Mep003 Putting out 300 VAC and stalling

[Davon]

Shows 300 volts on control panel and I verified this on posts. Stalls after running a minute or two.

I'm thinking bad voltage regulator, but open to any other ideas.

I tried finding the page in the TM about testing the ac voltage regulator, but couldn't.

I appreciate any help you can give me. Thanks in advance!

 

[Ray70]

Correct, most likely its the VR.
Typically 1 of the 3 transistors on the VR goes bad.
There is a testing section in the TM, but you have to build a test unit.
@kloppk can better explain the testing and he also offers an upgraded replacement VR if yours is in fact bad.

 

[glcaines]

Shows 300 volts on control panel and I verified this on posts. Stalls after running a minute or two.
I'm thinking bad voltage regulator, but open to any other ideas.
I tried finding the page in the TM about testing the ac voltage regulator, but couldn't.
I appreciate any help you can give me. Thanks in advance!

Welcome to the Site
You stated that it stalls after a minute or two. I'm assuming that you mean that the engine quits running? If so, you have more problems than just the voltage regulator and the high voltage. Is this MEP003A new to you? Have you seen it running previously? If this unit is new to you and has been stored with old fuel in it, have you cleaned the filters in the pumps, changed the fuel filters, dumped old fuel out of the day tank and cleaned out the fuel lines? If not, I would proceed with this prior to trouble-shooting running problems.

For the high voltage problem, as Ray70 stated it is most likely a failed VR. I had the VR on my MEP003A fail and I successfully replaced the failed transistor with one I got from a member here on SS. I then purchased a used VR from Delks as a spare, which I tested to make sure it was a good spare.

 

[kloppk]

Correct, most likely its the VR.
Typically 1 of the 3 transistors on the VR goes bad.
There is a testing section in the TM, but you have to build a test unit.
@kloppk can better explain the testing and he also offers an upgraded replacement VR if yours is in fact bad.

Also visually check the VR board for burned components.
I've repaired a number of the VR's and besides the three transistors failing I've also found burned out resistors. Obvious charring. The diodes are prone to moisture creeping into them causing them to open up internally. If the diodes have white bodies look closely at them to see if you can spot any corrosion at all where the leads come out of the middle white section of each diode. Any corrosion and the diode(s) have likely failed.

Testing the VR per the TM does require a test box that emulates the electrical environment the VR sees when in the generator.
The test verifies the VR can:
- put out the full load required current when needed
- not leak any current out when it shouldn't under various conditions
- put out the correct regulating current when regulating the AC Voltage