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mep 002a issue: lights (strob affect)

hahnkl

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I just got my mep 002a fired up and was checking the output with a halogen spot light plugged into the 120v output receptacle. The light works and has steady output when the engine runs at the lowest rpm. As I throttle up, the light output oscillates (like a slow strob light). This happens at all rpm's except the lowest idle speed. My frequency meter does not work (rusted)--but I have ordered a digital replacement from Hardy. Other information

+ genset is not grounded
+ AC reconnection switch is set at 120/240 1pH
+ Adjusting the voltage knob does not influence the strob affect.

Any help is much appreciated
 

Speddmon

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What Chevracer said...sounds like the damage is already done. You could have saved yourself the trouble if you had spent a few hours reading on the site here or reading the TM first. This issue has been covered here so many times it's not even funny.

What is your voltage while the set is running at speed? And can you adjust it with the rheostat on the control panel? This will help to determine if the VR is toast or not.

Get the generator running and set at 1800 RPM's (60 Hz) and don't touch the throttle again. That is the biggest mistake the military made on these sets....putting a throttle on them. People don't understand how to use them properly, so they revert back to what they have been taught about engines from an early age..."let it idle and warm up first", but that is a BIG NO NO with these generators.
 

Isaac-1

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Like they said, sounds like you cooked your voltage regulator, hope you know someone that knows how to solder and do electronic repair. There is a chance it may be something in addition to the voltage regulator also.

Ike
 

hahnkl

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What is your voltage while the set is running at speed? And can you adjust it with the rheostat on the control panel? This will help to determine if the VR is toast or not.

.
The voltage needle jumps between 100 to off scale past 300. No I cannot adjust voltage with the rheostat. I now have a sick ($$) feeling in my stomach. What would you suggest regarding how to proceed from here. I did find a VR for sale online via Green Mtn Generators $175. Also, my frequency meter does not work for it is rusted, so I ran the engine wide open.
 
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Isaac-1

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It is hard to say without knowing your skill set, generators combine need for mechanical ability with electronic and electrical ability and if you make a mistake they have the ability to injure or kill you in a number of ways. Having said that just about anyone with basic electronics skills can likely repair a faulty AC voltage regulator (note there is also a DC battery charging regulator on these generators which is sealed in an epoxy blob) as it is a reasonably simple circuit, and there are trouble shooting instructions in the TM, I have not read the ones for the MEP-002 lately, but I do know the ones for the voltage regulator in the MEP-016 family require a reasonably well stocked electronics repair bench. If you don't have access to a full electronics repair bench, the next best option is the shotgun approach, changing out the most likely suspects. On the MEP-002a the most likely suspect is the output transistor, this part ( commercial version is a 2N3584, original is mil spec JAN2N3584 or JANX2N3584, these cost 5-10 times the commercial part cost, and are the same thing, just with higher levels of fault testing ) sells for $5-$10 online (can sometimes be found on ebay, also check with Mouser.com )and is fairly simple to change. It is about the size of a dime and has 2 pins soldered to the board, plus it is held on by a pair of small screws and nuts. Someone that is moderately skilled with a soldering iron can change it in about 5-10 minutes (I did it on mine a month ago, and am far from an expert with a soldering iron), note diodes can be harmed by heat so certain precautions need to be done, like backing with a heat sink (pliers) and quick taps with a hot soldering iron to limit heat transfer. If the output transistor is not he problem then it would be time to move on to the capacitors, etc.

Ike

p.s. the frequency meter on this is really a 2 part system, the frequency transducer mounted in the center at the back of the control box, and the display gauge. Problems with the transducer are common, the gauge is a simple low amp style deflection gauge with a custom face plate, you can test the output of the transducer with a common multimeter. If you don't want to try tackling the front panel instruments now, there are a couple of cheap work arounds, one is a Kill-A-Watt P4400 (don't get the fancier ones, some don't have the Hz meter) that sells for about $20, another is a small volt/Hz meter sold on ebay by Hardy Diesel that displays volts / Hz on a red LED display, also about $20. If you have a multimeter it may have a Hz function, just be aware many of the cheaper models may get confused by generator power and give crazy readings, so if it is not something like a good Fluke meter, be wary of insane Hz readings.
 
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Speddmon

Blind squirrel rehabiltator
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The voltage needle jumps between 100 to off scale past 300. No I cannot adjust voltage with the rheostat. I now have a sick ($$) feeling in my stomach. What would you suggest regarding how to proceed from here. I did find a VR for sale online via Green Mtn Generators $175. Also, my frequency meter does not work for it is rusted, so I ran the engine wide open.

I have not seen one jumping around like you mentioned, but the fact that you cannot adjust it with the rheostat indicates that the VR is probably bad now. As Ike said, it's a fairly easy fix, I have done several. As a matter of fact I have several of the output transistors being delivered tomorrow for some repairs i'm doing for another member.

I think you just learned a valuable lesson the hard way. Please take some time while your machine is down for repairs to search through our aux. equipment forum or search for "mep-002a" or "mep-003a" (the 002a's big brother) and read about them to familiarize yourself with the machine. Playing with the machine that you don't know how to use will most definitely cost you more money in parts
 

LuckyDog

Member
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Freedom, NH
I think you just learned a valuable lesson the hard way.
:ditto:

Please take some time while your machine is down for repairs to search through our aux. equipment forum or search for "mep-002a" or "mep-003a" (the 002a's big brother) and read about them to familiarize yourself with the machine. Playing with the machine that you don't know how to use will most definitely cost you more money in parts
:ditto: + RTFM & RTFW :deadhorse::deadhorse:

Speddmon has links to the Manuals in his signature.
I have the link to the Wiki in mine.

Just click on 'em. :popcorn:
 

hahnkl

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Location
Illinois
....... On the MEP-002a the most likely suspect is the output transistor, this part ( commercial version is a 2N3584, original is mil spec JAN2N3584 or JANX2N3584, these cost 5-10 times the commercial part cost, and are the same thing, just with higher levels of fault testing ) sells for $5-$10 online (can sometimes be found on ebay, also check with Mouser.com )and is fairly simple to change.............


Ike

p.s. the frequency meter on this is really a 2 part system, the frequency transducer mounted in the center at the back of the control box, and the display gauge. Problems with the transducer are common, the gauge is a simple low amp style deflection gauge with a custom face plate, you can test the output of the transducer with a common multimeter. If you don't want to try tackling the front panel instruments now, there are a couple of cheap work arounds, one is a Kill-A-Watt P4400 (don't get the fancier ones, some don't have the Hz meter) that sells for about $20, another is a small volt/Hz meter sold on ebay by Hardy Diesel that displays volts / Hz on a red LED display, also about $20. If you have a multimeter it may have a Hz function, just be aware many of the cheaper models may get confused by generator power and give crazy readings, so if it is not something like a good Fluke meter, be wary of insane Hz readings.

Ike....I found the output transistor online and ordered a couple. Fairly inexpensive <$5 so I will try replacing it per your instructions above...Thanks!!

Because my frequency meter did not work from the start, I had already ordered the digital Hz/V meter from Hardy. It should arrive in the next couple of days.

Thanks again for your help. This Generator is intended to power our families hunting cabin. Opening day is on October 1, so hopefully I will be able to work through the current issues and have it up and running by then.
 

Speddmon

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Working these generators takes a lot of concentration at times. First off you have to get out of the habit of letting it "warm" up. Warming up one of these generators means to start it at 1800 RPM's (Which is where it should have been when you shut it down) and letting it run for a few minutes unloaded. These engines were designed to be started and to go right to speed with no idle period at all. That is why I tell people, when you get the generator putting out 60 to 62 Hz, never touch the throttle again unless it's for fine adjustments. That way, the next time you start the set, it goes right to speed.

The other thing you need to re-learn on these machines is to hold the start switch until it builds oil pressure, not just until the engine fires. And NEVER hold it for longer than about 10 to 12 seconds at a time. Another member on here had a heck of a time getting his 002a started while I was helping him. It was a warm early summer day (or late fall, I can't remember). His engine was firing off pretty much right away, but he was so used to letting off of the keys on cars and equipment as soon as the engine fired he would do that with the generator. Needless to say the generator would just die right off because it hadn't build the oil pressure up yet.
 

hahnkl

New member
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Location
Illinois
Problem Solved --MEP 002A voltage regulator.

It ....... changing out the most likely suspects. On the MEP-002a the most likely suspect is the output transistor, this part ( commercial version is a 2N3584, original is mil spec JAN2N3584 or JANX2N3584, these cost 5-10 times the commercial part cost, and are the same thing, just with higher levels of fault testing ) sells for $5-$10 online (can sometimes be found on ebay, also check with Mouser.com )and is fairly simple to change. It is about the size of a dime and has 2 pins soldered to the board, plus it is held on by a pair of small screws and nuts. ......

Ike

.
Ike....As you suggested, I ordered a replacement output transistor online. Cost was $3.65. I replaced it this evening. Since my frequency meter was not working, I replaced it with a Hardy digital frequency/voltage meter ($20 online) and wired it into 120 v courtesy outlet receptacle. Then I started the generator up and adjusted the engine throttle speed till I got 60 Hz reading on the Hardy meter. Output voltage is correct and I no longer have the "strob affect" with my lights. Thanks for your help Ike and also thanks to SpeddMon for his guidance as well regarding startup and operating engine speed to avoid damaging the voltage regulator.
 
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