Glitching RCS M4209 Coreless Digital Servos
10-22-2012, 03:39 AM
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Glitching RCS M4209 Coreless Digital Servos
Hi all
I have just installed 5 digital coreless 10kg servos in a 3D plane. I find that with three servos connected (2x elevator 1 rudder) the system is fine. But when I plug in the two ail servos I get severe giltches, particulary on the elevator pair with each elevator going in different directions at full throw!
It seems to me that the current spikes caused by the additional load of the two ail servos is generating cross interference as the elevators glitche when the ails are operated - more than the usual cross coupling of thumb movement I should add!!
So far I have tried different recievers (even diff manufcatures) and battery packs (4.8V instead of 6V) and diff combinations of leads. Nothing has worked so far.
The main components are Spekrum AR7000 Rx and RCS M4209 Metal Gear RC Digital Coreless SS818 servos.
Now I know these are relatively cheap servos for the type and if I need to I guess I will replace them. But I am looking for slightly more constructive comments than the usual knee jerk - "BUY SAVOX" etc... I
If anybody as direct experience with these servos and can help (even if it is "I replaced them and the problem went away") that would be great.
I have just installed 5 digital coreless 10kg servos in a 3D plane. I find that with three servos connected (2x elevator 1 rudder) the system is fine. But when I plug in the two ail servos I get severe giltches, particulary on the elevator pair with each elevator going in different directions at full throw!
It seems to me that the current spikes caused by the additional load of the two ail servos is generating cross interference as the elevators glitche when the ails are operated - more than the usual cross coupling of thumb movement I should add!!
So far I have tried different recievers (even diff manufcatures) and battery packs (4.8V instead of 6V) and diff combinations of leads. Nothing has worked so far.
The main components are Spekrum AR7000 Rx and RCS M4209 Metal Gear RC Digital Coreless SS818 servos.
Now I know these are relatively cheap servos for the type and if I need to I guess I will replace them. But I am looking for slightly more constructive comments than the usual knee jerk - "BUY SAVOX" etc... I
If anybody as direct experience with these servos and can help (even if it is "I replaced them and the problem went away") that would be great.
10-22-2012, 06:16 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
ORIGINAL: Doctor Whizz
Hi all
I have just installed 5 digital coreless 10kg servos in a 3D plane. I find that with three servos connected (2x elevator 1 rudder) the system is fine. But when I plug in the two ail servos I get severe giltches, particulary on the elevator pair with each elevator going in different directions at full throw!
It seems to me that the current spikes caused by the additional load of the two ail servos is generating cross interference as the elevators glitche when the ails are operated - more than the usual cross coupling of thumb movement I should add!!
So far I have tried different recievers (even diff manufcatures) and battery packs (4.8V instead of 6V) and diff combinations of leads. Nothing has worked so far.
The main components are Spekrum AR7000 Rx and RCS M4209 Metal Gear RC Digital Coreless SS818 servos.
Now I know these are relatively cheap servos for the type and if I need to I guess I will replace them. But I am looking for slightly more constructive comments than the usual knee jerk - ''BUY SAVOX'' etc... I
If anybody as direct experience with these servos and can help (even if it is ''I replaced them and the problem went away'') that would be great.
Hi all
I have just installed 5 digital coreless 10kg servos in a 3D plane. I find that with three servos connected (2x elevator 1 rudder) the system is fine. But when I plug in the two ail servos I get severe giltches, particulary on the elevator pair with each elevator going in different directions at full throw!
It seems to me that the current spikes caused by the additional load of the two ail servos is generating cross interference as the elevators glitche when the ails are operated - more than the usual cross coupling of thumb movement I should add!!
So far I have tried different recievers (even diff manufcatures) and battery packs (4.8V instead of 6V) and diff combinations of leads. Nothing has worked so far.
The main components are Spekrum AR7000 Rx and RCS M4209 Metal Gear RC Digital Coreless SS818 servos.
Now I know these are relatively cheap servos for the type and if I need to I guess I will replace them. But I am looking for slightly more constructive comments than the usual knee jerk - ''BUY SAVOX'' etc... I
If anybody as direct experience with these servos and can help (even if it is ''I replaced them and the problem went away'') that would be great.
10-22-2012, 06:22 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
I have long Y harness on the elevator servos. I havn't tried the seperate leads. I will do so and report back.
Cheers
Cheers
10-22-2012, 07:02 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
Back again
OK I have changed the Y lead to two leads and seperate channels. MASSIVE improvement - but still not 100% clean. One elevator and the rudder have slight glitches. Rudder servo is close to Rx and plugs straight in, so I'm now thinking I need a much more robust and clean supply, possibly not connected via the tiny little standard Rx switch. Any views out there/
Thanks Rich for suggestion so far. Much apprecaited.
OK I have changed the Y lead to two leads and seperate channels. MASSIVE improvement - but still not 100% clean. One elevator and the rudder have slight glitches. Rudder servo is close to Rx and plugs straight in, so I'm now thinking I need a much more robust and clean supply, possibly not connected via the tiny little standard Rx switch. Any views out there/
Thanks Rich for suggestion so far. Much apprecaited.
10-22-2012, 07:13 AM
#5
My Feedback: (2)
RE: Glitching RCS M4209 Coreless Digital Servos
ORIGINAL: Doctor Whizz
I have long Y harness on the elevator servos. I havn't tried the seperate leads. I will do so and report back.
Cheers
I have long Y harness on the elevator servos. I havn't tried the seperate leads. I will do so and report back.
Cheers
I finally bought a JR Matchbox and I have used this type of device, instead of a Y, ever since. Futaba also makes a Servo Sync device. It allows me to connect up to 4 servos to one channel and control Servo Direction, End Points, and Neutral, from each servo, independently.
Channel Mixing is the next best thing.
10-22-2012, 02:23 PM
#6
RE: Glitching RCS M4209 Coreless Digital Servos
ORIGINAL: Doctor Whizz
Back again
OK I have changed the Y lead to two leads and seperate channels. MASSIVE improvement - but still not 100% clean. One elevator and the rudder have slight glitches. Rudder servo is close to Rx and plugs straight in, so I'm now thinking I need a much more robust and clean supply, possibly not connected via the tiny little standard Rx switch. Any views out there/
Thanks Rich for suggestion so far. Much apprecaited.
Back again
OK I have changed the Y lead to two leads and seperate channels. MASSIVE improvement - but still not 100% clean. One elevator and the rudder have slight glitches. Rudder servo is close to Rx and plugs straight in, so I'm now thinking I need a much more robust and clean supply, possibly not connected via the tiny little standard Rx switch. Any views out there/
Thanks Rich for suggestion so far. Much apprecaited.
One real issue is that they can cause sever voltage depression as they start moving
The other issue - long leads especially light guage - with light connectors can cause poor signal to servos
You should be running High C rating batteries with your setup- If you tested using a amp/volt meter I would suspect you see an instant drop of 1-2 volts upon sudden application of control to the elevators .
I hav e run tests using servos that size (inexpensive ones and expensive ones) - the real issue is the sudden power draw.
You do not want any rx setup which will show ONE (1) or more volt drop upon stick movement
A two volt drop - a disaster waiting to happen.
small voltamp meters are not expensive and a must with current setups
10-22-2012, 06:16 PM
#7
RE: Glitching RCS M4209 Coreless Digital Servos
If you havent already, put a decent sized capacitor across the battery leads of an open channel to help with the voltage drop.
10-23-2012, 12:06 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
Hi guys.
Thanks for the thoughts.
I have the necessary tools and skills to measure the voltage drop and fit caps etc. Bloody well ought to as believe it or not I'm an ex- EMC electronics engineer so I should know better! [&:]I suspected that this would be the case. However 1st time I've used servos of this power so thought I'd double check my suspicions.
I’m going install high value caps as close as poss to each servo by making my own extension leads and seriously up rate the wires and switch. Also run the Rx and servo supplies from a central junction point so servo currents aren’t going through the Rx.
Cheers and happy landings
Thanks for the thoughts.
I have the necessary tools and skills to measure the voltage drop and fit caps etc. Bloody well ought to as believe it or not I'm an ex- EMC electronics engineer so I should know better! [&:]I suspected that this would be the case. However 1st time I've used servos of this power so thought I'd double check my suspicions.
I’m going install high value caps as close as poss to each servo by making my own extension leads and seriously up rate the wires and switch. Also run the Rx and servo supplies from a central junction point so servo currents aren’t going through the Rx.
Cheers and happy landings
10-23-2012, 04:03 AM
#9
RE: Glitching RCS M4209 Coreless Digital Servos
ORIGINAL: Link119
If you havent already, put a decent sized capacitor across the battery leads of an open channel to help with the voltage drop.
If you havent already, put a decent sized capacitor across the battery leads of an open channel to help with the voltage drop.
10-23-2012, 04:09 AM
#10
RE: Glitching RCS M4209 Coreless Digital Servos
Forget the caps - THEY CAN NOT FIX THE PROBLEM- It isnt just a micro spike - it isa prolonged voltage depression .
the buss on the rx will stand lots of power so a seperate buss not required
the weak link is the stock servo connectors we are all stuck with these and the simple thing is to use the very best set servo leads you can get -all of a snug, matching type.
The best battery set you can buy is a 2 cell genuine A123 cells wired properly for your application - you will neeed a good, cell balancing charger for FEO4 /A123 cells.
the buss on the rx will stand lots of power so a seperate buss not required
the weak link is the stock servo connectors we are all stuck with these and the simple thing is to use the very best set servo leads you can get -all of a snug, matching type.
The best battery set you can buy is a 2 cell genuine A123 cells wired properly for your application - you will neeed a good, cell balancing charger for FEO4 /A123 cells.
10-23-2012, 11:34 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
Hear what you are saying RMH. Have a good hi C discharge pack on order - NiMh not set up for LiP yet; and I will go through the wiring and make sure it is all hi current and the conns are a good fit. Will probably hardwire the extensions. I still think taking the servo current away from the Rx is a good idea, not just a question of capacity but also a matter of dI/dt. Thanks for the input.
10-25-2012, 08:53 PM
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RE: Glitching RCS M4209 Coreless Digital Servos
ORIGINAL: rmh
This really can't help low voltage - honest -
ORIGINAL: Link119
If you havent already, put a decent sized capacitor across the battery leads of an open channel to help with the voltage drop.
If you havent already, put a decent sized capacitor across the battery leads of an open channel to help with the voltage drop.
10-26-2012, 01:43 AM
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RE: Glitching RCS M4209 Coreless Digital Servos
Certainly won't fit in this bird - its got a very narrow fuselage.
I have tried a higher capacity high discharge capability battery with a heavy duty switch & harness 'lashed' togeather and it was all working OK
. Just got to 'squeeze' the battery under the tank now when I get back to it.
Thanks for all the advice it looks like the problem has been resolved.
I have tried a higher capacity high discharge capability battery with a heavy duty switch & harness 'lashed' togeather and it was all working OK
. Just got to 'squeeze' the battery under the tank now when I get back to it.Thanks for all the advice it looks like the problem has been resolved.
10-26-2012, 03:44 AM
#14
RE: Glitching RCS M4209 Coreless Digital Servos
Good show -
If you can- locate rx as far aft and up as you can manage - place satellite as far down and aft as possible -
I bought the longer leads for the 7000 and other rx so I can place the satellites in the empty room aft the wing -in the belly.
Overkill? - well- it takes a bit more time but with a good view of incoming signal and plenty of power to the servos - Your chances of radio problems become minimal.
If you can- locate rx as far aft and up as you can manage - place satellite as far down and aft as possible -
I bought the longer leads for the 7000 and other rx so I can place the satellites in the empty room aft the wing -in the belly.
Overkill? - well- it takes a bit more time but with a good view of incoming signal and plenty of power to the servos - Your chances of radio problems become minimal.
