Optima 7 RX Servo Binding

[tailwheelteacher]

just got 2 optima 7 RXs in, both of them move analog servos a significant amount on startup before going back the other way to center. one very bad thing is that IF THE SERVO IS NEAR ITS MECHANICAL STOP BEFORE POWERING UP, THE RX WILL DRIVE IT TO ITS MECHANICAL STOP! this only seems to happen with analog servos.

there are plenty more people out there with this problem, maybe they just think its normal but everyone needs to know about this before any servos are burnt up or airframes or broke by servo travel issues on startup. reference hitecs support thread on the groups: http://www.rcgroups.com/hitec-multiplex-usa-169/

one way this could make a bad day is with gas powered giant scale: ive got digitals all around a 50cc airplane and analog servos on the throttle and choke (as many others do). each time the plane is powered up the throttle and choke are slammed against their stops on the carburetor.

they'll be headin back to hitec.

[BubbaGump]

I have never had this happen and have been flying this system for about two months. This is a strange issue. Hitec will fix it for you there pretty good when it comes to customer service.

[tailwheelteacher]

Gump I sent both of them to Hitec, they said theyll try to find a fix, a couple other guys are having the same issue over on the groups but there are people that arent affected such as yourself.

Just a thought, my 8611s and 5625s dont jump on startup, just my analogs. I see you have digital all around, maybe you just cant see the jump?

[BubbaGump]

	Quote: Originally Posted by tailwheelteacher
	Gump I sent both of them to Hitec, they said theyll try to find a fix, a couple other guys are having the same issue over on the groups but there are people that arent affected such as yourself. Just a thought, my 8611s and 5625s dont jump on startup, just my analogs. I see you have digital all around, maybe you just cant see the jump?

Thats good that Hitec is taking care of you. I have analog servos and digital servos mixed on some planes with this system and have not noticed the problems people have noticed. And I do have the same optima 7s as everyone else. I also have one of the pre-production ones and that works fine also. This are mass produced and there is going to be bad ones in the run. Hitec should take care you, there pretty good with customer service. Hope this helps.

Forrest

[jsluga]

I have purchased from a total of six Hitec Optima 2.4 Ghz AFHSS receivers—four 7-channel and two 9-channel—along with three of the accompanying transmitter modules. I have been using three of the 7-channel receivers, with the Hitec module in a Futaba 9ZAP World Champion II transmitter, in three different electric-powered models with great success. Today, however, I had a great disappointment.

I was in the process of converting my 36% Aeroworks Edge540 to 2.4 Ghz with one of the 9-channel Hitec Optima 2.4 Ghz AFHSS receivers. I decided to do a bench test with the receiver, a 2600 MaH 4.8 volt Nimh receiver battery, and the wings from the Edge which each have one JR NES-4721 servo with 30" leads to actuate the ailerons. I had already bound the receiver to the Tx module, so I plugged the servos into the receiver, turned on the transmitter, and then plugged the battery into the receiver. Much to my surprise and chagrin, as soon as I plugged the battery into the Optima receiver, the JR servos began jumping around uncontrollably. I tried disconnecting the battery and servos and then reconnecting the battery first, then adding the servo. Same result: both servos jumped uncontrollably! I then tried the whole procedure again after rebinding the receiver to the module. Same jumpy result.

I then disconnected both of the JR NES-4721 servos and connected two Futaba S3102 servos, one with the original lead and one with an 18" extension. These servos both worked perfectly in the Optima 9.

Next, I tried the original JR NES-4721 servos with an Optima 7-channel receiver and got the jumpy result yet again. When I switched to the two Futaba S3102 servos, the jump again went away. It seemed that I had narrowed down the problem to Hitec Optima 2.4 Ghz AFHSS receivers with JR NES-4721 servos.

To be sure, I removed the Hitec 2.4 Ghz module from the 9ZAP transmitter and inserted a 72 Mhz module on channel 44. I then plugged my wings with the JR NES-4721 servos into a Futaba R149DP PCM 1024 receiver on channel 44 and then plugged in the same 2600 MaH 4.8 volt Nimh receiver battery I had been using with the Optima receivers. Both the JR servos were solid as a rock and worked flawlessly with this setup.

Okay, so I'm flummoxed! I purchased the two Optima 9-channel receivers for two of my giant-scale models, and planned to purchase two more if these worked out. Have I wasted $199.99? This problem with these JR servos may be a deal breaker for me. Can anyone offer me any insight or send me somewhere? Please advise. Thank you.

[tailwheelteacher]

After a few Months I finally got my RXs back from Hitec, unfortunately after the first month of waiting on them, my gasser was shelved for the winter. I haven't had a chance to see if they still jump on startup. I was told by Hitec that the 7-channel RXs were updated with a new resistor inside that eliminated the jerking. I guess you didn't get the updated ones?? Six months after I reported my problem and still these RXs have servo compatibility issues?

[Mike Mayberry]

Some of the first batches of the Optima RX's would cause analog servo to jump at start up but just once... the only time we have seen erratic jumping is with a poor power source like a low amperage BEC or low battery as the amperage at start up. I guess it's possible that there is some issue with this particular servo but I've not heard about it, and as far as I know all other JR servos work fine. I would try plugging in just one servo only to see if that makes any difference to know if it is a power issue.

Mike.

[jsluga]

I got help from another forum and from Hobbyhorse.com and solved my problem: low battery voltage.

I went back to the bench and reconnected everything with the Optima 9-channel receiver and an A123 battery. Servos were immediately solid as a rock and worked perfectly!

Had I simply installed everything and done my testing in the airplane, I would not have had this problem because I use a redundant A123 power setup (dual batteries and switches) there. I am new to the 2.4 Ghz band and had not realized the need for 6-volt power with the Optima receivers, having only used them in electric-powered airplanes with Lipo/ESC setups. Apparently my ESCs were providing ample power because the Optima 7 receivers I am using with these fairly small airplanes have worked flawlessly.

[tailwheelteacher]

I finally got a chance to test my new optima 7 rxs that Hitec sent me as replacements. Same problem, both recievers cause my analog throttle and choke servos to jump on startup. I've been out of an airplane for a long time now and I just want to know if the 9 channel recievers do the same thing? That makes 4 RXs that are a no-go for me. I'll be willing to trade 2 optima 7s for a flippin' receiver that won't jump!

[Brendan Lugo]

The 6's and the 9's have a different startup procedure than the 7's so you may not have the same issue using one of those receivers with analog servos.