Mks xj hv9930
06-01-2022, 06:50 PM
#1
Mks xj hv9930
I am setting up a jet with the MKS HV9930. When I test and move them with my servo tester the current has been between 1400 and 2000 mA. This is very high for a servo with no loads applied. I checked two of the 8 I bought and they both drew high current. The draw so much current that the servo tester overloads and comes up with a warning.
Maybe this is normal for this servo? Anyone else have this experience?
I cannot use them, this will overload the system I plan to use.
I checked some Futaba and Hitec servos with similar spec's and they draw less than 600 mA.
Maybe this is normal for this servo? Anyone else have this experience?
I cannot use them, this will overload the system I plan to use.
I checked some Futaba and Hitec servos with similar spec's and they draw less than 600 mA.
06-01-2022, 07:35 PM
#2
Senior Member
.................................................. ..................!!!!!!!!!!!!!!!!!!!!!!!
Never had a problem with running seven MKS 599's, using 20 gauge wire. They very seldom hit 4 amp draw and if the do it's only for 1/10 of second .
Just run them.............................................. .............
Never had a problem with running seven MKS 599's, using 20 gauge wire. They very seldom hit 4 amp draw and if the do it's only for 1/10 of second .
Just run them.............................................. .............
06-02-2022, 03:06 AM
#3
My Feedback: (53)
I am setting up a jet with the MKS HV9930. When I test and move them with my servo tester the current has been between 1400 and 2000 mA. This is very high for a servo with no loads applied. I checked two of the 8 I bought and they both drew high current. The draw so much current that the servo tester overloads and comes up with a warning.
Maybe this is normal for this servo? Anyone else have this experience?
I cannot use them, this will overload the system I plan to use.
I checked some Futaba and Hitec servos with similar spec's and they draw less than 600 mA.
Maybe this is normal for this servo? Anyone else have this experience?
I cannot use them, this will overload the system I plan to use.
I checked some Futaba and Hitec servos with similar spec's and they draw less than 600 mA.
06-02-2022, 06:04 AM
#4
I wrote Thomas.
It is amazing that this information about servos is not published. It seems important to know it, else how do you determine there is an issue?
I know from experience, that my airplanes have an idle current around 0.5A. If its is much higher than that, I start to look at stuff. A common issue is a flap servo binding at end of travel (because there is a hard stop when the flaps are up). It is better to notice it thru telemetry and fix it before flying.
It is amazing that this information about servos is not published. It seems important to know it, else how do you determine there is an issue?
I know from experience, that my airplanes have an idle current around 0.5A. If its is much higher than that, I start to look at stuff. A common issue is a flap servo binding at end of travel (because there is a hard stop when the flaps are up). It is better to notice it thru telemetry and fix it before flying.
06-02-2022, 06:08 AM
#5
Perhaps the high amps is due to in-rush current to get the motor going (LRA). Typically LRA is 5x running load current.
But I've tested a bunch of servos with my ToolKit RC tester and never had one go this high. I'm worried the high amps will fry the receiver.
But I've tested a bunch of servos with my ToolKit RC tester and never had one go this high. I'm worried the high amps will fry the receiver.
06-02-2022, 06:22 AM
#6
Servo testers typically do not deliver high voltage. You have HV servos. With such a voltage miss-match, the current will be higher causing the error massage in the more sophisticated testers. However, ...
When using HV digital servos, one needs to use a Rxer system that delivers more than the typical RXer's ~5 volts. Also, when using several HV components downstream from a 5V Rxer, the Rxer's output bus typically cannot handle the current load sometime casing Rxer failure. A HV Digital servo can peak >5 amps under load. Mutiple digital servos can all be moved at the same time. The current loads are cumulative. It is easy to exceed a low voltage Rxer's current limits with today's HV digital servos. 8 digital servos can easily peak at 40 - 50+ amps when under full load!
Powerbox, Smart-fly, etc. units separate the power driving the servos from the power driving the Rxer. When Digital servos just started coming available, some folks who used LV Rxers and HV/Digital servos just bypassed the Rxer by not running the servo power circuits through the Rxer. They just use the signal wire from the Rxer. These days, with Rxer units designed to bypass the power circuits, the whole power delivery arrangement is a lot easier. In jets, I use just Powerbox units.
Also, with the larger planes we have today with the servos in the tail, one has to consider using a larger diameter (low resistance) wire with minimal connectors for the more remotely located servos.
Just some food for thought. Good catch! You probably just saved your plane!
When using HV digital servos, one needs to use a Rxer system that delivers more than the typical RXer's ~5 volts. Also, when using several HV components downstream from a 5V Rxer, the Rxer's output bus typically cannot handle the current load sometime casing Rxer failure. A HV Digital servo can peak >5 amps under load. Mutiple digital servos can all be moved at the same time. The current loads are cumulative. It is easy to exceed a low voltage Rxer's current limits with today's HV digital servos. 8 digital servos can easily peak at 40 - 50+ amps when under full load!
Powerbox, Smart-fly, etc. units separate the power driving the servos from the power driving the Rxer. When Digital servos just started coming available, some folks who used LV Rxers and HV/Digital servos just bypassed the Rxer by not running the servo power circuits through the Rxer. They just use the signal wire from the Rxer. These days, with Rxer units designed to bypass the power circuits, the whole power delivery arrangement is a lot easier. In jets, I use just Powerbox units.
Also, with the larger planes we have today with the servos in the tail, one has to consider using a larger diameter (low resistance) wire with minimal connectors for the more remotely located servos.
Just some food for thought. Good catch! You probably just saved your plane!
The following users liked this post:
Halcyon66 (06-02-2022)
06-02-2022, 06:54 AM
#7
My ToolKit RC tester supplies 8.2V to the servos. I thought maybe it was set a 5V and this was the issue. But I got the same results with 8.2V.
+1 on all you said, we are on the same page.
I didn't want to use a power distribution box for this model.
If, in fact the servos are normal, then I'm switching to brushless ones which draw less current. I'll save the 9930s for a bigger airplane.
+1 on all you said, we are on the same page.
I didn't want to use a power distribution box for this model.
If, in fact the servos are normal, then I'm switching to brushless ones which draw less current. I'll save the 9930s for a bigger airplane.
06-02-2022, 08:08 AM
#8
Senior Member
You should use a power distribution unit like a Jeti CB box 200's, 300's and 400's. These types of units are really a needed when running multiply HV servos in a plane.
Switching to a Brushless servo your spending more money than getting a distribution unit whatever radio you flying.
I'm currently running JR 8911's coreless on my Viper with no issue of over current and have a new set of Jr 8911S brushless for the Rebel Pro.
If you're getting rid of those MKS9930 servos I would be interested.
Switching to a Brushless servo your spending more money than getting a distribution unit whatever radio you flying.
I'm currently running JR 8911's coreless on my Viper with no issue of over current and have a new set of Jr 8911S brushless for the Rebel Pro.
If you're getting rid of those MKS9930 servos I would be interested.
06-06-2022, 03:45 AM
#9
Hi,
I sent Thomas a video of the servos action and he had the engineer's review it. They said the servo behavior was normal.
When the servos are powered up, there is a large in rush of current to get the motor into position. Its is only a momentary current peak. That's what I was seeing with my tester.
I also was cycling the servo back and forth, kinda quickly. This also causes the current to spike, enough so that my servo tester would trip. I don't need to move the servos like that in flight, so this should not be an issue.
I do wish these servos had a soft-start function.
I sent Thomas a video of the servos action and he had the engineer's review it. They said the servo behavior was normal.
When the servos are powered up, there is a large in rush of current to get the motor into position. Its is only a momentary current peak. That's what I was seeing with my tester.
I also was cycling the servo back and forth, kinda quickly. This also causes the current to spike, enough so that my servo tester would trip. I don't need to move the servos like that in flight, so this should not be an issue.
I do wish these servos had a soft-start function.
06-06-2022, 07:47 AM
#10
Senior Member
So both JR and Futaba offer a soft start servo but they are about 50-60 more per servo
Glad you got an explanation to the sudden amperage spike..MKS makes great servo's .
Glad you got an explanation to the sudden amperage spike..MKS makes great servo's .
06-07-2022, 03:28 AM
#14
My Feedback: (53)
Soft start is nice y’a sure quite cute…..but require nope, in 40+ years ago when I started we didn’t have that, and I never since broke a surface horn……on the other hand a strong servo that return well to Center and that doesn’t develop play easily….now that is required.
Don’t MKS fine sell them and move on…..and go buy soft start servo’s…..no need to bashed some of the best servo’s with great service out there…
Don’t MKS fine sell them and move on…..and go buy soft start servo’s…..no need to bashed some of the best servo’s with great service out there…
06-07-2022, 04:37 AM
#15
No bashing here. Stating the facts.
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
06-07-2022, 05:52 AM
#16
My Feedback: (53)
No bashing here. Stating the facts.
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
It seem that folks come here before asking the dealer/distributors….I would have a lot of post if I did that….there’s a lot to learn and they have the knowledge…..we do pay for service..
Last edited by Dansy; 06-07-2022 at 07:13 AM.
06-07-2022, 09:44 PM
#18
No bashing here. Stating the facts.
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
Soft start has advantages.
The 9930s have the greatest in-rush current of any servo I've tested (extremely limited study). I will use them with a CB220, as I prefer to not have my REX12 handle so much current on startup. But others have done this without issues.
I use MKS with great success and will continue to do so. (I also like KST, Hitec, Promodeler, Savox & Futaba)
Look forward to see the UF at the field soon…
David
