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Old Jul 05, 2011, 12:53 PM
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Joined May 2009
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Dx8 Gimbal SB - potential need for more stringent test

At least in my case, the gimbal SB test procedure was not enough to catch the problem.

I have a new DX8 (HC code - post DSMX/DSM2 service bulletin). I initially checked my transmitter using the procedure in the gimbal service bulletin and the radio did not exhibit the behavior specified (ie. there was no aileron movement on the monitor screen when moving the elevator gimbal). That is still true now.

However: yesterday I noticed when checking aileron movement on a model that the left/right aileron movement wasn't adding up. I had +8% sub-trim on the aileron channel (I know .. I'm lazy .. ) and 50% travel set up. Moving the stick to the right would yield 58% deflection as expected. However moving the stick left produced only -30% (you'd expect about -42%).

In playing around with the elevator a little, I was suddenly able to observe the full expected left deflection. Essentially the system kept moving between full deflection and about 75% of programmed deflection. Clearly something loose or otherwise faulty in the gimbal setup.

I mention this because there may be people out there who think their TX is OK and may not necessarily notice this issue unless they carefully check full stick deflection. Missing this could potentially cause you some excitement when you try that fast roll close to the ground.

I like my DX8 - just wish the QC process on these key components was better. It's a little unnerving. This stuff must be costing HH a small fortune ..
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Old Jul 05, 2011, 01:11 PM
Air, Ground & Water
freechip's Avatar
Canada, ON, Rockland
Joined Aug 2008
23,839 Posts
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Originally Posted by philipm785 View Post
.. This stuff must be costing HH a small fortune ..
If not in money then in other aspect. Visited the LHS the other day and over heard them clearly swaying a customer away from it and mentioning all the issues past and present. When they saw me in the store knowing full well what radio I have he commented something I can't recall right now but it prompted me to respond by saying if they couldn't sell the other brand without bringing down the competition then how good was the other brand if all they can do is talk about the competition.

Instead of saying buy this one because its got this and that going for it they were selling it because the other brand has issues so you should buy this one...

Anyways its there shop and I wasn't there to defend my brand as its not my job to do so....
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Old Jul 05, 2011, 01:43 PM
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Dallas, TX
Joined Jan 2010
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Originally Posted by philipm785 View Post
Essentially the system kept moving between full deflection and about 75% of programmed deflection. Clearly something loose or otherwise faulty in the gimbal setup.
I really hope I'm wrong, but I'm beginning to think we still have another wave of problems to deal with as people get some hours in with their radios and the pots start to fail.

We've seen a few cases already that look to be a lot more like a pot failure than an issue with the gimbals or the wiring to the gimbals.

Time will tell and I really do hope it isn't the case as frankly the customers don't deserve to get even more issues heaped on top of everything else so far.
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Old Jul 05, 2011, 02:44 PM
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Joined Dec 2010
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if you have an air compressor, shoot some air near and inside the gimbals.
Long ago, I had a similar problem. Then I flipped the TX over to take apart the casing and a tiny pebble fell from the radio and bounced on my table. Problem solved for me. I'm hoping your issue might be similar to mine.
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Old Jul 05, 2011, 08:51 PM
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Originally Posted by Confuzshuz View Post
if you have an air compressor, shoot some air near and inside the gimbals.
Long ago, I had a similar problem. Then I flipped the TX over to take apart the casing and a tiny pebble fell from the radio and bounced on my table. Problem solved for me. I'm hoping your issue might be similar to mine.
Thanks Confuzshuz. I gave that a try, but the problem persists. Definitely the pot or gimbal assembly is somehow shot. The aileron values are all over the place while moving the elevator with aileron pushed left.

Took my DX6i out tonight. Flew perfectly as always, but I instantly missed the DX8. Guess I need to get used to the DX6i again ..
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Old Nov 21, 2011, 08:29 AM
Chester UK
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Joined Mar 2006
150 Posts
I definitely have the gimbal problem.
while hovering throttle about 50% every now and then the rudder kicks full travel and then returns to correspond with my stick position.
Following the procedure on the Spektrum website the problem is hardly noticable because it happens so fast.
Use this procedure instead to be sure your radio doesn't have a problem.
1) Electric model, remove the prop!!

2) power up Tx & Rx

3) move the stick vertically S L O W L Y all the time watching for any movement of the other channel on that stick. (so lets say you're on mode 2 - move the throttle stick up and down slowly while all the time watching for rudder movement) be careful not to move the stick left or right while you're moving the stick up and down.

My rudder suddenly kicks out full travel - there's no doubt!

AJ
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