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Radio - JR DMSS

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Calling all JR g500t owners

Norm

Heliman

Nova Scotia, Canada

I have a g500t that was removed from my t-rex 450. I found it was a little to big for the t-rex and replaced it with a smaller heading hold. I decided to install the g500t on a new 30 size project. I paired it with a brand new align ds620 servo on high rate settings.
When I tested my setup. I was getting a lot of visible jitter out of the servo. This jitter was also causing my volt watch monitor to drop from the top of the green to the yellow. I know what regular digital "buzz" sounds like. This was not it. I then plugged the servo into the throttle to test it. It checked out fine. next I tried the gyro with an analog servo. It resulted in the approx same amount of jitter as the digital servo. I even tried another rx to be sure.
I am certain it is being caused by the gyro. Thinking back I believe it may have presented itself the same way on the t-rex. Using a high speed micro analog. But it seemed to fly fine. I am a little worried about using it now on a more valuable & dangerous helicopter.
I did noticed that when gain was increased jitter would be increased. I did some research via Google. I found many others to have the same problem as myself. But no one seemed to have a proper explanation. Some say it's the nature of this gyro, fly it. Others say jitter is not normal and to remove it from service.
So I am looking for some new and fresh info from all you g500t users out there.

My exact setup is as follows:
Raptor 30v2
-hitec supreme 7 channel rx
-4 hitec hs-425bb
-1 ds620 anti torque
-g500t gyro
-4.8volt NiCd
-JR switch

03-27-2010 Over year old.
crflyer

Senior Heliman

Maine

What are your gain settings in rate and HH modes?

03-27-2010 Over year old.
HOMEPAGE  
dicharry

Senior Heliman

Franklinton, LA

Maybe you will find an answer in the following snipits I gathered from other posts when I was having problems with mine:

You change from tail lock to rate with the gyro sens.
The rate mode and is 0 to50.
The tail lock mode is 51 to 100.
With 0 and 100 being most sensitive and 50 and 51 being least sensitive.

Set the travel adj to max (Mines 150)
Set the rudder sub trim to 0.
Set the servo travel pot on the gyro to the max movement you want at the tail linkage.
Set the tail linkage for hover.
Go from rate to tail lock and if the servo moves any just change the rudder sub trim to get it to stay in the same place as in rate mode. This is only 2 in my setup. After this sub trim change you may have to go back and set the tail linkage to center it for hover.
Set the yaw rate by reducing the dual rate.
Set the expo for feel.

You will see normal servo movement in mode 0 (Rate mode) and side stop to side stop movement in mode 1 (tail lock mode).

This is a very fine gyro. In fact I'm considering getting rid of all my other gyros and using only G500Ts because they are easy to set up and dont drift.

Also its nice to not have to change the gyro operation every time I switch Helos.

Once you have it set up you will really like the total lack of drift in the tail lock mode!
That along with the small size is what I really like about this gyro.
Plus its ONLY like 150 bucks!


> Make sure everything for the tail on the TX, ie subtrims for Rudder and channel 5 is zero.
> Make sure the trim tabs on the TX are zero below the stick..

This is where the G500T (and all other JR gyros for that matter except the new G770T) differs from the Futaba gyros. With JR gyros, they do not learn what neutral rudder is at power up. You must almost always use subtrim to cancel out drift in HH mode on JR gyros. That's just how it works. You must match the neutral pulse width of the rudder channel to what the gyro is preprogrammed to as neutral.

03-27-2010 Over year old.
Rotowerkz

Senior Heliman

Windham, NH

I'm using a g500t with an 8700g (one of JR's analog servos that could do 250 Hz on the frame rate). It works well on DS mode.

I also have a g500t with an 8411 (digital JR), and it also works well in DS mode.

Perhaps the g500t does not play nice with the DS620? I find that hard to believe. You might need to set your rudder trim to zero out the centering signal.

03-27-2010 Over year old.
holzback

Key Veteran

noblesville IN United States

maybe lowering the rotation rate will help by lowering the rudder dr.

you aint crashin you aint learnin

03-27-2010 Over year old.
Norm

Heliman

Nova Scotia, Canada

Thanks, I am going to try the suggestions. I will report back.

03-27-2010 Over year old.
holzback

Key Veteran

noblesville IN United States

try a little expo also maybe that will help, this is asuming that your gain is right

you aint crashin you aint learnin

03-27-2010 Over year old.
jschenck

rrProfessor

La Vista, NE.

what is your gain setting? Also is the servo jittering with the linkage disconnected? You could also try hooking up the DS620 to another gyro to see if it's shakey elsewhere. I like the JR 500 gyro also.

Team GrandRC

03-27-2010 Over year old.
ChrisMoore

Senior Heliman

Bay Village, OH

Did you set up the gyro in Rate mode first? This seemed to be the magic bullet for my 500T. I put the gyro into rate mode, adjusted the linkage of the tail to hold the nose straight (test hover, land, adjust ball linkage, test again, and so on).

And I think that you can use subtrim with the gyro, which is unlike most HH gyros. When I set mine up with the help of an experienced pilot a couple years ago he just said, "throw it out, buy a Futaba. You do not need to get rid of your 500T, it is a great gyro.

I think that the KEY is to adjust the linkage to hold the nose straight in Rate mode, then worry about HH mode.

Chris. AMA 497715 IRCHA 3351

03-27-2010 Over year old.
tayas

Key Veteran

North East of the USA

that gyro worked fine for me when i was using a JR radio.
when i switched to Futaba 9c radio i could not get it to work the same way.
i have it stored. for the past two years.

03-27-2010 Over year old.
rcmiket

Veteran

El Paso,Texas

Every other gyro on the face of the planet has a certain set way of setting it up. The 500 seems to be the only one where there are differences of opinions on how it should be done. I own one and will be setting it up pretty quick on a 500. I own 3 401's a Logitech 2100 and have set up 25 Align 750 and 780 gyro's over the last 3 months doing builds.All of those were very straight forward set ups. Why does the 500 have to be such a hassle to get set up? I guess I'll find out pretty quick if its all that bad.I'm just curious.
Mike

"When Inverted down is up and up is expensive"

03-27-2010 Over year old.
Norm

Heliman

Nova Scotia, Canada

I forgot to mention I am using a JR 9303 tx. I set my endpoints to 150/150 and followed the setup instructions. The linkage was disconnected from the servo horn at this time. The servo still continued to jump and suck power. I played with the subtrim and moved it a few "beeps" in either direction. At this point the servo started to drift (still jittering) to full left position. I hooked the servo to a gy401 from another machine and it worked perfect. I am thinking about chucking this g500t in the trash and buying a spartan 760.

03-27-2010 Over year old.
dicharry

Senior Heliman

Franklinton, LA

I know that feeling of frustration. Just put it on the side, use the 401 for now, and a few weeks down the road, try the JR unit again. Maybe just try it in another bird. Don't know if any of this will help:

Gyro Sensor Setup in the JR PCM10X
On 7202, 8103, 9303, and PCM 10X JR transmitters, the gyro gain is expressed as a numerical value. First, enable the gyro sensor mode. When you are entering values, the gyro mode is selected as follows:
Tail Lock Mode –Values from 51 to 100
Rate Mode – Values from 0 to 49
No Gyro function – 50 (basically it is disabled)
In tail lock mode, the higher the numerical value from 51 up to 100, the greater the head lock sensitivity.
In rate mode, the lower the numerical value from 49 down to 0, the greater the gyro rate sensitivity.
The JR 6102 transmitter is somewhat different in that it does not have a “Gyro Sensor” mode. The remote gain feature will be accessed by using the sub-trim adjustment function. It will be necessary to use the Gear (retract) channel. First set the Gear reverse switch to “N” and travel values to “0” for both (+) and (-). When you enter sub-trim values for the gyro gain the mode will be selected as follows:
Tail Lock Mode – Sub-Trim values from +1 to +125
Rate Mode – Sub-Trim values from –1 to -125
No Gyro function – Travel value of 0%
When you begin test flying your helicopter, you will have to set the gyro gain to get the amount of tail rotor holding power you desire. The maximum gain that you can use will depend on the performance of the servo selected for the tail rotor control. The maximum you can use will be a value just below the point where the tail rotor “wags” back and forth when hovering. Further adjustment of the values used will depend on just how much response you want from the gyro for the specific maneuver performance desired.
It should be noted that there are other ways to control the remote gyro gain function in JR radios. Some people will have other methods, and these can work as well as the recommendations suggested above.
The second subject regarding the position of the JR 500 T gyro servo frame rate switch is not nearly as involved as the remote gyro gain settings. Helicopters benefit from the use of newer very high frame rate digital servos that are available. Before you can realize the benefits these servos provide, it is necessary to have a gyro capable of using the faster frame rate. The JR 500T provides a user-selectable switch to enable the high frame rate that digital servos can operate with. Non-digital servos will require the standard frame rate setting. The new digital JR 285 sub micro-servo works very well in the small electric helicopters.

03-27-2010 Over year old.
holzback

Key Veteran

noblesville IN United States

followed the setup instructions
i think there is an issue with the instructions if i remember right. i dont think they are accruate.

you aint crashin you aint learnin

03-27-2010 Over year old.
dicharry

Senior Heliman

Franklinton, LA

03-28-2010 Over year old.
Norm

Heliman

Nova Scotia, Canada

I found this thread. Same problems no answers. http://rc.runryder.com/helicopter/t89518p1/

03-28-2010 Over year old.
jschenck

rrProfessor

La Vista, NE.

Well guys I can say I've had 4-5 of them and they've worked well for me. I did not setup the ATV to 150, that's high. I'd suggest starting off with 100 ATV's on the rudder and a gain of about 70 just for a ball park (with a 9303 setup with gyro mode).

Setting the gyro up initially is about the same as the Futaba 401 except you *must* use sub-trim to take the drift out. You can do this on the bench by turning it on in HH mode. If the servo drifts to one end then add a couple of points of sub-trim until it stops moving.

Team GrandRC

03-28-2010 Over year old.
Norm

Heliman

Nova Scotia, Canada

Solved my problem. I bought a Spartan ds760

04-03-2010 Over year old.
tayas

Key Veteran

North East of the USA

that will do it

04-04-2010 Over year old.
vinver

Heliman

Enfield,NS Canada

Still have the JR?

Hi Dan,
Whatever happened to the G500T? I'm about to set one up and curious if you ever tried it again.
Vince

07-13-2010 Over year old.
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