Re: (ET) E20 down, only one speed forward

[Christopher Zach <cz alembic crystel com>]

David Brandt wrote:

> Chris, with your skills, you could make up your own controller, or at
> least simplify the circuitry. I'm not saying it's easy, (and who has the
> time?) but it does pay off in the end, by avoiding all this
> troubleshooting. Plus when something does go wrong, you pretty much know
> what the problem is.

True, however if I then sold it the new owner would have no hope of 
fixing anything :-)

Honestly though, the E20-AA is about the simplest controller one can 
have. The E12 is simpler, but only because of the lack of field 
weakening. Even the E12 had some weird sort of delay switch on the motor 
that would break.

The real weakness on the E20 is card 4. The diodes get old and they 
short. What I should do is totally rebuild the card with all new diodes 
and transistors, that should last for another 30 years or so.

Wiring on my E20 seems to be fine, the only insulation damage is from 
mice, and even that's not too bad. I should be able to replace the 
electrical tape with liquid tape this spring.

Now the E15... That's another ball of string. I can see why people 
wouldn't want to fix those cards; they were loaded with weird delays and 
reversing logic. For that, going to an Alltrax would be a reasonable choice.

Chris



> David Brandt
>
>
> --- On Sun, 11/22/09, Christopher Zach <cz alembic crystel com> wrote:
>
> > From: Christopher Zach <cz alembic crystel com>
> > Subject: Re: (ET) E20 down, only one speed forward
> > To: noaddress drmm net
> > Cc: Elec-trak cosmos phy tufts edu
> > Date: Sunday, November 22, 2009, 8:53 AM
> > David Roden wrote:
> > > I stopped having these kind of problems - and
> > headaches with those flaky little connectors GE used on the
> > card edge - when I put a modern (well, late '90s era anyway)
> > transistor controller in my ET.  
> >
> > True, there is that option, and to be honest it makes the
> > Elec-Trak a lot more survivable than say my US Electricar
> > Prizm. If that controller fails either we fix it or you have
> > a large rock in your driveway.
> >
> > That said, the thing that is annoying me about the
> > Elec-Trak is the same thing that annoys me about the Prizm:
> > Both controllers do not have proper fuses.
> >
> > On the E20 there is a "fuse" for the controller circuitry,
> > however it's rating is much too high for the circuits on the
> > control boards. As a result if a component shorts you don't
> > blow the fuse, you blow traces and the like. Very annoying.
> > On the other hand this is a single-layer board, and is as
> > dull as dirt to fix. Assuming I can find out the part
> > numbers for the transistors.
> >
> > That said, it looks like the smaller diodes are starting to
> > die. The bigger ones for the field control have all been
> > replaced, guess I need to get some smaller ones from Radio
> > shack now.
> >
> > Chris
> >
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>
>