New Maverick Blackout XB - servo fail - expected?

[Martyn_T]

Dear all,

 

I've just bought the Maverick Blackout XB and had a reasonable 10 minutes use out of it (breaking in the engine gently) and used about 2mm of fuel!

 

So far, bearing in mind I have driven it on grass only, it has a split on the rubber tube between the muffler and exhaust/tail pipe.

 

The next time I started it I could only get it to run after pressing the brake first (sort of got some momentum into the throttle).  Now it won't throttle at all.

 

A mate who knows much more about this than me has looked at it and diagnosed the 9kg throttle/brake servo has failed. Which made sense when he demonstrated it to me and explained what it should do.

 

It is still under warranty (owned it 5 days!) but do you think I have just been exceptionally unfortunate or is this par for the course with Maverick?  In my ignorance of R/C I though 600 notes was a lot of money.  Guess not :-(

 

Thanks for any comments or observations. 

 

 

Martyn.

[Oh How Original]

If you didn't set the end points up correctly it's not hard to burn them out.

Yes

[goldman]

As already said it pays to check everything to start with,but when someone is new to this,and as rightly said (

Edited March 23, 2014 by goldman

[Martyn_T]

Yeah - spent the evening reading through the threads and it looks like it isn't uncommon for this to be a (another?) weak link. 

 

I've emailed the shop and see what they say. 

 

I appreciate there is a learning curve involved in this but the literature does say add fuel and batteries and you're off.  I've deffo learnt more over the last few days via YouTube and these forums than by talking to people but ultimately, I think you learn a lot by doing (and making mistakes). 

 

Thanks for advice both. 

[Oh How Original]

It's best to research something before you buy, I'm not trying to be hard on you, but companies will put crap on the box to sell you it, they're making a profit from you.

That being said, if the shop didn't explain this to you, that's on them as well for selling someone with little to no experience a large scale RC.

I presume you've not got a remote killswitch either? Again not having a go or anything, but if you're not, then get one, provided you've got 3 channel radio gear, if not, you'll need to grab that too, last thing you want is a run away, then the servo will be the least of your worries lol, it won't stop until it hits something.

Remember, theirs no such thing as a stupid question, if you're unsure about anything, all you have to do is ask, theirs a lot of very knowlegable lads on this Forum

[Rossyra]

I don't think it's reasonable to expect your servo to fail after 10 minutes, even for a cheap box-in one. If the shop has any shred of customer service they should replace it. As already said, make sure you have your end points set correctly so that the servo isn't trying to travel past the limit of where it needs to.

[Oh How Original]

I don't think it's reasonable to expect your servo to fail after 10 minutes, even for a cheap box-in one. If the shop has any shred of customer service they should replace it. As already said, make sure you have your end points set correctly so that the servo isn't trying to travel past the limit of where it needs to.

 

You could have a

[Rossyra]

I agree, I don't know that it is user error though, but best to be safe

[Oh How Original]

Indeed, but it most likely is in this case, if a servo arrives faulty which can happen, then 9/10 it simply won't work from the off

[Martyn_T]

Hi again,

 

Yeah - once bitten and all that. I did explain in the shop that I was a complete novice and had never owned a RC before but was interested in this model.  The guy in the shop unboxed it and showed me all the different components (all the time me saying - yeah, OK but I don't really know what you're showing me). 

 

There was no advice with respect to setting up end points or anything... and breaking in the engine info was actually taken from the manual. 

 

I am a complete novice when it comes to this so thanks for the advice OHO.  I asked about the failsafe and was advised it comes with a 'basic' one and that anything extra wouldn't be necessary.  Strange - they could have made a few more quid out of me at that time. 

 

OK, first stupid question coming up: would the range go to the 'end points' even if I wasn't even revving it hard?  If you want to picture my driving think 'Miss Daisy' rather than Colin McRae.

 

Thanks, as always.

 

Martyn. (aka Driving Miss Daisy)

[Rossyra]

If your end points were left at the default, then it would be set for 100% travel in both directions. This is something you set on the radio.

 

Chances are your throttle and brake links will not need all of that travel, say at 80% you have wide open throttle, that's where you should set your endpoint. If the link can't physically travel any further it will push your servo to the limit, and most likely burn it out as it tries to reach a point it can't.

 

If you were running at less that 50% throttle, it seems unlikely to me that you have burned it out in this way.

[Rossyra]

That said, the same goes for the brake, so if your brake was set up the same, that could have burned it out just the same.

[MarkW2014]

On my Maverick XB I used my heli/plane tx on an ar400 rx and adjusted the throttle servo endpoints and mine still failed....

 

I was interested in what was wrong with my servo and seeing as it was replaced under warranty stripped the failed servo down.

 

Once I got it stripped down to the can soldered to the PCB I could feel the output shaft was solid as in it wouldn't move. I envisaged the stator and commutator being burnt out and melted/welded to each other...

 A lot of playing with it and I felt the output shaft start to rotate back and forth freely -  so I removed the can expecting to see a burnt mess at the electrical end.

The windings on the output end (opposite end to stator/commutator) had become loose and moved over the plastic washer to get jammed in the bush at the other end. The rest of the servo was was ok.

 

Conclusion: Windings not correctly wound.

[Oh How Original]

With regards to the failsafe, a failsafe is no good on a 2 stroke, a failsafe is for a nitro and it applies the brakes in a case of the battery being disconnected or losing signal.

A remote killswitch (which is what you need) actually goes to the coil leads and when you lose signal or the battery dies it actually cuts the spark completely, so if the engine starts revving it's nuts off, it doesn't just burn the servo out by trying to apply the brakes, it cuts the engine and problem solved

[iwik76]

The blackout stock servos are pants they are prone to go regardless of end points. best invest in a better servo I know you've paid a good chunk of money but it's less of a headache to buy another and get the enjoyment out of your new 1/5

[Martyn_T]

Thanks for everyones advice.  I'll look at getting it sorted.  I know there are better vehicles out there (at a cost) and will look at getting a better servo once this is sorted.

 

Nitro-someone (sorry - forget his name) wrote some advice on how to set the end points on a different thread but maybe they'll show me how it is done in the shop - or alternatively I'll be asking again once I get a replacement servo in there.  

[Oh How Original]

If they didn't advise you to do it in the first place, I wouldn't trust their advice on setting the servos up.

It's not hard to do, you simply go into the EPA settings, turn it down to around 40% to be on the safe side (for example setting your left steering end point) then turn the steering all the way to the left, slowly increase the end point setting while the steerings on full lock, once it gets to a point where it won't move anymore, dial it back about 5-10% to be cautious you're not fully maxing the servo, and to the same for all the others it's very easy once you've done it once... If you really want, I could make you a quick video, I'm sure theirs others on how to do it though.

[Martyn_T]

Thanks once more for the advice.

 

I took it back to the shop this morning and they were apologetic about the servo failure.  They have replaced it for me with an 'uprated' one and given me the receipt for that. They have also set the end points for me. 

 

I've brought it home and eventually fired it up (it has only had about 10 minutes run time so far from new).  The engine sounds sweeter now.  Before it was a bit like an angry mosquito but now it more like a contented bee. 

 

Then I found when I increased throttle the engine just stalled... boo! 

 

After a few online searches I checked the fuel vent on the cap was ok (I guess a pin in the top and pressing the rubber bit underneath should be sufficient?).  It all seems OK now so in about half an hour I am off out to continue the break in process. 

 

Miss Daisy rides again! (Wish me luck). 

[Nitroholic]

2 stroke motors like this don't need to be broken in like a nitro .... you'll just end up with a fouled plug.

 

Drive it gently for the first tank or so, varying the throttle, and not letting it labour. Avoid any prolonged wide open throttle, and just drive it about.

 

Then, if all is well, do any needle tweaking to get the pickup right, and just enjoy the truck.

 

Nitro motors need a long break in routine as they do not have a piston ring, and rely on the piston/liner contact to seal. They are overly tight from new and need to bed in. Petrol motors use a proper piston ring on a plated bore, so they don't need much bedding in. The first tank lets things bed in..so check exhaust and head bolts have not loosened.