Help! Almost crashed. Weird problem
 

Hi everyone. I have a Hirobo GPH and was getting throttle/pitch glitches at mid throttle while slightly descending from hover. Tried 2 different Fm receivers, same problem. Figured bearings going out, right? Anyway, switched to a PCM receiver, same Tx. Now throttle glitch seems to be gone, but during hover the heli locks up with a small amount of left aileron for around 2 seconds before I could get control again. Seems like the entire radio locked up with no control during this time. It has happened more than once. I thought bearings going bad didn't effect PCM receivers. I am stumped and need help. Thanks for any advice you have! :confused:

Help! Almost crashed. Weird problem
 

Have there been other people having trouble on your frequency in your area ,...... PCM is interference resistant.... Not immune ... If all else fails contact your local AMA District VP and borrow their scanner to see if there are probles in your area.... FWIW .... and best of luck ......

Help! Almost crashed. Weird problem
 

When you switched to PCM did you set up you fail safe settings ?Sounds like it glitched and your TX went into fail safe mode
(the 2 second lose of control).

Help! Almost crashed. Weird problem
 

Thanks for responding. I live in a very rural community in Oklahoma, so I don't think that interference is the problem since my friend has flown on this same receiver and had no problems. I just thought of something that might be a reason. Doesn't PCM have some sort of fail safe mode that locks the servos in their current position if interference is detected?

Help! Almost crashed. Weird problem
 

set up your fail safe to hold the last position or just have your throttle come to idle.I would check your bearings and any other metal to metal contact.

Help! Almost crashed. Weird problem
 

Thanks. How do you check bearings? I figured I would just replace them. I think you are right on the fail-safe thing. I will check my transmitter. I have a JR. Do any of you guys out there fly hitec? I just wondered what their heli radios were like.

Help! Almost crashed. Weird problem
 

Sound advice to borrow a scanner. To assist in tracking the problem down, invest in a pair of headloaders and re-fit the ppm receiver. Run the heli up to the speed at which the problem occurs and see if it glitches, from there on in its a try it and see which part is causing the problem !. Do not try and fault find with the PCM receiver this will only serve to mask the problem.
Good luck.

Help! Almost crashed. Weird problem
 

Wow ..... Just had a brain glitch or something .... I haven't tried to set a failsafe mode for PCM and have been real happy to leave it disabled, figuring it would get me back to controlling the model more quickly than the signal sampling of fail-safe .... Regardless , though , for those of you who have done the fail safe thing ...With Helis, does a fail safe setting of going to idle position also affect the collective as it does with the stick ...... Just curious

Help! Almost crashed. Weird problem
 

Is there a possiblity that this problem could be related to the transmitter? Just wondering. THanks.

Mark

Help! Almost crashed. Weird problem
 

I suppose it could be the transmitter , but I would guess it is more the receiver or something in the heli itself ....Antenna routing ..... Metal to metal interference etc..... Did it seem to behave OK before you changed something or has there been a recent OOPS ..... which may have caused a cracked crystal ... Damaged ceramic filter in the rcvr or something else that is intermittent.???? a damaged servo can also "feed back" radio noise into the whole system .... How about the switch itself ....

Help! Almost crashed. Weird problem
 

It has behaved this way since I got it. I bought it used and it has what are supposed to be good servos. Futaba coreless ballbearing. One of them has already died. I don't know how new the servos are. I went back to the PPM receiver yesterday and it did pretty well as long as I was flying in constantly. It had a little glitch or two during flight. It mostly gets them around half stick or so during hover. The voltwatch on the side dips down in the red like there is a big drain or something. Then it goes back to normal. I oiled all of the bearings yesterday to maybe help on noise before I replace them. It does have a metal frame.

Help! Almost crashed. Weird problem
 

This will probably cause some people to get angry with me but I personally don't care for the Voltwatch thingy .... It looks really cool but one of my friends whom I respect when it comes to electronics seems to think that the energy it consumes is about the same as another servo .... With a heli pulling five servos plus a gyro. I don't really want more drain on the battery than there absolutely needs to be .... I had a really unexplained crash with my first heli , an ERGO with standard mixing ( Not CCPM) and all can I figure is that something goofed up really badly ... Could have been me but I have replayed that event several times in my mind and can't come up with an error I made .....That heli was one I had bought used and it had a Voltwatch ... Seemed like the battery never gave decent life ... When I got another heli , I left the Voltwatch off and the batteries now last several ten minute flights and no excessive battery drain ... I do check them between flights with the standard Hobbico meter ...Have you tried flying the chopper with the Voltwatch disonnected or removed ??? Do youhave access to someone who has been down the road with helis and can look over you machine for possible causes of you glitches... And what is "normal" vs what may be a potential problem ???

Help! Almost crashed. Weird problem
 

The voltwatch uses 10ma of current.... a 1000MAh battery will take 100 hours to go dead on that level of current drain, that's 1% of battery capacity per hour it's connected. Judge from that yourself given your battery capacity how much drain is actually occuring.
By the way, the original post is a person suffering from the worst belief in PCM, they think it reduces eliminates or tolerates higher levels of EMI. It does none of these things, it just LOOKS like it does by being able to know if the data it's getting is correct and then it fills in the blanks.

Help! Almost crashed. Weird problem
 

I'd bet on it being a bearing, or it could be other metal to metal contact. The GPH, wasn't it a metal frame heli? Another thing to look for would be cracks. Cracks, even small ones, in a metal framed heli will generate lot'sa RF noise.

Even with a PCM rx, metal to metal noise, or bad bearings will show up, it's just that it will show up by going into failsafe. By default, failsafe is set to hold the last known good position of the servos. It does that for a minimum of about 2 seconds, longer is a good signal isn't received by then.

On my GPH one time, I had a small crack down close to the engine mount area on the left side that drove me dam near nuts with it going into failsafe.

Sounds like it's time for some disasembly and inspecting. . .

Good luck
CJ

Help! Almost crashed. Weird problem
 

Thanks for all of your responses. I only switched to the PCM reciever to see if my FM receiver was working correctly. I didn't expect for it to fix all of the problems if the problem was a bad bearing. I figured that if I didn't have any problems, then I might have narrowed it down to a faulty receiver.

The reason I thought this is because I had the receiver in an x-cell previously and the same behavior occured in it. I only flew it a couple of times before selling it for something that would be cheaper to fix. Could it be that both of these helis had bad bearings causing interference? I will check out the frame.

As far as the voltwatch goes, I am using a 2700 mah battery , so I don't think it is causing too much drain. I have ordered new bearings. Thanks for any advice and happy flying.

Help! Almost crashed. Weird problem
 

If you're testing for a faulty components make sure you always replace like with like, otherwise things like that happen.

Glitching
 

I agree CJ
I had an old metal frame X-cell 30 that caused me lots of grief with radio noise.
It was either bad bearings or a cracked frame to blame.
Of course this was after replacing all the gear and gyro and balancing everything several times.
A hidden crack won't show very easy on the black anodized frame, unless your looking for it.

Kirk

Help! Almost crashed. Weird problem
 

Hey, I had the same problem. I contacted Futaba and they said it was probably a cracked RX crystal from too many crashes :D

Anyway, after screwing around forever with this problem, I got a Gem 2000 (magic box) battery monitor and plugged it in. As soon as I started moving sticks, the Gem 2000 stopped blinking.

It ended up being a bad cell in my 1700 mah Nicad. It would charge, and test okay. However, the one bad cell would cause random power outages or whatever.

Anyway, I switched batteries, and now everything is fine.

Seems simple, but did you try switching batteries?

Help! Almost crashed. Weird problem
 

Yeah, ,I've been flying on 2 different 2700 packs and have got the glitches using both. Thanks for the info though. I'll remember that.

I'll check the metal frame tomorrow for some cracks. Thanks for the tips. I found out that replacing all of the bearings isn't cheap. I will check each one I think and see if I can find a bad one. Anybody have any good tips on checking them off of the heli? I know I could use a scanner somehow to check, , but I am unsure of how to do this and don't have a scanner. I might can find someone who does to borrow it.

Help! Almost crashed. Weird problem
 

same thing is happening to me i hope that by now you found your problem and can in form me what it was i just notice that in my heli the bearing where the hex start goes is making noise and when i pass half throt. it start to glitch i change the rx battery and switch but i still have the glitch i will try replacing that bearing to see what hapens hope you found yours thanks

Help! Almost crashed. Weird problem
 

Mrctatoo,

I ended up getting rid of that heli and trying a plastic framed heli. Surprise, the same problem was there which eliminated bearings and the metal frame. So, now I have changed almost all the servos out and am waiting for another part before I can see if it is fixed. I must have had a bad servo somewhere. It would only happen if the heli was running. In your case I would suspect bearings if the heli has been flying ok until just recently. Turn them with your finger and if they feel gritty then you should probably replace them. Check the main shaft bearings first. Good luck and keep me informed as it might help me too! I'm pretty frustrated!

Help! Almost crashed. Weird problem
 

Make sure the antenna to the receiver is not ziptied to "ANY" metal objects!!! My bosses heli was doing the same thing! Took me two friggin hours to figure out it was his RX antenna zip tied to the boom struts! Was virtualy unflyable...anything passed 1/4 throttle cause extreme jitters and sticking servos on the Raptor. The jitters were so bad I thought the Main shaft was bent! Cut the zipties and let the antenna hang freely solved it 110%.

Some Gyros like the JR 410T and 460T are known to cause interference with the receivers such as gittering / sticking servos etc.


Just my .02 cents...

Help! Almost crashed. Weird problem
 

AA8VL,

THANK YOU! Mine is set up the same way. I will try that and maybe that is the problem. Never thought of that. :)

Help! Almost crashed. Weird problem
 

I have the same problem once, I tried to find the reson again and again, at last I thought I should test the wires then I did it. Finally I found the problem: The wire of the battery was broken inside, and you couldn't see from the out side. When I tested this wire sometimes was OK, sometimes was broken.

Could this help!? :)

Help! Almost crashed. Weird problem
 

Well, I had a really good responce to this thread, then my computer ate it so I'll try again.....

I had all the problems Mrctatto is having, and even have the same heli.

I changed receiver, and receiver crystal, nothing.

I placed the receiver into a 3M non-static bag (you receive sensitive electronic parts in these) and never had the problem again.

I know this doesn't fix the real problem, just covers it, but who cares, at least now I only crash when I do something stupid.

I'm figuring a bearing is gritty or spinning or something (I green loc-tited my bearings but some still move) and causing RF interference.

-=Adam