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600 Class Electric Helicopters 600 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 09-19-2007, 05:21 PM   #1
onebads4md
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Default T-Rex 600 Fell out of Sky A little help please

Ok so here is the situation. I recently bought a t rex 600 off of this site and it is an awesome machine. When it arrived i set it up per the previouse owners specs and as promised all the servos lined up at 90 degress with 50% stick deflection. The chopper has flown 10 times like a dream. Like the idiot that i am i ran one of the packs down to far. After several attempts i was able to get the pack to charge and it took over 4500 mah and it is only a 4900 mah pack. After this charge i put it into the heli took of hovered for less then a minute made some circles and then without warning it shut off and fell out of the sky. So this is one problem why did this happen? I am in europe i have a spectrum dx-7 radio and this is a 7000 series reciever. I assumed it was a battery issue but the pack voltage was still good after the crash or at least it is sitting on the bench running the servos.

Next problem ----- the crash was not very severe the blades were not spinning fast when it hit the ground and they were not damaged it landed on the skids and it has bent one skid. It did then tip over and broke on of the plastic links on the end of one of the linkage rods. No big deal. But the big problem is now the servos dont line up like the used to......meaning at 50% stick defelection they are not at 90 degress. I have checked and none of the gears are stripped and the servos still act perfect. I have gone back and reporgrammed the radio from step one and still 2 of the servos or along way from 90 degress which was not the case when i got the chopper. There is no damage that i can see to the servos linkages are anything else. Other then the skid which has been replaced and the link everything is as good as when i got the heli. I of course can get the servos back to 90 degrees but the sub trim for the 2 that dont line up are a long way from the original specs that worked before my crash.
Long story short
why did the chopper fall out of the sky
why are the servos not at 90 degrees anymore as they were when i originally programmed the radio before the crash which i would call minor due to the small repair bill.

I will now go put on my nomex flame suit and what for some help
Thanks for helping out a rookie this forum has been great so far
Hansen
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Old 09-19-2007, 05:39 PM   #2
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It fell out of the sky because of GRAVITY !
But have you check that your servo gears are not stripped.
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Old 09-19-2007, 05:44 PM   #3
onebads4md
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yeah the gears are not stripped the servos still functional normally but 2 of the three do not end up at 90 degrees with 50% stick deflection at the same sub trim values as before the crash. I assume the fact that the servos still functional normally means the gears are not stripped.
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Old 09-19-2007, 06:14 PM   #4
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You fell out of the sky because you damaged your battery on a previous flight by running it down wayyyyy to low. Resting voltage may read fine but under a load it sounds like one or more of the cells can't handle the load and voltage falls off quick.
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Old 09-19-2007, 06:18 PM   #5
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the servos run off a seperate battery in a trex600

if the motor stopped its because your 4900mah battery that you damaged by overdischarging is stuffed

you have 2 batteries yes ? one for motor and one for servos
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Old 09-19-2007, 06:42 PM   #6
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As far as the servos, do not make that assumption, you're better off to just take them appart and check the gear teeth carefully. It may be possible that the horns moved (skipped a few teeth) on the output shaft, but not too likely.

Are you sure you had a fully charged receiver battery (all green lights still on on the align BEC)? Did you have control of the heli on the way down IE with just no motor power, or was it totally dead, IE no control at all?

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Old 09-19-2007, 07:12 PM   #7
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Did you unplug the servos at any time after the crash? If so, make sure you have them in the correct RX channels - they may be reversed (happened to me once). That may explain the trim differences - check the directions on the servos also of course:0) Cheers
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Old 09-19-2007, 08:49 PM   #8
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Quote:
Originally Posted by onebads4md View Post
Ok so here is the situation. I recently bought a t rex 600 off of this site and it is an awesome machine. When it arrived i set it up per the previouse owners specs and as promised all the servos lined up at 90 degress with 50% stick deflection. The chopper has flown 10 times like a dream. Like the idiot that i am i ran one of the packs down to far. After several attempts i was able to get the pack to charge and it took over 4500 mah and it is only a 4900 mah pack. After this charge i put it into the heli took of hovered for less then a minute made some circles and then without warning it shut off and fell out of the sky. So this is one problem why did this happen? I am in europe i have a spectrum dx-7 radio and this is a 7000 series reciever. I assumed it was a battery issue but the pack voltage was still good after the crash or at least it is sitting on the bench running the servos.

Next problem ----- the crash was not very severe the blades were not spinning fast when it hit the ground and they were not damaged it landed on the skids and it has bent one skid. It did then tip over and broke on of the plastic links on the end of one of the linkage rods. No big deal. But the big problem is now the servos dont line up like the used to......meaning at 50% stick defelection they are not at 90 degress. I have checked and none of the gears are stripped and the servos still act perfect. I have gone back and reporgrammed the radio from step one and still 2 of the servos or along way from 90 degress which was not the case when i got the chopper. There is no damage that i can see to the servos linkages are anything else. Other then the skid which has been replaced and the link everything is as good as when i got the heli. I of course can get the servos back to 90 degrees but the sub trim for the 2 that dont line up are a long way from the original specs that worked before my crash.
Long story short
why did the chopper fall out of the sky
why are the servos not at 90 degrees anymore as they were when i originally programmed the radio before the crash which i would call minor due to the small repair bill.

I will now go put on my nomex flame suit and what for some help
Thanks for helping out a rookie this forum has been great so far
Hansen
Hey Bads,
Are you running the spectrum servos? If so, my experience with a similar hard landing is that the servo arms are slipping on the splines. The arms from JR ( "S"shaped light weight ones), actually split from the center out, allowing the splines to slip. Dave
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Old 09-19-2007, 09:59 PM   #9
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Your motor stopped which means:

1) Your ESC shut down
2) YOur battery open circuited
3) Wiring joint failure in motor/EXC or radio wiring
4) Your motor jammed

I would say the most likely scenario is that your battery was damaged by overdischarge and that after a short period of use its voltage fell and was shut off by the ESC. Don't use that battery again exxcept for ground work & testing !!

As for the servos I would guess the arm slipped on the splines of the output shaft due to the sudden impact - have a good look at them with a magnifying glass - it has to be a mechanical disclocation.
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Old 09-19-2007, 11:13 PM   #10
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If the voltage to your reciever spikes too low, then the reciever will reboot itself. This leaves the ESC with no signal for a few seconds and causes the gyro to reinitialise while the heli is still moving. Not good. You didn't say weather or not you have a BEC or regulator with it's own battery. 6amp regulator instead of the 3amp unit is a better way to go with the spektrum stuff because of that.
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Old 09-20-2007, 06:15 AM   #11
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the heli has only 1 battery i assume it has a 6 amp regulator as the voltage on the gyro always says 6 volts. I agree with everyones opinion that my overdischarging toasted the battery. Live and learn i guess. I will check the teeth on the output shafts of the servos to see if the arms may have slipped. I have had stropped servos before and can feel the difference. These seem to be good and tight but if the horns have not slipped on the output shafts i will check the servo internals. Thanks for all your help and if you have any other helpful hints please let me know as i am a major noob to the rc heli scene.
Thanks
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Old 09-20-2007, 06:46 AM   #12
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Quote:
Are you running the spectrum servos? If so, my experience with a similar hard landing is that the servo arms are slipping on the splines.
DING DING DING.... I agree and I bet thats what happened... JR servos or not the servo wheels slipped on the splines!

Bob
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Old 09-20-2007, 11:07 AM   #13
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Well thanks for all the help they are JR servos but i removed the horns and there was plastic residue on the servo splines so i put the horns back on the splines in the correct orientation and tossed the battery in the junk bin so i wont have that problem again i hope..............one last questions what is the recommended method of lubricating the main shaft to prevent things from binding up i cant tell what is on the main shaft now but there is something on there for sure. I assumed some kind graphite.
Thanks for all the help
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Old 09-20-2007, 04:35 PM   #14
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Quote:
Originally Posted by onebads4md View Post
Well thanks for all the help they are JR servos but i removed the horns and there was plastic residue on the servo splines so i put the horns back on the splines in the correct orientation and tossed the battery in the junk bin so i wont have that problem again i hope..............one last questions what is the recommended method of lubricating the main shaft to prevent things from binding up i cant tell what is on the main shaft now but there is something on there for sure. I assumed some kind graphite.
Thanks for all the help
Hansen
Risky business reusing servos that have had their splines graunched You'd be safer to replace the out put gear and preferably horns too ! What sort of servos?

As for lubricating the shaft just light machine oil is fine or a PTFE containing oil like TriFlow - shouldn't be any graphite around unless you put it there !
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