No Voltage/power on 28v gen set

m139h2otruck

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At the Weare show, we picked up a 28 volt MEP-025A gen set for cheap money. Needs a new air cleaner element, a hose between the air box and the carb and the plastic tank has a pin hole in the side (fixed with screw and rubber washer) but other than these small items it is almost new. Runs real nice and smooth but only shows about 4-8 volts on the unit meter and on our test meter. Printed the manual from the manuals page and flashed the fields as stated in the trouble shooting pages. No help at all. Fields show only about 2-3 volts between the #5 and 6 connections on the regulator. Per manual should be around 24 volts.

Any suggestions?? Have already looked at Saturn's site and plan to call them for the air cleaner, hose and tank parts.
 

m139h2otruck

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Yes, we picked it up from Adirondack, $200 for 6 gallons of paint and the gen set, not too bad a deal. Son is the wheeler/dealer!!

I guess the problem is the voltage regulator, from what I can find out in the manual. Need to check the field and stator resistance next before I try to find the regulator.
 

m139h2otruck

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Also, need manual for the 3 hp 2 cylinder engine on this gen set. It does not have the newer style electronic ignition like the newer units. Don't see this manual in the manul listing below.
 

Recovry4x4

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m139h2otruck

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Thanks for the links. Any idea on the type and kind of transistor needed, and how hard is it to change? Radio Shack as a supplier?

No mention that I can find in the manual about the idling problem.

Want to rig this up so we can start 24 volt construction equipment in the winter if the batteries are down.
 

Recovry4x4

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I'll see if I can scare up the info on the transistor and the part of the manual dealing with the idling and overheating the regulator.
 

OPCOM

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If the set has not been used in a while, and has slip rings or brushes, you may be able to get it to produce by shooting some contact cleaner into the commutator while it is running. be careful though because it is flammable. I have some this on a couple of older slip-ring type AC generators successfully. Sometimes there gets a layer of oxidation on the contacts or brushes.
 

doghead

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I have used an eraser on the end of a pencil to clean the commutator of oxidation. (either running or not) This method usually looks as clean as if you used emery cloth but does not leave any scratches like emery cloth will.
 

m139h2otruck

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Thanks all for the input. The little 24 volt unit's regulator is a round can like thing (looks like a little oil filter) mounted on top of a squarish base (maybe 2"x3") with terminals on one side. Haven't taken apart yet, but it looks sealed.

Good question, if idling is NG why the lever on the carb marked "start/idle" and "run"? Would think that a stop or limit screw would be used when the motor is used as a gen set. Will make the mod our selves just to be sure no one idles the unit.
 

Recovry4x4

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These little engines are used on much more than gensets, thats why you can idle them.
 

m139h2otruck

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Checked the ohm readings on the fields per the TM. Both came up as within tolerance, so I guess that the regulator is the problem. There are no brushes on this type of gen set, so that can't be the problem. Next call is to Saturn.

Also won it's brother (120/230 volt) on Ebay last night so now have a matched set!
 

m139h2otruck

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Got the new regulator from Saturn (normal great service) and installed. Unit now runs great and makes correct voltage (22-36 vdc on gage). Also installed new air hose between filter and carb, new spark arrester (a little less noise) and new air filter element. Where would I get the replacement transistor for the burned one in the old regulator? You can see it on the bottom of the unit, connected to the #5 terminal.
 

m139h2otruck

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Used the new unit for the first time to charge and boost new Mack powered tractor. Runs great, showing 50-75% load @ 28 volts on charging, but kicks out the CB when you crank the engine too long. Likes gas too, 1 gallon in about an hour. Batteries ar mostly NG so high rate of charge is not a problem. Mack really cranks @ 28 volts!!
 

acetomatoco

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It lets you know that it is a battery charger and not a jump starter or booster.. 100 amps is the breaker, I believe...
 

OPCOM

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M139, do you have a good picture of that generator set, especially the control panel. I have one MEP-025 but it is not as shown in the TM 5–6115-323-14. The picture in there is an MEP-025A.. Mine works but a few things are loose, just trying to figure it out.
 
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