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



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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