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Receiver Glitches ????

Old 04-19-2004, 09:06 AM
  #1  
hilleyja
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Default Receiver Glitches ????

Mike,

I've been having a very frustrating problem with my Aeroworks X300L Profile since day one.

In a nutshell, the controls periodically jerk. It appears that all the controls jerk at the same time. It is momentary and at no time has it ever caused me to loose control of the airplane for more than a fraction of a second -- though if it happened just as the airplane touches down on the ground or just leaves the ground during takeoff it could be disastrous.

Configuration:

1) RX SuperSlim 8 (this is the 2nd one, and it is brand new)
2) Xtal Channel 35 (this is the 2nd one, original was channel 38)
3) (4) Hitec HS-5625s, airlons and split elevator
a) Airlon pushrods carbon fiber with nylon clevis to nylon control horns. (2) 12" Cermak extensions, each control
(I used to have 1 24" extension and 1 12" extension, changed out 24" with 12")
b) Split elevator pushrods carbon fiber with metal clevis to nylon control horns., (2) 36" Cermak extensions, each control
4) (1) Hitec HS-5645, rudder, carbon fiber pushrod with nylon clevis to nylon control horn, 36" Cermak extension
5) (1) Hitec HS-425, throttle (throttle servo is mounted within wing with nyron to engine), no extension
6) Antenna is routed immediately outside the wing and connected to virtical stabilizer with T pin and short piece of fuel tubing.
7) Transmitter is Futaba 9C -- FM Module for Channel 35
8) Flying wires on tail surfaces, Sullivan kit which does have metal-to-metal connections between clevis' and connectors.
9) Moki 180 with approximately 3.5 gallons FAI fuel (not quite broken in yet)
10) Mejzlik 19x8 prop (carbon fiber prop)
11) Tru-Turn spinner
12) Generic 3500mah 6Volt RX pack with Sanyo cells through an double-pole MPI switch.

NOTE1: The wires connecting to the RX are somewhat squashed into the small space along with the RX, i.e., a lot of cross overs
of wires. The RX antenna is not intermixed with those wires though -- it is free and clear between the RX and exit point.

NOTE2: I've gone through several stages to find and eliminate the glitching problem. I reduced the extensions in the wing from
24" to 12" and twisted the wires. I switched out the used RX with a brand new one. I finally pulled the channel 38 Xtal and replaced
it with a channel 35 Xtal. Each time it looked like I might have solved the problem but each time it resurfaced. I've had this
airplane for 6 months and have yet to really fly it because of the radio problems.

NOTE3: Several days ago I switched out the Xtal and flew the airplane 3 times that day. They were 3 flights that appeared to be
glitch free -- I declared victory and marked the old Xtal for destruction. Yesterday I flew it once. I performed an engine-off range
check, well in excess of 100'. I started the engine, still no problems. I then placed my TX on the ground, antenna fully extended, in preparation to pick the airplane off the ground restraint. As soon as I placed the TX on the ground all of the controls jerked. I then performed another range check with the engine running -- no problems. I launched the airplane and flew it for a couple of minutes.
It suddenly jerked violently in the air. I carefully landed it with no problems.

NOTE4: BTW, this is one of several airplanes I have on both channel 35 and channel 38. I'm not having problems with any of the others and they are predominently Hitec flight packs with the Futaba 9C TX. With one exception -- I have a Creeks 120 Sukhoi with the same flight pack configuration as the Aeroworks. It is currently waiting on a landing gear repair and has not flown for several months, but I recall I had similar glitching problems with it. RX, servos, etc are the same for it as the Aeroworks. It however, does not have the jumbled collection of servo wires within the RX compartment.

NOTE5: Though it hasn't happened for a while, I have had to reset/reprogram the left airlon HS-5625 twice because the centering of the servo significantly changed -- about 15 degrees each time in the same direction. Both of these occurred after the airplane had been idle for over a month between flights.

YOUR THOUGHTS??? I'm looking for you to compare these symptoms to similar problems that have surfaced from other customers -- any commonality? Are there some other tests I can run to narrow down the problem area? I could switch the TX from the Futaba 9C to my Hitec Eclipse 7/Spectra if you think it might be a Futaba/Hitec incompatibility.

QUESTIONS:

1) Could the jumbled arrangement of the servo wires within the RX compartment cause a convulsive interference with ALL the control
signals? (NOTE: the antenna wire is not intermixed with the jumble)

2) Could the extra-long extensions to the tail surfaces cause a convulsive interference with ALL the control signals.

3) Based on NOTE4 and NOTE5 above, could any faulty Hitec HS-56xx servo cause this convulsive interference problem with ALL of the control signals?

4) The flying wires on the tail surfaces are the only metal-to-metal connections anywhere in the airplane. Two of those connections are farely close to the point where the RX antenna is mounted to the virtical stabilizer, but they do not touch. Could these metal-to-metal connects cause a convulsive interference problem with ALL of the control signals?

Your dilligence in analyzing this problem will be greatly appreciated. At this point I don't have a clue as to what to do short of pulling the entire flight pack and starting all over. I'm also concerned because this RX/servo configuration has become my norm for all of my larger aircraft and I have lost at least 3 airplanes in the past due to mysterious radio problems -- nothing common in any of them with the exception of Hitec RX and Hitec servos; I've moved to strict usage of double-pole switches because of those losses.
Old 04-20-2004, 02:42 PM
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hilleyja
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Default RE: Receiver Glitches ????

I'll move this post to the general radio forum -- maybe get a response there.
Old 04-22-2004, 03:16 AM
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mglavin
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Default RE: Receiver Glitches ????

Jim

I have heard one circumstance of a servo that inadvertnetly caused a glitching scenario much like you describe. I would suggest pulling the 5625's and giving the model some flight time with another pair of servos. I'll see if I can find the info on the servo that caused this problem, but if memory servse me the servo appeared to work fine but later was determined to have a defective amplifier...
Old 04-22-2004, 10:40 AM
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Default RE: Receiver Glitches ????

I posted this in the Manufacturer forum with the hope of getting a definitive response from Hitec. I wish I knew why they have ignored it; there have been responses by Mike Mayberry in other posts since I posted this so it can't be because he is not available.

I'm starting to get a bad feeling about the Hitec HS-56xx servos again. I had one HS-5625 fail on me on the bench, locked into max deflection. This happened during the time frame when many adverse RC Universe posting appeared on the subject. I had a significant discussion on the phone with Mike Mayberry and he convinced me that the problem was no worse than any other servo. He also question why I was using a "SPORT" servo on an expensive airplane. What he didn't acknowledge was expense is relative to the owner. The advertised stats for the Hitec HS-56xx servos easily puts them into the category for 1/4-scale airplanes -- my configuration at that time was a Hanger 9 73" Cap 232, expensive for me but not to a 3rd-scale or 40%-scale owner. BTW, the servo that failed was not one of the early models. Since then I have gotten into the habit of "burning" them in, i.e., running them for at least 15 minutes with my Hitec programmer.

I've gotten several responses in the general Radio forum that aludes to a problem with the HS-56xxs reacting badly to 6.0 volt RX packs and effecting all control channels in the RX. The battery seems to be the only thing left that is common to my flight pack that I haven't replaced. I will be replacing the 3500mah 6.0volt pack this weekend with a 2200mah 4.8volt pack. If this solves my glitching problem it will only further concern me about the reliability of the HS-56xx servos.

BTW, I consider the use of the HS-5625 and HS-5645 in my Aeroworks X300L Profile to be of a "SPORT" nature. Even a "SPORT" airplane should not have to accept constant intermittent control glitching.
Old 04-22-2004, 01:58 PM
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mglavin
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Default RE: Receiver Glitches ????

The servos work fine on 6.0V, in fact I recommended this voltage over 4.8V for many reasons. I do not suggest you run them on 4.8V, yes they will work, BUT voltage degradation is commonplace and these servos consume 1-2amps under load easily. Spiking the power distribution system will cause the power to dip below 4.8V.

Another common problem is poor quality connectors, extensions and wyes. Many problems have been attributed to these items, MANY... Oxidation on the connectors also is an issue!

Mike Mayberry and I field the questions in this forum. My son Josh is Hitec Factory sponsored pilot we test, fly and use Hitec equipment in many applications.

The servo I mentioned above was a HS-5945. I offered this information as it was causing a similar problem as your experiencing. I have been using the Digitals since their release and have had two failures of the 5645's early release on the bench. Other than hundreds of servos later we've had NO problems at all.

Mike Mayberry and myself will be away the until the first of next week, we'll be at the RCX Tradeshow in Anaheim, CA..
Old 04-22-2004, 02:43 PM
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hilleyja
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Default RE: Receiver Glitches ????

Come on mglavin, that response adds even more confusion. How about some thought on the subject that doesn't require me to totally strip out the Hitec flight pack and replace it with something else. What would you recommend I try next?

All of my extensions are new with this airplane -- there couldn't be oxidation on them right out of the package. All of my extensions are 22guage wire and of commercial quality. Lets not forget, and I made this very clear above, we are talking about convulsive glitches on ALL control surfaces here, not just one surface.

As I have indicated in previous posts, I do have one HS-5625 servo on the wing that has lost its center neutral programming twice after lengthy idleness between flying -- this is the servo I alude to as possibly being bad, though after resetting it with my programmer she acts normally.

I monitor the voltage on the 3500mah NIMH battery in this plane regularly and will peak it if it gets close to 6 volts. It appears my glitching might be more pronounced after a couple of flights following a battery peaking but I can't swear to that.

BTW, I use a 3500mah NIMH battery on this airplane because I have one and it helps with the CG. The flight pack configuration of (4) HS-5625s, (1) HS-5645, and (1) HS-425 does not even come close to requiring that kind of battery. My flying todate on this airplane has not even come close to exercising the torgue potential of those servos. Likewise, my plan of replacing the 3500mah 6volt NIMH pack with a 2200mah NIMH 4.8 volt pack should not normally be detrimental in this configuration -- you alude to the fact that these servos should not be run at less than 6volts; they are rated for 4.8volts by Hitec. I probably pull more out of my RX pack on my Ultra Stick with its (7) servo configuration -- they are (6) HS-605s and (1) HS-425.
Old 04-26-2004, 12:09 PM
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mglavin
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Default RE: Receiver Glitches ????

ORIGINAL: hilleyja

Come on mglavin, that response adds even more confusion. How about some thought on the subject that doesn't require me to totally strip out the Hitec flight pack and replace it with something else. What would you recommend I try next?
You asked for help on solving your problem. I provided such by suggesting you pull the 5625's and testing thereafter. My recommendation is based on actual knowledge, not conjecture.

Hitec's Digital servos amplifiers are bi-directional unlike others. Problems seen with connectors and depredated voltage is plausible.

All of my extensions are new with this airplane -- there couldn't be oxidation on them right out of the package. All of my extensions are 22guage wire and of commercial quality. Lets not forget, and I made this very clear above, we are talking about convulsive glitches on ALL control surfaces here, not just one surface.
You did not mention that your extensions and such were HD or 22awg wire. In any event even components can be problematic. You might consider busting out a DMM and checking for losses of each extension and connector.

As I have indicated in previous posts, I do have one HS-5625 servo on the wing that has lost its center neutral programming twice after lengthy idleness between flying -- this is the servo I elude to as possibly being bad, though after resetting it with my programmer she acts normally.
Exactly you have a known abnormality! Why is this occurring? Is the servo the source of the phenomena or is the problem realized of the power distribution, i.e., connectors, wyes or extensions. I alluded to this previously, this is a common scenario and is more often than not the problem, and it’s been proven many times by users that swore up and down all was well with their gear. And as I suggested I am aware of a servo that simply caused feedback that was generating interference.

I monitor the voltage on the 3500mah NIMH battery in this plane regularly and will peak it if it gets close to 6 volts. It appears my glitching might be more pronounced after a couple of flights following a battery peaking but I can't swear to that.
It's unlikely the voltage realized after a flight or two is elevated, in fact its typically right where we want it... If elevated voltage was a factor it would be realized off charge not several flights thereafter.

BTW, I use a 3500mah NIMH battery on this airplane because I have one and it helps with the CG. The flight pack configuration of (4) HS-5625s, (1) HS-5645, and (1) HS-425 does not even come close to requiring that kind of battery. My flying todate on this airplane has not even come close to exercising the torgue potential of those servos. Likewise, my plan of replacing the 3500mah 6volt NIMH pack with a 2200mah NIMH 4.8 volt pack should not normally be detrimental in this configuration -- you alude to the fact that these servos should not be run at less than 6volts; they are rated for 4.8volts by Hitec. I probably pull more out of my RX pack on my Ultra Stick with its (7) servo configuration -- they are (6) HS-605s and (1) HS-425.
Your battery is fine it’s a very good choice IMO. My assertion is based upon voltage degradation under load as alluded to previously. Yes 4.8V works fine; problem is the servo may see much less than this under spike loads with a 4.8V system... A 6.0V system will not drop down to voltage levels that may cause problems. It’s well proven by myself and many modelers that 6.0V is the preferred power potential with these servos.
Old 04-26-2004, 01:35 PM
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Default RE: Receiver Glitches ????

The short of what I seem to get out of your last response is that I should suspect the left airlon servo.

I flew this plane several times last Saturday and paid very close attention to the minute details. Prior to flying I did pull the 6.0v 3500MAH pack and replaced it with the 4.8v 2200MAH pack. I really don't think it made any difference -- I did notice the difference in servo response to my controls and like the 6volt better.

Glitches??? There still there, sometimes very noticeably, sometimes very subtle. The only commonality is that they are convulsive on all controls. I will replace that airlon servo this week.

BTW, I came up with another plausible cause for the interference. My throttle servo is mounted in the wing root. I have a long metal pushrod encased in a plastic sleeve, unsupported, running from the wing leading edge to the throttle lever. During one of my engine runups I noticed this rod vibrated significantly -- kinda like twanging a guitar string. Midway during my flying day I added some limited support between the rod and the fuselage (I wrapped a plastic tie around the rod and hooked it to the fuselage, causing a slight bowl in the rod). It didn't stop the vibration but certainly reduced it significantly. She still experienced some glitches in flight but where of the subtle nature.
Old 04-26-2004, 01:59 PM
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mglavin
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Default RE: Receiver Glitches ????

Vibration from metal to metal contact will generate EMI with no rhyme or reason. Why not replace the clevis with a plastic or nylon piece?

The fact that you have had issues with the single 5625 reprogramming itself would lead me to this servo, no doubt. The reprogramming maybe an issue with bi-directional potential of the digital amplifier and degraded signal voltage. Again this is not uncommon. Look hard at the connectors and extensions for this specific servo. In any event I would pull it and have it checked out.

Any chance you have a hand held programmer with something other than V1.03 software revision?
Old 04-26-2004, 02:54 PM
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Default RE: Receiver Glitches ????

My programmer was of the earlier versions, but I have since returned it to Hitec and it was upgraded to V1.3.

I will take your suggestion and put plastic clevis' on both ends of the throttle pushrod. I may move the throttle servo out of the wing root and mount it to the side of the fuselage just behind the engine in front of the exhaust port as well.

This airplane/engine combo is just now really starting to rock. I've got just shy of 4 gallons through the Moki 180 and was finally able to tweak the needle almost a 1/3rd of a turn in. This gave me a very noticeable improvement to the top-end and a significant improvement to my fuel aconomy. A half-gallon ago I was unable to do this.

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