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Bertram 50 SF electrical problem.

Discussion in 'Bertram Yacht' started by sot, Jun 28, 2014.

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  1. sot, Jun 28, 2014
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    sot

    sot New Member

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    Need a little help. I have an 88 Bertram 50 SF with the old 32v system. Temp gauge in the console on the bridge didn’t work. Found this wire, apparently from the temp sender to the gauge broken. The wire appears to have a capacitor, resistor, don’t know what it’s called. This piece connects directly into the gauge on the one end and into the wire from the sender on the other. The questions are; what is it called, what does it do, why does it do it, and where can I get a new one. Also noted the same wire for the other engine gauge gets very hot to the touch when the switch prior to start is turned on. Any help would be greatly appreciated, Thanks, Rex

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  2. baltimore bob, Jun 28, 2014
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    baltimore bob

    baltimore bob Member

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    It is probably a resistor used to compensate for the higher voltage system. It should have color bands on it to show it's value in ohms. If you can determine the value, it's a Radio Shack part.
  3. Capt Ralph, Jun 28, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    Sad part, when they fry, the colored bands are lost. Look for a similar resistor on an other unit. I am feared somebody installed 12Vdc equipment and tried to knock your 32Vdc to 12Vdc. For monitor lights good, For variable current devices (gauges) not good.
    Keep us up on what you find.
  4. sot, Jun 28, 2014
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    sot

    sot New Member

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    Each gauge, main engine oil pressure, water temp as well as oil pressure and temp for the transmission have these things on them. The positive and negative wires go straight to the gauge. I stated earlier that this wire was from the sending unit when in fact it could be for the light bulb in the gauge. Will have to go back tomorrow and take another look at it.
  5. Capt J, Jun 28, 2014
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    Capt J

    Capt J Senior Member

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    It's a resister......Lauderdale speedometer sells them among many other people. They don't make 32 volt gauges and haven't for a while so you have to use the resister to drop the voltage down.......it's probably a standard vdo part.....meaning you don't have to look too hard at the others......see what the voltage is on one of the gauge stickers.....and you need one that either drops it to 24v or 12v, most likely 12
  6. sot, Jun 28, 2014
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    sot

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    I believe these gauges are original. I don’t think the stickers are still there but will look tomorrow. Just wondering, if the gauges needed 12v, why not power them from the 12v bank?
  7. Capt J, Jun 28, 2014
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    Capt J

    Capt J Senior Member

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    Because they're powered by the engine bank. So if you lose everything but the engines you still have gauges for the engines.....just measure the voltage at one of the gauges.....I think Bertram used 12 volt vdo gauges in that era with the resisters......there weren't a whole lot of 32 volt gauge choices in the late 80's.
  8. sot, Jun 28, 2014
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    sot

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    I’ll check tomorrow, thanks to all that have responded.
  9. Capt Ralph, Jun 28, 2014
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    Capt Ralph

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    If they are original gauges, and the plus & minus are intact. Is is for the backlight and monitor lights, Like my 32Vdc Bertram, not the senders.

    If you look at an intact resistor, you will find 3 or 4 ( to 6) bands around it with different colors. These bands will start closer to one end than the other end. Where the bands are closer to the end, record the colors.
    The size of the resistor makes the wattage value or amount of current they can absorb. Other than age, under wattage may have lead to their demise.

    Attached is a color chart I found. take your notes to Radio shack or an electronic supplier for your replacements.

    I can not find my notes, but if needed, I'll crawl under my dash and find some values for you.

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  10. sot, Jun 28, 2014
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    sot

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    I'll take a look tomorrow and report back. Thanks, Rex
  11. Capt Ralph, Jun 28, 2014
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    Capt Ralph

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    One last note; there is no standard resistor. Depending if the lamp is 12 or 24Vdc and how bright the lamp needed to be, the values can change a bit.

    ,rc
  12. sot, Jun 29, 2014
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    sot

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    Good morning Ralph,

    Just got back from the boat and here is how it stands as far as I can tell. The gauges are original VDOs as Capt J stated and they are twelve volts.
    The wire that supplies the current is the wire with the resistor. There are 34v going to the resister and then 14v going to the gauge. I could not tell of any markings on the resistors in as much as they have pretty much been fried yet still working. So as the Capt suggested I need to get a resistor to bring to voltage from 34v to 14v. I do not understand why are the resistors are getting so hot. They become too hot to touch after about a minuet once the master switch is turned on. By the way the light bulb in the gauges are feed by 12v.
    Again, thanks to all that responded.
    Rex
  13. Capt Ralph, Jun 29, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    12Vdc engine gauges with a resistor reduced common DC bus drawing from a 32Vdc supply. I’m not sure this is factory or how well it works.

    These in line resistors change the voltage by removing (consuming) a percentage of apparent voltage that pass thru them. This is not a regulated circuit. And burning those watts, they get hot.
    Every time a gauge is replaced, a new DC buss characteristic is made. Also every time the fuel level changes, the fuel gauge requires different current levels and the common DC bus values change again.

    To avoid a chapter on electronic theory that I would poorly be remembering from school, I would recommend a DC to DC converter to replace the resistor.
    With a regulated supply, you should observe more precise readings on your gauges.

    Where does your 12Vdc light supply come from?

    More help is available from High Tide Marine in Marathon. These kids support the old Bertram’s well. They may have a schematic or ideas to share.
  14. Capt Ralph, Jun 29, 2014
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    Capt Ralph

    Capt Ralph Senior Member

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    VDOs ? Humm..
    I thought most old Berts used SW biased equipment. You're still Detroit powered?

    Please keep us updated. There is always more to lean on da ole Bert stuff.
  15. sot, Jun 29, 2014
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    sot

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    Will call High Tide Marine tomorrow and yes, it is still and for the foreseeable future, GM powered.
  16. Capt J, Jun 29, 2014
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    Capt J

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    Call "Lauderdale Speedometer" in Fort Lauderdale,FL. They have a million gauges for marine in stock, that's about all the specialize in and they will know which resister you need from the top of their head......I have a couple of the resisters you need that I bought for a 1984 54' Bertram but didn't need, new ones, but won't be home until Wednesday. VDO makes the resisters for their gauges and Lauderdale Speedometer sells and stocks them.
  17. sot, Jun 29, 2014
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    sot

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    I'll give them a try, Thanks.
  18. Capt Ralph, Jun 29, 2014
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    Capt Ralph

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    Then My understanding is, (maybe was) Detroits, Stewart Warner, standard equipment.

    Next learning question (for me); fuel level gauges VDO also? 12Vdc? Newer sender units from Wema?
  19. Capt J, Jun 29, 2014
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    Capt J

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    No, a lot of detroits had (ac) Delco gauges, some manufacturers used SW, but I know Bertram, Viking, and Searay back in the D.D. days used VDO.
  20. sot, Jul 3, 2014
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    sot

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    Now to finish this up, contacted Lauderdale Speedometer, phone number can be found on their web site, told them of my problem and they knew what I needed. I went ahead and ordered one for each of the gauges that used them. For those that might have the same problem, their item number is 391-704, description is, KIT RESISTOR 24v. I had a question about the 24v part but they assured me this is what I needed and as you can probable see be the picture it appears that it is.
    Want to thank all the people that have helped me in solving this. Rex

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