.8V.
While it does accept 2s LiPo as power source (the motor driver stage is an AF4953 which has a GateSource Voltage of 25V max), the voltage for the Rx itself is run through a B772 with fixed resistors. I guess that means the Rx voltage is higher with a 2s than with 4 NiMh cells (you might want to measure the voltage on the servo outpus with both configurations).
Here is what I did (after the B772 blew up),
soldered in a standard 5V regulator after the switch. Still the servo would jitter and i assumed they can't cope with 5V, so I switched the servo to a standard micro type. Everything works fine ever since.
You can also find this on the 4x4 scaler forum under Micro Trux,

cheers

braq

 

[sgl]

Thank you, I'll run the checks, Any recommendations on the regulator, durability etc, or just off to Radio Shack or Fry's?
Sgl

 

[sgl]

Checked voltages , the 250Mah metered out at 4.9 pretty much what the 4 aaa metered out at. I swapped out a pair of old Hitec micro hs 60's . The problem still persists. The Rx looks good no discoloration all traces look good, I had always thought when something on the boards goes bad it simply fails and no longer works? I haven't looked at the Tx and wonder what to expect behind the wheel , contacts. potentiometers or what? By the way the previous advice was great went ahead and ordered a reg. I know lots of folks just junk the radio and go with something else. I really wish to stick with the stock electronics, they had worked well and clean install. I would prefer to fix what I have if for nothing else but the learning experience. Also the replacement Tx from Redcat actually goes for around $100.00 and you can get a new complete combo for near $90.00 and haven't seen either used. Thanks again.
sgl

1/24 RCMC
Losi MCRC Pro

 

[braq]

yes, usually one thing changes its value significantly (aka short or no connection).
Hm...I used a standard 1A regulator and standard micro servo.
Can you reach a good working system by using 4 AA batteries (stock or alternative servo), leave of the motor connection so it does not induce noise? Might want to check that the very short antenna lead is still soldered in place. I have not checked the internals of the Tx, however your problem sounded very much like the one I had ,

cheers

braq

 

[sgl]

Braq, I actually did what you suggested, original battery pack and swap out a servo, with the exception of reducing noise from the motor connection. Thanks again
SGL

 

[braq]

all right, but the jitter is still there (and was not from the beginning)?

 

[sgl]

Yes, it's still there and as bad as ever. I think it's time to disassemble the Tx. It looks pretty straight forward, the only concern I have is removing the wheel from the shaft. I an assuming it is a simple press fit as there doesn't seem to be a cap to cover a screw head. Thanks for all the help I'll let you know what I find.
sgl

 

[sgl]

I went ahead and opened up the Tx last night but wasn't able complete the dis-assembly. I couldn't get the wheel from the shaft. I reassembled the unit and find that works probably at 95% of new. Meaning there is still a bit of jitter at times and I suspect the improvement is tempprary. I would appreciate suggestions as I still need to get in there and replace the faulty component, although at this point I would be interested in a good used unit just in case.
sgl

 

[Charlie-III]

Cheap possible fix??!! Get a can of "contact cleaner" (electrical type....not EYEBALL type:shock::roll:....:mrgreen and soak the steering pot/pots and work them through their full throw.
Then, test & see what happens.8)

 

[sgl]

So it's simply a traditional pot? I had wondered about that, and about the contact cleaner. What I have isn't to gentle on the eye's (don't ask how I know:shock. I also have a aerosol can of electrical lubricant, it this something I should use afterwords or something to avoid? It is designed to improve conductivity.
Thank you
sgl

 

[sgl]

Thanks everyone for the suppport, I cleand unit with contact cleaner there was a slieght improvent but not 100 % . Any ideas about obtaining a new pot to replace the iffy unit? and jas anyone had a simular problem on this or another radio? I guess I should pick up a used LanSo for a replacement or maybe for the parts needed. I wonder if the stearing pot is simar across there range?
Thanks agian
Sgl

Redcat 1/24 Sumo Rock Crawler
Losi Mini Rock Crawler Pro

 

[Charlie-III]

Thanks for the update, glad it's better.8)

Not knowing the internals, I can't give direction on a replacement steering pot.

You may be able to measure the resistance across the pot, then try Radio Shack to find something you can make fit.
As to getting an original pot, not real likely. Even if you could, it's likely not cheap.

But hey, it's better and you have some time to research.
A picture of the existing pot may help one of us give direction.

 

[sgl]

Thanks, it looks like the only way to
ake ot function perfect is to place wheel under a little tension ( as pulling on wheel to remove it ). I will disassymble it and take a picture of the pot, hopefully that get the answer I need re: replacement ppt. I would prefer to avoid Radio Shack if possible, as the local store have been less than helpful in the past. I now newd to find a manual as well ( my little disk has disappeared) simple to change the throttle channel from reverse to normal function. I know it should be a snap but for some reason I can't remember the sequence.
Thanks sgl
Oh Happy Thanksgiving

 

[sgl]

Hello,
Cancel the assist on the reverse issue, figured out the controller buttons. I am
absolutely positive I'll find a manual to down load, now the immediacy of the problem is gone.
All else remains the same I'll snap a few picture of the pot and post tomorrow as it's almost time for guests to arrive for dinner.
sgl

 

[braq]

thanks for the update, shouldn't be too hard to measure out the value for the potentiometer, I'd expect something like 2.5K Ohm, but we'll see. Usually they are the same value for steering and throttle. As I haven't had the Tx open yet, please check if there is a pin/connector for CH3 (the third channel, which stock is just a button to direct the steering channel onto the third 3 channel on the receiver). If there is, one could use a 3rd (same value as 1 and 2#) pot and run channel 3 independent from the front steering.

cheers

braq

 

[sgl]

Hello,
I haven't had the opportunity to take the Rx apart yet, I should be able to get to it today. I will post details of both the Pot and details on the third channel.
Thanks

Sgl

RCMC Sumo 1/24
MRC Pro

 

[sgl]

Braq:
The 4ws button is momentary as you know and attaches to the main with a two pin connector. The switch leads are fortunately is not soldered to the board and pin spacing is 2 mm. Hope this helps. The real problem for me is removing the board with the Pot on it. The wheel has both a screw in the center under a press cap and a/white loctite/glue. The point where the shaft come though the case has a nice metal sealed bearing . Unfortunately it is very tight fit between the shaft and bearing and I haven't succeeded in pushing the shaft off the bearing and out of the case, I dislike the idea of damaging the pot to remove it, any suggestions?
sgl
P.S pictures will be taken when the units removed, depending how badly damaged it is!

 

[sgl]

Hello:
I'm getting a reading of 1.65K ohm, does this sound reasonable or am I looking at pilot/tester error? I was thinking I should be in the 2.5K to 5k range.
Thanks
sgl

RCMC 1/24 Sumo
MRC Pro

 

[sgl]

Hello,
What is the proper way to meter this pot? I have been unable to force it out and would rather not until I have a replacement in as I am certain the pot will damaged.
Thank you
sgl