Another Diff Brain Failure

Stitch

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Arrma RC's
  1. BigRock
Hi,

I have a Big Rock and after the 4th charge the rear and center diff started to make a constant noise.
As I thought that constant operation of the Diff Brain servos would destroy them fast, I opend the rear diff. But there was no mechanical problem visible. So I used the descrition https://arrmaforum.com/attachments/nero-diff-brain-configuration-20160704-pdf.2864/ to change the end points. But it was only possible to make either the locked or the unlocked position silent. The diff has to be open while doing this, because otherwise it can happen that the end positions are not locking or unlocking.

I set the full open mode to be silent because all other modes are rarely used.

When I tried to improve endpoint again one of the micro screws fell off.

I did send a mail to the support today.

I guess I will take out the Diff Brain and all servos for good.
 

Afro Samurai

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Arrma RC's
  1. Nero
Hi,

I have a Big Rock and after the 4th charge the rear and center diff started to make a constant noise.
As I thought that constant operation of the Diff Brain servos would destroy them fast, I opend the rear diff. But there was no mechanical problem visible. So I used the descrition https://arrmaforum.com/attachments/nero-diff-brain-configuration-20160704-pdf.2864/ to change the end points. But it was only possible to make either the locked or the unlocked position silent. The diff has to be open while doing this, because otherwise it can happen that the end positions are not locking or unlocking.

I set the full open mode to be silent because all other modes are rarely used.

When I tried to improve endpoint again one of the micro screws fell off.

I did send a mail to the support today.

I guess I will take out the Diff Brain and all servos for good.


hmmm...I am getting the feeling that the demand has quickly surpassed their build quality process ...I bought nero when it first released ..zero problems. ....lots of runs...diffs work fine. ...now with them flying off the shelves ..looks like these issues are cropping up...
 

Stitch

Well-Known Member
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Arrma RC's
  1. BigRock
hmmm...I am getting the feeling that the demand has quickly surpassed their build quality process ...I bought nero when it first released ..zero problems. ....lots of runs...diffs work fine. ...now with them flying off the shelves ..looks like these issues are cropping up...

Hmm, I thought it is a design flaw. Where the bending forces on the 6 pins lead to deformation. This increases the necessary actuation force which makes the servo noise.

I would need to closely look at the pins if a bend is visible. But first the Diff Brain electronics needs to be replaced. Or taken out of the truck for ever :)
 

mrfurious40k

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Arrma RC's
  1. Nero
  2. Senton 6s
Setting the endpoints on the diff brain servos will be a never ending battle. The actuation never seems to be the same in all conditions so you either wind up with a diff brain that doesn't work or an occasional buzz when you unlock a diff.

Here's my best, easy and so far never had to be repeated fix: take the diff brain servos out of the diff housings. Turn the truck on so they all set to a neutral position. Test all the modes on and off. Install the servos in the diff housings. Test the diff brain functions and reinstall in the truck.

I did this and it took care of all my buzzes and I haven't had to revisit the diff brain since.

Stitch, your diff brain controller is probably pretty far out of factory spec and the adjustments are so minute you will probably never get it back. If ARRMA sends you a warranty replacemrt, start with that. If not, grab one cheap from eBay and don't look back.
 

Stitch

Well-Known Member
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Arrma RC's
  1. BigRock
Setting the endpoints on the diff brain servos will be a never ending battle. The actuation never seems to be the same in all conditions so you either wind up with a diff brain that doesn't work or an occasional buzz when you unlock a diff.

Here's my best, easy and so far never had to be repeated fix: take the diff brain servos out of the diff housings. Turn the truck on so they all set to a neutral position. Test all the modes on and off. Install the servos in the diff housings. Test the diff brain functions and reinstall in the truck.

I did this and it took care of all my buzzes and I haven't had to revisit the diff brain since.

Stitch, your diff brain controller is probably pretty far out of factory spec and the adjustments are so minute you will probably never get it back. If ARRMA sends you a warranty replacemrt, start with that. If not, grab one cheap from eBay and don't look back.

Thank you for the proposal. You are defenitly right that setting the endpoints does not work.

I did try to solve the problem by disassembling / assembling the diff but it did not work in my case.

I like your idea of turning the servo on and assemble the diff.

The good news is that the arrma support promised me replacement parts. Let's see ...
 

Stitch

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Arrma RC's
  1. BigRock
Just a quick update. The arrma support is awesome. They send me a diff brain electronics board and two diff servos with the pin rings under worrenty. Now I can replace all parts that are not working. I am impressed by this service.
 

rleeh11

New Member
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Arrma RC's
  1. BigRock
  2. Nero
Just a quick update. The arrma support is awesome. They send me a diff brain electronics board and two diff servos with the pin rings under worrenty. Now I can replace all parts that are not working. I am impressed by this service.


Out of the box, my center diff makes the same sound as a bicycle wheel with card in the spokes. Doesn't seem to lock or unlock. Front works fine, diff brain led changes from mode to mode. Sounds like a bad servo so far.
 
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