Model Boat Mayhem - Forum

Please login or register.

Login with username, password and session length.
Pages: [1]   Go Down

Author Topic: RTR Conversion  (Read 536 times)

lilgoth

  • Heavy Metal pirate
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 51
  • Location: Lichfield - South Staffs
RTR Conversion
« on: April 17, 2018, 11:58:11 PM »

during my time in hospital i was notified that one of my RTR's had suffered some controller damage
i figured because it ran well ( albeit with limited range ) i would try to replace it. The controller is a total write off and the only other controller i have lying around is a '40mhz'  while the RTR ran on 27, i pulled the boat apart to see if i could find the crystal, but the control board appears to be lacking a crystal ( not even a flat one from what i can tell ) im hoping to save money by not having to replace all the electronics onboard and simply getting a new radio, especially considering if i replace the electronics i will need a new way to steer as the boat seems to have a generic motor to steer, rather than a servo so the question i have is would a 27mhz crystal work in the 40mhz controller so i can keep the boat on its original frequency of 27.145 or would i have to get a 27mhz controller for this ?


This is the control board, out puts are 3 for the motor ( so i assume brushless ) 2 to steering motor 2 to a wetness sensor so she can only run in the water, then power in and the Antenna
so i would likely need a ESC, a BEC, and some new mechanism for steering

Edit, Fixed
Logged
The Cake Is A Lie

The Cake Is A Lie

The Cake Is A Lie

BrianB6

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 681
  • I'm not sure if I can get up from here
  • Location: Melbourne
Re: RTR Conversion
« Reply #1 on: April 18, 2018, 07:47:35 AM »

Unfortunately the whole reason for specific frequencies is so that they do not affect others.
a receiver on 27.145 meg. will only work with a matching transmitter.   The crystals are there to ensure they match but if you can find them in both receiver and trannie they can be changed if you have spare 27 meg. ones.
You cannot put a 27 meg. crystal in a 40 meg as the circuit would not be set up for it
Logged

jarvo

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 683
  • Etherow model boat club
  • Location: Bredbury Stockport Cheshire
Re: RTR Conversion
« Reply #2 on: April 18, 2018, 07:55:45 AM »

Hi Lilgoth, first of all RTR boats radio's are crude, thats why you cant find a crystal, also why the Transmitter has stopped working. What type of boat is this? Buying another radio system is the best bet, 2.4ghz is the way to go. Removing the old receiver and soldering new connections is only a couple of hours work, following the wiring as you have you can identify the motor and the servo connections.
Chances are that on 27mhz the original system is quite 'dirty' and would be prone to interference.
A new Tx and Rx with an ESC will not cost that much, but, would give far better control and more enjoyment for your model, plus when you want a second,  it is simply a matter of swapping the parts over.
Hope this helps, post again if you want more details


Mark

Logged
Tugs are for pulling

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,147
  • Location: Blackpool, Lancs, UK
Re: RTR Conversion
« Reply #3 on: April 18, 2018, 08:43:43 AM »

Usually, a fixed frequency radio in an RTR will only work with its dedicated transmitter.  Even getting another transmitter to broadcast on the right frequency won't work since the signal coding will be different.  The crystal acts to fine tune and stabilize a coarsely tuned circuit that is close to what is wanted, there have been instances of 35MHz sets working with 40MHz crystals (not really recommended) but going to 27MHz is a step too far.
Since the receiver board in an RTR often carries the motor controls, not only would the receiver need replacing with a hobby grade one, but the ESC(s) will need replacing as well.  Since the built in motor controls are usually quite crude (cost reduction), the replacement will give a huge improvement in handling.  Actually fitting the gear in the same space might be a problem.
Logged
"Trying is the first step towards failure" - Homer (Simpson)

lilgoth

  • Heavy Metal pirate
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 51
  • Location: Lichfield - South Staffs
Re: RTR Conversion
« Reply #4 on: April 18, 2018, 06:56:51 PM »

yeah i figured i might have to replace all the electronics,

the controller looks to have had something heavy dropped on it during the collapse of a shelving unit ( i dont know ) and many of the components on the PCB are loose, including the 27mhz crystal

considering it now looks like i will have to replace the whole electronics, im in need of recommendations for a ESC, and a BEC, also im concerned i might have to figure a new steering mechanism out

looking at the steering gear, it has 2 wires going to it, removal of some of the cover panels shows that its a small generic DC motor turning a gearbox that turns the armature for the rudder, im assuming all of this will need to be replaced by a servo setup and a custom mount ?


Logged
The Cake Is A Lie

The Cake Is A Lie

The Cake Is A Lie

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,147
  • Location: Blackpool, Lancs, UK
Re: RTR Conversion
« Reply #5 on: April 19, 2018, 09:20:18 AM »

Without knowing the likely current draw of the motor, its guesswork.  But an Mtroniks marine viper 10 will probably be OK, or a Viper 15 to be on the safe side.  Both have BEC built in.  Not the cheapest on the market, but you only need to buy once.
The servo might, with a bit of luck, mount on the same fittings as the existing unit.
Logged
"Trying is the first step towards failure" - Homer (Simpson)

lilgoth

  • Heavy Metal pirate
  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 51
  • Location: Lichfield - South Staffs
Re: RTR Conversion
« Reply #6 on: April 19, 2018, 06:38:20 PM »

well i took the motor housings apart, the rudder motor is indeed a small DC motor turning a gearbox, so i might try to make or 3d print a servo mount

the Prop motor looks like a Brushed DC motor but has 3 wires, Blue, Red and a smaller black,applying voltage across Blue and red spins the motor, so im not 100% is ( maybe a ground ? )
Logged
The Cake Is A Lie

The Cake Is A Lie

The Cake Is A Lie

malcolmfrary

  • Full Mayhemer
  • *****
  • Offline Offline
  • Posts: 5,147
  • Location: Blackpool, Lancs, UK
Re: RTR Conversion
« Reply #7 on: April 19, 2018, 09:09:54 PM »

"Could" be a ground connection for the motor casing as part of whatever RFI prevention is fitted.  Applying DC and having the motor spin does indicate a DC motor. 
A thought - some "racy" type boats do not have the ability to reverse and there RFI can consist of a knobbly diode connected the "wrong" way across the motor terminals.  It just soaks up back emf's developed by the spinning motor.
Logged
"Trying is the first step towards failure" - Homer (Simpson)
Pages: [1]   Go Up