Topic Subscribe
WATCH  2 pages [ <<    <    ( 1 )     2     NEXT    >> ]1186 viewsPOST REPLY
Thunder Power RC . Mikado . Futaba-RC
. .

Radio - Servo - Gyro - Gov - Batt

 >

JR G500t drifting with Futaba Radio issues?

Zaneman007

Elite Veteran

Texas - USA

I am experiencing drift in the JRG500t gyro:

Here is my set up:

Raptor 1:
Futaba 7CHP
Futaba F R138DP receiver
JR G500t gyro
JR DS810g servo
at 4.8 volts

Raptor 2:
Futaba 7CHP
Futaba F R138DP receiver
JR G500t gyro
Futaba 9254 servo
at 5.3 volts (regulated)

I have drift issues in both gyros. I have to use sub-trim but it does not totally eliminate it. So as an experiment, I took Raptor 2 and swapped out the JR500t with a Futaba GY401. Wow, no sub-trim, no drift, Rock solid. I cannot believe that I have two bad JR gyros. Is it the radio? Is the negative v. positive shift effecting this?

Do I need to sell the gyros or buy a JR radio?

Help me.

11-05-2006 Over year old.
z11355

rrMaster

New England

yes, you need to use subtrim w/ those gyros. They do not
'measure' pulsewidth at poweron like the 401's do.

perhaps you need to lower your rudder trim step on the 7C to get it
down to minimum. page 39 of the 7C manual

11-05-2006 Over year old.
Zaneman007

Elite Veteran

Texas - USA

Thanks,

I set the trim step from 04 to 01. Does this adjust the sub-trim or just the trim?

Is the GY401 a better gyro than the G500t? I have people telling me the G500t is better, but the GY401 didn't require any sub-trim, and is rock solid. The G500t keeps drifting.....

11-06-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

The 500T works very well when the tail pitch geometry is large and smooth like on a Hirobo Evo 50/90. It works quite well on the Raptor 50's too. The 8700G is the best servo to use on the 500T's and while the 810G and the 9254 will work they don't work like the 8700G does.

Here's a trick that I do on the 500T. Run the gyro gain up to full on the aux channel making the gyro as sensitive as possible, then adjust the subtrim so the tail servo doesn't drift. This works well. Once this is complete reset the gyro gain to normal settings.

TM

11-06-2006 Over year old.
HOMEPAGE  
WATCH  2 pages [ <<    <    ( 1 )     2     NEXT    >> ]1186 viewsPOST REPLY
HeliProz . Boca Bearings . Encore RC
. .

Radio - Servo - Gyro - Gov - Batt

 >

JR G500t drifting with Futaba Radio issues?

JKos

rrProfessor

Redondo Beach, CA

IMHO, the G500T is a better gyro. After you fly the G500T for a bit, the GY401 feels mushy and inconsistent.

Follow TMoore's advice and you should be able to dial out the drift with the subtrim. On the bench, with the right subtrim setting and the gyro in HH mode, the servo arm should not move as it sets there.

BTW, on JR radios there tends to be no sub-trim or trim needed. It's when you mix the JR gyros with other brands of radios (all of which have ever so slightly different neutral pulse widths) that you have to tweak the subtrim.

- John

RR rules!

11-06-2006 Over year old.
Zaneman007

Elite Veteran

Texas - USA

on JR radios there tends to be no sub-trim or trim needed. It's when you mix the JR gyros with other brands of radios (all of which have ever so slightly different neutral pulse widths) that you have to tweak the subtrim.
So it is the radio. I have a Futaba 7CHP, and I experience drift on the JR G500t, but not on the Futaba GY401. In my attempt to stop the drift, I'm using subtrim. Problem is I can not find the sweat spot.

So, per Z11355, I've decrease the trim step on my radio.
Run the gyro gain up to full on the aux channel making the gyro as sensitive as possible, then adjust the subtrim so the tail servo doesn't drift. This works well. Once this is complete reset the gyro gain to normal settings.
On the Futaba radio, I have channel 5 at 140, should channel 4 be at 140 also?

11-06-2006 Over year old.
BarracudaHockey

rrMaster

Jacksonville FL

Set them both to 100/100 if you are using the gyro sense screen on the 7c. Make sure the limit pot is set so that the pitch linkage doesnt bind.

Go into the Parameter menu and AUX CH set 5 to the switch you are using for your gyro or null.

Go into the gyro sense menu and set
Mix=ACT
Mode=GY
Rate up A100
Rate dn n50
Switch = whatever switch you are using for your gyro.

Then play with the SUB TRIM on channel 4 to get the slider to stay put in avcs. Trim Step wont do anything for you in this case, that only controls how far the servo move with each tap of the trim tabs, not the step for sub trim.

Once you get the drift sub trimmed out, and I've never seen it take more than 10 points of ST, usually 5 or 6, go back to the gyro menu and set rate up to A50 and take it flying and see how it does.

Once you get that straight, set the channel 4 atvs to whatever you want to get your piro rate.

Andy
AMA 77227
http://www.jaxrc.com

11-06-2006 Over year old.
tnbulldog

Senior Heliman

Cookeville, TN

Channel 5 is for the gain to the 500T assuming you're using the gyro program. This should have zero subtrim.
You need to adjust subtrim to channel 4. Generally with a Futaba radio and the 500T I need about 14-18 points of subtrim.

11-06-2006 Over year old.
Zaneman007

Elite Veteran

Texas - USA

BarracudaHockey,

I did like you said. It took -16 in the subtrim to get it to stop drifting. I stared at if for awhile, it looks good, but... I will not know until I get it out this weekend.
Go into the Parameter menu and AUX CH set 5 to the switch you are using for your gyro or null.
I did this, so what did I do?

11-07-2006 Over year old.
BarracudaHockey

rrMaster

Jacksonville FL

I did this, so what did I do?
It makes sure that the only thing using that switch is the gyro.

16 is alot, more than I've ever seen, might consider sending that tranny and rx in for a tuning over the winter.

Andy
AMA 77227
http://www.jaxrc.com

11-07-2006 Over year old.
z11355

rrMaster

New England

IMO, 16 is just fine. that is approx what I had when I used one
w/ a 9Z

11-07-2006 Over year old.
JKos

rrProfessor

Redondo Beach, CA

> IMO, 16 is just fine.

Concur. I've seen up to about 23 in some setups. I can't remember what radio it was, though.

- John

RR rules!

11-07-2006 Over year old.
BarracudaHockey

rrMaster

Jacksonville FL

I've just never seen higher than 10, thats cool though.

Andy
AMA 77227
http://www.jaxrc.com

11-07-2006 Over year old.
PietervA

Veteran

New Zealand

Two JR 9XIIs and a 8103 at our field with 500Ts: all needed subtrim between 2 and 6 points. Used TMoore's technique (thanks for the advice, btw), and now have zero drift.

R

11-08-2006 Over year old.
Zaneman007

Elite Veteran

Texas - USA

Well,

It appears to have worked. I have the gyro gain in heading hold at on 27%. Anything above that and it starts wags, on climb out.

11-12-2006 Over year old.
Zaneman007

Elite Veteran

Texas - USA

I just wanted to update this post. The JR Gyro is still drifting, and it will frequently swing out ten degrees, in either direction. It is not hunting, because it will swing out and lock, but, If I attempt to correct for it, the tail will swing out ten degrees the other direction and lock. It gyro flys like the one in my BCP? Whats up with JR Gryos. I was told the 500t was better than the GY401. But, the 401 holds great and has no subtrim. The JR500t is making it impossible to fly. Not happy

11-19-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

The 500T does not work the same as a 401 so subtrim is a fact of life.

If it were mine I would send it back and have the gyro checked out.

TM

Flybarless - "Some silly gyro thingy for some whirlie birdie machine......."

11-19-2006 Over year old.
HOMEPAGE  
Zaneman007

Elite Veteran

Texas - USA

Well, I made a bonehead move.

I went to replace the G500t with a GY401. When I went to remove the G500t, it was loose. Yep, the gyro was just sitting there. I had apparently torn it loose from the double sided tape while making adjustments. After I reinstalled it with a new piece of double sided tape, it worked just fine.

I have to thank all of those at that flying field today for giving me crap about that one.

The G500t works, it drifts and needs subtrim to correct it, but it does work.

11-20-2006 Over year old.
TMoore

rrMaster

Cookeville, TN

The G500t works, it drifts and needs subtrim to correct it, but it does work.
The biggest difference in the 500T and the 401 is the 401 uses the stick center that the TX puts out while the 500T doesn't. That's why there is drift sometimes with the 500T, in that if the center settings of the gyro doesn't coincide with what the TX outputs it will take subtrim from the TX to compensate.

TM

Flybarless - "Some silly gyro thingy for some whirlie birdie machine......."

11-20-2006 Over year old.
HOMEPAGE  
Zaneman007

Elite Veteran

Texas - USA

I wanted to update this for my new findings.

After applying new gyro tape and setting the heli up on my new JR9303. I still had some tail holding issues. The tail wouldn't quite lock. Too much gain and it would wag, but if a went down a step or two, it wouldn't lock. So upon inspection, I noted some play in the servo JR810. This is the servo that is sold as a package deal with the G500t. The servo was not stripped, it just had some play when it was powered on. So I replaced it with a Futaba 9254. What a difference. The tail now locks. Wow.

So now I have two JR810 servos, one has play, and the other one makes noise as if it is stripped around the outer travel limits. I will be staying clear of those servos. One I have had for about a year, but the other, the one with play in it, is new. Is it me or are these servos junk?

11-28-2006 Over year old.
WATCH  2 pages [ <<    <    ( 1 )     2     NEXT    >> ]1186 viewsPOST REPLY
Thunder Power RC . Mikado . Futaba-RC
. .

Radio - Servo - Gyro - Gov - Batt

 >

JR G500t drifting with Futaba Radio issues?

 Print TOPIC Advertisers 

Topic Subscribe

Sunday, September 21 - 1:06 pm - Copyright © 2000-2014 RunRyder   EMAILEnable Cookies