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Generac Generators (SEARS, etc.)

Generac 4000xl System Board?

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Old 05-21-2019, 07:05:33 PM
mrdouble mrdouble is offline
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Default Generac 4000xl System Board?

Hi members. I have a 4000xl model 09777-1 serial 5560726
Had it running after a power failure than another storm hit and its outside in the rain lost power. First I checked the 84132 voltage regulator board and it smelled burnt. Than I visited this site and followed the troubleshooting recommended by the fellow members. I ordered a new voltage regulator board 84132. Voltage at the outlet return to 124 Volts. Although the idle control did not work and the low oil pressure safety kept shutting the engine down. I have a whole house fan in my barn plugged it in and I could tell something wasn't right. I have a fluke 867 Scope meter I measured the frequency and it was only 53 hertz. Hi speed up the engine to get the frequency right in my voltage was 150 volts. At this point I think I have all system board problem.
83970 The circuit resistor down from the left has took a lot of heat not sure all the problems with the board I need to schematic or a parts list to troubleshoot this further
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Old 05-22-2019, 03:41:06 PM
Bassplayer1985 Bassplayer1985 is offline
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Default Re: Generac 4000xl System Board?

Yup common failure point that resistor. Also a common misconception (albeit the wrong action) to reduce the engine speed to get the correct output voltage because the SCB is not working with the VRB to regulate voltage.

Resistive loads wouldn't be damaged, but inductive loads like motors would eventually overheat and fail. Likely why your VRB failed, its working 100% duty cycle all the time until the SCR burnt out.

I have a thread on here that has the parts list you need. something in the neighborhood of ~45 parts to check on REV P, and about 22 of them deal with the voltage regulation.
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Old 05-22-2019, 09:54:36 PM
mrdouble mrdouble is offline
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Default Re: Generac 4000xl System Board?

Thank you for your reply bassplayer
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