Oh they know....It just all boils down to $$$$$$$$$$$$$$$$$$$$$,They have really hurt their reputation here,Its a shame!

I have one 7990 that I purchased last week that jumps about 15 degrees when you move the transmitter stick slowly from the center. I connected the servo with four different new extensions and got the same results. I connected a second 7990 to the same extensions and it works perfectly, steady and smooth. The interesting thing I noticed was the bad servo was 5* hotter (checked with my laser temp meter) than the good servo when both were connected for the same time to two equal extensions. I called Hitec and the technician claimed the problem was my poor quality extensions even though I explained I had a second servo working correctly on the same extensions.
I'm disappointed in Hitec !!! I have installed over 100 Hitec servos and this is the first bad servo I've had. They should offer to exchange a new servo that is defective right out of the box.

Originally Posted by flyguy2

YouTube - ‪Hitec 7950 troubleshoot part 4.wmv‬‏

So that's it then !!
Man that's so frustrating. After all your time and effort. I was expecting the Futaba pots to be the answer to the problems. No one deserves to solve the problems more than you Tavis after all the work you've put in.
Got any other ideas in mind or are you now at the mercy of the Hitec engineers?
Damn this really sucks.

Hey Tavis, I know whats wrong with your servos! They are scared because you fly too low. Nice flying!

nice investigative work flyguy.

Nice flying Travis!!!

Was that a futaba rx in your plane flyguy? Thought Mike said that there aren't any problems with the futaba rx.. or hitec. Just jr and spektrum.

Originally Posted by flyguy2

YouTube - ‪Hitec 7950 troubleshoot part 4.wmv‬‏

Well thats conclusive as far as I am concerned. This proves the location of the problem. Great job Tavis!

Have you given any thoughts to disassembling the round pot and taking a look at the tracks and wipers to see if they are burnt or just worn out?

I showed my buddy my servo "jitter" yesterday and he couldn't believe it. My servos are going in a box and will never be flown untill a valid solution is found. I have purchased close to 100 hitec servos, but, these servos are the last Hitecs I will ever buy. Sorry for the rant.

Originally Posted by rcpilot82

Well thats conclusive as far as I am concerned. This proves the location of the problem. Great job Tavis!

Have you given any thoughts to disassembling the round pot and taking a look at the tracks and wipers to see if they are burnt or just worn out?

.

i was wondering the same thing, or even install them in a jr or futaba servo just to see if the jidder is there also. but sounds like he did narrow it down to the root cause though.

Originally Posted by jamesrxx951

i was wondering the same thing, or even install them in a jr or futaba servo just to see if the jidder is there also. but sounds like he did narrow it down to the root cause though.

I am wondering if the pots are having too much current flowing through them and causing the failure or if it is the decoder pulsing the pots to failure. If the tracks are burnt and the wipers discolored then that could point to an over current failure. Plain old wear on the tracks could indicate the decoder is the failure point. just thinking out loud here.

flyguy2, A very noble experiment at your own expense. That's the kind of thing I would do.

It's probably the batch of chips. Hitec engineers give the design to a completely different set of engineers who design the actual chip. These guys were probably totally unaware of the power environment at the chip. You have a scope. You can look at the power when you slowly move the servo.

This is like GM selling cars that the wheels fall off of because that is cheaper than fixing the problem.

Awesome testing flyguy. I thought the pot was going to fix it. I wonder how a circuit can wear out a pot? The pot is just a variable resistor. I can see it mechanically wearing out....but electrically wearing out? How? Putting too much current through it can burn it out. But you can't electronically wear something out. Nothing is moving...just electrons. You can overheat electronics and shorten their life. Is it overheating? Those are the questions I have now. I see the results and believe them, but I am not aware how you can wear out a resistor in a circuit besides just burning it open with a large current (heat). Then it wouldn't work at all. Man what a weird problem. Has my head spinning a little right now.

Originally Posted by flyguy2

YouTube - ‪Hitec 7950 troubleshoot part 4.wmv‬‏

Flyguy2,
A very though demonstration of the effects of a noise source coming from the servo. I’m far too conservative to risk my plane as you did. I highly respect what you did. Flying at a private field with no one around was a very intelligent thing to do. I hope others appreciate what you have done.
Paul

Mike,

Please also test with the new JR add-on for DSMX, which make the JR system a frequency hopper.

Might need to take a voltage reading at each point of the 3 legs of the pot and determine what each leg is. One should be voltage in, the second will be a variable voltage as the pot is turned and the third should be referenced to ground. The importiant thing to look at is the first voltage, is it a regulated voltage by the servo circuit or is it independent and what ever the battery voltage is, thats what the pot sees. If that voltage is regulated then the higer voltage from lipos is not the problem.


Scott