Anomander

Broken (?) technic servomotor 88004

Recommended Posts

Hi all,

I'm new here, but been an AFOL for a few years after my "dark ages". I'm a collector - I like the big cars and constructions machines, so recently I decided to get the Crawler 9398 before it goes out of production and get ridiculous prices... I really liked the suspension, looks and the possibilites with the PF parts that we get in this set.

So I got a new one, and unfortunately the servomotor (the one used for steering) seems to broke after just 6 days (I still used the 1st set of batteries on it, it wasn't used in any hard conditions or abused in any way, used only indoors). The servo does not autocenter anymore after releasing the controls. This is my first IR remote set, so I don't have many ways to troubleshoot if it's the servo or the IR receiver fault (tried both channels, new batteries, didn't help). Wrote to lego support, but I don't have any proof to show that I bought this set recently (lost the docket), still didn't get any reply from them (it's 4 days). I took a look inside the servomotor, there was a lot of white grease inside it, removed most of it and it started working again after reassembling, but then finally broke the next day (again no autocenter, this time for both directions). I made a youtube movie that shows how it behaved before I took it apart - has anyone seen something like this, is there any fix?

I must say I'm a bit disappointed with this set and lego quality - my previous 'flag ship' 42009 came with 2 missing parts, and now this...

Share this post


Link to post
Share on other sites

Removing the grease was not a good idea, should try and put it back.

Now, those motors only auto-center while still under power. If somehow you turn the motor all the way to either position, then cut the power (disconnect the cable), it will NOT return to center. That is why, even in the crawler's instruction book, they show how to zero such motor before installing it. In summary:

1. Put grease back.

2. Return to center (zero) only happens when motor is still under power.

Edited by DrJB

Share this post


Link to post
Share on other sites

Not sure which country you are in - LEGO provides different support level, depending if the are official stores in that country or not. Waiting for reply isn't always a good idea, you should better call them and sort this issue while on the line.

Btw, the logic behind replacing damaged parts is to keep them as they are - do not disassemble - otherwise void of warranty and no way for LEGO to figure out the initial problem with that motor.

Share this post


Link to post
Share on other sites

The finger is there only by coincidence, I was recording with one hand, and had to keep the pilot in place :)

The setup in the video is [power box] <-> [iR tower] <-> [servomotor].

I've turned off the power at the very end (shown) and put it back again to show it does not autocenter from this position.

I'm unable to zero the servomotor using the instructions given in the 9398 book, it's just doesn't happen anymore. In the movie the servo was ok when turning to one side, then it went back to center. When I tried the other direction it would go there, and get stuck. The only way to move it from there was to use the opposite direction on the pilot.

I can put the grease back again (I can understand it is needed longterm, removed it because I thought it may cause some connection problems between the copper path and the arms that move with the head of the servo), but I'm sceptical about it (I don't think it will solve the issue). Will update you once I try it out.

Edited by Anomander

Share this post


Link to post
Share on other sites

Wow, Lego just contacted me and offered a replacement (it will take 2-4 weeks, but I understand, no problem). I had a second case opened with them when I described them how the insides of the servo looked like when I removed the grease and that it solved the issue back then (I was sure it was it, was surprised when it got broken again next day). I never denied to them that I was trying to fix it by myself - they had all the right to not helping me and I would understand that. I'm very impressed by this gesture of good will, and I will surely recommend buying Lego sets to my friends, knowing how good support they will get, even with something goes wrong.

Please don't overuse this...

Share this post


Link to post
Share on other sites

Customer support indeed works great. They replaced my servo with no questions asked. Mine rapidly jumped from one postion to another.

Share this post


Link to post
Share on other sites

interesting looks like it can be made to go all the way round

It would be hard - the motor itself moves in any direction for a limited time (~1s) even when there is no physical limitation or force - it just stops, must be some electric safety measure. Because of the huge ratio of the planetary gears, this 1s move is not enough to move the head of the servo all the way around... speaking of which - there are plastic pieces that limit the movement of the head (the piece that you put axles into) to roughly 90 degrees in any direction, so someone would have to literally carve in the plastic mold to remove it...

Edited by Anomander

Share this post


Link to post
Share on other sites

I have problem with 2 Servos now !!!

Same as in Video in the first post of this Topic. Servos turn to one side but do not return to center... turning and returning to center to other side functioning OK... only one side does not return to center... When it happend to 1 my servo last week I was sad... But today it happend to 2nd Servo and I'm asking what it does mean???!!!

I'm really worried now that think that Lego made a Construction Failure???

I'm really sad now...

Anyone else with same experience?

MaxSupercars

Edited by MaxSupercars

Share this post


Link to post
Share on other sites

My servos are only 1-2 months old... I don't understand that...

I bought third servo this week... when it goes broken I will be crazy...

MaxSupercars

Edited by MaxSupercars

Share this post


Link to post
Share on other sites

I have problem with 2 Servos now !!!

Same as in Video in the first post of this Topic. Servos turn to one side but do not return to center... turning and returning to center to other side functioning OK... only one side does not return to center... When it happend to 1 my servo last week I was sad... But today it happend to 2nd Servo and I'm asking what it does mean???!!!

I'm really worried now that think that Lego made a Construction Failure???

I'm really sad now...

Anyone else with same experience?

MaxSupercars

mine broke and now 1 side turns normal and the other returns to the 1 side then back to the other and than 1/3 to 1

Share this post


Link to post
Share on other sites

Try customer sevice, they sent me a new one without asking further questions. Mine was jumping rapidly from one side to another...

Share this post


Link to post
Share on other sites

I didn't send anything back, they didn't ask me a thing about it. A new one was in the mail in about three weeks after I told them of thr malfunction. And yeah, you don't go tell'em that you drove it to the water...

Share this post


Link to post
Share on other sites

I heard, that sometimes they ask for photos or set receipt, but I guess you have those... I'm from Slovenia and we don't have S&H or phone customer service, so the only option is their website form for filing a broken piece. It seems they don't bother to much about our little country, since I also received new Eiffel Tower BI after the one from the box totaly fell appart. Again no questions asked... Good luck.

Share this post


Link to post
Share on other sites

BUMP

Sorry for reviving this thread but my servo motor broke a while ago but I waited to contact Lego because none of my projects needed it. I contacted them 2 weeks ago and they have not sent me anything back...... has anyone else had this happen to you? I have heard people say it takes them awhile but this just seems way to long. Or I am just impatient :)

Thank you

Share this post


Link to post
Share on other sites

BUMP

Sorry for reviving this thread but my servo motor broke a while ago but I waited to contact Lego because none of my projects needed it. I contacted them 2 weeks ago and they have not sent me anything back...... has anyone else had this happen to you? I have heard people say it takes them awhile but this just seems way to long. Or I am just impatient :)

Thank you

Yes, you are ;)

Edited by Vodnik

Share this post


Link to post
Share on other sites

I decided to use this thread instead of creating the next one.

My servo works fine, but not perfectly. When turning left, it works good, the sound is like it did originally (identical to the sound of servos I saw on YouTube). However, when turning right, it makes an ugly noise, like it was overloaded. Was is strained somehow or something? My RC model bumped into something once or twice.

The noise occurs both when I rotate it right and when it autocenters from left position, either on loaded (geared) or lose (standalone) servo. The rotation iteself is fine, autocenters perfectly and both left and right turns are 90 degrees as they should. But I live on this technology-filled globe long enough to to be worried about a machine that starts making ugly noises.

What can I do? Some lubrication is necessary?

Edited by Immo

Share this post


Link to post
Share on other sites

After two weeks of usage, my servo started jamming at one side, and not going back to center.
Long story short, I found the solution. 
The root of a problem is a small gaps between contact pads. I've marked them yellow on the attached picture. After intensive rotation copper smeared between two pads, and they become short circuited.
Solution is very simple - clean the gap with knife or so. 

Of course if I was able to send my servo to LEGO I'd rather do that.

 

servo_problem.jpg

Edited by Winter Terapy

Share this post


Link to post
Share on other sites

Good solution, my servo broke so I took it apart and I found that the wires somewhere in between the lego plug and the motor has become stripped out, it was just a simple, cut the wires and re-solder to make it work again.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.