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Mystery Box in Engine Room

Discussion in 'Ocean Yacht' started by jlresq, Nov 5, 2019.

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  1. jlresq

    jlresq New Member

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    I have a 14” X 18” closed electrical box wall mounted next to my battery charger in my ER on my 56 SS. It has three switches on the outside labeled hi/low, on/off and hi/low respectively. I opened the box and found two transformers and a few relays. It has one 110v lead going in and two 12v leads coming out. Any idea what this box is for?
  2. Capt J

    Capt J Senior Member

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    Sounds like a battery charger or an AC to DC converter. A picture would help.
  3. jlresq

    jlresq New Member

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    Working on the picture but if so, why would t have three switches on it —- hi/lo, on/off, and hi/low.
  4. Capt J

    Capt J Senior Member

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    One Hi/Lo for each 12 volt lead, and on/off for the machine itself.
  5. captholli

    captholli Senior Member

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    Please take a pic of the inside wiring arraignment and the outside face plate to make this easier .
  6. jlresq

    jlresq New Member

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    Will do this weekend.
  7. jlresq

    jlresq New Member

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    Here Is a photo (I hope) showing the AC line from the bottom and two DC lines from the top. The three toggle switches are not pictured but are on the left side of the box. Hope this helps.

    Attached Files:

  8. 45SS

    45SS New Member

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    Any chance they run engine room fans?
  9. jlresq

    jlresq New Member

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    No fans in the ER. Blowers are 12V.
  10. Tashmoo

    Tashmoo New Member

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    block heaters
  11. Capt Ralph

    Capt Ralph Senior Member

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    That is a 120Vac to 12 or 24Vac step down box.
    AC step down transformers. The relays may be for bypass or for bright / dim for the lights.
    It converts 120Vac (dockside electricity) down to a voltage (12 or 24 (32?)ACv) for interior lights.
    You may think you interior lights are DCv from the battery, but the same bulbs can run from ACv.

    Until it sells (probably never) one like it is on e-bay.
    https://www.ebay.com/itm/STAHLIN-12...972370?hash=item46a13f0452:g:jMUAAOSwZ15dqLgi
    I think this ad proposes power for electric fishing reels. Not sure a DCv motors can run on ACv. So bunk on the title of the ad.

    But, low voltage Light bulbs can run on ac or dc volts..
    Does all of your low voltage lights work off the dock, with no gen-set or inverter running?

    I had a similar system on my 34 (glass) Pequod many years ago.

    jlresq, Where is your ship hiding. If close, I can show you all about these things.

    ,Ralph
    Last edited: Nov 8, 2019
  12. jlresq

    jlresq New Member

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    She is docked in Huntington, NY and thanks for the explanation. What are the hi/lo switches for?
  13. captholli

    captholli Senior Member

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    Look under your cockpit covering boards port and starb for 12 volt electric reel outlets or for an outlet for a gin pole with a 12v winch .
  14. Trak

    Trak Member

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    .

    This is actually a AC to DC step down box. See those little square things with yellow red and black wires going to them? Those are full wave bridge rectifiers. They convert the low voltage AC from the transformer to DC. It is an unregulated chopped DC but it would work fine for lighting or electric reels.
  15. Carver440

    Carver440 New Member

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    It is for Electric Downriggers or reels. Had one on my Pursuit. You should find outlets somewhere near the stern, they may look like regular electric outlets, but they are there for the power fishing equipment.
  16. jlresq

    jlresq New Member

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    If that is the case, I can just turn the box off since I never use those. So now the question comes down to whether it is for lighting or reels.
  17. Capt Ralph

    Capt Ralph Senior Member

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    Trak Has good eyes. I did not see the diode packs. So it does out put a noisy DCv.
    Still could be uses for lights but electric fishing reels seems a better use now.

    I'm guessing the hi - low switches are for different voltage power reels (or down riggers).
    To know for sure, pull out a volt meter and check it all out.

    Think we all are learning something here.
    Last edited: Nov 9, 2019
  18. jlresq

    jlresq New Member

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    Sounds good.
  19. Capt J

    Capt J Senior Member

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    Follow the DC wires.
  20. jlresq

    jlresq New Member

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    Looks like electric reel outlets is the winner. Thanks to all.

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