Re: (ET) crap - started mowing, and lost forward speeds

[David C Robie <mycroftxx1 juno com>]

On that field weakening relay;  When the field is not being weakened (1st
3 speeds) one on those normally closed contacts puts full E onto the
field.  If that contact ain't making,  there are all your 'open field' 
symptoms.    Wiggling the board may have been repairing (for the nonce) 
power to that set of contacts.   At any rate, before you do anything
else, get a relay cleaning 'stone' (extremely fine diamond file) in a
pinch a point file and clean those relay contacts.  Make sure also that
it  in adjustment to make the upper contacts at rest and lowers when
actuated.  To adjust it, carefully bend the leaves.  I should be a clean
make and break on both sides.  (I replace these with 24V ice cubes)
(which puts the mind at ease as it's better than having a 30 yr old relay
go flooey when I'm blowing snow)

Dave
Weymouth MA



On Mon, 24 Jul 2006 16:23:46 -0400 "Konstanty, Walter \(GE Indust,
ConsInd\)" <Walter Konstanty ge com> writes:
> 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
> 
> -- 
> 
> --------------------------------------------------------------
> Michael S. Briggs
> UNH Physics Department
> (603) 862-2828
> ---------------------------------------------------------------
> 
> 
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