MEP 026C voltage output too high

Keith_J

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Finally got one of those round toits and dug into my 026C (3kW 28 volt DC version of the 016C). I had fixed the carb and fuel system, starts and runs fine but even with the voltage adjustment in the lowest position, output is 35 volts. The voltage adjustment works, peaking out at 44 volts. That variable resistor is fine, linear between 0 and 750 ohms per specification.

I fear the voltage regulator has failed from the previous owners/operators running it at lower engine speed than 3600 RPM as I had to adjust the governor for proper speed and droop. I tried running it at lower speed and that works to get lower voltage output.

I've yet to load test because I don't want to fry my load bank, namely as a battery charge and jump system.

The -14 TM is vague on high voltage output. But it could be the power transistors?
 

Keith_J

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Took the VR apart, finding one of the 110 microfarad tantalum capacitors blown open. Frags of tantalum and paper were everywhere. This is a polarized axial lead cap with color coded polarity. Still trying to figure out how to remove the power output transistor.

well, this is the older regulator, FSN 2920-299-0637 so it isn't what is covered in the generators -14. The output transistor is a 2N1488 and it tested fine. But when the capacitor exploded, it sent shard of foil all over so that could have shorted out something. Will need to test the other transistor.
 
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Keith_J

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Guess I am the expert now ;). IT IS ALIVE! Yes, voltage is smoothly adjustable between 21 and 38 using the control panel adjustment knob. Next step is to make a gasoline tank and filter setup. Also will add a propane carb and electric start.

My goal is to make an inverter based 120 volt generator with a battery bank and a PLC system. I already have the 24 volt inverter. When the battery bank voltage gets below 22.5, the PLC will start the generator and once running at 3600 RPM, the breaker will close to recharge the bank and take some of the load of the inverter. Just running the generator for testing, it burns over two quarts an hour with no real load. Hopefully the loaded consumption isn't much higher.
 

Keith_J

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Load test done. How? Hooked it to the M1031 and loaded it with my 24 volt air conditioner, a motor rated at 70 amps. It only drew 63 amps but that was through 20 feet of #4 wire so the alternators were picking up the slack.

anyone need a jump start? 107 amps at 28 volts;-)
 

Keith_J

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Location
Schertz TX
Just the capacitor blown. But the tantalum foil confetti was blown all over the regulator and printed circuit boards, that could have shorted something out. Brushed off all the mess and blew it out with compressed air.

Still need the the left exhaust manifold replaced, it is far gone. A new filter set will make this 12.3 hour beast like new, save the paint. Feels good to save another generator.

Another $21 sunk into it, ordered the parts. I should mention the float needle valve seat was toast, I made one from a tiny Viton o ring, spun on a Dremel tool shaft and dressed to shape by silicon carbide sandpaper. Far cheaper than a new carb. I remove ethanol from pump gas, using only this fuel in the engine due to carb float damage.
 
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