w8ye

My Feedback: (16)

Often the RFI is getting into the servo amplifiers and it doesn't matter about PCM or 2.4

jedijody

My Feedback: (1)

Put a small hose clamp on the spark plug cap right where the hex of the plug is, tighten it until the cap cannot rotate on the plug easily. About 95% of RFI is caused by a loose fitting spark plug cap.

pc55bomber

I have the same engine and had the same problem initially.
Check that the spark plug cap is on properly, it was tight but it was not pushed all the way home.
They are really hard to get on properly.
Ever since then this engine is sweet as, very happy with it.
Cheers
Paul

jetrichie

Yes plug cap was the problem thanks for that

LUDS96

My Feedback: (23)

I checked it it seems tight. I will double check it and maybe put a hose clamp on it!!

wingswinger

HI guys need some help on a CRRC 50 pro. I have the silver ignition box installed on a Great Planes Giant Stick. When I crank and run the engine I have a hit through the ignition on my controls. I have disconnected the metal throttle linkage and still have the same problem. Can anybody help me? Thanks.

LUDS96

My Feedback: (23)

Read all the post. Alot of ideas

jedijody

My Feedback: (1)

Put a small hose clamp on the spark plug cap right where it goes over the hex portion of the spark plug, tighten it until the cap cannot be rotated easily, no more RFI.

wingswinger

thanks for the it i will try it and get back to you

wingswinger

thants for the tip that did the trick Jody .

LUDS96

My Feedback: (23)

PCM Reciever cleared up my problem!!!

cuwaert

Don't believe it, it MASKS the problem. Primary electronics must operate flawlessly before you put a
microproc in (The PCM briefly goes into failsave so the glitch will be difficult to detect).

Best Regards

cuwaert

I saw a few problems with glitching, I have a GF45i and it didn't glitch once in the year that I use it, even with the stock CDI.
And I never used PCM in my life, so what's happening?
It's always difficult to solve problems 4000 miles away from it but I'll give it a try.
There's a lot to say about computers ( that what is inside a PCm receiver) so I 'll keep quite about it.
A good setup requires that you start with the most sensible configuration that is a PPM receiver that sees and hears
everything. When you experience glitches it means something(s) is(are) not quite as it should be.
How to generally solve?
The following goes for all engines, cheap and expensive, gas and electric
1) try to establish source of glitches( ignition , speedcontroller, metal to metal). OK you are sure, it's the ignition.
2)keep it and it's battery as far as possible from the receiver and / or electronics that are connected to te receiver.
3)make unit, battery and switch as compact a bundle as possible and in case of electric motors keep the wires of power bundles as close to eachother...you guessed it... as possible or twist.
4)make sure that the screen of the plugcable doesn't touch any other metal than there were it should touch
more explicitly the base of the spark plug. Wrap it in plastic tape all along from cap to cdi and see to it that ik doesn't
wiggle about too much.

Some other remarks are, watch out for killer switches, ferrite coil in series with cdi power won't hurt but keep it as close to
the unit as.... possible.

If you can cure this business with a PPM receiver, your system is ready for PCM.
If you got glitches with PPM you allso have them with PCM only the receiver will experience short datacuts that result in
poor response time, short failsave situations and while you are walking with one foot over the cliff, a randomly small
deterioration of the situation can turn your receiver in prolonged failsafe what will kill your modell.

Best regards

The Raven

I was going to suggest the same thing. PCM is great for filtering out the odd problem but it shouldn't be used to hide an obvious issue. Your receiver could be fraction away from locking out at all times and you'll never know.....until it's too late and locks/holds you out (which could be for quite some time if the problem is that bad).

LUDS96

My Feedback: (23)

That's how it started. I have a plane with a PCM receiver. I need to put a PPM reciever in it to make sure I don't have any glitch's. If I do I must reconfigure the whole plane move the battery's all around and make it Glitch free with my PPM receiver. Than after I have pulled all the rest of what little hair I have left out. I can put the PCM receiver back in and go fly knowing! I've punished myself enough for posting a question on RC Universe. Let the opinions Fly!!!

pc55bomber

I dont know anyone that flys gassers with PPM, its all PCM or you have trouble.
Don't believe PCM masks anything at all, it just works. (I dont use failsafe either)
All my gassers and everyone I know use PCM RX's with no problem at all.

Why waste time and sanity on PPM.

Too many people get too technical.

Cheers
Paul

jedijody

My Feedback: (1)

It's not getting technical, it's getting it right. A properly set up gasser works fine with PPM, I do it all the time. Just like in the old days when we were flying gassers on unshielded magneto ignitions with AM radios. If you can't set up a gasser to work safe and trouble free on PPM you are not going to be safe with PCM, 2.4, or anything else.

pc55bomber

A very misleading and incorrect statement.
You are indicating that PCM etc is wrong from day 1.
We use PCM all the time without issues, and thats my point you can use PCM without any issues and without it masking problems, we do it every weekend.
Sure if not setup properly you will have issues with anything PPM, PCM or 2.4.
To say it must work properly with PPM first or it wont with anything else/masks problems is just rubbish, if setup properly there is nothing to mask.
The RF noise from the plug cap not being on properly still shows up with PCM as it does with PPM.

Hope this helps clear up some confusion.

Cheers
Paul

jedijody

My Feedback: (1)

Sorry but you are the one who is confused, I never said that "PCM etc. is wrong", or anything else is wrong for that matter. The meaning of my statement is that if you are having RFI issues with a good PPM receiver, you have a problem that needs to be addressed, just tossing the PPM aside and installing a PCM receiver will not cure the problem, if that makes the problem disappear then it has been masked. Your statement that "its all PCM or you have trouble." is totaly false, using proper methods and practices that should be followed no matter what guidance technology is used works great for all systems.

To tell someone that is having RFI problems on PPM to forget it and use a PCM instead doesn't help them at all and could be dangerous to at least his model airplane, helping them find the problem and work through the solution with proper and proven troubleshooting and set up technique is the right thing to do.

LUDS96

My Feedback: (23)

Thanks Paul

We were in your Country in 2002 Very nice experience.

That's my point. If I did not put the PPM in the plane I would not have noticed a problem. I run PPM with three other gassers I have. 1) Cinmaster Revoultion 50,2) Brison 3.2, 3) Zenoah G-38 magneto. I usually shield the ignition away from everything else and it works well. I never had issues like I have had with this engine. I put the PCM in it under recommendation, and now I can fly it. I've had no problems in the air or on the ground.

pc55bomber

Hi Jody
No I am not confused, what you wrote, what you meant and how people interpret it is confusing.
I agree if you have a problem you must fix that problem, regardless if it is PCM or PPM, setting it up right in the first place is the key.

The inference that comes across is that PCM only masks problems, when that is clearly not the case.
Yes I have experienced problems with PPM and going to PCM has eliminated that problem without any further issues.
So it can and does happen in practice but it is not the cure for all problems.
Cheers
Paul

The Raven

PPM receivers are used to determine what, if any, interference issues you have. Jumping to PCM is tempting fate.

PCM does mask poor signals, it's the nature of the beast. PCM rejects bad packets and, if it gets enough of them will go to hold or failsafe. Without prior testing you have ZERO idea if you have any glitching or how much of your signal is being rejected (because PCM is masking it).

Yes, move to PCM once you've ascertained you have no interference. Use PPM to determine any interference and deal with that first.

The Raven

Sorry Paul but I think you've missed the main issue. No one is suggesting PCM is not a good idea.

You use PPM to test for glitches, then minimise them as much as possible, only then can you take on the added safety PCM gives. You rely on PCM to protect you from occaisional glitches, not as the primary means of filtering out persistent interference. To jump straight to PCM means you have no indications of any glitches.

Testing with PPM will show any glitches, giving you the opportunity to resolve them before the maiden flight. PCM doesn't do that.

PCM does mask glitches by rejecting bad packets of data. How many glitches is your PCM receiver rejecting? Unless it tells you (and some can) you have zero idea. You could be so close to a failsafe/lockout you won't know until it happens.....a bit too late to claim PCM saved you.


By all means use PCM BUT don't be lulled into thinking it's going to magically protect you if you have installation related interference.

The Raven

Hi Paul,

We definitely agree on fixing problems prior to flight, hence why a good test regime is required prior to a maiden flight.

I do disagree with your belief PCM doesn't mask problems. A quick google on receivers, PCM signals, and review of manufacturers sites will change your mind.

Every time a PCM receiver gets a packet of data it decides whether it's correct or not. If incorrect it decides what to do with it, which is generally to ignore it and read the next packet. This happens approx 50+ times per second (depending on manufacturer etc). If a string of suspect packets are received, then hold or failsafe is applied.

If the odd packet is rejected you won't notice it, hence those packets are masked from you. If enough packets are being rejected the receiver will go to hold/failsafe, only then will you know you have a problem.

PPM isn't superior to PCM but at least you can see the problem as it occurs (hopefully on the ground). Not testing using PPM means you have no idea if you have an underlying problem.

wingswinger

Thanks for all of the tips. I flew my plane for the first time today. After 3 dead stick landings, I finally got it operating correctly. I did find out that the spark plug cap on the crrc50 pro must cover the hex head on the spark plug. I did not have the silver cap all the way over the hex head; didn't realize it was that important. That was the source of a lot of my problems. The motor runs flawlessly now.