Re: (ET) E-15 Reverse relay Arcing

["Christopher Zach" <czach computer org>]

Well, another thing you can do is go to the contactor reversal on the
armature. My personal opinion is that they should have used the same
contactor setup to reverse field current. Going to switching field current
is a good thing, but doing it with a little relay is not a good thing.

Chris

----- Original Message -----
From: "Bob Murcek" <rmurcek geisinger edu>
To: <elec-trak cosmos phy tufts edu>; <ssawtelle fcc net>;
<daveb seanet com>
Sent: Friday, May 02, 2003 10:53 AM
Subject: Re: (ET) E-15 Reverse relay Arcing


> All this reverse relay misery might be another answer to the question
someone posed a while ago about why convert to a solid-state controller!
>
> The diode thing can't be used in this case since the purpose of the
reversing relay is to reverse the polarity to the field, which means no
matter which way you put the diode across the field, the diode's going to 
be
a short circuit in either forward or reverse.
>
> Has anyone tried anything nice and complex, like back-to-back Zener
diodes?  Or a snubber circuit?
>
> >>> Dave & Debbie Barden <daveb seanet com> 5/2/2003 7:40:32 AM >>>
> I have an E12 with this same problem.  Admittedly still unsolved.  after
> repairing the relay several times it finally fused together beyond 
> repair.
> before putting in the Bill Gunn version ($20) I came across the Hosfelt
catalog
> that had  some surplus relays of similar specs for $2.00each. I bought 6
(they
> were subsequently stolen along with my van but that's another story).  I
burned
> up one of those before putting in a fuse in line between the relay and 
> the
> field.  now I just blow fuses but all the time.  On the E12 the varistor
($4
> from Bill) is behind the lower panel cover jumping the field wires in the
> connector.  I replaced it.  A friend of mine thought putting in a diode 
> to
> block the electrical surge of the collasping field when the motor changes
> direction would help.  It didn't.  I suspect in my case something else is
amiss
> but I haven't found it yet.  good luck with yours!
>
> dave
> E12S in Seattle
>
>
> > - Yep, the schematic shows one. I'm not sure offhand where it is
located,
> > but I imagine it's on the reverse relay or on a small card nearby.
> >
> > Also  the E12S, E15 manual (Elec-Trak.Org) has reverse relay
troubleshooting
> > and a service bulletin at the very end.
> >
> >
> > >
> > > There might be a varistor that goes across the relay to absorb the
> > > sparks, or a capacitor. If so I'd bet it's blown.
> > >
> >
> >
> >
> >
>
>
>
>
>
>
>
>