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Old 07-06-2007, 12:07 PM   #1
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Default NOVAK Refurbished motors, need assistance.

Good afternoon,

I have a problem with recent refurb motors I received from Novak ( I think)
I have emailed Charlie about this problem, and he offered me some suggestions, but to no avail. I will respell this below for your consideration.


I have many SS and GTB escs, as well as 5800 and 6.5 motors. All functioned great new, until for whatever reason they failed. I sent them back in and got some refurbs in exchange.
After installing the refurb 6.5 for example, I get motor chatter when the current draw is high. Low throttle does no do this. I thought that my plat LiPo was too much for the esc, and asked Charlie. Charlie thought there was a voltage dip caused by the spektrum causing this trouble. I installed the spektrum cap for a bit of leveling just to be sure.
I gathered all my parts on the table and this is what I have found;
both the 5800 and the 6.5 have a chattering effect at high rpms with the 4800mah LiPo, a 4200 NiMH and also with a 3300 turd pack I have.
Both of these motors have this chattering effect. I tried the motors again with the same 3 packs, and a DIFFERENT GTB. same problem.
Charlie thought that the spektrum could be to blame. I swapped it out and used a Novak XXtra synth...same thing, no difference. now, I am stumped so far.
someone said " hey, maybe its your transmitter." so I changed from the M8 to a synth futaba ( i think it was a 3ps, not sure) and the problem persisted.

So, across all types of GTBs and receivers and transmitters, with power caps and without, I am having this trouble.

Can anyone shed some light on this?> Would a refurbished motor have a chance at causing this somehow? I would just send these back to Novak, because the service is so good, but based on what Charlie told me, the problem isn't theirs, it's mine.

I appriciate your thoughts.

Pete
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Old 07-06-2007, 10:48 PM   #2
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pete

you definitly got a problem somwhere but where is a darn good question. i dont know how new the GTBs are that you have but the new ones are suppose to be programed to the specs of a futaba fast system. my first guess would have been that you were using the spektrum stuff as i have heard of alot of people having problems with them lately but other than that i dont know what you could have going on that would cause it with both motors, both speedos, and all your different batteries. sounds like you let the gremlins out
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Old 07-06-2007, 10:48 PM   #3
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wish i could help you more but even i am confused
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Old 07-07-2007, 04:46 AM   #4
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Are you running a lipo cut off? If you are try taking that out and trying it again.
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Old 07-07-2007, 05:30 AM   #5
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I'm going to break this down a littlel

I have many SS and GTB escs, as well as 5800 and 6.5 motors. All functioned great new, until for whatever reason they failed.

So by reading this - you had problems before you received a 'rebuilt' unit

I sent them back in and got some refurbs in exchange.

so I guess the question might need to be - what happened with the first failure?

After installing the refurb 6.5 for example, I get motor chatter when the current draw is high. Low throttle does no do this.

Is that what it was doing - which caused you to send them in?

I thought that my plat LiPo was too much for the esc, and asked Charlie. Charlie thought there was a voltage dip caused by the spektrum causing this trouble. I installed the spektrum cap for a bit of leveling just to be sure.


I gathered all my parts on the table and this is what I have found;
both the 5800 and the 6.5 have a chattering effect at high rpms with the 4800mah LiPo, a 4200 NiMH and also with a 3300 turd pack I have.


Are these all rebuilt motors?

Both of these motors have this chattering effect. I tried the motors again with the same 3 packs, and a DIFFERENT GTB. same problem.


Have you tried any different motors? (Borrow one?)

Make sure everything (especially the SENSOR harness) is plugged in securely and not partly unplugged (since it happend with various esc's probably not the concern)

Try a different radio/receiver combination?

Make sure the wires are all in the correct orders A B C

Make sure the sensor harnesses are not damaged (and have the protectors on them)

<-- probably not any help - but maybe someone can pick up on something...
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Old 07-07-2007, 08:42 AM   #6
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The only time I've seen the chattering/cogging was either when using
1. lipo cutoff
2. over heated stock(bonded) rotor
3. wires touching meaning a,b,or c
4. capacitor damaged inside the motor itself
5. The big cap(attached to the GTB) was damaged
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Old 07-07-2007, 09:40 AM   #7
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I've seen it happen if the phase wires are mixed up, but not just at certain RPMs.
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Old 07-07-2007, 11:49 AM   #8
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Pete, although it would be a little odd that this is the problem on both motors at the same time, it's certainly not impossible or even unlikely....

Have you checked the motor bearings closely? Many times a bearing will chatter at high RPM right before it starts to fail completely. The best way to check this would be to put a drop of thick oil in them and retest. If the chatter goes away or changes tone, then that's most likely the problem.

Thick bushing oil will work, but something a little thicker lick 40W engine oil would be better.

If that's not the problem, at least you and other guys who read this will know how to check for a bad bearing in the future...
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Old 07-07-2007, 09:37 PM   #9
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If you have the bonded rotors they will chatter. The brass sleeves cause it.

If you have the the sintered rotor and the profile customized to a more low end punch that will cause a sort of jingle noise. If you set the bottom end to punchy it will work better with 4 cell.

mine is jingling when I hit the brakes. weird.
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Old 07-08-2007, 12:45 PM   #10
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Thaks for all your replies, peoples.

SWTour, The original problems I had with my motors were widespread, but unrelated to what I expierence now. The usual missing spacers, blown endbell bearnigs etc, shorted the speedo, smoked it, etc. nothing like this chatter.

something I forgot to mention earlier, is that on the speedo, during the chatter, the red LED flashes at the same rate as the motor chattering.
UN$, can you explain a bit more about the sintered motors and the brass sleves causing the chatter? I think this is electrical in nature. and need it resolved soon, or Im switching to Mamba or something.
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Old 07-11-2007, 10:18 AM   #11
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ok I did some more testing and found that the 13.5 with the sintered rotor DOES NOT CHATTER on the GTB. Thanks to Nick for borrowing me that thing for testing.

so, the refurbished motors from novak seem to be the trouble.

Does anyone know if novak will swap out "new" refurbished motors with refurbs that have the sintered rotor? Just wondering.
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