So first up is an Overview of the JT G770 gyro: Video Link ->JR G770 Overview and video plans (28 Megs). Now to start the basics that I think need to be understood in order to OK here are the 2 radio setup videos. First one is on setting up Piro Rate using end points and dual rates per the manual. INSTRUCTION MANUAL Thank you for purchasing the JR G770T Gyro. 1 HANDLING CARE 2 FEATURES WARNING WARNING When Setting Up The Gyro is exclusively designed for use with radio-controlled hobby helicopters. Using it for any other applications may lead to an unexpected problem, resulting in an accident. The Gyro is designed to work properly with JR.
One of my few Sandown buys was a G460T gyro to which I added a DS 3728 digital servo as a I was told this was one of the fast mini servo available. This is to be fitted to my Logo 10.
I am removing my CSM 400 due to size, it set up well but has never 'done anything for me ' in HH mode, but is fine as a normal gyro. Anyone who has a CSM will know of the pages of set up instructions, the G460T has about 2' of instructions on set up & 3 lines on HH mode.
I havent flown it yet but any comments on set ups?? It tells me to set rudder travel to 150% each way but with the standard LOGO 14mm arms it travels too far, I know in HH mode it will dial back but will it cope in normal mode?
Other HH gyros use the aux sensitivity for 'Holding power' and rudder travel for 'rate of rotation' is the JR the same? Any suggestions welcome I hate shocks at the field, I get too few a visits to waste them playing around. Regards Jaydee. Well I have done it the hard way - my own, the servo I was sold turned out to be as slow as you can get a DS, either I was given the wrong one by mistake or else I was sold a pup! The manual with the 460 gives you to believe you can use any channel for gain adjustment - WRONG!!! If you use gear as I did for manual switch you do not get anything like the right% movement on the gain & the gyro is un adjustable in one switch point. I download the full JR 378 manual from the net (mine was the original Japanees translation - early import), you need to use Aux 2 only.
To switch it you only have the option in standard mode top use the Throttle hold/Aux2/Rudder dual rate switch, this only adjust one flight mode as the other is in Hold mode. The correct way is to use the Automatic gyro software in the TX to assign the gain against the 'flight mode' switch (idle up) this works great once you get your head around it, I tried it on my 388,on a seperate Aux 2 switched channel - no joy either, one side of the swich inverted the gain setting & the other did very little change. So the moral - 'look before you leap' - check out the specs even if they are from the same manufacturer they may not be compatible, mine is finally thank god.
If you have an older TX forget the JR 460. Now I just need my new h/s servo!!
Regards Jaydee. I take in all you say.
The supplied info on the 460 is on a 3'.2' paper that covers non of the above issues, it just states a seperate channel for gain adjustment. The 190 page official 378 book makes no ref to the type of channel required to make the gyro function, talking to the importers helped with this, but I stand by my initial reaction in that the gyro is only as good as its instructions and for the common modeller these are poor, you should not have to research your new product just to get it going. I think the CSM 400 is an OK gyro but its instructions are excellant, as is its set up proceedure. Regards Jaydee. I use a Futaba GY240, Futaba GY501, and Helimax HH with JR8103 TX on 3 separate birds.
I think the GY240 is similar to the 460T in that you can't activate the HH on/off remotely. Basically, there is a micro switch on the sensor module to switch it from HH to normal. The separate input is just used for gain, so you can mix this channel on the flap dial. I do the following set-up on all my gyros. Set rudder ATV to at least 100%.
Check travel and make sure there is no binding at the tail. If there is binding, then try using a smaller servo horn.
If there is no binding, then increase ATV until just before it binds. Fly the heli in normal mode and trim out using mechanical linkage. Avoid using the tx trim unless:1) your radio has individual trim for each flight mode or 2) you re-center the servo each time you fly HH.
Futaba GY401 Gyro How-to Futaba GY401 w/ JR 9303 Gyro How-to Mount the Gyro on the back plate behind the main shaft. Yes, the tape that comes with the gyro is not very cushiony, but that's the way it needs to be. The cushioning is done inside the gyro. The tape works great, use it. As you can see in the picture to the left, I mounted it with the cords coming out toward the back of the helicopter.
Make the connections just as shown in the manual (picture to the left comes from the manual). This is very simple, nothing special here, just connect the rudder servo to the female connector.
That leaves two other connectors, one with 3 wires and the other with 1 wire. Connect the one with 3 to the rudder channel of the receiver (labeled 'Rudd'). Then plug the 1 wire connector into the Aux2 channel - make sure the yellow wire is on the signal side. The signal side will be opposite of the black (ground) side. Note: To get the two Futaba connectors into your JR receiver you will have to trim the flat piece that sticks out on the side. Use an exacto knife to shave this off. Before we continue it helps to understand the characteristics of this gyro.
You have to start up this gyro in heading hold mode. Also as with all heading hold gyros you have to wait for the gyro to initialize after power up before you can move the helicopter. The gyro initializes fast, only about 3 or 4 seconds. Also when using a high frame rate servos like the Futaba 9253/9254 you need to flip the tiny switch on top of the gyro to 'on', the swith is labeled 'DS'. Note: The 'DS' label is deceptive.
![Jr g490t gyro manual pdf Jr g490t gyro manual pdf](/uploads/1/2/5/5/125514441/529442214.jpg)
It does not mean turn it on if you have a digital servo, it is only to be turned on if you have a servo that can support the high frame rate (370Hz). Common misconception of all heading hold gyros Another thing that a lot of people don't understand is that the rudder travel adjust (ATV's / EPA's) does not adjust how far the servo moves.
You cannot use this to prevent linkage binding. This adjustment only effects how fast the tail moves (your pirouette rate). Radio setup Press the 'LIST' button then scroll to GYRO SENS. Highlight the item just under that (it will either be INH or AUTO) and change it to 'RUDD D/R'.
Set position '0' to 85% and '1' to 15% zero center position Go to Sub Trim and set 'RUDD' and 'Aux2' to 0. Also make sure the trims are centered. Set limits to 100% Go to Trvl. Adj. and set 'rudd' left to 90% and right to 100%. Dual rates to 100% Go to D/R & Exp and set the value for 'D/R' to 100% and 'EXP' to '+20' for both switch position 0 and 1. Turn off Revolution mixing Go to REVO.
Mix and set all values to 0. First make sure the rudder d/r switch (the front switch on the top/right) is flipped toward the back. Next disconnect the rudder link from the servo. Turn on the receiver. Wait 4 seconds for the gyro to initialize. It may or may not initialize correctly depending on where the gyro channel reverse setting is set in the radio. Remember the gyro has to start up in HH (Heading Hold) mode.
Continue with the next step to determine if it's in the right mode. Set to start up in HH Move the rudder stick to the right, then back to center, if the rudder servo does the same then you are in normal mode which is wrong. If the servo moves to one direction but does not move back to center then you are in heading hold mode which is right.
If you ended up in normal mode then go to REV. SW and change the Aux2 channel 7. Then turn off the receiver and then back on and let the gyro initialize in heading hold mode. Set to normal mode Now that you have the gyro initialized correctly, flip the D/R switch. This will make the gyro go into standard rate mode. Servo direction Check the servo direction. Move the rudder stick to the right and watch the servo arm.
It should move the servo clockwise which thereby should pull the rudder control link forward. This will make the nose of the helicopter rotate to the right. If not, then go to REV. SW and change channel 4 'Rudd'.
Gyro direction Rotate the helicopter so the nose goes to the left and watch the rudder servo. The servo needs to rotate clockwise. If not, then flip the reverse switch located on the top of the gyro. With the rudder link disconnected from the servo. The first thing to do is make the link slide as free as possible.
Adjust the guides to acheive the least resistance. I added a slight bent to the front section of the rod as you can see if you click on the photo to the left. I did this so as to stop the resistance the rod had on the first frame guide due to being pulled down to the servo.
I also use a JR Ball link resizing tool to remove unecessary resistance from the ball links. Once you get the link as free from resistance as you can. You need to take off the rudder servo arm and install/move the ball to a position that is about 13mm from the center. The instructions with the gyro say to use the recommended distance that the helicopter instructions say to use. I used the 13mm position and found it to work great. A friend tried a much longer distance and it did not work as well. Next set the rudder servo arm so that it points with the rudder stick and rudder trim centered.
The best position for tail centering is to adjust the rudder link so that you have 4.5mm between the pitch slider and the tail rotor casing (see the picture to the left). Another way to find center other then measuring 4.5mm is to visually align the control arm to be parallel with the tail shaft. Check that the front link is centered with the ball on the servo arm. If it's not, turn the link clockwise to move it toward the back or counter clockwise to move it forward. Once the center of the ball link matches with the center of the ball and you have the 4.5mm at the tail slider, then you can move to the next step. First make sure the 'Limit' on the top of the gyro to it's max (140), while you're adjusting that go ahead and make sure the 'Delay' is set to 0 if you are using the 9253 servo, otherwise start around 30 and later experiment to find the best value for the servo you use.
Hold the tail rotor stick full right and pull the control rod all the way forward. Pull the link as far forward as it can go then adjust the 'Limit' control on the top of the gyro so that the ball on the servo arm centers with the link. Once you are finished you can snap the link on the ball. Set back to HH Now that you're done with that, you need to flip the Rudd D/R switch back to heading hold mode. Notes about the gyro HH/Standard Rate With the GY401 there is no reason to use standard rate mode. I leave mine in HH all the time.
On other gyros I would prefer to have Normal flight mode use standard rate because the HH mode would have a kinda jerky non-fluid motion when doing ground maneuvers such as slow piroueting circles. With the GY401 I have found it is smooth all the time in HH mode so I just leave it there. Flying adjustments To get the tail to move faster or slower, adjust the rudder channel travel. Adj. and set 'rudd' left and right. A higher value will make the heli pirouette faster and a lower value will make the tail slower. Also if you are using a servo other then the 9254 then you may need to adjust the Delay pot on top of the gyro to stop the tail from wagging after a quick stop.
If you the tail wags in a hover then decrease the gain. Go to the Gyro Sens menu and decrease the value in position '0' if wagging in HH or position '1' if wagging in standard rate mode. Cause Gain values have to be set low to stop any tail wagging.
The helicopter is out of balance. Vibration is the cause of low gain settings. Check the blades, check for bent main shaft, spindle shaft, tail shaft, out of balance tail blades, etc. I found that a sticky clutch caused me to have to turn down my gain by 20%. Check the and look for a broke shoe. The ball on the rudder servo is too far away from the center.
HH doesn't hold good 1. The RPM's should be 1850 to 1950 for 3D flight. It's also important that your engine is running good.
If your engine loads up a lot then you won't be able to keep a consistent RPM. Remember that a few hundred rpm drop on the head is several hundred rpm drop on the tail. Tail wags only right after a pirouette, or anytime I move the tail then stop. If you are using the 9253 servo then you probably have some resistance in your tail control rod. Make sure the guides are aligned for least resistance.
Also keep your tail shaft oiled. If it is dry and tacky this will cause the problem. If using a servo other then the 9253 then increase the value of the delay (pot on top of the gyro).