G500t Problems

[J Anderson]

Maybe someone can help me. I have a G500T Gyro, and It will not hold the tail! It drifts!
Could it be my servo?
I have an HS51 on the rudder, but have ordered a futaba S9257.
Will that help or do I have other problems?

[cbflys]

Does it drift from the start?

The JR G500T does not 'sense' neutral as the Futaba gyros do. It expects a specific pulse width. With the gyro in HH mode, adjust your sub-trim on the rudder channel until the rudder servo does not move.

If it starts off OK then begins to drift, could be a bad gyro. Also, change in temperature will cause drifting issues, so let it adjust to any change before using it.

[pvande]

Just started experiencing drift on my 500T today as well - on the 4th tank. As soon as I switch from normal into HH my servo slowly drifts all the way to one side - takes about 3-5 seconds.

I always thought that in HH you should never adjust subtrim or trim. So much for JR gyro's...

[cbflys]

With the JR gyro you're not using sub-trim to position the output arm, you're using it to set the 'expected' neutral pulse width.

[BarracudaHockey]

Turn the gain all the way up.

Slowly adjust the sub trim on the rudder channel until the arm stays put.

Turn the gain back down and test fly it.

[Mark J]

I currently have the same drifting issue with mine.
Have upped the gain to full and adjusted the subtrim and when set the gain back down so it dosnt wag itself to death I still get the drift.

It is setup mechanically via rate mode so it holds etc, but in HH it keeps drifting the nose to the left.

I even put the link in a hole on the servo arm and readjusted the gain but still drifts.

It drifts from the start, dosnt start off ok and then starts drifting after a while.

setup as per the sticky in this section of the forum but using the Futaba FF7 2.4gig tx but just cant seem to get rid of the drift etc.

Mark.

[BarracudaHockey]

Then you have a vibration problem and are getting precession.

Check your mounting tape/method. Make sure there's no straps transmitting vibration from the frame to the gyro and make sure there is strain relief on the wires so they aren't pulling on the case.

[Mark J]

Cool thanks Andy, will check those out.
Also went back through my settings in the Tx and noticed the rudder channel wasnt set to max +/- endpoints but the gain endpoints were! so id got those the wrong way round, so the gain points are now back to 100 where theyre supposed to be and the rudder is at 140 both ways (futaba radio)

Will post results when I get chance to test fly (UK weather at the mo is all over the place!)

Mark

[BarracudaHockey]

140 on the end points is going to give you an alarming piro rate, I'd start at 100

[Mark J]

Yeah had thought of that, but according to the sticky in here from John Garst about setting them up, it says to have them at max as its the dual rates that control the piro rate etc.

[Mark J]

Just a quick question.

I know you do the sub trim stuff to get rid of the servo drift, but do you have to do it 'on the floor' or when its actually flying to remove the drift when hovering etc?

Might be a dumb question, but just thought about it and realised that in the instructions etc dosnt mention whether to do it on the bench or in flight!

Mark.

[cbflys]

You'll adjust the sub-trim while the heli is sitting still (on the bench). Make sure you give the gyro time to acclimate to the ambient temperature before adjusting, as that will effect its performance.

[pvande]

I just discovered another issue with the JR gyro this weekend. Hovered in normal mode without having to make any adjustments to get rid of the drift. However as soon as I switched to IdleUp1 the tail started drifting.

Switched back to Normal mode and the drift was gone. The gyro is fairly new - about 18 months wihtout any crashes.

I've given up on JR gyro's - why hassle with the drift if you can use a Futaba 401 and have nearly perfect heading hold every time without having to worry about trimming the gyro...

[pvande]

Forgot to mention that the gain was the same in both modes.

[Mark J]

Mine did exactly the same, rate mode fine, HH it started to drift, so last night at the field, I thought id tweek the subtrim while I was flying and managed to get it to stop drifting and it seemed fine!

With the price of fuel at the mo been horrendously high, its anoying to have to waste it with trying to get the gyro to stop drifting, hence why I tweeked the sub trim while hovering and thought 'its stopped drifting so that'll do' and then went off and had a bit of a whizz round the sky lol.

[Mark J]

Just a quick update,

I looked at the subtrim on my heli last night and noticed that when I changed it in flight it had only changed by 1 number, so it looks like its a bit of luck if it dosnt drift in HH in the hover as there is quite a bit of leaway on the subtrim where the servo stops drifting and I tended to find the centrepoint within that band etc, but it might just need a little tweek while hovering to either increase or decrease the number depending on which way the heli is drifting.

So that 'could' be why some people get drift and others dont, so might be worth considering if you get drift in the hover in HH.

Also noticed that servo dosnt drift still when its on the bench, so all seems good with my gyro at long last LOL!.

Hope this might help anyone else who might be having problems still.

Mark

[cbflys]

Another common culpret that can also cause this problem is radios that keep different trim settings in different flight modes. Make sure that you have no rudder trim in any of your flight modes.