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Re: (ET) Fast Starts

Thank you for the reply, it got me rolling. Again, its an E12.
I was able to verify the resisters were wired up using circuits 6, 7 and 24 as long as #7 was the center of the two resister connections up front. On this tractor #6 was wired up on the left side, #24 on the right side and #7 in the middle. It looks like 6 and 24 could be swapped and it would still work, #7 was the critical one, unless I misunderstand it.
Contactors 1A and 2A both energize as expected via circuits #31 and #33, I could see the 36V switch correctly with the throttle level past the [Start] setting into speeds 1 and 2. The mosquito army came in for an attack before I could start tracking back the outputs of those contactors, but it was encouraging to see, hear and feel them work as expected.
I don't see how the power-pulse switch could affect anything with the throttle level in the [Start] position. If I pull that dash out again I will verify the switch function.
I see the diode assembly down there in the diagrams, would a shorted diode cause this problem? Visual inspection showed no obvious cracks in the containers of the magic smoke.
With those variables settled I'll continue tomorrow back-tracking the output side of the contactors. Any further guidance is GREATLY appreciated as this is all new to me. The more I absorb and understand its all rather clever for late 60s technology, neat stuff to see it still working as designed now. 

On 2024-08-13 11:27 am, Christopher Zach via Elec-trak wrote:
Well, first the tractor should be stepping through the speeds. If it goes straight to full power then either the contactors are shorted closed, or all contactors are closing in speed 1. Fix this. :-) 

Or maybe the resistor up front is not wired properly. Check that.
There also should be a centrifugal clutch on the end of the motor that doesn't allow full power if the motor is stalled. There is usually a "power pulse" button that bypasses this, check to see if that switch is always closed. But even then it should go to speed 1,2,3 as you move the throttle forward.
And yes, an E12-E20 going from nothing to full power will kick. The E20 depended on the contactors closing in sequence to prevent this, the E15 used SCR based time delays. 

C

On 8/13/2024 7:53 AM, David Kirk wrote:
Getting my E12 back on four wheels after complete restoration. The tractor came with one electrical speed, "Start" or speed #1 works while speeds #2 and #3 engage the contactor(s) which I can hear clicking but the speed does not change. I need to spend some time with the repair manual and track it down.
The immediate problem is that when the tractor is first engaged it starts so fast the front wheels lift off the ground. Sure it isn't supposed to do that, is there a slow-start system that has failed, or what makes the tractor start without lifting the front wheels? Even in L2 it really throws the driver back. 
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