Re: (ET) Odd reverse behaviour

[Chris Zach <czach computer org>]

>     One of the neat things that poor connections at that card can give 
> you is unexpected low field voltage in Reverse. That provides a ride 
> that you will not soon forget !

Yaknow, that might be it.

I noticed in the Elec-Trak manual that the 1A,2A,3A solenoids to cut 
around the resistors are powered by a pair of diodes off the card 4. 
They draw their power from either leg of the FR circuit, thus you need 
diodes. Probably to give the tractor some delay time after you floor it 
to keep the motor from going zero to full power.

My guess is that D403 is open (which would keep the tractor from 
engaging 1A,2A,3A in reverse and lead to one slow speed) and D402 is 
still good (giving 1A,2A,3A in forward)

Funny you should mention that low field because when I was working 
yesterday once I went to reverse and got no movement but all three of my 
battery LED monitors went solid RED (meaning the batteries were dropping 
below 10 volts). I stopped immediately, went to fwd, then to reverse 
with no problem. Might be a loose connector.

Chris