From: Christopher Zach <czach computer org>
To: noaddress drmm net
CC: elec-trak cosmos phy tufts edu
Subject: Re: (ET) one speed, no power E20
Date: Thu, 02 Jun 2005 07:38:14 -0400
David Roden wrote:
I strongly recommend that you give up.
On the GE controller, I mean, not on the tractor!
I strongly disagree.
There are several components on the control cards which suffer from age -
notably the electrolytic capacitors. Yes, they can be replaced; but after
repairing the main card in my E15 a few times and struggling with the
truly awful connections to it, I decided that rather than rebuild the card
it was time to let the tractor join the late 20th century.
The E20 has one transistor, one FET, and a bunch of diodes. True that it
does have a few resistors, but you can get a new one from Harold for $50 if
card 4 really blows up.
Remember the E20 is not like the E15: It's built using discrete components.
There really isn't much to fail on them.
The GE control system is simple and comprehensible to anyone with a little
electrical background. That's the good news. The bad news is that it's
not only obsolete, it's also old.
In 30 years the AllTrax will be both old, unsupported, and impossible to
diagnose. What then?
Though I'll admit it has some downsides - for example, the tractor speeds
up more going downhill than it used to - overall I'm pleased with it.
That would drive me insane. The rock solid speed control of an E20 with CC
is one of the reasons I like contactor control plus shunt motors.
The best part of an electronic controller is the fine level of control.
For example, today I put the tractor away in the garage, feathering the
throttle pot to advance the tractor by millimeters - literally - until the
blade (still on it) just touched the back bumper of the car. Try THAT
with your factory controller!
Eh. I can cruise around at a rock solid speed, regenning coming down hills.
Can't do that with an Alltrax :-)
That said, an E20 has eight speeds and four gears. So you have a possible
32 speeds to choose from. More than enough for most people.
And glory be, there is no more reverse relay to burn or flake out.
The E20 does not use the reverse relay. It has a quad of big interlocked
contactors to handle reverse. They don't wear out much.
There are other modern controllers that can also be used if you'd rather,
though you're more on your own with these (the Alltrax comes with fairly
detailed instructions for performing the conversion). Regardless, I
recommend that you discard the old system (Mark Hanson calls it "Apollo
Era controls" and modernize. You won't regret it.
So far the Apollo stuff is the only thing that got us to the moon.
Sorry David, I think the E20's control system is great. The only weakness
is that the open frame relays are probably out of alignment. A quick call
to Harold for a few new closed relays will fix that and the time the
tractor will be down to swap them can be measured in minutes.
Chris
Chris
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