Re: (ET) Alltrak DCX300 ET in E20

[SteveS <ssawtelle fcc net>]

There may be some confusion here and perhaps I can add to it ;-)

The E20s I know have the wire cable shunt (as Chris described) to 
measure battery current draw. They also have the metal strip shunt 
(again, as Chris described) as a safety device in line with the armature 
to shut things down if armature current gets too high. From the 
schematic it looks like it activates at a about 1.4V (diode drop and a 
transistor P-N junction). But that's when it should activate. Normal 
drop should be much less. Any appreciable voltage drop would cause 
wasted power. I should measure the thing and calculate it out....

BUT - the E12S (and probably E15 and maybe others) use a metal plate 
shunt similiar to the motor cut-out shunt as the battery current draw 
shunt. The power use gauge is connected across that shunt. It is located 
essentially in the same place the motor shunt is located - middle of the 
'firewall' (E12s and E15 don't have the motor shunt). Perhaps some 
models of E20 used that setup. Anyone know if that's possible?

- SteveS

Raymon Ellis wrote:

> Chris, please forgive me for any inference that I might have implied 
> that did not reflect honor to your knowledge of electronics. I respect 
> you for your vast knowledge and your willingness to drop down to my 
> level of conversation when speaking of the AllTrax conversion. You are 
> correct; the power resistor should not be termed a shunt. But when you 
> said I should not “put the ammeter across the shunt” I saw red. Chris, 
> you are a great influence on this site. I did not put the ammeter 
> across the shunt. GE installed the ammeter across the shunt before I 
> bought it new 35 years ago when they built my E20 where it has 
> remained since. I think this is a case of poor communications on my 
> part. Steve Richardson’s AllTrax installation schematic also specifies 
> the same power use meter in the circuit of the DCX300 ET. There is no 
> card #3 or card #4 in my tractor now and there never will be because I 
> do not know how to rebuild my E20 back to the original setup. If the 
> AllTrax conversion is not successful my wife and I have already 
> decided to head for the dump with it and move on. I’ll be fine when a 
> new working controller is installed in my precious ElecTrak.
>
> Chris, I want to continue to read your helpful writings without bad 
> feelings, so please understand that my intentions are in the best 
> interest of you and this forum and all the good people who are trying 
> to keep their ElecTrak moving. Best regards, Raymon
>
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