MEP-003A Voltage Stuck at 157Volts

[Cleisthenes]

I power the house every month for a couple of hours. No adjustments have been made to the generator settings over the last year. All indications were normal. I tweaked the voltage adjust knob (to bring the voltage down a couple volts) and could not get the voltage readout to change. It was steady at @ 120 volts. After 30 seconds the voltage jumped to 157 volts and will not move. A multimeter confirmed the 157 volts is correct. I swapped out the voltage adjust unit with my second MEP-003A and the voltage does not respond to that one either. Any thoughts come to mind? Thank You. This is my first post and the whole forum site is quite overwhelming at this point. Hope I can find the responses.

 

[Isaac-1]

Sounds like a failed output diode on the voltage regulator board

 

[Triple Jim]

Ike, I know you meant output transistor. That would be Q3, mounted to the board with two screws.

 

[Isaac-1]

Sorry yes output transistor, had diodes on my mind from an unrelated project

 

[Cleisthenes]

Thank you Ike and TJ. I can solder a transistor. I see there are three (Q1, Q2, and Q3) on the diagram. I've located them on the circuit board also. Which one is the output transistor and where do I buy one? Thank you both, Isaac and Triple Jim.

 

[Cleisthenes]

Oops! It's Q3. Thanks

 

[Triple Jim]

I suspect that mouser.com will have them. If not, you can just search the net for 2N3584.

Edit: Newark has them cheaper, but I haven't compared shipping.

 

[Isaac-1]

You might also check ebay sellers, sometimes they have cheaper shipping, remember when installing the new one to hold it with pliers, and use short bursts soldering with time to cool between so you don't cook it.

 

[Triple Jim]

As much as I like good deals from eBay, I've had to quit buying electronic parts from anyone except the suppliers that can't afford to have their names tarnished by counterfeit parts getting out to their customers. I had a very bad experience with counterfeit FETs last year.

 

[Cleisthenes]

Thanks Jim. I just sent you an email.