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Skookum Robotics Skookum Robotics SK-360 SK-540 & SK-720 Digital Flybar


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Old 05-29-2012, 01:50 PM   #1
yosemite
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Default DX8 caused crash, warning!!!

I posted about this earlier at http://helifreak.com/showthread.php?t=416980

short story:
trex 450, dx8, sk720. flew perfect for over 50 flights, really fun. it was about 100' up from me when it dropped out of the sky, no control, no motor, nothing. when i got to it the esc was trying to initialize. not to bad damage considering but of note, the blades are still good, meaning to me that it was a complete loss of power.

just got a new trex 550e so decided to scrap the 450 for now and build that. got it all done, went through the setup with the same sk720, setup went perfect. power it up to test, all lights and sounds normal. move the sticks around and then the servos freak for split second (in my original post see where it surges for a split second) and then everything resets with the sk720 blinking red and the esc (brand new ice 100) beeping(sometimes one beep, sometimes 5 beeps.

hmmm run through setup several times, double check everything same result. frustrated and wanting to fly i decide to rebuild the 450. rebuild it, reload my 450 file into the sk720, check all functions in the software, all looks perfect.

go for normal power up, all lights and sounds normal, move sticks and same result as on the 550, split second servo freak out, complete power loss, red light flashing on sk and esc beeping.

after rechecking everything a hundred times i notice the right aileron servo arm is down by several degrees when out of setup. after trying to figure this out i go to the dx8 monitor screen and the aileron is showing -28!

i believe this is the cause of the crash as in the sk720 software it said something like , "error reinitalize with sticks set to center "

now to make this even more interesting i sent the dx8 back for repairs and bought a brand new one. the monitor screen shows everything at zero, perfect! and the the sk720 and trex 450 are now working perfect!
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Old 05-29-2012, 09:11 PM   #2
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How old was you DX8? Everyone at my field is telling me to get rid of mine and telling me about horror stories similar to yours ( heli drops from the sky).
Most run Futaba at my field, but I really don't want to convert everything over and have to learn a whole new radio when I barely know much about my DX8.
This all comes as I experienced some strange behavior the other day at the field ( I will be posting more about this).

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Old 05-29-2012, 11:32 PM   #3
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Happened to me! Heli fell from the sky dx8. Got rid of it and bought a jr radio
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Old 05-30-2012, 01:08 AM   #4
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I had one of my dx8s do somthing similar just not as severe.
I updated the firmware for the hell of it and then recalibrated the dx8.
I was amazed how much re trimming my planes and sim needed after the calibration.

Its a pretty easy process to recalibrate the dx8.
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Old 05-30-2012, 04:34 AM   #5
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I hear the same stories...they are all dated.
Futaba had the same problems, still have some but is longer in the game.
All recent DX8s are totally fine, like mine.
But same as old SK720s , with firmware 1.0 are being sold by some, so are old DX8s.
Please go to the Spectrum page, register yours and check the number in the bulletin.
They are super nice at Horizon and will take of them asap.
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Old 05-30-2012, 09:36 AM   #6
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the dx8 in question was bought 6/1/11 and i had checked it against the recalls and it was not on the list. i did notice one other time that on the elevator and aileron they would sometimes read 3 or 4 and jump around on the monitor screen but then go back to 0

tried to update(to recalibrate) but i could never get the spek site to accept the sn, it always said it was wrong even though i know it was right. just figured out on the new dx8 that you can copy the sn to the sd card, open the file and copy and paste the sn at the spk registration site, worked 1st time! the new dx8 is all updated.

just a good lesson that another preflight check should be the monitor screen on a dx8, i know i will be doing it every time.
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Old 05-30-2012, 09:49 AM   #7
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You didn't have one of the counterfeit dx8's did you?
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Old 05-30-2012, 12:57 PM   #8
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Quote:
Originally Posted by yosemite View Post
the dx8 in question was bought 6/1/11 and i had checked it against the recalls and it was not on the list. i did notice one other time that on the elevator and aileron they would sometimes read 3 or 4 and jump around on the monitor screen but then go back to 0

tried to update(to recalibrate) but i could never get the spek site to accept the sn, it always said it was wrong even though i know it was right. just figured out on the new dx8 that you can copy the sn to the sd card, open the file and copy and paste the sn at the spk registration site, worked 1st time! the new dx8 is all updated.

just a good lesson that another preflight check should be the monitor screen on a dx8, i know i will be doing it every time.
Yes - at the start of each session, I check the monitor while moving the sticks.

A problem with some (early ?) DX8s was with the wires to the rudder & aileron pots. These wires get moved by throttle/elev input, and you could see funny things happening. This seems to be related to the connector at the pot end.

One of my DX8s went off for repair, and came back with the rudder pot connector bypassed (soldered), and the aileron pot connector glued in at the pot end. Both still unplug at the board end, so it doesn't compromise future maintenance.

IMO it's a good radio at a good price - but (like anything electro-mechanical) needs periodic checks.
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Old 05-30-2012, 02:30 PM   #9
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not counterfeit as far as i know, bought off amazon brand new

just got a email from spektrum, fixed and on its way back

will let you know how it works
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Old 05-30-2012, 07:06 PM   #10
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Quote:
Originally Posted by yosemite View Post
go for normal power up, all lights and sounds normal, move sticks and same result as on the 550, split second servo freak out, complete power loss, red light flashing on sk and esc beeping.

after rechecking everything a hundred times i notice the right aileron servo arm is down by several degrees when out of setup. after trying to figure this out i go to the dx8 monitor screen and the aileron is showing -28!

i believe this is the cause of the crash as in the sk720 software it said something like , "error reinitalize with sticks set to center "
That's a pretty solid indicator that you have accidentally moved the trim on your DX8.

Quote:
Originally Posted by yosemite View Post
tried to update(to recalibrate) but i could never get the spek site to accept the sn, it always said it was wrong even though i know it was right. just figured out on the new dx8 that you can copy the sn to the sd card, open the file and copy and paste the sn at the spk registration site, worked 1st time! the new dx8 is all updated.
You do realize that it means the S/N you "knew it was right" you were actually punching in wrong?

HH added the "export" function for the S/N because some combination of the characters were creating end user confusion, a fault of low-res display, really. Happened to me with my first DX8, before the export function, spent a good time with tech support on the phone to solve the mystery:



The first 4-character group was actually HRQi while I was repeatedly insisting on HRQj
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Old 05-30-2012, 07:59 PM   #11
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Quote:
Originally Posted by jperkosk View Post
That's a pretty solid indicator that you have accidentally moved the trim on your DX8.
Can't you disable the trims on a DX8 in the model setup?
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Old 05-31-2012, 07:23 AM   #12
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Never tried it, the trims are actually difficult to move by accident unless you're playing with them and not realize that your trim bar has shifted. I imagine if you set your trim step to 0 in the system menu it should effectively disable the trims, maybe someone can confirm? I'm away from my DX8 on a business trip at the moment...
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Old 05-31-2012, 08:31 AM   #13
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Default This issues is exactly what I had

I couldn't get my SK-720 to initialize because the alerion servo showed it not centered. I also had some drift in GPS mode on my DJI equiped heli using the same transmitter. I bought a new DX8 and no problems since then. I sent in my old transmitter and Horizon repaired it and sent it back. It has since been working just fine. I had something to do with the gimble sensors getting dirty I think.
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Old 05-31-2012, 11:30 AM   #14
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Quote:
jperkosk
That's a pretty solid indicator that you have accidentally moved the trim on your DX8.
did not accidentally move the trim. the aileron was reading -28 on the monitor screen with stick centered and no trims, should of taken a photo before i sent it in and a video of the boot up. could not get aileron to read close to zero even after jiggling it and re centering.

after figuring out that the faulty aileron was causing the problem the trex 450 was left on the bench just as it was untouched until i got the new dx8. binded the dx8 to the trex and it worked perfect. many flights now and no problem, monitor screen shows 0 on all gimbals on the new dx8
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Old 05-31-2012, 05:49 PM   #15
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Hey guys,

Just to throw in here the other side of the story:
I'm using Spektrum since day 1 and using my DX8 since 1 year now.
- No errors
- No faults
- No problems
- No issues
- Just 110% satisfied with it

All of us, especially the guys who think "I won't by a DX8" after reading this thread, should keep in mind that only negative stories make it into forums!
Not the thousands and thousands satisfied customers...

The issue is the same with every product we buy... Tx, Servos, ESC, Cars, Dishwasher...
No production line produces at 100%. There are some fault devices that leave the factory.

Soko
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Old 05-31-2012, 07:24 PM   #16
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Of the 6 DX8s at our club 100% have had to go in for "pot" issues, so you are one of the lucky ones.
Its good idea to periodically check the Monitor screen for drift.
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Old 05-31-2012, 07:43 PM   #17
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Quote:
Originally Posted by panzlflyer View Post
Of the 6 DX8s at our club 100% have had to go in for "pot" issues, so you are one of the lucky ones.
Its good idea to periodically check the Monitor screen for drift.
How old were they, the new ones should have direct soldered pots that eliminated the issue?
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Old 05-31-2012, 08:18 PM   #18
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They were in the 1st production wave,I think, dont really keep up on dates.
It is is probably more noticable as FBL units come out, at least one guy hadnt noticed on his plank, just trimmed it out in flight.
HH was replacing pots for people at Joe Nall for free so its getting fixed.
The ones Ive seen are pretty obvious if you look at the monitor screen and/or press around the sticks.
I never had an issue with my old Dx7, 9303 or 11x as far as sticks go
Not bashing the radio just suggesting a periodic check as we should do with the other brands as well now that centering is a little more critical.
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Old 05-31-2012, 08:52 PM   #19
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Quote:
Originally Posted by panzlflyer View Post
They were in the 1st production wave,I think, dont really keep up on dates.
Yeah the first few batches had the issue.

I agree, it makes sense to check the radio before flying (we check the heli). I check the monitor screen myself before the first flight of the day, sometimes a change in temp can cause them to drift off centre by a percent or two. Fortunately the DX8 is very easy to re-calibrate.
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Old 06-01-2012, 10:40 AM   #20
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Does recalibrating help the pot drift issue? I would think you'd need to replace the pot to fix it.
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