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Nick,
Thanks for the very detailed response! I'll do some testing and see what I come up with. I'll also dig out my manual and look over the pages you mentioned.
Hmmm... I'm assuming those capacitors are soldered into place - which unfortunately means I can't independently measure the capacitance of each of them while they are part of the circuit.
Thanks, Mike
Michael S. Briggs, PhD
UNH Physics Department
(603) 862-2828
From: Nick Skinner <kc2dzb nycap rr com>
Sent: Monday, April 25, 2016 10:30 AM To: Briggs, Michael; elec-trak cosmos phy tufts edu Subject: RE: (ET) Speed controller acting wonky Operating on the assumption that this is the earlier generation with Card 1 (since you mentioned it). Get your multimeter out and check for ~36 volts on pad 10 and pad 11 of Card 1 in speed setting 2, and ~36 volts on pad 13 and pad 14 in speed setting 3. Also, the FW relay should kick in speed setting 3 (36 volts on pad 15). Note, you can use pad 12 as your 0 volt reference (“ground”).
If you’re not getting control voltage on these pads, then you either have broken or worn out microswitches in your speed controller. The plungers on the switches do wear out over time and can get flaky. If the switches are OK, then you’re likely up against bad wiring or connections.
If you are getting voltage to the input pads (10 and 13) but not on the output pads (11, 14, and 15), then my first suspicion is that the control card capacitors for speeds 2, 3, and 4+ are failing. In the diagram on page 5-24 of the HSM, they’re called out as C103, 104, and 105. My thought is that their capacitance is marginal at this point, so they just can’t store enough charge to function with the added voltage drop of the mower deck running. The “Control Card” section on page 5-2 has a good description of how the circuits are supposed to function. Jim C (www.electrictractorstore.com) has these replacement caps.
If you have voltage in and out of the control card, then my best guess is that the issue is the 1A and 2A contactors or their wiring.
Nick
From: Briggs, Michael [mailto:Michael Briggs unh edu]
I have an E-15 that I restored several years ago. Over the past year or two, the speed controller has been getting increasingly wonky. When going forward, it sometimes will not go past the lowest speed setting. Especially if I turn the mower blades on first, and then try to start moving forwards. It's more likely to obey my command to go faster if I first move the speed controller to a higher speed setting, and once it's going at that speed, then turn on the mower blades. Of course, that's rather inconvenient.
Last weekend, I couldn't get it to go out of first speed no matter what I did. I found something in the archives about connections 10 and 11 (if I remember correctly) on card 1 being related to speed control, so I cleaned those up with some Deoxit, and reseated the contact "plugs", and that got it to work somewhat. It was still misbehaving a lot, usually requiring me to start moving before turning on the mower blades, but at least I could get it to go past first speed.
Anyone have an idea what the problem is?
In general, I try to drive around in 3rd speed while mowing - so bypassing the big resistive bands, but not using any field weakening. I *think* that the system may often bypass speeds 2 and 3, but allow me to do the field weakening. Is the resistor bypass controlled independently of the field weakening? (I know the speed selector on the dash lets us choose speed, what I'm wondering is if the field weakening circuit is independent of the resistor bypass, such that the latter may work while the former does not. I suspect that would be the case)
Hmmm... I should drive around in a higher speed for a while, and see if the resistive bands are hot.
Thanks! Mike
Michael S. Briggs, PhD UNH Physics Department (603) 862-2828 |