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Newer Kohler standby problems....


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  #1  
Old 01-26-2019, 12:14:11 PM
1936JDB 1936JDB is offline
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Default Newer Kohler standby problems....

A friend of mine has a 20kw Kohler home standby that he asked me to take a look at. It wouldn't start when run was selected manually at the generator, when using the self test from the transfer switch or when power was lost. Upon inspection, I found the gm35950 board in the transfer switch was showing green corrosion. Unplugging the white connector on the right allowed the generator to run and transfer manually. He ordered a replacement board from colburn power systems, and I installed it. After installation, the transfer switch self test is able to start and transfer the generator, we let it run for a generous amount of time after telling it to transfer back to line power. But even after the transfer, the generator didn't shut down. Also the auto/off/run toggle in the generator, still won't start it in the run position. Apparently, I didn't get a picture of the generator nameplate, and I will attempt to add that info later. I'm an electrician by trade, however I have no formal training, or manuals from any generator company. Only past experience from working on other machines (mostly generac) when the job demands. I have included pics of the transfer switch, its tag, and the board we replaced. Any ideas what to check into next?
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  #2  
Old 01-26-2019, 12:39:03 PM
Birken Vogt Birken Vogt is offline
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Default Re: Newer Kohler standby problems....

The problems on the control board, around U1, C12, R4, etc., could there be any blown out components there?

Could it be lightning damage?

I have my suspicions as to what generator it might be, but I want to wait for your report.
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Old 01-26-2019, 01:02:49 PM
1936JDB 1936JDB is offline
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Default Re: Newer Kohler standby problems....

I'm absolutely certain I took a pic of the generator tag. But several looks through my phone show nothing. I didn't fully disassemble the generator control panel since it was snowing and COLD. But I did pull the side off the enclosure, and the very un-handy segmented, layered control box But saw no obvious corrosion or damage. Though under the circumstances, I could well have missed a burning dynamite fuse. We agreed that I should come back when weather would permit a further inspection. The owner is a lineman, and a single dad, so it seems he only remembers it when the weather is threatening an outage, IE: the worst possible time to tear into it.
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Old 01-26-2019, 02:06:28 PM
Birken Vogt Birken Vogt is offline
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Default Re: Newer Kohler standby problems....

Describe the generator to us. Do you know how many KW? What the switch and display look like? Approximately how old?
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Old 01-26-2019, 02:17:26 PM
1936JDB 1936JDB is offline
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Default Re: Newer Kohler standby problems....

The generator is 20kw I believe. It has an enclosure that reminds me of an older generac with the squared off corners, in a grey/tan color. The generator controls consist of only a 3 position flat toggle of run/off/auto. With a small, one line, red digital display. The transfer switch which was bought in a package with the generator say 2007.
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Old 01-26-2019, 02:40:49 PM
Birken Vogt Birken Vogt is offline
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Default Re: Newer Kohler standby problems....

The rocker switch should have battery voltage to the center pin (VBAT) at all times. And if you turn it to the run position (RUN wire) it should start right up no questions asked. What is it doing instead? I would check that the run wire is getting voltage.

There is another VBAT wire in the main harness entering the controller. And then the VBAT wire for the switch which exits the controller and goes to the switch about 4" long. Once I had one that was not letting battery voltage through the controller and I was able to backfeed it to the switch center instead and still working that way. But that was a very strange problem.

Needs further testing. These generator controllers almost never fail, but first time for everything....
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Old 01-26-2019, 02:57:16 PM
1936JDB 1936JDB is offline
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Default Re: Newer Kohler standby problems....

THANKS. I will do that the next time I get my hands on it. Currently when switched to run the display goes blank and nothing happens at all. They sure didn't make accessing the generator control box and its internal components very easy. Metric fasteners, blind holes, etc.
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Old 01-26-2019, 03:46:12 PM
Birken Vogt Birken Vogt is offline
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Default Re: Newer Kohler standby problems....

Take off the roof of the generator (4 bolts) and the right side panel (2 bolts back, 1 floor, 2/3 on control panel) and the back cover of the control box (2 screws) to work on it. It will be much easier but better if not snowing.

Battery voltage should come straight from the battery, wire P1, through fuse F3, then to the controller on wire PF1, main connector pin 24, then out on another wire VBAT, main conn pin 12, then back in thru the RUN or AUTO wires.

Also check for good grounds to everything.
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Old 01-26-2019, 03:48:29 PM
1936JDB 1936JDB is offline
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Default Re: Newer Kohler standby problems....

.
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Old 01-26-2019, 06:21:28 PM
Zephyr7 Zephyr7 is offline
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Default Re: Newer Kohler standby problems....

Looks like you have the start leads running in the same conduit as the generator power wiring. Thatís a no-no, although I doubt itís causing your problems. Shielded wire should prevent any issues if you have no choice but to run the start wires together with power like that.

Iíd check if those start leads have chafed anywhere (like at conduit entry fittings into boxes) and have gotten wet enough to rot a little in those spots. You might also try replacing the little green pluggable connector those wire attach too since they can get ďcorrosion bridgesĒ internally. If you need a new one, itís a Phoenix contact pluggable header and digikey stocks them.

Also, your transfer switch isnít service rated and isnít keeping ground and neutral seperate. That could be a safety issue, and itís something you should check.

Bill
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