Blowing Diodes in Voltage Regulator

Toro 266H Year:1994
Model: 72083 s/n:4901032

Kohler Twin V CV16S
Spec: 61514 S/N: 2408009097

About 900 hours of use.
New Battery
New Clutch

Hi.

My Toro has blown out 2 Voltage Regulators – the original one back in June, and the replacement last month. Each one had a blown diode.

The replacement ran for about 10 hours of cutting - then just died in a field.

Note: The first one blew around the time I changed the clutch if that has any bearing on the situation.

After I replaced the original Regulator, I ensured that I had 14.2 volts across the battery with the clutch OFF.

When I tried to start the mower yesterday, the solenoid chattered. I boosted it and got about an hour of grass cutting. Than it completely died, and would not even “chatter”. The battery was reading 11.5 volts. I guess it ran for about an hour without getting charged.

I have since recharged the battery – it now reads 12.8 volts.

I am concerned that the Toro will blow out the next regulator, so I am trying to figure out what to do.

The problem seems intermittent. No fuses are blown, and there is no apparent bare wires exposed that might short out when vibrated.

Could the the Stator winding under the flywheel intermittently be shorting out when hot? The stator checks out fine when I test it – but what happens after an hour of use later?

It's a 60 mile round trip to my cottage, and there are no tools out there. It's a big deal when it fails.


So 4 questions:

1. What is the typical life expectancy of the Stator?
2. Does it make sense to just go ahead and change the Stator?
3. Any idea what a Stator is worth?
4. Is it a big deal to change?

Any info will be greatly appreciated.

Thanks,

M...

1. What is the typical life expectancy of the Stator?
2. Does it make sense to just go ahead and change the Stator?
3. Any idea what a Stator is worth?
4. Is it a big deal to change?

Click to expand...

1 ) almost forever
2) No there is a problem
3) About $ 30 for genuine
4) 2 screws and 1 plug about 5 minutes.

What do you mean by " blown a diode "
Diodes fail either open circuit or closed circuit.

so you get pulsed DC or nothing out of the unit.
Rectifiers generally fail due to over heating or break down of the potting mix causing an internal short circuit.

Kohler use a flat strap to ground out the rectifier to the engine via one of the mounting screws and this strap regularly breaks if the screws are not kept tight.
I make up 2 grounding wires and ground both of the mounting screws.

If this is kept in a machinery shed then a better than average chance you have rodents nesting under the blower housing which reduces the air flow and overheats the rectifier

Hi.

Thanks for the prompt reply.



"1 ) almost forever - Am I barking up the wrong tree by arbitrarily changing the Stator?
2) No there is a problem - Not sure I understand what you mean here.
3) About $ 30 for genuine. Do you mean $30 for the Regulator/Rectifier? I was wondering what the Stator costs.
4) 2 screws and 1 plug about 5 minutes. Do you mean 5 minutes to install the Regulator/Rectifier? I was wondering how difficult it was to change the Stator.

What do you mean by " blown a diode " No continuity between one of the "AC" terminals and the center "B+" terminal in either direction.
Diodes fail either open circuit or closed circuit. Appears to be OPEN circuit.

so you get pulsed DC or nothing out of the unit. I would assume nothing, since the battery is not being charged.
Rectifiers generally fail due to over heating or break down of the potting mix causing an internal short circuit. Okay, that is good to know. But could a faulty Stator "blow" the Regulator/Rectifier?

Kohler use a flat strap to ground out the rectifier to the engine via one of the mounting screws and this strap regularly breaks if the screws are not kept tight. Screws are tight.
I make up 2 grounding wires and ground both of the mounting screws. Would I be wise to add a second grounding wire - could a poorly grounded Regulator/Rectifier cause it to "blow"?

If this is kept in a machinery shed then a better than average chance you have rodents nesting under the blower housing which reduces the air flow and overheats the rectifier"
The Toro is kept in a proper garage - and is immaculate. No rodents.


My situation is that I have just purchased a new Regulator/Rectifier for about $50 Canadian. I am worried about installing it, and it too will "blow". The original Regulator/Rectifier lasted 22 years. The second one lasted 3 months. Maybe it was just defective, or maybe the Toro has problem. I can easily add another ground wire if that would help. That is why I keep wondering about the possibility of a quirky Stator, and the possibility that it is damaging the Regulator/Rectifier.




Thanks,

M...

Changing the stator about 10-20 minutes on a Kohler, if the flywheel comes off easy.
Stators can not damage rectifiers unless they are exceeding the capacity of the rectifier. ( voltage and ampage )
Both the stator & the rectifier must be properly grounded, are you getting ~ 30 V AC between the two AC wires with the engine running at full speed ?
Did not notice you were in Canada so you will be paying about the same we do down here $ 50 for the rectifier and $ 200 - $ 300 for the stator.
Worthwhile to pull the flywheel to check the magnets they can come loose and do all sorts of damage although you usually know about it.
I did have one come in with only 3 still there .

Hi.

Here is an update for anyone interested:

I found the stator wire had some insulation rubbed off, and this caused an intermittent short which blew out the diode. After 20+ years of great service, I decided to change the stator ($130 Canadian) and the regulator.

All works perfect.

Thanks for all your help.

M....