Oh Man!

[Dale W]

Well, I fired the 'G' up yesterday (fortunately without the main blades on) and after bliping the throttle to about 1/2, the heli locked out and went to about 3/4 throttle! Yee Gads! I forgot to set my failsafe (Multiplex PPM with IPD receiver). It finally recognized throttle cut and shut down... good thing as it was a full tank. I had done a fully collapsed antenna range check to ~100' with the engine off and no problem and was doing about a 30' range check with the engine running when it happened. It ate up my tail gear and it looked like snow all over the mechanics! I went to my LHS and picked up another, setting the mesh right this time. (the tail never touched the ground)
I swapped out the receiver to one with a full-length antenna, checked all the wiring and set the failsafe in the new receiver. I went out to a park today (less stress than the driveway) and the same thing happened, but this time it failsafed to engine shutdown and the tailgear remained intact. The head was removed for this run, so that eliminated any interferance from that.
I never had an issue with any of the Vario gasses I've put together and flown, so I guess its time to ask for any help on this. It idles fine and runs up to a certain point (close to 1/2 throttle) before locking out. I noticed a whole lot of vibration going on with the fuel and I never seem to remember that kind of bubbling on my Varios..
Dale

[carey shurley]

sorry, I wound up being out of pocket most of today.

I can probably spend some time with you on Thursday or Friday afternoon if you want to go out to the field and fool with it.

Just have to go through things until we find something interesting.

[Dale W]

No prob Carey. I found a slice of time and wanted to see if the receiver replacement fixed it.
I did just notice that the spark plug spring wire (the one you muck with to put the braided sleve on) seemed to be going in at an angle rather than straight down into the plug wire. I put a tie wrap on it to make sure it stayed put. I'll keep looking (Its sitting on my desk right in front of me!) to see if I can eyeball anything else. Thursday I might be tied up, but I can probably slide out Friday, as I'm off work.
Dale

[WillJames]

I am definitely no gasser expert and sounds like you are on the right track for sure getting together with Carey. I am curious if you have you tried checking it with one of the 10 dollar A/C Testers from Lowes or Home Depot? They work great!!

http://www.helifreak.com/viewtopic.php?t=3622

[Dale W]

I didn't have the tester with me when I went to the field. I'll try to do that test tomorrow.
Dale

[DavidH]

Dale,
Just curious. Have you used the Multiplex receiver on other gas engine models before?

David

[Dale W]

David,
Yes. The last one was a scale Agusta 109 K2. No problems.

[WillJames]

Did you ever figure out what was happening Dale? What did the checker detect if anything. Do you have it flying now? Mine is AWESOME with zero glitches or range issues so far. I really like it. Installed some servo supports today just so I could touch it. :)

[Dale W]

John,

I went through the whole thing.. Checked it with a different battery, switch, receiver (with and without a Revolution whip) put a grounding lead from the motor to the receiver (plug into the -) and it still gives the problem. I went out to the field today and Carey was nice enough to come out in the crappy cold to look at it. Tim just happened to be in the area and came out also. Carey found a couple spots ~30' away with the TX antenna down that the heli didn't like. He pulled the receiver antenna out (toward the front) and it did the same thing. However, when he fully extended the TX antenna, everything seemed to be ok even walking out almost to the other side of the field. These problems are found with the engine running and is more noticable when at 1/4 - 1/2 throttle. Engine off radio checks with the TX antenna down are ok.

I think the next steps are to do one more check as-is with the antenna fully pulled out (it was still going through the front plate grommet) and then swap the receiver to one of Carey's futaba units. When I told Tim my radio was PPM (Multiplex Evo 9), his eyebrows went up a notch. I never had a problem with using this unit on other helis (even my scale Agusta 4-blade), but the combination of a gasser and graphite frames may be throwing out crap that is being picked up as signals (where PCM would probably mask them).

If that is the problem it would be an expensive fix for me, as I got rid of all my JR PCM reveivers and the 10X I had.

Anyway, we may hook up again Sunday to do those last checks. If that goes ok, we will put the head back on and check it further before bolting on the blades for a first flight. (hear my optimistic pain?)

It would be interesting to know if anyone else is running PPM of any kind on the 'G'.
Dale

[DavidH]

That is why I asked earlier had you use this receiver before in this application.
I tried a PPM receiver in a gasser a few years ago. No matter what I tried or did the model would glitch. Only reason I put the PPM receiver in the model is because I built it from someone else. I told him before I built the model for him it would glitch. Well I built the model and got it flying. It would glitch every 20 to 30 seconds. Well gave the model to the owner, he flew it like 5 mins and it must have glitched 10 or 12 times. He put the model in his truck and went to the hobby shop and got a PCM receiver 129 DP Futaba. Put the receiver in and is still flying the model with no problem today. That was about 5 years ago.

I know the Mulitplex is the IPD technology. Do you not have the failsafe feature set up to pull the throttle to idle ?

David

[Dale W]

David,
I have used this receiver in other gassers (not graphite), used other receivers (the ones I swapped in for diags) in other glow planes & glow & electric (Joker and Voyager E) helicopters, and used this transmitter with other JR receivers (R600, 700, etc.).
The first time I fired the 'G' up, I had neglected to set the failsafe correctly and it scared the bejessus outta me. It is set not to full off throttle until I figure out what the problem is.

Dale

[WillJames]

Did you install your MA Plug wire shielding kit? John and I are going to soon do a video detailing how it needs to be done. You have to make sure and keep the shield about 1/4 inch away from the boot and you have to secure very well the ends of the wires with wire ties and then RTV because if a single wire gets under the boot it can arc back through the shielding wire, which could definitely cause glitches. Also you should check your red wire coming from the coil to see if it is hot to. On my motor, it was so John installed a shield on it to and no more hot spots anywhere on my Spectra.

Did the checker identify any hot spots on your Spectra?

Best of luck (process of elimination) identifying the cause.

[Dale W]

Yup, I installed the shielding kit and I think 1/4" is too close. I could see an arch going from the wire that pierces the plug cable to the grounding shield. I increased this spacing to ~1/2" and the arching is gone. Carey went over the whole thing with his checker and gave it the thumbs up.

I decided to change out my throttle servo (a JR DS8231) for a Futaba 9202. When I took the screws out, one of them came out a bit shorter (!) and I looked at the PEM nut and saw the remaining 1/16" or so snapped off in there. I don't know if it was that way before or after I unscrewed them, as they all came out with the same amount of resistance. Blue loctite was used so I think either it got a cross thread on install or it broke from stress of how the JR servo fits in this spot - the Futaba servo fits much more 'square' than the JR, which looked like the width distance is a little shoter, causing a stretch outward to the PEMs. Anyway, I'll give this a try tomorrow (cold & a 70% chance of rain - as well as being Christmas!) to see what happens.

I would much rather this problem be something like this than being PPM related.

Dale

[carey shurley]

I think the "checker" is a good way to ensure that the high voltage lead is properly insulated. I don't think it really does much for problems with RF emissions in the frequency spectrum that we care about though.

Dale's model is a good example. Using the checker, the model's clean however its definitely glitching in certain circumstances. Whereas my house is near high tension wires. When I just walk outside with the checker, it goes wild. However I test models in the same place all the time and I've never gotten any glitches.

Dale did a good job building his model though. We'll get it straightened out.

[conrod]

You are the man Carey...and by the way....received the goods to help me straighten out my motor issues.

[carey shurley]

excellent. I'll want to hear the details

[WillJames]

Sounds like you and Carey are on the right track to figuring it out Dale. Please keep us informed of your progress.

[big dee]

i had the arcing problem to until i cut the sheilding back 12mm then no problem

mine is flying awesome cannt get over how much power it has and so

crisp :badair:

[WillJames]

My shield is less than 3/16 from the cap and no arcing. I know Johns is also very close to the cap on his TRM231. John installs the shield and wire ties it on the cap end, then wraps it back over the first tie and secures the ends with a second tie. Then he uses RTV to make sure there is no way the ends can work their way toward the cap. Also be very careful (yes it is a little tricky) to make sure the wire from the cap is back peircing the high tension wire and fully inserted into it. If it is not completely back in, that has been known to contribute to the arcing. You can see in teh photo below how close my shield goes to my cap, very close. You can also make out the first wiretie that is covered with RTV and the second that is holding the ends.

On my SE, since I am very anal about this kind of stuff, we installed shielding on the red coil wire to. Is it necessary..no.... The way I see it, I want to take every precaution to ensure my new baby does not meet terra firma unless it is because of my thumbs. I love working on my helis, it is an outlet for me, so I do a lot of maintenance and tinkering.

Hopefully by Saturday we will have a video out of how John installs the shielding and his tips, tricks and techniques.

[Dale W]

At least two instances have found the 1/4" is too close and causing problems and that either by increasing the distance 1/8" to 1/4" or by doing Baja170s method the problem goes away. The manual doesn't go into any real detail here, so if you have any starting problems, or (more obviously) see arching in this area, either of the methods can be used as a fix.
It might be good to modify the manual. My guess is after going through this is that the little hairs on the grounded braid are too close at 1/4" when pointing toward the anode and can easily bridge the gap. By either folding the braid or increasing the distance, the problem is eliminated.
Dale

[WillJames]

Very good suggestions Dale. I am pretty sure Carey is working on the manual for this shielding install. Carey has quite a job with the documentation when new models come out, and he is doing GREAT!! We should also have a video How-To out by Sat or very near Sat.

It is John's method, not mine. I am not near that smart or experienced. :oops: I do love to pass along good info as I get it though. Working with John has been very rewarding to me in the gasser learning curve, and I am lucky he lives so close and wants to help so many people!!

[Festus1567]

When you guys say "away" from the boot, do you mean 1/4 inch shy of the very bottom edge of the boot?

Just want to make sure I've done this right.

[Dale W]

1/4" to 1/2" from where the coil cable goes into the red spark plug boot. Depending on where the straight piece of the spark plug spring connector is located (poked into the coil wire under the boot), this should put the braid ~3/8" to 5/8" away from that high voltage point. This may be why there is a problem. Some of these taps may be closer to the edge of the boot than others, causing a spark jump.
Dale

[big dee]

id like to thank Cary John and Wil for all the imfo and all the time you guys take to

get on here and reply to all our ?'s ....... and to thank you in advance for all for

any ? i have in the future .... i hope to meet you guys one day so i can buy you a

Beer............:noteworthy

[Dale W]

Well, Carey and I went out to the field today to debug my Spectra. Although I could get a lot farther away with the antenna collapsed than before, it still glitched. Also, with the antenna fully extended, I would get an occational hit when all the way across the field. Carey put his PPM receiver in and with the antenna down to the first section, walked around halfway across the field with no glitches at all. So, the problem appears to be my radio, since it glitches for me with any of 3 receivers I put in the thing.
After thanking Carey for his time, I told him he was either going to see my Spectra on the BB for sale, or I would have to get another radio, as I was too spooked with this one and with all the talk about 'needing' PCM for this heli (even though his PPM seemed to work), would have to go that route.
So, I've got the fix and have done what I needed to do... No, you won't find the Spectra in the For Sale section... I just ordered a 9303 radio with the 770 PCM receiver that should be here Thursday. I really could have used not spending the extra money (new house to be built in 05), but it was the right thing to do.
Now, if I have one more friggin problem.... Well, I'll try not to think about that and be more positive. This thing should be flying this weekend!
Dale