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Asked — Edited
Resolved Resolved by Richard R!

Questions With A Hd 1501Mg Servo

I have one of these HD 1501MG servos. I'm having problems with it fluttering towards the end of travel. I would guess it's the pot inside with a bad spot or some grease on the wiper. I took the servo apart but it a sealed unit. Also I'm only getting about 60 degrees of travel. Has anyone seen any of this behavior using this servo? I thought it may just be this unit but I found a couple reviews with people having the same problems. I also found a video by our own josh demonstrating this servo and he had the same issue. Maybe it just effects a few servos and not all? Any ideas?

This would be a perfect servo for me as I need a standard size servo no bigger then this one and it needs to be analog with as much torque as I can find. The torqueier standard size analog servos seem to be going away in loo of digital. I'm using a Hitec HS-545MG now and it's just barely doing the job. It's OK with springs added but I really don't want to use them. ;)

Here's Josh's Vid. You can see the flutter at about 2:50 point.

#9  
@Steve... Ok... your first link didn't have the reference to rotation, just speed so I assumed... sorry about that... So the servo has limited travel to 60deg from centre instead of a normal 90?

@Dave, ok thanks no worries.... The PDF you posted says it is a 180 deg servo, however so maybe a faulty pot?...
United Kingdom
#10  
@Richard.

Hey no worries. The link I posted for some reason reverts back to the "description" page, so I added the "click specification" bit. As Dave has the PDF stating the servo he has is 180, you could very well be right about the pot then.

@Dave.

Sorry about any confusion.:)
#11  
Yes, the servo will only rotate to 60 not 90. However with power off I can turn it to 90 with my fingers.
United Kingdom
#12  
@Dave.

Well if you can turn it by hand to 90, my guess is that yourself and Richard are correct then, and it could be a faulty pot. So there's no way you can open the rest of servo up then? I know you said it's a sealed unit, but I'm just asking on the principle that "it had to be put together in the first place" theory.
#13  
I haven't had any issue with these servos and they do almost 180 deg. not 60.
If you modify the servo then you need to use the right pot to get the full movement.
A servo tester or RC receiver never moves a servo the full 180 deg at least the ones I have used wont give you full movement.
Test it with your EZ-B to see the limit it will move. If it stutters at one end of travel the pot could have a bad spot.
So far all of my 1501MG servos have tested good.
Anyone test how strong these are with 7.4 v?
They have passed every test I have given them and if you release your servos, they hold their position without overheating the V3 or the V4.
#14  
Well, I'd like to bring this to a close and tell you how it all ended up;

I ended up buying two more of these Power HD 1501MG and I'm glad I did. The first one I posted about here did have a bad pot. After replacement of the pot the servo didn't have the shutter anymore but the pot I used couldn't be re-installed into the servo where I needed it. Relocating it on the joint is not an option. So I decided to get two more of these because I really liked the torque they put out, they fit where I need them and they are smooth.

The position hold feature when the servo is released may or may not be a good thing for me. I haven't worked that through yet but it doesn't seem to heat up when sitting and released. I also haven't placed an amp meter on it to see what the draw is when as it sits idle. The spec sheet says it draws 5ma when stopped and idle. Another worry I have with this feature is longevity. Will the servo sitting and released but holding position shorten it's life span? I wont know this till time wears on.

My last concern with the 1501MG is quality. As I said above I bought two more of these. The cost was $16 USD on Amazon or $20 from Pololu. I ought from Amazon. Not a lot for such a strong and smooth servo. However the first one had the bad pot (Reviews have stated that others have had this same problem). Then the second 1501MG I installed froze up after just a few swings back and forth with hardly any load on it. When I took it apart I got the motor to work again but only in one direction. Then the board flamed out after a few seconds of running. However, now I have the third 1501MG installed and it seems to be holding up with no problems. Not sure why I had to go through two servos before I found a good one. I did buy from Amazon and suspect they were returns that were reshipped to me. This has happened to me several times when buying from amazon. Perhaps if I buy directly from Pololu I would get newer and vetted Power HD 1501's with no problems.

Anyway, I'm going to stick with this servo for the time being as it does exactly what I want. At 6 V: 0.14 sec/60°, 240 oz-in (17 kg-cm), 60 g it's a monster.

@Mcsdaver, The spec sheet says it is only rated to to 6 vdc. I guess you could run it at 7.4 v but given my concerns of quality I'd be afraid to push it up to that voltage. The extra voltage may not hurt it but the extra torque may put too much stress on the circuit board. However you never know till you try and go too far. ;) Here's a link to this spec sheet:

Power HD HD-1501MG Datasheet

If your looking for a way to to drop the voltage from 7.4 down to 6 or lower I found a great little Bec 10A 6S Switching Regulator by Castle Creations. It's super small (only about 1 inch x 1/2 inch), programmable output voltage (With an extra unit you have to buy), runs cool and will handle up to 10 amps draw. Here's the specs:

Code:


*1.2" (30mm) x .6" (15mm) x .4" (10mm) , Weight: .4oz (11g)
*Input voltage: 5V to 25.2V (2S to 6S LiPo)
*Current output: 12 volts input = 7 amps continuous, 10 amp peak
*Current output: 24 volts input = 5 amps* continuous, 7 amp peak
*Selectable Output: 4.8 - 9.0V via the Castle Link (sold separately), Default voltage is 5.1V


www.amazon.com/gp/product/B000MXAR12/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1

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