JR nes591 servo's

[nasa_steve]

hi guys
having read the letter in RCM&E this month relating to not running jr591 servo's on 6 volts according to general concensus you can run them on 6volts i've posted several threads on various forums across the web and every one agree's that you can and many do run NES591 servo's on 6volts i'd be interested to find out if anyone else has had any more experience on this
regards
nasa

[Model-pro]

Hi
About 80% of my models use 591 servos.I have used these for years and I run all of them on 6vots.Free torque and speed why would you not. I have never had a single problem with these on 6 volts.
Simon

[John Clark 2]

This issue came up in my magazine recently, too, regarding a review helicopter. The reviewer (who will remain nameless) has also run them on 6v without problems.

The truth is, since the offical JR spec doesn't rate them at 6v MacGregor Industries aren't prepared to recommend it - understandable, really. But, they certainly appear to work on 6v when asked to!

JC

[Ogg]

Hi
Interested in the 591 debate. I've got a number of these in various aircraft, but I run them at 4.8v. I've had 5 fail on me, 1,in a Glens model extra 58" (gear train) on the elevator and 4 on the throttle of a a venture 50 heli.It seems the potentiometer fails on them , which is a bit worrying when its stuck flat out.It has caused a lot of head scratching to find a cure but without success,if there was excessiive vibration I could understand. Just wondered if any one else has had similar problems.

[Chris Dickens]

I've used JR servos for 20 years (507, 517, 591, 811, 8231) and never had one fail. To have 4 pots fail it must be something common, either in the instalation, setup, or your particular receiver/battery combination.
Was it always with the same receiver?

I've never broken a gear through normal use either, I have broken one when I droped themodel and it landed on the elevators (broke the model as well!!)

[Ogg]

Yes it was with the same receiver/battery combo . The instalation was fine, as in rubber grommets fitted and the servo isolated. The setup was set correctly so the servo was not bottoming out either end of its travel. I'm not knocking JR gear becauce that is what I normally use, I'll just think twice about where I fit a 591.

[Anthony Crawley]

I contacted MacGregor in April last year on exactly this voltage subject, and Ken Brewer replied to me that JR servos do not like 6v, but the receivers are fine to work on 6v. So whatever you find in practice, that is the official word! He also suggested I use a large (NiMH) 4.8v pack rather than a 6v battery in the RCM&E Lanc.

[Brian Young]

Hi, I've been using JR591s for a while on 4.8v with no problems. For my latest project I have bought Cirrus CS601BB servos. They appear to be the same size and spec as the 591, and quote 6.5kg/cm at 6v or 5kg/cm at 4.8v. Admitted I have not had much use out of them yet but on the face of it they appear fine. Oh, and finally they are considerably cheaper than 591s. Just thought you may be interested.

[Linda Hewitt]

591's - got about ten - two have failed - end of!

[nasa_steve]

end of what ??????? linda you seem very abrasive on this forum take a chill pill and calm down!! better still if you've nothing but short non descript answers to post don't bother!! :-)

[Peter Roberts]

I have a problem too for which I would appreciate some advice.

I was recommended to fit JR 579 servos to my new YT Adrenaline which I have done. However these boys shift up to 8.3 kg / cm and I've got 6 of them on the plane.

I wondered about the power supply and had 3 questions for which I will be grateful for some experienced answers please.

a) will 4.8v 2400 mah rx battery be sufficient

b) should there be a separate servo battery

c) should I be using 6v battery and if so can JR servos take 6v?

Does anyone have any experience with the JR Multibox as a means of adding a separate battery?

Many thanks

Peter

[nasa_steve]

peter

   firstly the 2400mah pack you mention is it a sub c pack and not a normal aa sive cell pack. secondly check the rating for the 579's to see if 6v is recommended or mentioned on the rated power. i cannot say anything about the multibox as i've not used one someone else maybe able to answer that one.

regards

nasa

[Peter Roberts]

Thanks nasa,

I also have several receiver 4 AA packs rated between 1800, 2300 and 2500 bought from the likes of overlander (sorry Over-tech).

Without wishing to sound thick - where do I check the 579 rating - I didn't think it was shown on the servos, there's no spec or instruction leaflet supplied with them and when I look at website (MacGregor etc) they quote everything but volts capability.

I've seen a couple of comments from a JR spokesman some time ago that they don't recommend anything other than 4.8v but that's all. Some say that the receiver is what won't like 6v?

All advice and help gratefully received!

[nasa_steve]

hi pete

to be honest those pack are probably only man enough for one flight if at all but not much more. they don't have a high current delivering capability where as sub c based pack will. and to be honest i'd be looking to run sub-c packs in anything over .90 size. 579's are rated at 8.3kg at 4.8v

regards

steve

[Anthony Crawley]

As I mentioned earlier, the official word from Ken Brewer of MacGregor is use a large 4.8v 4-cell pack (NiMH if poss) rather than 5-cell 6v, as the servos apparently don't like 6v. If you've any questions, just ring or e-mail Ken at MacGregor and he'll answer your queries, as he did mine.

[Peter Roberts]

Thanks nasa_steve - advice much appreciated. Will have to swat up on what the difference is between the standard packs provided by Futaba, JR, Ripmax and the like and sub-c! Could you get better by y lead linking say 2 2700 packs together?

 Anthony thanks for suggesting contacting Ken at MacGregor - I tried to contact him using a number found with his name in an article on their website and got the unobtainable tone!

Cheers Peter

[Peter Roberts]

Just another thought - I've been to the Overlander website looking at sub c 4.8v batteries - c 4100 mah. What if I put two 2.4v 2700 Nimh batteries in parallel e.g. via a Y lead as the power source. Wouldn't that be similar or better than 1 sub c 4100?

Peter

[nasa_steve]

no you miss my point the packs you speak of don't give anywhere near the current capabilities you need whether in parallel or not plus the configuration you talk of will only give 2.4volts one of those packs could be giving completely different output ........bite the bullet and buy a new pack if you value your model why spend £250+ on the kit and put £5 worth of cells in there its a big gamble with a model of that size

steve

[Peter Roberts]

Sorry my typing as well as my brain was bad. I didn't re read the message before I sent ir. I have two 4 cell packs each 4.8v 2700 mah Nimh. If I put these in parallel would it not equate to 1 x 4100 sub c pack?

Have you seen the following - I support it might be a possible solutioon and doable for JR servos as less than 6v.

http://www.sloughrc.com/pages/Products/Radio/SRCM-Radioaccess_emcotec.asp

Bit pricey too.

Thanks 

Peter

[nasa_steve]

no as i've said these packs are only intended for use up to 60 ish size models...... i'm sorry but how many other ways do i need to reitorate this AA cells do not have the current giving capacity its like putting a mini engine in a 7 series BMW.

   but at the end of the day its up to you if you don't value the model much and/or only want one flight per day go for it but don't say we never told you.

 the dual battery unit its a lot of money better spent on a decent 4.8v sub-c pack!!!!! why do you need 6v anyway????plus  that unit only brings it down to 5.5v which is still not 4.8v!!!!!!

steve

[Peter Roberts]

Steve,

Thanks for your patience. Naturally I care for the model I'm building as it represents a major investment for me. Its because I want it to be safe that I keep asking questions.

Sorry, I don't doubt your advice but through ignorance I want to understand the pros and cons of the different oprions. I find batteries a complicated subject and see folks suggesting everytrhing from NiCads to Lipos with regulators - I thought Rx batteries were all the same!

 Sub c Nimh it is then. What do you suggest Overlander's 4100 4.8 as per this link?

http://www.overlander.co.uk/products/default.asp?cid=2&scid=51&pid=1401

Thanks

Peter

[nasa_steve]

hi peter

that would be more than adequate the rule of thumb i always use is "always have more power availiable than you need" you will then never have power issue's and when ever i go over 90 sized models i always fit sub -c sized packs.

regards

steve

[David Martin 2]

Hi  All,

Intersesting thread to me as I have just fitted 8 x 591's to my YT Spitfire.

 I chose them for their torque rating but I have a niggle with some of them...

I've never had JR servos before only Futaba (which I didn't use this time due to 8 of their 5kg rated servos being a lot more sterling..!) but at least half of them hum as if they are under stress. This is with them out of a model and as new last year.

I got back to Ali about it and he said it was normal for JR servos to do this..? Still perturbed by it, I contacted Macgregors and they also said the servos were just hunting in stationary conditions and with airflow over the model surfaces, would be fine. They were good enough to inspect them for me and seeing I wasn't overly convinced, sent me 5 new ones. 3 of which still do it.

When I turn on the juice at the field for the first time, everyones going to think I have a duff setup as the cavernous space in the body amplifies it further..! Let lone in my experience humming servos take more power (you can always see the next LED down on the voltspy flickering with them)

Just a further note on 591's...if you need to reverse the direction of travel for one of the flap servos like I did (both on a Y lead), no need to buy a servo reversing lead, just reverse the wires on the motor and the blue and brown wires from the outer legs of the pot. These are the ones that come out on the top of the pcb. I am electronics trained and had all the fine tools at hand for this though. Better off getting a reversing lead if at all unsure..

[Martin McIntosh]

David, don`t worry about your sevos constantly buzzing. It generally means that you have servos with good tight centring, PROVIDED THAT YOUR LINKAGES ARE NOT BINDING! Just listen to digi servos singing away to the weight of a control surface alone using ball raced linkages. Just ensure that your horn and servo links will fall due to gravity when disconnected. Much better to have a loose link than a tight one, because not only will your battery drain increase, you will have problems finding neutral on control surfaces.

[Peter Roberts]

Mmm. I've just fitted a 4100 4.8v sub c battery to my Adreneline with 6 x 579 8 kg servos. Will it hack it?