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kohler6.5C61 generator sudden load dump

miraclewhip

Registered
Engine starts and runs normally.Voltage output less than 30v ac. Rechecked all connections and found ground of output connection loose in controller along with terminal block ground from both 120v and 240v ground lugs.I need wiring diagram for Kohler generator serial#265617,5080A 120v/240v generator.There were 2 condensers/capacitors attached to two slipring brushes.What are the specs for these? What is their purpose?Do they influence ac output? How do I test Selinium Rectifier? How do I test Transformer?Wirewound resistor on bell end appears intact with voltage adjuster in good shape.
 

Zephyr7

Registered
The capacitors are likely for noise suppression.

I’d bet that selenium rectifier quit. Just replace it with a silicon rectifier. Even if the selenium one hasn’t quit yet, it’s still a time bomb just waiting to fail when you most need your generator to work.

Bill
 

miraclewhip

Registered
How do I select proper silicon rectifier and wire it in circuit? I am more mechanically capable than electrical! Thanks for your fast response!
 

Zephyr7

Registered
How do I select proper silicon rectifier and wire it in circuit? I am more mechanically capable than electrical! Thanks for your fast response!
Post a pic of what you have. Many people use half of a silicon bridge rectifier (which looks like a square block with a mounting hole in the center), but sometimes you only need a single big diode. It all depends on what kind of “selenium rectifier” you currently have.

Bill
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
They're full wave rectifiers in these. Under full load they are around 40 volts and maybe a few amperes.

Since silicon rectifiers are SO inexpensive, I bought a ten pack of them rated at 50 amps and 1 kV lol. Don't recall where I ordered them from, but someone here should be able to help with that.

When the selenium rectifier fails open, it doesn't merely result in the generator no longer working. It can very easily result in the destruction of the compounding transformer. So it is crucial to replace them before they fail. And supposedly they ALL WILL fail sooner or later. Even just from age. Silicon is the way to go. :brows:
 

Zephyr7

Registered
Full wave bridge rectifiers can be had from:
Digikey (north Dakota)
Mouser electronics (Texas, I think)
Jameco electronics (California)
All electronics (usually, this is a surplus place in California)
Marlin p Jones and associates (usually, surplus again, in florida)
Fair radio sales (maybe, surplus, friendly people, Ohio)

Lots of other suppliers too, but those I use the most. Fair radio sales has a lot of defense surplus, sometimes even generators.

Bill
 
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