Big Help need with 9252 problem

[Ade_Law]

i tried multiplex ipd a while back. they work but not a patch on true PCM for glitch rejection.

also the failsafe sets all channels you cant set some to "hold" and the rest to a failsafe position.

Ade

[Steve]

Is this problem in your Airskipper nightstalker?

I've got JR PCM in mine with 3152 servos and it's absolutely smooth as can be. No noticeable delays either.

[nightstalker]

Yeah it WAS in my skippy, a friend of mine in the states sent me over 3 brand new 9252 servos and that's when it all started,
The funny thing is the servos i had in there before was hi tech HS6635HB and they seemed fine, but when i checked them on a PPM rx i could not believe how slow i was running them on PCM, they was smooth and scrisp on the ppm,
very strange indeed im lost on what could be wrong,

so im going to send a long email to FUTABA and see if they could shed some light on this matter

[Raptorite]

Another silly observation maybe, but when you tested these servos, was thre aerial on the transmitter up or down, and was it close to the receiver aerial or a short distance away?

I have had situations in the past which have been fairly similar, these ended up being caused by the effect of the transmitter shouting in the receiver's ear, confusing it

Cheers,
Pete.

[nightstalker]

Tried everything you just said mate, i was on it from 3pm and was still trying to work it out till 2am, i had some friends chatting to me with ideas and even Colin mills (csm guy) no one could work it out,

Even at the shop we could not understand why pcm with this radio was slowing the performance of the servos

[Twister]

Sounds like you have a 3 way compatibilty issue bettween the CCPMe processing, the PCM processing and the servo frame rate.

Any 2 work ok together but when the 3rd is added probelms arise.

I would be inclined to say you have dicovered a peculiarity which affects this transmitter or you have a faulty transmitter.

When you say in post #14 you tried another 7chp transmitter but it was running PPM and yours was running PCM, did you try the other transmitter in exactly the same PCM / CCPMe configuration as yours?

If you did and that worked ok then you have a faulty transmitter, if not then contact Futaba, you may have found a software bug or incompatabilty issue.

Another thing which sounds odd and makes me think you may have a faulty transmitter is when you mentioned that even the Hitc servo's were running really slow in PCM mode, it does sound like your transmitter is not processeing as fast as it should.

From what i can gather if you just use CCPMe or just use PCM but not both together it can operate without the problem being noticed.

But if you use both CCPMe and PCM together the loss of processing speed has the Hitec's complainig but still working at reduced speed.

When the digital 9252's are used the frame rate or information rate becomes too slow for them and they jitter.

Me brain hurts now

[nightstalker]

Thanks TWISTER good info there mate,
yeah we dod swop the TX from ppm to PCM and it was the same, its very strange, i think il do what you say and contct futaba and see what might be wrong, as u say might be the TX or could be a fault buit either way i need to look into this much more,


im keep this post updated once i know more