Fun, Learning, Friendship and Mutual Respect
START  HERE


Unregistered
Go Back   HeliFreak > R/C Helicopter Support > 250 Class Electric Helicopters


250 Class Electric Helicopters 250 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


Reply
 
Thread Tools Display Modes
Old 04-18-2012, 10:38 AM   #1
Sndflea
Registered Users
 

Join Date: Sep 2011
Location: Richmond, VA.
Default DS420 Faliure

I had just taken off and was hovering fine when I lost the tail. Landed fine. Seems like the Align DS420 is dead. I probably don't have 50 flights on it. All of my electronics are stock. Is it fairly typical that a servo would fail this soon? I am replacing with a MKS DS95-i.
Sndflea is online now        Reply With Quote
Old 04-18-2012, 11:08 AM   #2
JoeW
Registered Users
 
Posts: 1,877
 
My HF Map location
Join Date: Apr 2011
Location: Oakville, ON - CDN
Default

Sometimes... I find if it's going to fail out of the box, it will usually do it within the first 20 flights or so. If it survives past that you'll be fine.

I've had about 1 in 4 420s fail within the first dozen flights... the others were fine for hundreds of flights.

Even a light crash though can bump the servo case just right so the servo starts binding a bit and it will fry itself within a few flights.

You won't be disapointed with the DS95i though.

The DS420 is fine for light flying, but you'll want something better if you're doing more than loops, rolls and maybe stall turns.

I heard Bert Kammerer recommend the Futaba 9257 or JR 3500g... they're bigger and heavier but he seems to think it's a fair trade.

I haven't used that Futaba or JR but prefer the DS95i, it's not that much more money than the Futaba or JR and it's the same footprint as the DS420 and it's the undisputed champion of 250 tail servos
__________________
TRex 250 DFC | TRex 250 DFC (Scale)
2 @ TRex 450 DFC | TRex 450 Pro 3G (Scale)
TRex 550 DFC
DX8 + Telemetery on all
JoeW is offline        Reply With Quote
Old 04-18-2012, 11:10 AM   #3
litehawkdown
Registered Users
 
Posts: 3,403
 

Join Date: May 2011
Location: Canada
Default

Quote:
Originally Posted by Sndflea View Post
I had just taken off and was hovering fine when I lost the tail. Landed fine. Seems like the Align DS420 is dead. I probably don't have 50 flights on it. All of my electronics are stock. Is it fairly typical that a servo would fail this soon? I am replacing with a MKS DS95-i.
Not sure. Were your gyro settings right to begin with? I noticed a warning that you can fry a servo if you set it up wrong.
litehawkdown is offline        Reply With Quote
Old 04-18-2012, 02:33 PM   #4
Sndflea
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2011
Location: Richmond, VA.
Default

I've been flying with my Gyro settings for quite a few flights so I don't believe that was the culprit - but who knows. I was just surprised that it failed so soon.
Sndflea is online now        Reply With Quote
Old 04-18-2012, 06:17 PM   #5
litehawkdown
Registered Users
 
Posts: 3,403
 

Join Date: May 2011
Location: Canada
Default

Quote:
Originally Posted by Sndflea View Post
I've been flying with my Gyro settings for quite a few flights so I don't believe that was the culprit - but who knows. I was just surprised that it failed so soon.
Might want to check it over to make sure.
litehawkdown is offline        Reply With Quote
Old 04-18-2012, 10:38 PM   #6
upankatz
Registered Users
 

Join Date: Jan 2009
Location: toronto
Default

i've blown my last 3 tail servos all within about 5 mins of flight time each, after a couple of minutes flying I noticed the tail servo getting real hot...These were all different name brands, one was the 420, the rest were cheapies....I noticed my gyro plate was sitting in the frame a little loose so it was vibrating quite abit....I fixed the vibrating, and now tail servo seems okay....Is it possible for the gyro vibrating to cause the tail servo to overwork itself into self destruction?
__________________
Helis
Mcpx bl, Align 250se/pro, Align 450 pro, Align 500e....
upankatz is offline        Reply With Quote
Old 04-19-2012, 07:45 AM   #7
Sndflea
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2011
Location: Richmond, VA.
Default

I don't believe this to be the case but I'll check when I install the new servo. I had a minor crash / boom strike on the flight before the failure so it does bear looking at.
Sndflea is online now        Reply With Quote
Old 04-19-2012, 10:14 AM   #8
ahahn
Registered Users
 

Join Date: Aug 2010
Location: Chicago 'burbs
Default

Quote:
Originally Posted by upankatz View Post
i've blown my last 3 tail servos all within about 5 mins of flight time each, after a couple of minutes flying I noticed the tail servo getting real hot...These were all different name brands, one was the 420, the rest were cheapies....I noticed my gyro plate was sitting in the frame a little loose so it was vibrating quite abit....I fixed the vibrating, and now tail servo seems okay....Is it possible for the gyro vibrating to cause the tail servo to overwork itself into self destruction?
You need to check if the tail control system is binding under load. I assume you have setup the gyro servo update rate correctly.

3 blown tail servos aren't normal.
ahahn is online now        Reply With Quote
Old 04-19-2012, 02:41 PM   #9
litehawkdown
Registered Users
 
Posts: 3,403
 

Join Date: May 2011
Location: Canada
Default

If the servo limits are not correctly set I could see that killing a servo too.
litehawkdown is offline        Reply With Quote
Old 04-19-2012, 05:25 PM   #10
JoeW
Registered Users
 
Posts: 1,877
 
My HF Map location
Join Date: Apr 2011
Location: Oakville, ON - CDN
Default

Possibly... One direction will cause it to bind... The other bends the crap out of the flimsy pushrod

I'd be more inclined to blame the crash. Don't let the metal case fool you. They're easy to pinch enough that it causes binding internally. They go belly up within a few flights after that.
__________________
TRex 250 DFC | TRex 250 DFC (Scale)
2 @ TRex 450 DFC | TRex 450 Pro 3G (Scale)
TRex 550 DFC
DX8 + Telemetery on all
JoeW is offline        Reply With Quote
Old 04-19-2012, 06:17 PM   #11
Sndflea
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2011
Location: Richmond, VA.
Default Servo Lead Colors

OK - got the 95i today (great service from A Main Hobbies). Lead on the Align was black / red / white. The 95i is brown / red / orange. Which way does it get plugged in? i.e. does the 95i brown wire equate to the Align black wire or white wire?
Sndflea is online now        Reply With Quote
Old 04-19-2012, 07:12 PM   #12
JoeW
Registered Users
 
Posts: 1,877
 
My HF Map location
Join Date: Apr 2011
Location: Oakville, ON - CDN
Default

Brown=black=negative
Orange=white=signal

Make sure you change your gyro to 760uS mode before you plug it in.
__________________
TRex 250 DFC | TRex 250 DFC (Scale)
2 @ TRex 450 DFC | TRex 450 Pro 3G (Scale)
TRex 550 DFC
DX8 + Telemetery on all
JoeW is offline        Reply With Quote
Old 04-19-2012, 10:07 PM   #13
Sndflea
Registered Users
Thread Starter Thread Starter
 

Join Date: Sep 2011
Location: Richmond, VA.
Default

Will do - thanks
Sndflea is online now        Reply With Quote
Old 04-22-2012, 05:03 PM   #14
GeorgiaBoy
Registered Users
 
Posts: 344
 

Join Date: Jan 2012
Location: U.S.A. Georgia
Default

The Align 420 case is put together with two screws instead of the standard four making it easier to rack so even a slight offset on the boom mount could cause bind. And running your gyro on digital will constantly feed power to the servo and cause it to get hot. If it cooks another servo of any brand maybe consider setting gyro to analog and see if you can live with it. Servo replacement can get expensive after a short run.
__________________
Blade 450,T Rex conversion 450,Cheap Clone 450
EXI 250 (wife's heli),HK 500 3GX,Cheap clone 500(wife's other heli),T-Maxx 2.5r,HPI RS4 12t (batt eater)
Fly naked, neighbors wont see the crash.....
GeorgiaBoy is offline        Reply With Quote
Old 04-23-2012, 11:23 AM   #15
ahahn
Registered Users
 

Join Date: Aug 2010
Location: Chicago 'burbs
Default

Quote:
Originally Posted by GeorgiaBoy View Post
The Align 420 case is put together with two screws instead of the standard four making it easier to rack so even a slight offset on the boom mount could cause bind. And running your gyro on digital will constantly feed power to the servo and cause it to get hot. If it cooks another servo of any brand maybe consider setting gyro to analog and see if you can live with it. Servo replacement can get expensive after a short run.
Most of us fly the 420 in digital mode with no issue.

Update rates are just that. If the gyro detects motion, then it can tell the servo to move to correct it. A faster rate is just that. A properly setup heli isn't going to cause any issue.

On the other hand, if you have a severe vibration in the heli, it is possible that the gyro interprets that as a motion in constant need of correction. In that case it is indeed possible that the gyro overworks the servo which can cause it to overheat. Going to analog rates in that case may actually help the servo, but it is masking the problem.

Also binding in the tail can really overheat a servo. Testing for binding when the tail isn't spinning may not catch the issues with bearings going south, or other dynamic problems (see the whole Chinese weight threads). In this case, going analog won't help.

By the way, the gyro isn't sending power to the servo. Power is supplied by the middle servo lead (and the return ground lead). It is always there "DC". It is the signal line that is being updated at the higher digital rate. If the update pulse width is the same as the previous pulse width, the servo does nothing, if it is already at the commanded position.
ahahn is online now        Reply With Quote
Reply




Unregistered
Go Back   HeliFreak > R/C Helicopter Support > 250 Class Electric Helicopters


250 Class Electric Helicopters 250 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


Copyright © 2004-2011 - William James - Helifreak.com