Re: (ET) Reverse issues

[Chris Zach <czach computer org>]

Well, I expect the draw to be higher in reverse due to the fact that the 
series field in the motor is running counter to the natural field under 
load, thus causing a defacto "field weakening".

Well, nothing works in reverse at this point.

I think I might try "hot wiring" a diode manually from the take-off 
point of the reverse solenoid at the motor armature end to the power 
supply side of 1A. This will basically bypass (well work in parallel) 
with the whole card assembly. If it works, the problem is in the wires 
to and from the card. If not, it's got to be an insane tractor.

Thoughts?

Chris


RJ Kanary wrote:
>       You've shown that you have a high resistance in the current path, 
> or excessive armature current draw . Is the Cruise Control still inop in 
> Reverse? If that is the case, many of the diodes on the right hand page 
> of the diagram now become suspects.
> Is the Reverse lamp still functioning ?
>       Last, but not least, Wire #8, and Wire # 24, and the area they 
> originate from
> bear  another once over, since they are the beginning of the field circuit.
>        From this distance, these are the things that I would explore.
>
> ----- Original Message ----- From: "Chris Zach" <czach computer org>
> To: "Elec-trak list" <elec-trak cosmos phy tufts edu>
> Sent: Monday, October 25, 2004 8:47 PM
> Subject: (ET) Reverse issues
>
>
> > Ok, I think I have an idea what is going wrong with the E20, but it 
> > doesn't make much sense.
> >
> > The problem is that when you're driving around the contactors for 
> > 1A,2A,3A (the bypass around the resistors) are not kicking in when in 
> > reverse. I checked the voltages on the diodes to the 1F and 1R 
> > contactors and they read like 26 in forward, but only 21 or so in 
> > reverse.
> >
> > Is the problem this: When in reverse and in series with resistor 1,2,3 
> > there is not enough voltage at 1R to power the 1A,2A,3A contactors? It 
> > sounds insane, but I checked the diodes and the traces and everything 
> > looks fine. Simply not enough power to the contactor buss.
> >
> > Still doesn't quite explain why I can get 1A and 2A to come in if I 
> > floor it, something is missing here.
> >
> > Any thoughts?
> >
> > Chris
> >
> >
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