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Old 04-13-2006, 04:41 AM   #1
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Default New Servo not quite right...help

i'm running a yokomo bd, with Jr xs3 radio gear, nosram dominator ESC (with 5.8v BEC) and matched 3700mah batteries....
...i've just brought a new bluebird 621mg, when running it normally powered through the ESC it works normally if turned from one full lock to the other slowly.
As soon as you do it fast after about 3 times it locks up at about 3/4 of full lock in one direction and sounds like the servo's under strain, as soon as you ease the steering back slightly and then go full lock it will travel to full lock again.
this happens while nothing is connected to the servo horn and no throtle is used. the problem also goes away with different radio gear

I've tried powering the servo with a reciever pack and the problem goes away. I'm wondering is it possible the servo is getting too much/little voltage. and if so, how can I test the output BEC voltage from my ESC.
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Old 04-13-2006, 04:52 AM   #2
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The bluebird 621mg is a 6V servo by the looks of the specs. I had the same problem with a KO 2343 and a Nosram Power Missile. The Nosram only had a 5V BEC and nothing, including capacitors, solved the problem.

My problem was only solved by going to an ESC with a 6V/3A BEC, which for me was a Novak GTX.
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Old 04-13-2006, 03:13 PM   #3
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surely .2 of a volt wont make that much difference
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Old 04-14-2006, 03:08 AM   #4
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i'm going to try a capacitor tomorrow, i'll see if that helps
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Old 04-14-2006, 04:00 AM   #5
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anybody got any ideas why my brand new ko 2343 servo goes so slow? ive got a ko vantage radio gear and a lrp qu2... any sort of turning will not reaxt quickly at all concidering its supposed to be a really quick and torque servo...
Have i got something set wrong on my transmitter or?
thanks for any help...
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Old 04-14-2006, 04:26 AM   #6
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If some of you guys are having servo / voltage related problems due to your ESC not putting out enough power, check this link out.

http://www.rctech.net/forum/showthre...&page=41&pp=30.
http://www.rctech.net/forum/showthre...&page=42&pp=30

I had similar problems with a QC2 and Digi servo. After building 6v voltage regular to plug into BEC of ESC the servo works fine and fast. With my GTB did not need it as it was already 6v but QC2 is only 4.8v.
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Old 04-14-2006, 04:37 AM   #7
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so can you buy a "power booster" anywhere to just plug in or are you talking about adding it in to the speedo? cant get that image to work.. and aint qc2's supposed to run at 6volts?

Last edited by cyclone; 04-14-2006 at 04:48 AM.
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Old 04-14-2006, 07:36 AM   #8
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The thing with blue bird servo's is that the bushing that the first gear is on, wears like crazy and then you have a lot of play in the servo- not good...

PS- how many amps is the esc's bec rated for at 5.8 amps?
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Old 04-14-2006, 02:08 PM   #9
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Quote:
Originally Posted by cyclone
so can you buy a "power booster" anywhere to just plug in or are you talking about adding it in to the speedo? cant get that image to work.. and aint qc2's supposed to run at 6volts?
Spektrum Voltage Protector

Get one of these to plug into the receiver, when the voltage tries to drop the capacitor discharges to help hold the voltage up.
And no, you don't have to be using a Spektrum for it to work.

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Old 04-14-2006, 02:13 PM   #10
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not sure how many amps, cant find it anywhere. its a "nosram dominator power" which apparently is a rebadged LRP ESC
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Old 04-14-2006, 02:18 PM   #11
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Quote:
Originally Posted by Drewdc90
If some of you guys are having servo / voltage related problems due to your ESC not putting out enough power, check this link out.
i'm not sure my problem is a voltage issue, anyone know for sure looking at my symptoms(first post)
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Old 04-14-2006, 05:12 PM   #12
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Quote:
Originally Posted by Stoffa
I've tried powering the servo with a reciever pack and the problem goes away.
You have answered your own question here. Your ESC BEC does not put out enough power to supply your servo. The Nosram is an LRP so your BEC will only be 4.8V You need to power the servo from a 6v source. Run the receiver pack as you have done or make the small voltage regulator I posted earlier. You will have to buy the parts from an electronics shop, wire them up to a plug that will fit into the Batt slot of your ESC. This is powered from your battery at 7.2v and drops it down to 6v. You could try a cap but if your BEC is too low such as the QC2 (4.8v, I know I own one) it wont work
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Old 04-14-2006, 08:38 PM   #13
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brilliant, thanks for that...the BEC for the ESC is 5.8V according to the box it came in, so i'll try the cap first.

i've noticed a few different ways to use the voltage regulators, whats the difference between your way (same as diagram) and using 2 regulators??
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Old 04-14-2006, 10:08 PM   #14
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The diagram was off someone else's post. I have wired two in parallel and then to a plug for the BEC. Keep it simple. When my battery is close to dumping the servo behaves very strangely. So make sure your battery has enough power to finish the heat or you will lose steering
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Old 04-15-2006, 12:44 AM   #15
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I have tried all these options and the problem is still there, so i guess maybe there's something wrong with my radio gear. Or maybe I should just buy a "real" high speed servo, stay away from the cheap stuff
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