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Home✈️Aircraft🚁Helicoptere-AlignT-REX 500 › Trex 500 Gyro issue
03-01-2012 01:34 AM  9 years ago
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rrApprentice

Toney, AL. USA

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Trex 500 Gyro issue
Is there anyone that has had any issues with the GY780 Align gyro with a Futaba S9257 tail servo? That is my setup and I'm having some tail wag issues and was wanting to know is there any special setup procedure for this combination I have.

I'm new to this sport and this is a new build (first build really) for me and any comments are welcome.
Gary
Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 02:18 AM  9 years ago
hampilot

rrApprentice

Sparks, NV USA

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My issue was with the 780 itself. First gyro was bad from the factory, it was replaced. Second gyro was also bad, would wag constantly, no matter what. Replaced that with a Mini G, never looked back.
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03-01-2012 02:24 AM  9 years ago
integy2

rrVeteran

California USA

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Try to reduce your gain.
Should be on trv adj. (gear)
Try +35%
I believe u got DX6i, try it 1st see how it goes.
(Good flight end up with ...... big smile :D)
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03-01-2012 02:31 AM  9 years ago
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rrApprentice

Toney, AL. USA

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Thanks for that info Hampilot for that info, I'm not sure if this gyro is bad or not.

As for the gain I have got it down to 50% and the wag is still there but slower. I was told not to take the gain below 50 but for what reason I don't know. Just what/how does this gain adjustment do to the process?
Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 02:40 AM  9 years ago
hampilot

rrApprentice

Sparks, NV USA

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I tried several things before trashing the gyro. Sandwitch the gyro with two layers of tape between the metal plate-- tape, plate, tape, gyro. That should get rid of any vibrations. I even tried Zeal tape, didnt help. The gain effects how fast the gyro reacts to rotation of heli. too much gain and it "hunts" aka fast wag. A slow wag or wandering is not enough gain. General rule of thumb is to turn up the gain till it hunts then turn it down a bit. It didnt matter on mine. also make sure you have it set in "small heli" mode. I was also told that electrical noise could cause wagging however I gave up before that was fully investigated. The new mini G worked without any problems so I assumed it was another bad gyro. still have it if you want it! FREE!! comes with the plate..
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03-01-2012 02:55 AM  9 years ago
hampilot

rrApprentice

Sparks, NV USA

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Just a note, between the time I sent in my first GP780 and the time I installed the replacement, I flew a loaner gp750. No wag at all on that one, with only one piece of tape and no plate. The gain was set to 55% on my futaba radio and it was rock solid. I gave back the 750 when the 780 came in and it wagged like a dead fish. I changed the gain from 0 to 100 with no effect. Personally I think there is a problem with the 780's.
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03-01-2012 02:59 AM  9 years ago
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rrApprentice

Toney, AL. USA

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Thanks Hampilot for that info, did you also have the belt drive as I do? Don't know if belt vs TT is any issue/problem here or not.Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 03:02 AM  9 years ago
hampilot

rrApprentice

Sparks, NV USA

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no belt, TT on a 500esp.
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03-01-2012 03:04 PM  9 years ago
Richardmid1

rrProfessor

Leeds, England

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Well known issue with the 780 especially on the 500! As you have seen the 750 is much better.

Align carbon tail blades help and also try adding some delay.

Other than that make sure the carbon boom supports haven't come unglued or even just coming loose. Also make sure the tail pitch machanics are very smooth with no binding and check the tail control rod is in a nice straight line (look down it from the back).
60% of the time, it works every time!
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03-01-2012 06:20 PM  9 years ago
Big Edge

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Oldsmar, FL USA

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I found a problem on my 500 ESP..
The TT drive gear (the one below the main gear) was out of round, there was easily visible run-out.

Ordered new gear and runs much better. No run-out.

I mounted my 780 on the lower frame plate inside the frames. Worked very well after that.

YMMV.
-----------------------------
Don't taze me bro...
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03-01-2012 06:31 PM  9 years ago
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rrApprentice

Toney, AL. USA

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I switched to the stock align DS 520 tail servo. AerialSkyCam found ou the the voltage from my ESC was to high for the Futaba servo. He told me to put a step down in-line but I elected to go with the stock Align servo. Now I'm trying to get it to not turn right (rudder) while in flight.

I had the same problem with the other servo but I was able to lengthen the tail rod linkage and that fixed it. After 7 flights today and adjusting after each I still can't get it to stop turning. It's only a slight turn but it's a pain.

Also the wag is still there, just so slight back and forth. I mounted my 780 gyro also on the bottom plate (belly).
Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 07:01 PM  9 years ago
integy2

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California USA

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@SGM Retired

Gear ch. ATV
+100-------+50-------0(-100)-------(-50)----------0

Gain value
100------------------------------------------------------0

So your +35 = around 70% gain.
(Good flight end up with ...... big smile :D)
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03-01-2012 07:09 PM  9 years ago
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rrApprentice

Toney, AL. USA

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Wow, should I be able to make some logic out those numbers integy2? Is this one of those puzzles? Just kidding, so adjust to 35 or 70%??Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 10:18 PM  9 years ago
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rrApprentice

Toney, AL. USA

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I think I might got the gyro hold straight issue fixed. I just kept adjusting tail rod linkage and it is now almost at a steady hold.

Question: during a 7 minute hover flight would you have to touch the rudder at any time to bring it back straight the way you took off?

Does the wind have any effect on the gyro to keep the tail straight in the same orientation as you took off at?

I might be to tight on my expectations in thinking I should not have to touch the rudder during hover. If that's the case and everyone else must touch left stick to keep it oreinted straight then I'm cooking with hot grease.
Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-01-2012 10:21 PM  9 years ago
Richardmid1

rrProfessor

Leeds, England

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Firstly if the voltage from the ESC BEC is too high for the 9257 it will be too high for the DS520! Secondly I think it is adjustable from 5-6v when programming the ESC. Third even set on 6v the 9257 and DS520 would be fine although 5-5.5v would be better.

About your tail turning in flight, sounds like the gyro is in rate mode, check the light on the gyro is green not red.

I think what Integy2 is trying to say is that 0-50% in the tx gives you 0-100% in rate or HH mode and 50-100% in your tx gives you 0-100% in the other mode (can't remember which way it is just keep checking the light is green which means your in HH). So it is possible you are at 70% and in rate mode. Try 70% in your tx, that should put you at 70% but in HH (Heading Hold, thats good! ) mode.
60% of the time, it works every time!
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03-01-2012 11:03 PM  9 years ago
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rrApprentice

Toney, AL. USA

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Thanks Richard for that explanation of terms. I still in the learning mode here. Question, why would Align put the 520 in the kit without a step down for the ESC? I took the Futaba servo off and have flew 10 flights of 7 minute hovering and it took me the longest to adjust to make this this stay straight. Although it still turn slightly in a 7 minute flight I can deal with that.

There is still a slight wag so I just adjusted gyro gain to 70% and can flip switch to 65%. Will give it a try now. You got me thinking about that high voltage warning though. Not sure how you program a Align ESC to lower the voltage.
Trex 500FB Trex 600ePro McpX. Synergy E7SE
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03-02-2012 09:36 PM  9 years ago
Richardmid1

rrProfessor

Leeds, England

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It tells you how to program the esc in the manual, if you dont have one it can be downloaded. The 520 will be fine on 6v.

Best thing you can do to save alot of head aches is to get another second hand gyro like a futaba 401 or Align GP750.
60% of the time, it works every time!
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03-02-2012 09:56 PM  9 years ago
SGM Retired

rrApprentice

Toney, AL. USA

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Thanks Richardmid1, looks like I might just do that. Got to get through these darn tornados first.Trex 500FB Trex 600ePro McpX. Synergy E7SE
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