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Thread: Fixing things is easy, once you know whats wrong!

  1. #1
    Join Date
    Aug 2007
    Location
    Reno NV
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    13,360

    Fixing things is easy, once you know whats wrong!

    So, I've got a utility trailer I let the registration lapse on. Got it registered this week and need to use it this weekend.

    Hooked it up to the truck to make sure the lights worked and everything was in good shape.

    Yep, Lights just 'barely' worked. Cleaned the connectors, no luck. Checked the bulbs, no luck.

    Finally broke out the multimeter and checked. Only getting 5 volts to the lights. Truck connector checks out good. Connect on the trailer checks out good.

    Where the heck is this thing grounded? Found a bolt on the frame with 12 volts, bolt right next to it only 5.

    Took the bolt off, used a dremel to remove some paint, hooked it back up. 12 volts everywhere.

    I wish I had started by looking for where the ground wire was connected to the trailer.

    Everything is good now and ready to roll!
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  2. #2
    Join Date
    May 2007
    Location
    Kansas City, Missouri
    Posts
    13,442
    Electriks is no fun sometimes. I need to put a new deck on my trailer, plan to re-wire it all while I've got the old deck off.
    Darren

    To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault

  3. #3
    Join Date
    Oct 2006
    Location
    ABQ NM
    Posts
    30,014
    Facing a similar (I think) conundrum with the evaporative cooler on our house. We have a pretty standard 2-speed swamp cooler with an electronic thermostat. You can set it to run the blower with or without the pump, and also choose between high or low speed on the blower. Pretty simple. For the past couple of weeks, the low speed didn't want to kick on, but it would run if we used high speed. Then last weekend, the high speed also stopped working.

    I figured the thermostat had gone bad, so I disconnected it, figuring I'd run down to Lowe's and pick up a new one. On a whim, I decided to try hooking up a jumper wire to the hot lead to see if the blower motor would run with the thermostat bypassed. (The common wire was still hooked up.) The motor didn't move with hot connected to either the low or high speed wires. (But the pump ran fine if I connected hot to the pump wire.) Aha! Not the thermostat, the motor's dead, I surmise. Pulled the motor out, and indeed it looked pretty long in the tooth. Went to the electric supply store and both a new swamp cooler motor. Hookup and installation took all of about 5 minutes.

    Before wiring the thermostat back up, I try bypassing it again, repeating the steps (and connections) I'd done to test the motor. Nothing. Bad words were said. Pump still ran fine when hooked to the hot wire, but neither the high or low speed worked on the blower motor. So now I suspect the problem lies in the wiring between the roof and the hallway where the thermostat is. I'm hoping I can figure out what's wrong (and fix it) this weekend. Thankfully, our house also has a refrigerated air unit, so we're not without air conditioning (It was about 90º here today.) Still, I'd rather run the swamp cooler to save on the electric bill.

    I'm open to suggestions from any of you electrically-minded guys who might be reading this.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

  4. #4
    Join Date
    Jul 2011
    Location
    The Gorge Area, Oregon
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    4,698
    Well, I assume you have a multimeter... if not they're pretty cheap and worth having

    Start checking continuity and voltage and drawing pretty little pictures.

    Make sure that high speed to neutral has the appropriate voltage. Ditto low speed.
    Then check both to ground which should be the same.

    Then check ground to neutral and make sure they have continuity but no (significant) potential between them.

    Unhook the two hot wires at the source.
    Check that there is no continuity between them and any of the other wires (each other, neutral, ground).

    That won't tell you where but it will tell you what... Hopefully (otherwise I'm stumped).

    You probably don't have a toner, but if you know a sparky out (more likely) a low voltage guy you can borrow one and use that to find a break if it's in the wall. Make absolute sure the mains is disconnected before connecting the toner or the magic smoke goes poof in very exciting ways.

    My bet is that a wire is either shorted or broken someplace real close to the swamp cooler. They tend to vibrate quite a bit and the moisture can be hard on things. Either that or a critter chewed a wire, which would be worst case.

  5. #5
    Quote Originally Posted by Brent Dowell View Post
    So, I've got a utility trailer I let the registration lapse on. Got it registered this week and need to use it this weekend.
    While the safety lights are a different discussion, I learned just last weekend that my state doesn't require registration/plates for trailers under 2,000 lbs. I've got a Horrible Fright 40"x48" utility trailer that I've been paying $35/3 years for tags on that I don't need to. Heck, I trail it behind a car w/ a 1000lbs tow limit.

    Your state may be different, and it's a little late this year. But you may want to check on that.

  6. #6
    Join Date
    Aug 2007
    Location
    Reno NV
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    13,360
    Quote Originally Posted by David Agnew View Post
    While the safety lights are a different discussion, I learned just last weekend that my state doesn't require registration/plates for trailers under 2,000 lbs. I've got a Horrible Fright 40"x48" utility trailer that I've been paying $35/3 years for tags on that I don't need to. Heck, I trail it behind a car w/ a 1000lbs tow limit.

    Your state may be different, and it's a little late this year. But you may want to check on that.
    This trailer is a little bigger than that, I use it to tow my bobcat, which is probably at the top end of it's limit

    But I have often wondered about those little trailers. I'll have to check on the laws here about that.
    Programmer - An organism that turns coffee into software.
    If all your friends are exactly like you, What an un-interesting life it must be.
    "A door is what a dog is perpetually on the wrong side of" Ogden Nash


  7. #7
    Join Date
    Oct 2006
    Location
    ABQ NM
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    30,014
    Quote Originally Posted by Ryan Mooney View Post
    Well, I assume you have a multimeter... if not they're pretty cheap and worth having

    Start checking continuity and voltage and drawing pretty little pictures.

    Make sure that high speed to neutral has the appropriate voltage. Ditto low speed.
    Then check both to ground which should be the same.

    Then check ground to neutral and make sure they have continuity but no (significant) potential between them.

    Unhook the two hot wires at the source.
    Check that there is no continuity between them and any of the other wires (each other, neutral, ground).

    That won't tell you where but it will tell you what... Hopefully (otherwise I'm stumped).

    You probably don't have a toner, but if you know a sparky out (more likely) a low voltage guy you can borrow one and use that to find a break if it's in the wall. Make absolute sure the mains is disconnected before connecting the toner or the magic smoke goes poof in very exciting ways.

    My bet is that a wire is either shorted or broken someplace real close to the swamp cooler. They tend to vibrate quite a bit and the moisture can be hard on things. Either that or a critter chewed a wire, which would be worst case.
    Thanks for the suggestions. That's a pretty good outline of the steps I have in mind. From the breaker, I have a known good hot and neutral. (Confirmed with the meter.) At the thermostat, I have a pump wire, a low speed wire, and a high speed wire. Connecting any of those three to the hot should send voltage to the 4-prong receptacle inside the swamp cooler. If all of those check out, then it's got to be in the 4-prong power cord attached to the motor. (One of those prongs supplies 120v to the pump, but I already know that one's working.) If it's not in the cord itself, I suspect it might be a corroded connection inside that 4-prong receptacle, but it shouldn't be too hard to trace it all out. It's just gonna require repeated trips up to the roof to trace it all out.
    When the going gets weird, the weird turn pro. - Hunter S. Thompson
    When the weird get going, they start their own forum. - Vaughn McMillan

    workingwoods.com

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