Re: (ET) Debugging ET 12S (was Power Disconnect for an E12M)

[dave barden <daveb speakeasy org>]

Darrryl et al,
        
        Thanks for the responses.  What time zone is Bill Gunn in?  It 
might be
to late today for me to call him today.

        I have a service manual or parts of one and have a schematic blue 
print
as well.  I think we scoped it out pretty well and correctly determined 
that the
motor was reversing by changing the direction of the current through the
field.  And it did indeed turn in a different direction when we reversed 
the
wires on the motor.  I am new not only to these machines but to 
electronics as
well (the E12 is a "teaching machine" for me).  I'll take another look at 
the
motor wiring on my way home but I think mine has 4 large wires (1 or 2ga 
?) and
two small gauge wires (14ga?) that go to the field.

        Could it be that some of these tractors came with different type 
motors? 
Or more likely am I out in left field with this.

        I am work and don't have the blueprint or the wiring diagrams in 
front
of me so can't be anymore specific than that.

thanks much, I really appreciate this resource!

dave    

On Thu, 11 May 2000, Darryl McMahon wrote:

> Dave, WHOA!!!!
> > I should be starting a new thread here but don't know how.  maybe 
> > someone
> > could enlighten me.
> 
> Just change the subject line in your reply message.
> 
> > 
> > Anyway my friends and I were debugging my newly acquired E12S (it 
> > doesn't
> > move).  After cleaning all the battery terminals and various other
> > connections and dropping the motor to the ground we finally got the 
> > motor
> > to spin but always in the same direction, reverse.  Swapping the field
> > wires at the motor didn't make any difference.  This was really 
> > puzzling. 
> > Then we pulled the field wires off altogether and lo and behold the 
> > motor
> > turned still in reverse.  Tracing the wires we discovered one of the 
> > wires
> > from the siamesed relays (installed by the previous owner to  simulate 
> > the
> > original reversing relay) had at some previous time taken enough 
> > current
> > to burn the little jumper between pins inside a connector further down 
> > the
> > harness.  Bypassing the burnt out connector and removing the siamesed
> > relays we got voltage to the field and then reversing the field wires 
> > had
> > the expected and desired result of turning the motor in opposite
> > directions.  My friend Craig has found a double pole double throw 
> > relay in
> > the Hosfelt catalog that appears to have adequate specs  10amp at 
> > 30volts
> > but for the ridiculously low price of $1.49!  I wonder if it is 
> > advisable
> > to use it?
> 
> On the E12 series, I believe the motors have permanent magnet 
> fields.  There are NO field wires!  On my E12S, there are 6 wires to 
> the motor.  The 2 heavy leads are the armature power leads.  The 
> four lighter wires are for a centrifugal switch interlock cutout, and a 
> thermal switch cutout.  These act in the same manner as the brake 
> switch cutout and seat switch cutout.  These wires do not carry 
> significant power, just solenoid control power.  This is why the 
> motor will turn the same way if the "field" leads are reversed, or 
> disconnnected.
> 
> If you do not have an owner's service manual, please get one.  (Bill 
> Gunn at Technical Service & Parts (608-868-6228).  You need the 
> schematics for this level of debugging.
> 
> If you have the manual, start following the wires in there.
> 
> To change the direction of rotation, you have to change the 
> connection of the armature leads.  This is normally done via the 
> contactors under the dash, and controlled by the speed/direction 
> controller stick.  Perhaps something in the maze of wires between 
> the solenoids and control switches is reversed, or one of the 
> solenoid contactors is welded.
> 
> Disconnect the armature leads at the bottom of the controller area, 
> then apply power to the leads directly.  Check direction of rotation.  
> Reverse the connections.  Check direction of rotation.  I suspect it 
> will be reversed.  Then you can continue your debugging of the 
> wiring from there.
> 
> 
> > 
> > I see the original relay/contactor is rated at 36v but no amp rating.  
> > It
> > is fried and I don't know for sure how it got that way but suspect the
> > cable under the tractor that had its insulation ground off when it
> > evidently came in contact with the pulley at sometime might have 
> > something
> > to do with it.  It says Technical Services on the coil inside the 
> > relay. 
> > Can someone give me an idea what this relay costs?
> 
> Call Bill (see number above).
> > 
> 
> Darryl McMahon             http://www.econogics.com
> 1973 Elec-Trak E12 electric tractor
> 1974 Auranthetic Charger electric motorcycle
> 1975 EVA Metro (Renault 12 conversion) electric car
> 1986 Pontiac Fiero (conversion) electric car
> 1997 SpinCraft Explorer electric boat
> current project - B&D Model 8080 electric reel mower
> next project - 1973 Porsche 914 conversion
> "The Internal Combustion Engine, it's so 20th century."
>