4200 Excavator problems

[gmmiller06]

Hey everyone. I just started having some electrical issues with my earth digger. It will work ok for a few minutes and then it starts doing several things erratically at once. It moves the digging arm, rotates, and the tracks move all at once without my input. After a second or two of doing that(I immediately turn off the hydrualic pump when it occurs) it will stop moving erratically but if I switch the hydraulic pump back on afterwards it is very sluggish.
After I disconnect and reconnect the battery it works normally for another minute or two and then the same thing happens. Also, I noticed that it seems to run fine and the glitching doesn't happen if I don't use the hydraulics after switching the model on. Any suggestions on what to check first? I was thinking the brushed esc maybe since the servos and rotation use it. I really haven't been able to find much info on it.

[Cooper]

I would systematically unplug servos, turn on check, I had similar and a cooked servo was the reason. Also do track esc and pump esc. One at a time. And also make sure battery is good, but I would bet it is a bad servo giving electrical interference feedback.

[osikasculptor]

Servo needs to be replaced! I was going crazy trying to figure it out it is just one of the servos and it will be good to go..cheap and easy replacement.

[gmmiller06]

Thanks for the quick replies guys. I will surely check out the servos first thing. I seem to have read someone else having a servo issue and experienced similar. I will update on the cause once it is pinpointed. Hopefully it's only a servo!

[osikasculptor]

I bet it is because mine did the same thing and a few of us had no clue until we experienced the same thing with servos. It seemed to make no sense..pump barely running..tracks moving backwards..but as soon as the servo is replaced all normal. When you replace it..make sure to center it.
Power up then with trim on radio at zero -move the control by hand so what ever function it's on-floats in neutral..or as close as you can get it then pop the servo in. It always moves a tad because of the gear but if close you can trim it manually.

[thebigo]

I am sure it's happened to all of us, but make sure you put a rag or something under the pressure regulator when you are operating. It leaks from some where in these connections, haven't found out how to correct mine yet?

[gmmiller06]

I will be checking into the issue hopefully sometime over the Thanksgiving holiday. I am sure it is probably one of the servos based on all of you guys input. Does anyone have any recommendations on possibly upgrading to a better servo since I am replacing it anyway most likely? Or should I replace it with another servo of the same type? I also have a video that captured the malfunction twice the other day. If you don't care to see the whole video the malfunctions happen after the 10 min mark in the video.


https://www.youtube.com/watch?v=kwEUVxiwz-Q

[thebigo]

I bought the same servo, I think it was the upgraded or newer servo to the one' that came with it, I think i got it from tower hobby, or one of the larger hobby supplier's, just get the model number off of the old one and one of the hobby sites will tell you which one is the upgraded version of that servo.

[osikasculptor]

They are cheap enough and last long enough in my view not to worry much about it..I only had to replace one so far. Let us know how it goes!

[Rimrock]

There is nothing special about the original servos for the xl4200, they are one of the most common used sizes out there and the cheapest ones the fabricator was able to pick up in a 'Shanghai roadside sales stand a Monday morning'...who knows Just a matter of finding the same size when replacing one, TowerHobbies, ebay and so on.
When were're at it..if needing to replace a ESC in the future...The original speed regulators on the 4200 are way oversized, and draws more 'standby/idle power' and gives more 'waste heat' during operation than necessary, like 1 Amp + total. The (oversized) pump motor is the largest motor on-board, and draws up to in the neighbourhood of 10A in this set-up. The fabricator have chosen a 150A ESC...In an airplane one would take out 50 Amps + from the same motor, so one would need a big regulator there for sure..The ESC for the track and swivel is rated at like 160A (!!) but the motors draws in the neighbourhood of up to 2-3 Amps each..All these original regulators are cheap though, but one could have used other cheap smaller ones in order to get the battery last longer.

[Rimrock]

Originally Posted by Rimrock

There is nothing special about the original servos for the xl4200, they are one of the most common used sizes out there and the cheapest ones the fabricator was able to pick up in a 'Shanghai roadside sales stand a Monday morning'...who knows Just a matter of finding the same size when replacing one, TowerHobbies, ebay and so on.
When were're at it..if needing to replace a ESC in the future...The original speed regulators on the 4200 are way oversized, and draws more 'standby/idle power' and gives more 'waste heat' during operation than necessary, like 1 Amp + total. The (oversized) pump motor is the largest motor on-board, and draws up to in the neighbourhood of 10A in this set-up. The fabricator have chosen a 150A ESC...In an airplane one would take out 50 Amps + from the same motor, so one would need a big regulator there for sure..The ESC for the track and swivel is rated at like 160A (!!) but the motors draws in the neighbourhood of up to 2-3 Amps each..All these original regulators are cheap though, but one could have used other cheap smaller ones in order to get the battery last longer.

Must adjust my numbers a bit; newest versions has 125A for the pump motor and 50A continuous, probably over 100A temporary, for the other motors..) Anyway, you got my point

[Cooper]

If I remember correctly, the problem I had with servos, the threaded internal end of spline (where servo arm would normally attach) is hollow and allowed leaking oil to enter servo case and short circuit the dial pot or micro electronic board. Some electrical contact cleaner probably could save it. But I replaced anyway. Suggestion is if servos are hollow shaft and no screw is inserted into shaft then put a spot of silicone to plug the hole. Should not have oil present to even leak into there but that is another story