Defective Micro Servo

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GallopingGhostOfTheJavaCoast
 
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Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

Hello Adafruit Support,

I purchased some things from you on July 7th (I have the order number if you need it) to build a model rocket with my friends. I purchased two micro servos in this order (PID 169), and both worked fine when I very briefly tested them before installing them in my rocket. I had to wait a few weeks for some other parts to come in from other manufacturers, and I was able to launch today. However, before launching, I discovered one of the servos was not working and had shorted out my microcontroller, an Adafruit ItsyBitsy 32u4 - 5V 16MHz (PID: 3677). After cancelling the launch and analyzing what was happening, I discovered my brand new servo was sized. It would not move freely (when I tried to move it with my hand with the power off) unlike the other one, causing it to not function at all. Note, I did have both servos connected to a power supply and not the microcontroller’s pins. Because of this, I’d like to have some kind of replacement for the servo (everything else in the order worked wonderfully, thank you guys).

Thank you for any help you can provide,
Jaden

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Franklin97355
 
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Re: Defective Micro Servo

Post by Franklin97355 »

Can you try to take it apart and see just what is wrong with it? Our warranty is only 30 days and it seemed to work when you first got it. You can post a close-up picture of the bottom if you would. Thanks.

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

Thanks, but I’ll wait on official Adafruit support for this one before I do anything drastic.

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argonblue
 
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Re: Defective Micro Servo

Post by argonblue »

GallopingGhostOfTheJavaCoast wrote: Sun Sep 04, 2022 2:33 pm It would not move freely (when I tried to move it with my hand with the power off) unlike the other one, causing it to not function at all. Note, I did have both servos connected to a power supply and not the microcontroller’s pins.
It might be helpful if you could provide some clarifications? First you say that you tried to move it by hand with the power off, and then that both were connected to a power supply. When you tried to move it by hand, was it fully disconnected from all power sources (and control inputs) or not?

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

Thanks for the response and yes, it was fully disconnected when I tried to move it by hand. When I said they were connected to a power supply, I meant that at the time of the incident they were connected to something other than the microcontroller. I just wanted to immediately dispel the obligatory “You’re taking too much current from the microcontroller” response. Thanks for any ideas you can provide.

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adafruit_support_mike
 
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Re: Defective Micro Servo

Post by adafruit_support_mike »

GallopingGhostOfTheJavaCoast wrote: Sun Sep 04, 2022 4:56 pm Thanks, but I’ll wait on official Adafruit support for this one before I do anything drastic.
Franklin and I are both official Adafruit support. Taking the servo apart on our advice means we pay for the consequences, not you.

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

Alright, I see. He didn’t have the support tag on him, so I wasn’t sure about his advice. How should I take apart the servo and what should I be looking for when I do it? Also, thanks for responding on a holiday.

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adafruit_support_mike
 
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Re: Defective Micro Servo

Post by adafruit_support_mike »

The servos have four screws on the bottom that hold the motor and control board in plate.

It's unusual for a servo to seize, so look for anything that's holding the rotor in place.

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

adafruit_support_mike wrote: Tue Sep 06, 2022 8:38 pm The servos have four screws on the bottom that hold the motor and control board
Wow I can’t believe I actually asked that question, I guess that’s what you get when you ask something late at night. Anyways, I finally got around to opening up the servo and found that one of the gears (circled in the image) was is apparently no longer on our plane of existence.
Attachments
Top view.
Top view.
9823D62C-6DBA-4BA7-AF93-DBD0057AB88B.jpeg (730.27 KiB) Viewed 101 times
A more clear side view.
A more clear side view.
094A7C51-D6A6-47BD-8929-B162543F1B15.jpeg (569.64 KiB) Viewed 101 times

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adafruit_support_mike
 
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Re: Defective Micro Servo

Post by adafruit_support_mike »

Wow.. is that mess in the down view melted plastic or a blob of grease?

Also, given the apparently missing pinion in the gear train, does the last/top gear spin freely on the shaft?

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

It’s grease. The gear broke but didn’t melt. It kind of spins freely. The bits of destroyed gear block it, but it would otherwise spin freely. The other gears seem alright.

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adafruit_support_mike
 
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Re: Defective Micro Servo

Post by adafruit_support_mike »

Okay, it's obvious why the servo was frozen. That opens the questions of how the servo worked during the first test though, and what made the broken gear disintegrate. At minimum, something happened after the device arrived.

Since your first post was a month past our 30-day return/replace period, I can't authorize a full replacement. I can offer shop credit for the cost of the servo on the chance that the gear was broken before shipping and just came apart during the original test.

Send a note containing a link to this page and your order number to [email protected]. The folks there will handle the shop credit.

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GallopingGhostOfTheJavaCoast
 
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Re: Defective Micro Servo

Post by GallopingGhostOfTheJavaCoast »

Alright, I’ll do that. Thanks for working with me through this. Have a great evening.

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