Re: (ET) E20 review: Day one :-)

["SteveS" <ssawtelle fcc net>]

Looks like others have answered your questions, but don't forget
elec-trak.org. There is a huge array of manuals there - especially under
Resources - GE Service Manual Collection. There are schematics and even 
info
on how to read the schematics and troubleshoot.

I used the section on the charger to check out my charger. It had a great
step-by-step procedure and now I know my charger is basically ok. The
schematic shows the clips in the plug you mention - a bit strange, but
legit.

- Steve
E12


----- Original Message -----
From: "Christopher Zach" <czach computer org>
To: "Elec-trak" <>
Sent: Sunday, January 20, 2002 3:58 PM
Subject: (ET) E20 review: Day one :-)


> Well, I just came in from doing a preliminary inspection of the wiring on
> the E20.
>
> It's complicated. Far more complicated than the Home power schematic for
the
> E12. Hm.....
>
> I started by removing the top of the charger. The charger timer is
attached
> to the transformer and diodes by a molex connector. Two of the wires on
the
> top side of the molex connector had fallen off completely. I also noticed
> what seemed to be a piece of metal bridging two of the wires on the 
> bottom
> molex connector. Is this normal, or is this some sort of a hack? Anyone
have
> the pinouts for the E20 molex plug? I've got the tools to fix molex, but 
> I
> need to know which wire goes where and if that jumper is supposed to be
> there...
>
> From there I checked the outside wires. They all look to be excellent in
> condition. The strain relief is broken on the 110 volt wire; I'll have to
> build a new strain relief somehow as the plastic where the grommet went 
> in
> was broken out (maybe someone tried to drive off with it plugged in :-)
>
> Then I pulled the plate covering the control systems on the tractor. It's
> like Disneyland in there :-) Very clean, the wires look excellent, and I
> didn't see much in the way of overheating or other bad things. The main
fuse
> appears to be a big strip of copper in the center; it was intact. The 
> main
> disconnect was rading rather high resistance; I think I will remove it 
> and
> clean the contact plate. Very simple; very efficient.
>
> In the upper right corner I found the obligatory mouse nest. Sigh...
> Couldn't pull it out with my forceps, so I removed the two bolts on the
> battery side and opened the panel. Lots of relays, and the main part of
the
> nest (looked like an old rug) *right* on top of the only electronic thing
I
> have seen on this tractor. Sigh. The vacuum cleaner got rid of that, and 
> I
> sat down to take a look.
>
> It looks like the E20 has some sort of rudimentary electronics.
Transistor,
> bunch of diodes, thermistor, and what might be a little triac or SCR.
> Definately not high current stuff; I'd guess this is the "cruise control"
> system; any other ideas?
>
> All the relays looked good, except for the one on the left that was
covered
> in mouse-nest-crud. Bit of vacuuming and some contact cleaner cleaned 
> that
> up. I also noticed that the relay to the far right (when standing in 
> front
> of the tractor looking back) had it's wires bent in such a way that it
would
> never be able to close it's contacts. Straightened the wires, and now it
> closes properly with finger pressure.
>
> The number of relays in there surprised me. I was expecting one or two, I
> think there are eight double pole, double throw relays. They don't seem
> large enough to be switching motor current; perhaps they switch current 
> to
> the solenoid switches (there's a bunch o those too).
>
> Back when I was a little tyke, my first job was programming PLC units for
> Beth Steel using ladder logic diagrams. My guess is this tractor system
has
> a similar ladder-logic diagram somewhere around that would help me make
> sense of what relay triggers what and when. Anyone have one of these?
>
> Overall the wiring appears to be in excellent shape. Nothing chewed,
overtly
> broken, etc. I did notice that the "Control" fuse had blown (rather
> spectacularly I might add), this might not be a good sign. Then again it
> might have been the mouse crud that shorted something out. Don't know.
>
> The next step of course is to get some batteries and fire this thing.
Aside
> from cleaning up the main disconnect switch, is there anything else I
should
> do to ensure that nothing will blow out/up when I fire it? And how does
one
> take apart that pedal switch? And what is the sequence for starting the
> tractor?
>
> Thanks!
> Chris
>
>
>