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Old Aug 03, 2012, 05:36 PM
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Dr.M's Avatar
United States, WA, Issaquah
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Careful!
WARNING to all users of Solar Servo D654

The motor inside these servos is not supported by the backplate. Under the vibrational environment characteristic of a heli, it can slide down into the case and lose grip on the servo gears allowing the output shaft to rotate freely.

How I found out: following a crash of my 450, I did a few bench tests to figure out what happened. With some shaking and proding the servos while running the motor at full RPM (blades off ) I noticed inconsistent behavior from the elevator servo. What happened was that the motor inside the elevator servo case slid a few mm lower (away from the output shaft) allowing its small pinion to only make partial and intermittent contact with the first gear of the servo transmission. Under high load, the pinion would loose grip on the gear and allow the servo output shaft to rotate freely, though in static tests the servo would act and feel normal.

Solution: Open up the servo casing and add enough foam to push the motor body against the backplate. Not too much, as the servo case won't close properly, but enough to create some pressure in there.

Edit:
Another issue related to gears disengaging has been reported. It was caused by the pinion on the motor shaft being installed too low for a positive contact with the first gear. See this post here: http://www.rcgroups.com/forums/showp...postcount=5482

Edit:
Maiden flight report for Solar D770 added:
http://www.rcgroups.com/forums/showp...4&postcount=61
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Last edited by Dr.M; Nov 09, 2012 at 01:20 AM. Reason: added another solution
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Old Aug 04, 2012, 01:50 AM
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Could shoe goop work too?
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Old Aug 04, 2012, 02:34 AM
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Yeah, but it would be hard to remove if you ever wanted to and would add significantly more weight. I like to keep my helis as light as possible.
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Old Aug 07, 2012, 03:02 AM
mixfisto
Joined Feb 2012
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Dr M,

I'm planning on getting 3 of these for my Blade 300x. Does Solar also make a decent tail servo?
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Old Aug 07, 2012, 12:17 PM
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Originally Posted by mixfisto View Post
Dr M,

I'm planning on getting 3 of these for my Blade 300x. Does Solar also make a decent tail servo?
Solar doesn't have any servo with specs good enough for tail duty. Many people like the Fitec 9357 (ebay) though it may be a bit too big for a Blade 300.
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Old Aug 08, 2012, 04:19 PM
mixfisto
Joined Feb 2012
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Thanks.

That Fitech looks pretty good. Just wish it had metal gears.

It seems the stock tail servo has a bit of extra room, probably allowing a bigger-than-stock servo to fit.
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Old Aug 09, 2012, 10:07 AM
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Savannah, Ga, USA
Joined Feb 2009
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I can confirm what OP says. Just received qty 6 of the Solar D654, and right out of the box, 2 of the 6 the servo motor is running but gears not turning. Opened up the case and pushed the motor up into case aprox 1 mm and servo/gears started working.

There is a piece of foam under the rear cover, but was over the circuit board rather than the end of motor. I have relocated foam to hopefully be pushing on the motor with end cover replaced. Fingers crossed.

I was hoping these Solar would be more reliable than the EXI servos I used in the past. Had a batch of those with the jitters at mid-stick so quit using EXI. Still looking for a reliable under-$10 servo.
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Old Aug 13, 2012, 11:49 PM
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I just want to add that I also had this happen on two out of four servos. One of them is actually completely shot even after pushing the motor up. It spins all the way right or left without stopping until reaching the end or back to center. I also had the rx on with the rudder and elevator connected and there were a couple times in five minutes when the rudder spazzed out for a second (as if I had bumped the tx). I don't think I want to fly with these servos at all, I just don't trust them This was going to be used on a 3dhs 41 edge...
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Old Aug 14, 2012, 12:06 AM
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Quote:
Originally Posted by bcamphaus View Post
I just want to add that I also had this happen on two out of four servos. One of them is actually completely shot even after pushing the motor up. It spins all the way right or left without stopping until reaching the end or back to center. I also had the rx on with the rudder and elevator connected and there were a couple times in five minutes when the rudder spazzed out for a second (as if I had bumped the tx). I don't think I want to fly with these servos at all, I just don't trust them This was going to be used on a 3dhs 41 edge...
China Crap for sure!
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Old Aug 14, 2012, 03:21 AM
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Quote:
Originally Posted by bcamphaus View Post
I just want to add that I also had this happen on two out of four servos. One of them is actually completely shot even after pushing the motor up. It spins all the way right or left without stopping until reaching the end or back to center. I also had the rx on with the rudder and elevator connected and there were a couple times in five minutes when the rudder spazzed out for a second (as if I had bumped the tx). I don't think I want to fly with these servos at all, I just don't trust them This was going to be used on a 3dhs 41 edge...
I'm guessing your motor slipped just enough to strip the pinion and/or the first gear. Anyways, they seem to be hit or miss...

I got a D770 to test as a potential HV option.
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Old Aug 14, 2012, 10:49 PM
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Joined Jun 2005
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I'm very interested to see what you find. I was asking around about the D771 for my 550 FBL, but nobody seems to want to be the guinea pig. I was hoping to hear some field reports. $22 for a fast, strong, HV servo, but if it's not reliable, it's not worth $2. Especially when going into 550-700 class helis.

Mike
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Old Aug 14, 2012, 10:55 PM
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So, an update to my solar servo issues... The one I referred to that was turning until it hit the end point, or the center, and nothing in between had a loose wire on the feedback pot. I re-soldered that and then it was properly responding to the tx. The other problem with the slipping gear was actually the result of the motor gear being pressed on too low. When the servo was mounted in the aileron (upside down), the second gear would slide up just enough to miss the motor gear. It was not from the motor sliding down as I originally thought. I pressed the gear up the shaft and now everything works perfectly. Not sure what caused the flutter I referred to earlier, it has not happened again so I'm gaining more confidence in them. I will be taking every last one of them apart to inspect them though...
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Old Aug 15, 2012, 12:52 AM
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The D770 is gonna be opened up and inspected, sent thru some pretty tough bench tests, then, if all goes well, it will be installed on my Pantera 6 tail (600mm main blades).
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Old Aug 16, 2012, 05:06 AM
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why is this solar servos attractive? are they selling them cheap? or too cheap? its kinda hard to rely on cheap servos that once it fails will cost more $$$$ on crash parts
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Old Aug 16, 2012, 11:52 AM
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I was wondering the same thing soneebee,It seems to me better servos (and true allso more expencive) would save on heli repairs. Being able to fly with peace of mind has to be worth something.
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