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Thread: Pinta auto helm

  1. #1
    Join Date
    Feb 2004
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    7

    Default Pinta auto helm

    My 1965 Van Lent is fitted with its original Pinta self steering system. This worked tolerably until a couple of years ago when it became very erratic and unusable. Kind members have e mailed me copies of their manuals but my compass unit (original) appears to work differently to those described. Ideally I should like to get the system working again, if this is not possible is there any way of interfacing a modern GPS unit with the existing helm servo motor which still functions correctly. Just to complicate matters I am based in Southern England and the boat is kept near Rome! Any help appreciated! Kilmaine

  2. #2
    Join Date
    Jan 2011
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    2,593

    Default Re: Pinta auto helm

    Quote Originally Posted by KILMAINE View Post
    My 1965 Van Lent is fitted with its original Pinta self steering system. This worked tolerably until a couple of years ago when it became very erratic and unusable. Kind members have e mailed me copies of their manuals but my compass unit (original) appears to work differently to those described. Ideally I should like to get the system working again, if this is not possible is there any way of interfacing a modern GPS unit with the existing helm servo motor which still functions correctly. Just to complicate matters I am based in Southern England and the boat is kept near Rome! Any help appreciated! Kilmaine
    I had a Pinta from 1972 on the previous boat which was sold 5 years ago. Brilliant piece of kit for its era and up until then it worked, as you say, tolerably well but with a disconcerting habit of throwing 90deg turns at will. I think you have to accept that it is in late stage dementia where it will sometimes be coherent, sometimes work intermittently but always with the risk of total incapacity and the inability to communicate with anything beyond its scope of understanding. I kept mine going with smoke and mirrors but don't think I could anymore.

  3. #3
    Join Date
    May 2007
    Location
    Cambridge, UK
    Posts
    5,692

    Default Re: Pinta auto helm

    Given it's age, it is very likely that the electronics includes germanium transistors. Unfortunately, these have a limited lifetime and are no longer made, so if they've gone west, the equipment is unrepairable (the electrical characteristics of silicon transistors are too different). If they haven't gone west, they probably will! I did have a search online and found this: http://www.barbaryketch.co.uk/wp-con...0Manual001.pdf, which includes circuit diagrams of the electronics, but which doesn't identify the transistors!

    Note that the circuits are very simple; in those days, transistors cost an arm and a leg, and there was no such thing as integrated circuits. So the control loops will be very simple, compared with even the cheapest of modern autopilots. Futher, the compass uses a swinging card with a photoelectric sensor - again, compared with modern fluxgate devices, it will have poor accuracy and responsiveness.

  4. #4
    Join Date
    Jan 2008
    Posts
    375

    Default Re: Pinta auto helm

    Quote Originally Posted by AntarcticPilot View Post
    Given it's age, it is very likely that the electronics includes germanium transistors. Unfortunately, these have a limited lifetime and are no longer made, so if they've gone west, the equipment is unrepairable (the electrical characteristics of silicon transistors are too different). If they haven't gone west, they probably will!
    I have one of these too, that's working, so am interested in this topic, also have hard copy manuals.

    There appears to be germanium transistors available here: https://www.mouser.co.uk

    How are they 'limited lifespan', usage based or time based?

    OP: How is the operation erratic? And can you expand on "my compass unit (original) appears to work differently to those described".

  5. #5
    Join Date
    May 2007
    Location
    Cambridge, UK
    Posts
    5,692

    Default Re: Pinta auto helm

    Quote Originally Posted by mersey View Post
    I have one of these too, that's working, so am interested in this topic, also have hard copy manuals.

    There appears to be germanium transistors available here: https://www.mouser.co.uk

    How are they 'limited lifespan', usage based or time based?

    OP: How is the operation erratic? And can you expand on "my compass unit (original) appears to work differently to those described".
    I don't know the exact mechanism, I'm afraid. I think it may be length of operation, but I only know of it because a piece of equipment I used in the 1980s depended on them, and our electronics guru had to replace transistors fairly frequently to keep it working.

    I looked at the site, and it doesn't appear to have the ancestral type of germanium transistor - they are silicon-germanium.
    Last edited by AntarcticPilot; 09-11-18 at 23:43.

  6. #6
    Join Date
    Feb 2004
    Posts
    7

    Default Re: Pinta auto helm

    Thanks for your interest! A few years ago in calm seas the unit would steer a reasonable course. However since being based in Rome we noticed that although she would normally work OK going South to the Pontine Islands she was hopeless when we headed back North. This season it wouldn’t hold a course in either direction.
    The manuals refer to the compass unit having a floating card and light bulbs to sense the direction. I have taken the cover of my compass and there is no sign of liquid, a card or lights, just a gimbled horizontal bar. I will try to attach photos of this to see if anyone recognises it!

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