Re: (ET) Speed / power drain / reverse problems C185

[Chad Bush <bushman165s aol com>]

Chris,

You might have to physically disconnect those diodes to check them 
correctly. I haven't looked at that board specifically, but you should 
also be able to check the field voltage at the motor and figure out 
which one, if any, is bad. Also, you can check for resistance across 
the field windings AND each lead-to-case to make sure it hasn't shorted 
somehow.

Good Luck,

Chad


-----Original Message-----
From: Christopher Zach <cz alembic crystel com>
To: Biophiliac <keljefs sbcglobal net>
Cc: et <Elec-trak cosmos phy tufts edu>
Sent: Mon, Aug 20, 2012 9:36 pm
Subject: Re: (ET) Speed / power drain / reverse problems C185


On 8/20/2012 10:56 AM, Biophiliac wrote:
> Chris,
> Thanks for your response.  There appears to be two cards, a diode 
assembly and
diode varistor assembly and a field resistor. The diodes all visibly 
look ok,
although when I replaced the varistor which was originally broken / 
blown.
> If these are the cards, can I easily test them for integrity? Or 
should I just
replace one or both ? Do you know which one is likely causing my speed 
control
problem?

Sure. Just test the diodes with a diode tester or meter. The four on 
the
bottom right of the board are normally what fail, most of the rest of
the board is for the field weakening control.

If the motor has no field, this could be the cause.

Chris


> Jef
>
>
> Chris Zach <cz alembic crystel com> wrote:
>
> > On 8/16/2012 1:18 AM, Biophiliac wrote:
> > > CZ,
> > >
> > > Forgive my ignorance / inexperience.  I've heard talk about these 
cards and
I don't see anything visibly under dash panel resembling a card 
(printed circuit
board?) or on the detailed wiring views of my worn copy of C185 1975 
parts
manual.
> > >    So my question is where is card 2 located and will diodes be 
visibly
blown and/or can I test them with a basic multimeter?
> > If the C185 is basically the E20, then the card is located on the
> > firewall, right size. The Four diodes on the bottom left control 
power
> > to the field, sometimes they blow up so you get reverse but not fwd 
and
> > such.
> >
> > Chris
> >
> >
> > _______________________________________________
> > Elec-trak mailing list
> > Elec-trak cosmos phy tufts edu
> > https://cosmos.phy.tufts.edu/mailman/listinfo.cgi/elec-trak


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