RE: ds821 dx7 servo defect  
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All Forums >> Radios, Batteries, Clubhouse and more >> RC Radios, Transmitters, Receivers, Servos, gyros >> Radio Manufacturer Direct Support >> JR Radio & Spektrum Radios >> RE: ds821 dx7 servo defect
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RE: ds821 dx7 servo defect - 1/30/2007 2:20:30 AM   
Jack Skip


 

Posts: 158
Joined: 9/8/2003
From: Marsh Harbour, Abaco, BAHAMAS
Status: online 		Nope. Maybe everyone but me. But not me.

Are there any warnings against LockTite in the packaging, or is it just common knowledge?


(in reply to kolarshooter)
       Post #: 76

RE: ds821 dx7 servo defect - 1/30/2007 4:43:41 AM   
bentgear


 

Posts: 2754
Joined: 3/25/2002
From: Brandon, MS, USA
Status: offline 		Jack Skip, its pretty common knowledge. Its something that has bit a lot of folks in the butt before. Hitec now has a warning on their servo's paperwork. Some rc car kits list it as a problem. Most of the mags have run a warning about it several times. It keeps coming up on the forums from time to time. One of the good things about nylon, plactics and some composites is they tend to hold screws without the screw coming loose unless it is overtightened to begin with.

Ed M.

_____________________________

Did you bother to Read The Fine Manual yet?

(in reply to Jack Skip)
       Post #: 77

RE: ds821 dx7 servo defect - 1/30/2007 10:57:57 AM   
Jack Skip


 

Posts: 158
Joined: 9/8/2003
From: Marsh Harbour, Abaco, BAHAMAS
Status: online 		Looks like I was lacking in common knowledge, common sense and common courtesy.

Sorry everyone.

Thank you for your time and help.

< Message edited by Jack Skip -- 1/30/2007 10:58:30 AM >

(in reply to bentgear)
       Post #: 78

RE: ds821 dx7 servo defect - 1/30/2007 11:53:59 AM   
robl45


 

Posts: 134
Joined: 12/29/2005
From: , FL, USA
Status: offline 		I can tell you the guys on the forums I'm on are not using loctite on their plastic servo horns and they are shearing clean off in flight. The thing needs longer screws. People put in longer screws, servo horn didn't break. This isn't rocket science.

(in reply to Jack Skip)
       Post #: 79

RE: ds821 dx7 servo defect - 3/1/2007 12:41:21 AM   
Jermo


 

Posts: 3
Joined: 11/20/2006
From: Fort Mill, SC, USA
Status: offline 		I wonder if those that encountered DS821 servo failures used threadlock on the servo horn screws?
Jermo

(in reply to kolarshooter)
       Post #: 80

RE: ds821 dx7 servo defect - 3/1/2007 3:22:52 PM   
dsnyder



Posts: 9365
Joined: 6/27/2002
From: Champaign, IL, USA
Status: offline 		http://www.horizonhobby.com/Products/Support.aspx?ProdID=JRPS821

_____________________________

Danny Snyder
Horizon Hobby / Team JR

(in reply to Jermo)
       Post #: 81

RE: ds821 dx7 servo defect - 4/9/2007 1:46:46 AM   
luv2fly2


 

Posts: 139
Joined: 1/4/2002
From: Batesville, MS, USA
Status: offline 		I Got 8 of the servors to used in my new plane and now I Have had my 3rd one to break on the table, and NO I am not using loctite. I am sending all of mine back as for me they are junk!

< Message edited by luv2fly2 -- 4/9/2007 1:47:08 AM >

(in reply to dsnyder)
       Post #: 82

RE: ds821 dx7 servo defect - 6/6/2007 8:27:38 AM   
goroviro


 

Posts: 60
Joined: 8/11/2005
From: Charlemagne, QC, CANADA
Status: offline 		At my local hobby shop there's has been 4 JR DS821 broke last month and 9 (all broke on the output shaft) last year.
I had one who broke on the output shaft last winter during tests on raptor 30.
This aircraft operated 2 years with futaba S148 on aileron and 2 flights with DS821.
You still beleive HONESTLY that trere's no problems with the use of the DS821.??????????????????????????
This aircraft crashed close to a 10 yo girl with many withness.



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(in reply to dsnyder)
       Post #: 83

RE: ds821 dx7 servo defect - 6/6/2007 11:57:09 AM   
luv2fly2


 

Posts: 139
Joined: 1/4/2002
From: Batesville, MS, USA
Status: offline
quote:

ORIGINAL: goroviro

At my local hobby shop there's has been 4 JR DS821 broke last month and 9 (all broke on the output shaft) last year.
I had one who broke on the output shaft last winter during tests on raptor 30.
This aircraft operated 2 years with futaba S148 on aileron and 2 flights with DS821.
You still beleive HONESTLY that trere's no problems with the use of the DS821.??????????????????????????
This aircraft crashed close to a 10 yo girl with many withness.





I have been very bless. I have had five out of ten break, I sent them in and was told they could find nothing wrong with them. I now have them sitting on the table and will not used them.

(in reply to goroviro)
       Post #: 84

RE: ds821 dx7 servo defect - 6/6/2007 3:43:58 PM   
dsnyder



Posts: 9365
Joined: 6/27/2002
From: Champaign, IL, USA
Status: offline 		When used in the proper applications and used properly (no thread locker used and no abuse) there are no trends of any problems with the servos. If you have a problem, contact our service department.

_____________________________

Danny Snyder
Horizon Hobby / Team JR

(in reply to luv2fly2)
       Post #: 85

RE: ds821 dx7 servo defect - 6/7/2007 2:51:23 PM   
goroviro


 

Posts: 60
Joined: 8/11/2005
From: Charlemagne, QC, CANADA
Status: offline 		Hi

i can understand that it's recommanded to send the servos to the dealer and PLEASE KEEP YOUR MOUTH SHUTTED AND DON'T TELL ANYONE THAT THOSE SERVOS ARE POTENTIONALLY HASARDOUS.

My opinion is that the servo output gear could have been manufactured under an uncontrolled process and a pourcentage of them does not meet the requirements they have been design for.

The plastic induction process may not be sutable for different materials.

I wonder what means ''proper application'' and ''no abuse'' when the servo output shaft brakes on a 30 heli size while testing (engine not running) and on throttle application.

I consider that a 70 ozin servo is sutable for 120 size airplane aileron and 50 size helicopter. Many DS821 and less strong servos works great on those applications. That why i beleive DS821 problem is a sporadic inadmitted problem.

I beleive that the main proportion of the servos are ok but many of them are quite risky. That's not the kind of risk i like to deal with. After so many evidences, JR does not seems to admit the problem (contact our service department, send them to your expenses, pay your reparations, we will replace the gears with ??? gears) so i will stand with Futaba.

Jack

(in reply to luv2fly2)
       Post #: 86

RE: ds821 dx7 servo defect - 6/7/2007 3:29:36 PM   
dsnyder



Posts: 9365
Joined: 6/27/2002
From: Champaign, IL, USA
Status: offline 		You mention that it occured on the set up of a heli, was there any binding or any other set up issue that caused the failure? Our service department is there to help our customers. This is not the place to receive service on equipment. There are literally thousands of 821's out there performing very well.

_____________________________

Danny Snyder
Horizon Hobby / Team JR

(in reply to goroviro)
       Post #: 87

RE: ds821 dx7 servo defect - 6/8/2007 4:17:31 AM   
goroviro


 

Posts: 60
Joined: 8/11/2005
From: Charlemagne, QC, CANADA
Status: offline 		reply first
comment after

Reply

HONESTLY it could happen that the switch has been ''on'' with the baldes holder on, but i dont think so. Any way thay happens often and shall not cause an output shaft breakerage.



Comments

Power train.

In a normal power train (please bring me back on heart if i'm wrong, i'm not the specialist ) the strongest part shall be in sequence :

1- the model control horn (strongest)
2 - model control linkage,
3- servo arm
4- output shaft
5- gear train
6 - motor torque (weakest)

If you have an ''abusive'' outside binding, you will break the gears (what often happen on cars or on heli crashes) if the motor and gear firsts reductions inertia is too strong.
If you have an internal obstacle or too much torque required, the motor should not have enough torque to break the gears, output shaft , or the linkage. (if so, that's a bad design)

I can beleve you that thousands of ds811 did not have problems yet ( unknown or undeclared yet). But in my mind so many reported output shaft failure (wich shall never happen in a normal power train) would need a better answer.....

Personally i'v got 9 planes and 5 helis RTF. $4.50 of epoxy, $7.00 aircraft plywood, 16 beers and 20+ hours in reparing is not a big deal for me. (as long as there's no injuries) For those wich it happens with their first and only bird it could be less funny and destroy long term entousiasm fot that wonderfull hobby.(JR representatives shall be aware of that).

Within more than 35 years into RC planes cars,boats and helicopters (submarines did not catch me), i never saw (and heard about) so many output shaft broken on the same servo type.

If i'm wrong in my statements please recall me
If i didnt answer correctly to your question please recall me

NOW COULD YOU PLEASE ANSWER TO MY QUESTION???


*****************************************************************************************
You still beleive HONESTLY that trere's no problems with the use of the DS821.??????????????????????????
*****************************************************************************************


ANSWER 1: YES I still beleive HONESTLY that there's no problems with the use of the DS821 servo
ANSWER 2: ??????????????????

Rc fanatic

Jack

P.S. My 6 (5 brand new) remaining DS821 are not for sale, i prefer have a quit sleep.



(in reply to dsnyder)
       Post #: 88

RE: ds821 dx7 servo defect - 6/8/2007 2:24:06 PM   
dsnyder



Posts: 9365
Joined: 6/27/2002
From: Champaign, IL, USA
Status: offline 		There isn't a trend of any problems with the 821 servo when used properly as I have stated.

_____________________________

Danny Snyder
Horizon Hobby / Team JR

(in reply to goroviro)
       Post #: 89

RE: ds821 dx7 servo defect - 6/8/2007 3:42:20 PM   
goroviro


 

Posts: 60
Joined: 8/11/2005
From: Charlemagne, QC, CANADA
Status: offline 		Dany would you please accept my excuses.

I must admit that all servos DS821 arms broken are due to incompetents users who in certains way abused their DS821 (by a misterious hazard they abuses only that particular model)

JR being a serious company would not have put on the market a servo with inadequate quality control leading to hazardous utilisation. JR has just being unlucky to sell few of them to incompetents users.

They are so incompetents that none of them can explain why they break the servo arm instead of the gears.

having break two on a same set i consider myself as a very very incompetents users.


Your truly
Jack the incompetent DS821 abuser

(in reply to dsnyder)
       Post #: 90

RE: ds821 dx7 servo defect - 6/8/2007 5:12:56 PM   
Mac_Man_UK



Posts: 1415
Joined: 7/25/2003
From: Slough, UNITED KINGDOM
Status: offline 		Well, all I can say is that there have been no reports of any failures on this servo on this side of the pond. We know it under a different name outside the USA.

_____________________________

UK JR Tech.

(in reply to goroviro)
       Post #: 91

RE: ds821 dx7 servo defect - 6/8/2007 10:39:53 PM   
goroviro


 

Posts: 60
Joined: 8/11/2005
From: Charlemagne, QC, CANADA
Status: offline 		Hi

Quite happy to ear that, many foroms also pretends that new batch of Ds821 are ok.

If you still use them i would suggest to keep your fingers tightly crossed lol

Jack

(in reply to Mac_Man_UK)