Raptor 90 glitching

[ez2bgman]

Sup guys,

I need some of your wisdom here.

This is my set up:
Jr PCM 10SXII
950 PCM rx w/ a Revolution whip antenna
Raptor 90
YS 91ST, MP2
Ace DS1211's on cyclics
Jr Z8550 on pitch
Standard servo on throttle
CSM 560v4 w/ 9254
Arizona duel volt. reg.
Li-Ion 7.4v 4800 mah rx pack

Here's my problem. I just got this bird together and took her up for her maiden flights on Wednesday. Everything was fine on Wed., except for a small gyro issue on my part. I put two tanks through her without any problems.

Yesterday, myself and 3 of my buddies meet to go flying. I wanted to show them how nice the big heli flew. I spool her up and she starts glitching like crazy on the elevator and ailerons (more on elevator than aileron though). I spool down, let it sit for a moment and try again. Same exact thing.

I shut her down and bring her in. We did discover a couple of screws loose, but nothing else. I fired her up and same exact thing again. Back at the bench, I open the receiver box and loosened all the wires. We notice glitching when the connection for the Revolution antenna is wiggled. I found that it was a little loose, so I take it apart and tighten it up. Fired her up and it started glitching again.

This time we go through every wire, one by one. We were able to get it to glitch a few times while the engine was running and on TH. With the engine off, no glitching at all. We tried everything. This same rx was previously installed on my Raptor 50 and never, and I mean NEVER, gave me any trouble, even with the whip antenna on it.

Finally after a couple of hours of trying to get it sorted out, I decided to call it quits for the day. I didn't want to risk flying it and possibly hurting someone or damaging any property.

I did dial indicate the fan/clutch (the TT aluminum one for the YS) . The fan and clutch were both within .002". Other than the 2 screws that we found loose, nothing else was loose. As stated earlier, I have been using this rx in R50 for 4-5 months with no problems what-so-ever. We did notice a high freq. vibration when the engine was idling. Could it be that the fan/clutch unit is out of balance and this vibration is causing it to glitch.

Any help/advise would be greatly appreciated. I am completely stumped on this one. The only thing that I can think of now is that the fan is out of balance. We literally went through every screw and only found the first 2 to be loose.

Thanks for your help.

[DavidH]

Well since it is PCM reciever. I don't think it is getting interference due to loose bolts or metal to metal contact. If it was due to the above, the reciever should be going into HOLD or Failsafe. With what your describing it should not glitch constantly with a PCM receiver if it is interference.

That would tell me there is a chafed wire, or loose connection maybe in the battery system.
I have never heard of the ACE DS 1211 servos. So don't know anything about using them on a heli.
Check and make sure that your crystal is well seated in its slot on the receiver. The JR receivers are well known for allowing the crystal to disengage.

David

[flyinfool]

Just to help narrow it down try putting in a nicd 4 cell battery and a heavy duty switch harness and disconnect the arizona from the system.

I agree with David, it sounds like a power issue.

[WayneBrown]

For sure tape the crystal in...I can attest to that suggestion!
Killed a chopper when the crystal came loose...

[ez2bgman]

Thanks for the tips guys. I planned on bypassing the Arizona reg. and batt. with a regular 4.8v batt. and HD switch. If that is not the problem, than I am going to try swapping gyros and put the 401 from my Raptor 50 in it. I am 99.9% positive that the rx is perfectly fine, I flew my R50 for months with this rx w/o any problems at all. It had a Revolution antenna on it and I switch it back to a full length antenna when I got the severe glitching on the R90. Unfortunately it still glitched just as bad with the full antenna as it did with the Revolution.

I'll keep you updated on teh progress.

[WillJames]

Make sure you don't have any chafed servo wires. I had one a few weeks ago on my Tempest that was causing slight glitches like you describe, and not bad enough to get the RX into full lockout. Turned out to be my poor installation of the Rudder Servo and the wire chafing on the carbon frames. Glitch city.

Thanks for finding it so fast Hammer!!

[charles]

Will,,

You should be careful letting your wife chaff on your carbon frames..

[WillJames]

HAHAHAHA Good one Charles. Fixed.

Thanks for pointing that out. She gets chafed at carbon sometimes...

[wattybotts]

Gary

When I had my Raptor 90 I was chasing glitches since day one. After all my struggles, my pinion bearing was notchy and causing RF when spun at 15,000 rpm's. Also, the starter shaft bearing can cause glitches if notchy. It is a real hassle to take the cluch stack apart, but its a real possibility that it could be ur problem.

Good luck!

[Daniel Jetschin]

How old is the engine ? Maybe rusty rear bearing ?

[ez2bgman]

Watts,

I checked all the bearings with a buddy of mine and we could not find any notchy bearings at all. I may just go ahead and take the clutch bell stack out and check it that way.

alu,

The YS 91 has 3-4 gallons run through it. When I balanced the fan and checked the runout, we also checked the rear bearing and it appeard fine and didn't feel notchy at all. I may go ahead and get a set of ceramic bearings from RC-Bearings just in case.

Thanks again for all the tips.

[ColinB]

My R90 glitched bad with the CSM gyro mounted behind the mast running long wires up front to the RX. I mounted the CSM 560 micro and servo up front and no more problems I have the 601 on the back without any issues...the CSM gyros are "dirty" if you will, they caused minor glitches in the past on some of my other machines too but it was particular bad on the 90. The rear mounted tail servo caused bad glitches with the CSM gyro, by mounting that up front almost all problems were gone but there were still some very minor issues so I put the gyro up front too.

Colin

[ez2bgman]

Glitching solved...

After going through virtually everything, I was almost ready to throw in the white towel and put her away for awhile. After talking to a buddy of mine, he advised me to change out my rx (a Jr 950 PCM), although this rx was just yanked from my Raptor 50 where it worked flawlessly. As a last resort, I pulled out the PCM rx and put in my FM rx from the R50. Took her out to the yard and spooled her up. No glitching.

So I packed up and went to the field. Gently lifted into a hover and all was good, no glitching at all. So off I went. I burned up the remaining half a tank just doing some basic circuits, stall turns, etc.

Afterward, I went to a buddies house and confiscated :mrgreen: a gallon of Magnun 30%. Went back out and had 2 trouble free flights.

Looks like the Jr 950 rx has to go in to get serviced.

Thanks for all the help.

[Phaedrus]

Originally Posted by ez2bgman

Glitching solved...

Looks like the Jr 950 rx has to go in to get serviced.

Thanks for all the help.

Just curious. Did the replacement receiver have the stock wire antenna or the Revolution antenna??

[ez2bgman]

Originally Posted by Phaedrus

Just curious. Did the replacement receiver have the stock wire antenna or the Revolution antenna??

The Jr 950 PCM rx had the Revolution antenna that I replaced with a full length antenna while I tried to chase the glitch. The FM rx (Jr 549, I think) has always had the stock, full length antenna on it.

While tracking down the glitch, I picked up the PCM rx and tapped it on the servo frame and I was able to get it to glitch. This was done without the engine running. I was also able to get it to glitch be jiggling the antenna wire where it comes out of the rx. I think that something is definitely loose in the rx and the slightly higher vibration from the larger heli caused it to glitch. When this rx was in my R50 (with the Revolution antenna on it), not once did I experience any glitching.