One relay is for Reverse/Forward and the other for field weakening.
You'll should be able to see each work. Field weakening comes on after
3rd speed forward.
Check the 2 wires that come from the coil and trace them back to the
circuit board - those are also trouble spots
with bad connections. Crimp/fix as required.
Check relay fingers - contacts welded/corroded....
Gator blade issue: mower motors turn same direction so all grass may
head for right motor so it "sees" higher loading, especially if you have
RHS discharge. Make sure motor is not bound up or hot bearings. Spin
blades by hand to check (power off). Brushes not cause. Check voltage
at each motor if possible when running but don't get close to blades.
If possible, measure amps with a clamp-on ammeter. Remember, it's not a
brush hog.
...Walt
-----Original Message-----
From: elec-trak-bounces cosmos phy tufts edu
[mailto:elec-trak-bounces cosmos phy tufts edu]On Behalf Of Michael S
Briggs
Sent: Monday, July 24, 2006 4:03 PM
To: elec-trak cosmos phy tufts edu
Subject: Re: (ET) crap - started mowing, and lost forward speeds
Thanks for the tips from everyone (haven't had a chance to read all of
them yet, since the classes I'm teaching had 5 hours of lecture today -
bleah). A quick update though:
I found *where* the problem is, and was able to finish mowing.
There's apparently a loose connection somewhere either on the panel that
card 1 is on, or on one of the wires that connects to it. When I took out
the screws and tilted that panel out to start debugging, with the tractor
in neutral (seat switch bypassed), as soon as I pushed the speed switch
forward, the motor started spinning, instead of the weird behavior I was
getting. I closed the panel up, hopped back on, and tried driving - same
weird behavior again. I found that wiggling that panel around I could get
it into a position where it worked fine. So, apparently some wire
connecting to the panel has a flaky connection, that is apparently
creating a short (I think) at times.
I was able to finish mowing, but definitely don't want to leave it
like this, so I'll need to find the flaky connection.
I can take a picture tonight of where I *think* it is, but want to
find out if it seems reasonable. There's two relays over on what would be
the passenger's side of that panel, just behind the speed switch. What do
those relays control? I'm guessing one is the forward/reverse switch?
One of the wires connecting to one of those relays had a wire
spliced in, that looks like a bad connection waiting to happen (and
wiggling that wire around, it seems like it was sometimes braking the
connection there, using my multimeter to measure the resistance on
opposite ends of that connection). So, I'm guessing that's the source of
the problem.
Also, I was not happy with how well the Gator Blades worked. But,
I'll address that in another email in a minute....
Thanks,
Mike