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-   -   New to the R/C world - Need motor help!! (http://www.rcuniverse.com/forum/rc-boats-general-discussion-77/8286268-new-r-c-world-need-motor-help.html)

joe32725 12-27-2008 12:33 AM

New to the R/C world - Need motor help!!
 
Hey guys,

I just got a Water Open PX-16 electric r/c boat ( http://www.wowzzers.com/product_info...roducts_id=135 ) for Christmas from my girlfriends parent's but after about 5 minutes of use, one of the electric motors have stopped working. I opened the top to see what was going on, and there is definitley no movement of the motor or propeller shaft on the one side. When I turn the remote wheel back and forth though, I can here a clicking noise coming from what sounds like a relay inside of the speed control box. Is there anyway diagnose and/or test an electric r/c motor? I am new obvoiusly, and I would like to fix this thing so I can have fun with it again! Any help or pointers would be great. Thanks.

Joe

pompebled 12-27-2008 06:12 AM

RE: New to the R/C world - Need motor help!!
 
Hi Joe,

Welcome to the wonderful world of boating!

When you say "there is definitly no movement of the motor or propeller shaft on the one side", do you mean the motor doesn't spin when you use the throttle on the transmitter, or doesn't the motor/propshaft want to turn when you try to turn it by hand due to binding?

If the motor/propshaft can be turned by hand; there can be a defective relay in the black box, or the motor has died on you (unlikely after just 5 minutes, but possible)

The speed control box is just a bunch of relays, switching the motors on and off, you could check with a Volt meter if there's power going to the motor that won't turn, if that's the case, a relay, or the electronics that make it work is defective.

Normally those boats come with a warranty, I'd make use of it. Although the boat is just a toy, it should work longer than 5 minutes...

Regards, Jan.

mfr02 12-27-2008 08:15 AM

RE: New to the R/C world - Need motor help!!
 
Just using a combination of logic and guesswork, if the control is a relay for forward and another for reverse for each motor, then forward or reverse should still work provided the motor and its wiring are OK (this includes the wiring supplying power to the relay contacts).
Does the boat have separate batteries for power and radio? The relay could be powered off the RX battery, but be switching a failed supply from the power battery or to the motor. If the prop/motor can be turned by hand, this eliminates the motor being seized. If it suddenly comes back to life after a manual turn, the comm has cooked itself and has a burnt bit that gets hopped over when the motor is spinning.
The clicking indicates something moving in the relay - if this results in full movement of the contacts is another story. With the power off, checking the motors with a resistance meter will show if there is a circuit there or not, but if there is a warranty, let the shop do the worrying.
I have known motor brush gear fail after a very short time, same with relay contacts, same with wonky wiring connections.

joe32725 12-28-2008 01:35 AM

RE: New to the R/C world - Need motor help!!
 
Thank you for your replies! I'll try to clarify things a bit and let you know what I have checked....

- The bad motor does spin when you turn the prop by hand, so it is not siezed.
- The resistance across the good motor is 0.4 ohm
- The resistance across the "bad' motor is also 0.4 ohm
- The voltage across the good motor when remote trigger is pressed is right about 7.2 volts
- The voltage across the "bad" motor when remote trigger is pressed is 0 volts
- Voltage across good motor when remote steering wheel is turned to the left is 7.2 volts
- Voltage across "bad" motor when remote steering wheel is turned to the right is 0 volts

I opened the speed control box to take a look at the board, but didn't remove the board because all of the input wires are sealed with silicone and I didn't want to take a chance of voiding any possibile warranty!

When the steering wheel is turned to the right there is a definite " clicking" coming from one of the two relays on the board.

There obviously seems to be a problem getting power to the bad motor since there is no voltage across it, right? But, wouldn't a measurable resistance eliminate the possibility of an open in the circuit? If I remember correctly, an open is equivilant to infinite resistance....

Other than that, I guess I'll have to see if what you guys think, and just have to wait while someone checks on the warranty info.

I also have another quick question for the tech guys lol:

What is the reason for the small capacitors that are soldered onto the electric motors? I noticed there is three on each motor, and I think other electric motors that I have seen also have the capacitors. Hopefully I don't sound stupid because I'm pretty sure they are capacitors lol. Two of them are brown circles with "104" on them, and the other is a familiar cylindrical cap.

That's it!!

LtDoc 12-28-2008 03:39 AM

RE: New to the R/C world - Need motor help!!
 
joe32725,
From the sound of it, the ESC is the problem, not the motor. (ESC = Electronic Speed Control) Since there doesn't appear to be a rudder, that ESC also contols direction by varying the speed of each motor. That complicates things if you don't know exactly what you're doing, but since those thingys are not typically "user repairable", I hope your warranty is good.
Those capacitors across the terminals of a motor are for 'dumping' AC components of the power fed to the motor to ground, getting rid of what's normally interference. They are almost always required for interference free operation. Adding them to a motor will VERY seldom ever hurt anything, and is just a generally good idea.
Some people are born knowing all of this stuff. The rest of us have to learn it. If we all haven't asked a 'dumb' question about parts of this hobby, it's only because someone beat us to it! So, don't worry about it. If someone laughs about a particular question, it's usually because they've asked the same @#$ thing at some point, or wish they had! To them/us, it is funny! It means we weren't the only one making the same mistake. (Except me, of course, I neber make mistakes.)
- 'Doc

pompebled 12-28-2008 05:59 AM

RE: New to the R/C world - Need motor help!!
 
Hi Joe,

Judging from your observations and measurements, either one or more relays are defective, or more likely, the electronics feeding the signal to them is defective.

Like Doc already mentioned, this isn't something you can easily repair yourself without having the schematics and the equipment at hand to check out the entire layout.
I'd go for warranty.

Another way would be to remove all stock electronics, leaving you with a bare hull with only the motors and propshafts and rebuild the boat with hobby grade equipment.
You'll need a two channel radio set, a servo, a receiver, an ESC (or two if you want to keep the tanksteering..., nah) and a seperate rudder.

Depending on what you purchase, this may set you back more than the entire boat has costed in the first place, but hey, that's hobby...

Regards, Jan.

mfr02 12-28-2008 06:26 AM

RE: New to the R/C world - Need motor help!!
 
It begins to sound like either a wonky bit of wiring in the supply to the non-working motor, or a relay contact not making it all the way to where it should be going. As there is neither forward nor reverse, I would guess at the wiring, but it could still be a dry joint in the relay contact wiring on the back of the PCB. As these things are usually designed for one-time assembly, without much regard for servicing, I would go for the warranty, should there be one.
Replacing things with hobby grade I would consider either two ESCs and a mixer, or one stronger ESC and a rudder.
Somebody once described boats as a money shaped hole in the water.

joe32725 12-29-2008 01:09 AM

RE: New to the R/C world - Need motor help!!
 
I appreciate the help guys. Sometime tommorrow afternoon I'm going to call the company about the warranty issue!


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