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Electric lawn mower starts up as soon as it is plugged in. Needs new start button? Answered

Hello everyone,
I have a Kobalt electric lawnmower that initially stopped working after I cut grass that was too high. I searched this forum and found out what I needed to do - replace the rectifier.  I was very excited! I replaced it and now when I plug the mower in, it starts as soon as the wires are connecting. I do not need to push the button and lift the handle in order for it to start as one normally does. In other words, it seems the start button is now malfunctioning. I am thinking that all my attempts to start the mower when the rectifier was not functioning , and me tripping the circuit breaker, etc. somehow damaged the start button. However, I don't know. So, my question is is it bad for the mower to start right up like that? Also, does it sound like it could be the start box up by the top or is it possibly something else? I would appreciate any ideas someone has.

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iceng

Best Answer 2 years ago

You don't say, if the switch works to turn off your mower once it is running.

So I believe you have made a wiring error putting it back together.

Compare your wiring to this representative mower schematic.

Click the picture to see the whole image

LawnMower.jpg
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icengiceng

Answer 2 years ago

If there are no rewiring errors..

It is possible, that if current destroyed the bridge the switch contacts were tip self welded shut...

Often a sharp rap with a plastic rod, like a screwdriver handle, to the switch body can dislodge a tip weld contact and let the switch resume normal operation.

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AnnieSage

2 years ago

I mowed fully yesterday, the first time since the mower had the problem. It made me think of your suggestion, iceng, to wrap the starter box by the top of the mower handle which finally made it work after I put in a new rectifier. It felt good to be using the mower again and not to have to have bought a new one. I still need to look at the rest of the wiring set-up you sent a picture of to see what is causing the slow braking, but meanwhile I am able to use the mower.

Thank you again for everyone's input!

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iceng

2 years ago

Note the black_wire interrupted by bottom switch is in the Mains OFF position and the motor_blue_wire to green_wire through top of switch to red_wire to RESISTOR to red_wire to yellow_wire to motor.

LawnMower2.PNG
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AnnieSage

2 years ago

I double-checked the rectifier wiring, and all is correct. I then tapped the starter housing with the screw driver end, which worked! The lawnmower shut off (because I was not holding the lever up) which is how it should be! BUT, one thing I am noticing now is that while it shuts off when I release the bar, the brake does not work. When it shuts off, it has the same feeling as when the plug would sometimes come undone while I was in the middle of mowing. The motor slowly winds down, and the blades slowly stop spinning. I can definitely live with that, nevertheless it would be nice to have the mower be just like before, including almost immediately having the blades stop spinning when I release the handle. Any ideas how I can possibly fix the brake?
So excited about making so much progress. Thank you!

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icengAnnieSage

Answer 2 years ago

The Dynamic Brake Large_Sized_POWER Resistor is what goes across the motor to rapidly slow it down.

This is only allowed when the mains is disconnected by opening the black_wire path and only then the red_wire connects to the green_wire.

Sorted by ease of correction ;

1] A disconnected wire.

2] A burnt out or broken Resistor.

3] Bad switch contacts.

4] All of the above.

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AnnieSage

2 years ago

Iceng - thank you for your input. So I have only so far replaced the
rectifier. I have done nothing yet with the switch or anything else on
top. As far as the mower shutting off, the way this one works, is that
it only runs as long as I hold the handle up. Letting the handle go
makes the mower shut off. To put it on, there is a button I need to
push, and while holding it, I need to pull the handle up. Once it is
running, I can let go of the button and it will keep running, provided I
don't let go of the handle. That is how it normally is supposed to
work. Now, however, I just plug it in and it starts. It doesn't matter
what I do with the handle or button, it is as if the whole starter
system on top is being bypassed and the current is going straight into
the motor to start it. So are you saying that I may have put the wires
in the wrong sequence on the rectifier square? Would that possibly have
the effect of the motor starting right up without the starter being
involved on top of the mower? Regarding your second post, I will go and
rap a screwdriver against the housing. While out there, I will also
double check to make sure I put the sequence back on the rectifier
correctly. Thank you for posting that helpful diagram. I will post my
results after I double-check the rectifier wiring and also rap on the
starter housing.

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AnnieSage

2 years ago

Thank you both for your thoughts. I am glad to hear it is safe to run the lawnmower without the starter components working properly. At least I can still mow while figuring out the problem. So I will first open up the start/stop housing on top and see if I see anything obvious, but I doubt I will only because everything feels exactly the same. With this mower, one first pushes a button then lifts a lever in order to start the mower. It also has to be done in that sequence. After checking the components visually, if I see nothing obvious, I will get a new starter switch and hope that will fix it. I would like to have the mower run as it did before, including being able to stop it without having to unplug it every time.

Again, thank you so much for your input!

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rickharris

2 years ago

I think if it doesn't bother you and it is safe to use then you can leave it. BUT should you plug in out of sight of the mower and someone, a child perhaps has their fingers nearby there could be a disaster.

An inspection of the start lever may show you what is wrong though . It could be mechanical.

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steveastrouk

2 years ago

Start switch is the most likely thing, for the reasons you suggest.