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  1. #1
    Join Date
    Sep 2013
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    5

    Default Bow Thruster Control Circuitry

    Having recently been involved in attempting to recover a water-damaged control Printed Circuit Board for a Volvo Penta QL BP600 Bow Thruster, I'm surprised at its relative complexity? (..1 integrated circuit; 6 transistors; 2 relays; numerous diodes and many other discrete components).
    I would be grateful for any expert comment on why a simple left/right joystick command to a reversible, albeit powerful, 12vdc motor needs a control circuit of this type?
    More importantly, I would be very grateful to hear from anyone who has a circuit diagram for the PCB or knows of anyone with a diagnostic/repair capability for it.
    Many thanks

  2. #2
    Join Date
    Jun 2011
    Location
    Volos-Athens
    Posts
    4,673

    Default

    sorry, just noticed this thread.

    I have a QLsomething (5KW 24V motor twin propeller thing)
    Haven't noticed a PCB, where is it, around the relays area as there's nothing on the actual joystick end!
    not helpful I know, but at least you're up at the top of the forum


    V.

  3. #3
    Join Date
    May 2001
    Location
    Jersey/Antibes
    Posts
    22,357

    Default

    It's very hard to reverse engineer a PCB without a photo but I'd guess there is a timer circuit in there so that if you are running the motor one way then quickly flip the joystick the other way it introduces a second or two of delay.

    If this is your own boat, and you're careful, and want to save money, you could dispense with the time delay functionality and just switch the motor with a pair of relays. Usual disclaimers apply!

    If you can see a shunt anywhere then parts of the board might also measure current and do something (I dunno what) with that data. Again, if you're careful and happy to take the risk, you could just jettison all that functionality

  4. #4
    Join Date
    Jan 2009
    Location
    Stratford on Avon
    Posts
    11,053

    Default

    Does the PCB introduce some degree of proportionality to the control? Ie not just an on/off, but some control to build up of motor speed? Is this strictly necessary? Not really. But can be "nice to have".

  5. #5
    Join Date
    May 2001
    Location
    Jersey/Antibes
    Posts
    22,357

    Default

    Quote Originally Posted by rafiki_ View Post
    Does the PCB introduce some degree of proportionality to the control? Ie not just an on/off, but some control to build up of motor speed? Is this strictly necessary? Not really. But can be "nice to have".
    From the components described it can't rafiki. The joystick is a switch not potentiometer, and the motor is DC but there is no heavy duty power management gear on the board, as described. Furthermore there is no logical reason to engineer this in, with a small DC thruster (unless you're going the whole variable speed hog, as Sleipner/Side Power do)

  6. #6
    Join Date
    Jan 2009
    Location
    Stratford on Avon
    Posts
    11,053

    Default

    Quote Originally Posted by jfm View Post
    From the components described it can't rafiki. The joystick is a switch not potentiometer, and the motor is DC but there is no heavy duty power management gear on the board, as described. Furthermore there is no logical reason to engineer this in, with a small DC thruster (unless you're going the whole variable speed hog, as Sleipner/Side Power do)
    Sure, it is a bit of a leap, given the list of bits on the pcb, but I'm struggling to work out why this degree of complexity without control? Can you?

  7. #7
    Join Date
    Sep 2013
    Posts
    5

    Default

    Thanks vas/jfm/rafiki for your interest: The 4" x 2" PCB is housed in a moulded black plastic top-hat - On boat in question, its parked between thruster battery and Isolator SW panel, in bilge at foot of bed in for'd cabin (..not the cleverest installation design I hear you say? not least having shower cubicle located adjacent).
    The thruster is a BP600: theres an Installation Manual for the Volvo Penta(QL) BP Series thrusters available on-line (Publ. No. 7741095-9 12-2001) with wiring diagrams should anybody be interested - unfortunately theres no circuit diagram/parts list.
    On the up side, I've made a bit of progress with the assistance of some very helpful folk at VP(QL) who have supplied a more detailed wiring diagram and a v/useful fault-finding test sheet - On the down side they say theres no cct diagram/parts list available (Interestingly jfm, the test sheet makes reference to a 2sec delay - so I quess, with two relay driver channels; a delay cct; some voltage stabilisation and probably, some interference protection, it starts to account for some of the component count - though I concur jfm, that if push comes to shove, you could get by with due care and a PCB by-pass lash-up.
    Anyway, if anyone is still interested in any of the above I'd be happy to supply photos, fault-finding test sheet, etc.
    Cheers All and thanks again

  8. #8
    Join Date
    Feb 2004
    Location
    West London/Gosport
    Posts
    5,568

    Default

    The controller introduces a 2 second delay switching between port/starboard. This is so you don't wreck the motor/gearbox by instantly switching directions.
    The controller also introduces a timer. (10 mins.) This is so you don't leave the thing on and accidentally operate it.
    Other than that it does nothing fancy. You can get rid of it completey if you wish because ultimately it is just connects 3 wires at the thruster end. A common in the middle that is connected to one of the other two wires. Which one depends upon port/starboard. The other wiring is just to power up the controller board.
    We don't have a controller. Just two foot switches. One mounted either side of the Binnacle.
    Attachment 35380
    Last edited by Talulah; 19-09-13 at 06:19.

  9. #9
    Join Date
    Sep 2013
    Posts
    5

    Default Bow Thruster Control Circuitry (cont'd)

    Quote Originally Posted by Talulah View Post
    The controller introduces a 2 second delay switching between port/starboard. This is so you don't wreck the motor/gearbox by instantly switching directions.
    The controller also introduces a timer. (10 mins.) This is so you don't leave the thing on and accidentally operate it.
    Other than that it does nothing fancy. You can get rid of it completey if you wish because ultimately it is just connects 3 wires at the thruster end. A common in the middle that is connected to one of the other two wires. Which one depends upon port/starboard. The other wiring is just to power up the controller board.
    We don't have a controller. Just two foot switches. One mounted either side of the Binnacle.
    Attachment 35380
    Thanks for that Talulah - tres interesting/informative.

  10. #10
    Join Date
    Jun 2005
    Location
    Fleet, Hampshire
    Posts
    2

    Default

    Hi, I also have a 5KW QL bowthruster that had suffered from water damage (mine is 24v). I managed to get the motor reconditioned but I still have the control box and relays etc to sort out. What I can't understand is why can't I plug in any 24v controller but they don't seem to be readily available on line.

    What did you do about yours in the end? I'd be grateful if you could email me the documents you manage to track down, when I searched for that reference the only result was your post!

    All help, advice or just info on experiences would be much appreciated.

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