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Help finding field flashing procedure for a running/not producing AC MEP 701A please

rivercreek

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I have a MEP 701A that is running but not producing any AC power. I am having a heck of a time trying to locate instructions to try field flashing and/or any other useful troubleshooting procedures. Can anyone advise me what the correct procedure is? I have the TM downloaded and have been through it fairly thoroughly, but I am repeatedly being referred to a "higher echelon of maintenance". Any advice/input from a "higher echelon of maintenance" would be greatly appreciated. Thanks! aua :confused:
 

Guyfang

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I am not at home to look at the schematics, but on the volt regulator, I think, please check, but I think the two wires on the left side of the VR, go to F1 and F2. Please look, my brain is like Swiss cheese, only the holes are smaller in the cheese.

keep in mind, there is often two troubleshooting diagrams in the manual. One for operators, (simple problems) and one for D.S. Maintence. So if operators TS sends you to a higher level, look farther in the book. And there is more then one TM for the set.
 
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rivercreek

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DieselAddict, thank you for your useful and pertinent reply.

Guyfang, I have located and downloaded TM 05929B/06509B-35 for this unit. For the record, I was unable to locate this TM on Steel Soldiers - I eventually found it somewhere else. I am aware that the problem is likely in the Voltage Regulator - but would like to attempt to field flash the generator before I completely remove the VR and disassemble it. I am unclear on what you are suggesting that I do with F1 and F2. I am unable to locate instructions for field flashing in this TM or in the Operators Manual. The only reference I am able to locate in the service/maintenance TM is in Section 8-1.a and reads as follows:

Field Flashing Circuit. The field flashing circuit provides a generator
flashing current during engine starting. The flashing circuit removes the flashingcurrent once the engine is at its normal operating speed. Flashing of the generatorfield windings ensures that the generator output will buildup properly.

While this is a well written definition of "Field Flashing", I am not able to locate any instructions in either of these manuals to complete the flashing procedure. Perhaps I've missed them somehow in the TM, but it isn't for lack of looking. The search term "field flash" produces 6 pages of results on SS, all of which I've read through without finding an answer to my question. I've searched SS for "MEP 701a field flash", I've searched "MEP 016B field flash", and several other variations with no success. I've seen references several times to "Flashlight Batteries" and "Drills", but I have yet to find a post that defines a "flashlight battery" as a D Cell ??? or advises what type of drill to use and/or how to use it to field flash this generator. I found a post that contained the question "Have you tried applying 24VDC to F1 and F2?", but there was no response to that question. The writer of that message did not advise correct DC polarity to apply to F1 and F2 or if that even mattered. There were no further instructions on how long to apply DC voltage and/or the condition/settings of the generator when applying 24VDC - running? not running?, voltage setting, main breaker on/off, etc.

The specific question that I am asking for help with is this: Can anyone advise proper field flashing procedure for a MEP 701a Generator?

I would be grateful if someone could advise me specifically where I might find detailed instructions on completing this procedure and/or if someone out there happens to know the correct procedure and would be kind enough to advise me how to do it.

I don't mean to stray off topic too much here, but I've been a member of this site for quite some time and have given advice/information when I was able to, and have received truly a wealth of knowledge from this site and its members. It seems that more and more lately, there seems to be almost an unwillingness of members to help "newbies". Senior members often take the time to respond with sarcasm while an answer or perhaps a pointer to where the answer may be found would take no more time than typing the sarcastic/negative response did. I've got all kinds of TM's and all kinds of camouflage equipment - I've got a M35A3, 6 - M923's, 3 MEP 701a's, several trailers, etc and I've got TM's galore for all of them. As most of you well know, these TM's are sometimes great, but they are also sometimes very confusing and difficult to navigate. The point of my listing my equipment is not to attempt to brag about how much crap i've got, it is to say that even guys with a fair bit of experience with MV's and volumes of TM's sometimes need a hand. Perhaps what you may see as silly "newbie" questions really don't have as clear or easily found answer as you pros may think. I understand that nobody wants this site clogged up with 900 people all asking for an answer to the same question that is easily found with a bit of looking - but please keep in mind that every question is not necessarily stupid or an answer as easily found as one might think at a glance. I'm sure everyone here can relate to how frustrating it is to struggle with a problem and spend hours and hours digging for an answer with no result. Then, after hours of digging, finally you decide to ask your question through a post only to receive one or more "Hey Stupid, check your TM" responses instead of an answer to your question. Everyone shouldn't have to preface their question and defend/explain how much searching or trying they've done to solve their problem on their own to attempt to avoid being snubbed, insulted or attacked. It seems a guy has to preface his question with an apology for asking and a list of just how much @#$% they've tried and how many places they've looked with no success to get any type of useful reply anymore. I'm sure we can all agree that part of the problem with getting answers is that there are sooooo many posts on here. Perhaps the moderators could consider deleting repetitive/not useful posts? Perhaps members could more thoughtfully title their post to reflect its content? Guys, everyone needs a little help from a friend sometimes. Before you start typing the sarcastic response thats swirling around in your head, try and recall when you were banging that same head against the wall for hours and didn't receive anything but sarcasm or silence to YOUR question. We've all been there - checking emails on your phone 9 times a day hoping that someone has answered the question you posted - only to find replies like "Some days I shouldn't be allowed on the internet". Seriously? What does that even mean? End of Rant.



TM 05926B/06509B-34
 

Zed254

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I own an MEP-803A and an MEP-802A so this information is from a search of SS and my experience with my units.

https://www.steelsoldiers.com/showt...16B-MEP-021-amp-MEP-026-3kw-Diesel-Generators has a TM posted that refers to the MEP-701A but the manual is titled MEP-016B. I think I read here https://www.steelsoldiers.com/showthread.php?129612-TM-and-Wiring-question-for-MEP701A-16B that the 16B is the same or similar to the 701A.

My machines require you to turn the S1 switch to the start position UNTIL THE OIL PRESSURE is reading normal value. I think that during this time the unit is flashing the generator. If I don't leave the S1 switch in the start position until oil pressure is showing the unit will shut itself down. I'm thinking the 701 flashes itself the same way. Below is a cut/paste from the referenced manual on starting. Note the requirement to hold start position until voltmeter reads normal.

Good luck with your machine.


2-7.
a.
Starting and Operation (all models).
Make sure that the DC control circuit breaker is in the ON position.
Rotate master switch to PREHEAT position and hold for 30 seconds.
Roate master switch to START position and hold until voltmeter reads normal
operation. Release master switch. It will automatically go to the RUN
position.
 

Guyfang

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The MEP-701A is a MEP-016B, with an ASK kit installed.

I accept responsibility for the Manuals not being posted correctly. The manuals you needed were posted in the SS TM forum. But under the heading, All the Manuals you need to work on the MEP-016B. My mistake. I assumed most folks would know that the gen sets are both the same.

There is NO description of how to MANUALLY flash the main generator fields, unless, there is a switch in the control panel for that function. And there are several generators that DO have said switch in the control panel. The manual field flash process is taught in the schools, but is not normally in the manual.

When I told you to look for the F1 and F2, (Once again, I assumed) I assumed you would know what they are, and what they do. I assumed wrong again.

For the main generator to light off, and produce power, F1 and F2 have to be energised with DC voltage. Normally, between 3-10 volts will do it. But the military uses 24 volts. Its normally a function of the S1, (start switch). Most gen sets operate in this manner. When you turn on the S1, the starter engages. The terminals F1 and F2 get sent a signal of 24 volts, and it lights the main gen off, and it produces power. To check to see if this happens, you place your multimeter leads on the F1 and F2 terminals on the VR1, (volt regulator) and have someone start the set up. You have to hold up the starter until the oil pressure builds up and you let go the S1. During that time you hold the S1 in the start position, you should measure 24 volts on your multimeter. If you get 24 volts to the F1 and F2 terminals, and no output on the LOAD TERMINALS, the VR1 is bad. If you do NOT get 24 volts at the F1 and F2 terminals, the S1 is bad, the K1, (start) relay is bad or the wires between. Please look at the schematic, bottom right corner, page 207, (PDF reader page number). The K1, is located on the A4 terminal board. These type relays often go bad.

If you look at the schematic, there is a "schedule", (page 208, PDF page number) that shows which terminals HAVE to have voltage on them, for the F1 and F2 to be energized. So have someone help you, to test the S1. One test lead on GROUND. Then turn the S1 into the start position, and measure pins 25, 27 and 28. They ALL should have 24 volts on them.

So before you start manually flashing the fields, try these steps first. THEN try to flash the fields, buy applying 24 volts to the two terminals on the VR1. Like I posted before, the two far left terminals on the VR1 are F1 and F2. They should be labeled F1 and F2. There is also a chart on the side of VR1, that tells you HOW to hook up the VR1, and where the jumpers should be on the terminal board, mounted on VR1, for the gen set model you are using. The chart is there because the VR1 is used in 3-4 (at least) different types of gen sets. CHECK THE CHART! Someone before you, could have wired it wrong. You can also find a chart in the TM 5-6115-615-34, page, (PDF page number 109). I do not know if the set is new to you, or if it worked before and stopped. You didnt share that information.

F1 is ALWAYS 24 volts positive. F2 24 volts negative.

The Flashlight reference is to the old trick of taping two D cells together, and then taping a wire to each end. Then the positive wire would be put on F1 terminal, the Negative wire on the F2, and you start the set. The reason you check first to see if you have voltage there from S1, is to prevent you applying voltage twice to the F1 and F2 wires, at the same time.

Have you followed the troubleshooting diagram on page 47, (PDF reader page number) in TM 5-6115-615-34?
 

rivercreek

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Thank you Zed and GuyFang for your detailed response, that gives me a lot to work with. I'll post my test results once I've had the opportunity to spend some more time troubleshooting. Although I thought that I did, it turns out that I did NOT have the correct/complete set of TM's for this unit - so that was certainly part of my problem. Thanks again guys.
 

Jericho

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Guy Fang brings up a good source of multi purpose tool, In the Air Force we frequently checked The MAG PLUGS on the sumps on Aircraft engines and AGE equipment with a mil spec angle head flase light TWO CELL, easy t do, take two spare multi meter leads , POS NEG and attach them to the neg and pos on the flash light on the opposite ENDS of the battery pack, we used to drill a small hole too run the leads into the flashlight then seal it with RTV ( they all had to be explosion proof) So when you completed the circuit , between neg and Pos it lit the light, indicating that the two elements on the mag plug were bridged ( a short) and the plug had metal on it , Also worked for flashing the field on NF twos and small gensets I have found Guy Fang s information Infallible , We are lucky to Have A Quality former CWO who still has the time and experience many of us need !
 

Guyfang

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Thank you Jericho,

There are a lot of things to make your life easy, if you spend a lot of time working on these things. My first "Test Equipment" was a Deuce dash panel blackout light socket. I attached two multimeter leads to it. It was my 24 volt tester. Did not matter which end you hooked up to pos and neg, when power was there, the red light came on. Didn't have to worry about the batteries going dead. Wrap the leads around the socket, stick it in my pocket. In the field it was invaluable. I carried every tool I needed in my field pants pocket. Thank goodness I had wide suspenders!! The reason I had to use this rig was simple. In 1972, the army had no money for such nonsense things for a multimeter! All the money was going to Vietnam. We were supposed to us the good old, (anyone remember it????) TS-352 multimeter. About the size of a small briefcase and as heavy as a gold ingot. There was only 3 workable TS-352's in the unit, and the radar guys needed them. So we used a light socket. Know what? I used it up until 2010 when I stopped working on 24 volt systems.
 

rivercreek

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GuyFang - funny you should ask, 'cause I just finished switching voltage regulators about 15 min ago. I've been working on the road and time has been a valuable commodity. Let me give a bit of a backstory to my question: In 2011, I bought 4 MEP 701A's at auction. I sold one, I gave one to my Mom, one to my Dad, and kept one for myself. I did well $$ wise, the one I sold paid for all 4. 5+/- years ago or so, we had one !@#$ of a storm on the East Coast (Derecho sp? I'm told) and my Mom, who lives out in Nowhere, WV called me (landlines were still up) and said her power was out and from what she had heard it would be days if not weeks before her power was restored. I hopped in the truck and made the 250 mile hike out there to try and help out. Her generator was already out there but had not been properly wired to her panel - so once I arrived I did what I had to do to get her up and running - I tripped the main and backfed her panel with her 701A. (Yes, yes, yes, I know the rules. As I said, I did what I had to do with what I had to work with at the time). As it turn out, the power was out at her place for 8-1/2 days and we ended up with much of her several neighbors frozen food in her chest freezers. This had been by far the biggest workout of any of the three generators that I kept and I must say that I was thoroughly impressed by its performance for the duration. So, to skip to the end of the story - on day 8-1/2, Mom's neighbor called, apparently rather frantically excited to inform my Mom that the power was back on. In her excitement, she ran to the main (Completely disregarding our informal safety meeting and flipped the main panel disconnect while her trusty 701A was dutifully humming away - backfeeding her panel. The rest is history, as they say. Never stalled the generator, no magic smoke that I saw or evidence thereof after the fact - but although running beautifully, no output was being produced. Several years have gone by, and I just haven't gotten around to troubleshooting this unit. As it turns out, I recently needed a 220V gen to power my welder on a jobsite to perform a few days of mobile welding. My generator (previously running flawlessly) would not put out any A/C power either for some strange reason, spI borrowed Dad's to complete the job. 31 hrs of real work on that generator and she's still purring like a ktten. So, I thought that I'd take the voltage regulator off Dad's unit and swap it with Mom's unit - which I just did this evening. Still no power, so my theory is kaput. I did check F1 and F2 per your advice prior to the swap and had no voltage between those leads. The next step per your guidance was to check K1 Ohms, and I don't seem to be getting consistent readings. Have to leave the house by 4:45AM tomorrow and hopefully will get home around 5PM and will resume testing from there. Thank you guys for your patience, I've got more work than hours in the day at this time - not that I'm complaining - just frustrated. P.S. - My generator (MEP701-A) has always performed amazingly well for me although has not been run in at least 3 years - and it will not produce any AC power either at this time by some strange coincendence. I will try and dig further into the service manual tomm eve and see what I can se. Thanks again all for your help so far. - Aaron
 

strycnine

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Maybe it's just the rotating diodes?

I had a coworker trying to swap between two 933kw generators, but the only problem was he put them both on the buss at the same time. Only thing I changed was the 6 rotation diodes and that got it back going. We were probably very lucky that's all that happened.
 

DieselAddict

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Rotating diodes should be the first place you look when troubleshooting reverse EMF damage. Seen it a LOT on grid tie systems.
 

Guyfang

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Rotating diodes should be the first place you look when troubleshooting reverse EMF damage. Seen it a LOT on grid tie systems.
Roger that. Check the diodes and windings.

You might put your fathers VR into your set, to see if it makes a difference. Or put your VR into his. You know your fathers works right.

Sadly, the small gen sets do not have a reverse power relay. If they did, your mothers set would not have been damaged
 
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