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Electronic Parts Replacements Info for the MEP-802A

K

kb3bf

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The original pads are the pink ones, notice the small tears at the corners probably due to the FET screws being too tight. Not wanting to risk a dielectric breakdown, I replaced them with the gray ones. Thermal compound was added to offer better thermal dissipation for the FETS.

The fuse holder was mounted on the regulator's bottom side, facing downwards. This was not the best choice, but the only possible one. The top side is blocked by two transformers and a pair of caps, the sides are blocked by the FETs and heat sink. I had to find the smallest 250 V type fuse holder to make it fit. A few dry runs determined where to mount it on the bottom surface.

So the goal to check the regulator out also resulted in addressing the critical fuse mod.
 

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Guyfang

Guyfang

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Thats a good solution. You will have to install it again if the VR ever goes bad. Or since you seem to know your way around electronic repair, simply repair the VR. Not everyone can do that. But still, I think its a very good solution. When I did the Quad mods for the army, I simply bent some sheet metal into some simple brackets, and screwed them to the bulkhead. Such a mod as yours is "Verboten" in the military.
 
K

kb3bf

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.........".Such a mod as yours is "Verboten" in the military"........

Thanks for your comments Guyfang.

I would have never done that type of mod while in the service, but since the generator and I are both retired from the Army due to old age, anything goes as long as it is restored back to full operation.

I'll send more images when I have addressed the remaining issues and have your sharp eyes look for any screw ups.
I am constantly cross checking the two MEPs for differences.

It's been impossible so far finding the newer S1 replacements "off the shelf", but I'll keep looking. The existing switches are still working but I can tell the plastics shafts are going to snap sooner or later, they feel very flimsy. Metal shaft is the way to go, but I am not as concerned about S6 since I will not be changing its position very often.
 
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K

kb3bf

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Thanks Kloppk,
I am aware of Daybreak's listing, but I prefer the metal shaft one since both of mine are still working, and I can wait until one breaks.
It's an item I would like to add to my replacement parts bin and not to have to worry about S1 anymore.
Did you replace S1 in yours?
 
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K

kloppk

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kb3bf said:
Kloppk,

what was the source for S1? I am still trying to figure out if there are two separate part numbers for plastic vs metal/ceramic versions.
Click to expand...
I got both of mine on flea-bay a couple of years ago. I just checked and the vendor I got my last one from is no longer a flea-bay seller.
According to my notes the 88-22829 and the 75902LV are metal shaft versions. I believe the 88-21160, CHR10-C57400, CHR10-C57400EF are the plastic shaft version.
 
K

kb3bf

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OK, at least knowing the part number assures getting the right part.
I will be checking often online and see what gives.

Many thanks for your repeated help.
 
K

kb3bf

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Guyfang,

............."If it ain't broke, don't fix it, YET.

Spend your money on what's missing first. And yes, the info in message 29 looks correct"...........

but I am taking your advice of 1-13-16:

If your start switch, S-1 is made of all plastic, I would get another switch. The replacement S-1 switch is similar to the start switch for the old MEP-002 and MEP-003's. It is made of porcelain and metal.

Take anything you can get. You can always sell things later you don't need. Having said that, the Magnetic Pickup would be something you may need later on in life. Filters need not be mentioned, as you ALWAYS need them. Both electric fuel pumps. CB-1 main AC contactor. At least one of the replaceable relays, (figure 8, item 38), the switch, (figure 8, item 37), a GFI, (figure 8, item 11) along with a volt regulator and fault indicator. Both fuel tank floats along with the the fuel float switch assy., (figure 17, item 13. All above mentioned parts can be found in the TM9-6115-642-24P. I could go on forever.
 
Guyfang

Guyfang

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OK, ok, ok.

What I mean is to concentrate on the missing and or unserviceable things. If you get a chance to pick up an S-1 switch cheap, go for it. But first make it run. If S-1 works, its good to go a while. You have time to find it. If S-6 has a broken knob, so what? The S-6 ONLY switches between the different phases, for the purpose of allowing you to monitor the voltage outputs via the volt meter, and the percent of load meter, showing what your load is on that particular phase/setting is. That's its ONLY function. It has nothing to do with switching phases, or outputs. Every reading it gives you, can be had with a multimeter. Time consuming, cumbersome, but doable. You can live without it.

Here is some backround. The S-1 and S-6 switches come in three different styles, (yes, three, not two). The first one, (mach 1) to be issued, was round, blue plastic. It had a REAL high failure rate, but normally only in dusty or sandy environments. The second one, (mach 2) was square, also blue plastic. Also high failure rate in dusty and sandy environments. The third, (mach 3) was white. plastic, porcelain and metal. Same manufacturer as the switches for the MEP-002 and 003. Super, indestructible switch. If I had a copy of FEDLOG, I could tell you all kinds of interesting info on the switch. But I don't have FEDLOG. Lots of smart guys in SS have that info. It's in several threads.

I never saw the first two types of switch break off. The only failure I ever saw, in almost 8-9 years working on the MEP-8xx series was internal problems. It failed to send voltage to the right place, or it failed to move at all. But never broke off. And that's why I said, YET.

If it breaks, or if you get a chance, replace it. But you have other fish to fry right now. Make that baby run first.

I would not toss the old switch if it worked. You never know when you might need it. Or someone else might need it.
 
K

kb3bf

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Guyfang,

I could not resist replying with your own post of 1/13/16. However I fully agree with everything you said.

The darn S1 replacement is turning out to be a bear to find.
Even the ISO Group could not locate one.

I have memorized the # and search the web when I can. I have a parts guy at work helping me with the search. We just found a 74902LV rotary switch, but while it is close to the 75902LV, it is no cigar....
I did get a new plastic S6, still in a wrapper, dirt cheap. But like you said I am in no hurry to replace it yet. Even with a broken shaft it should work; but I cant tell in what position it is in.

S1 feels awfully flimsy on the second generator, so I am babying it very very carefully.

My biggest problem has been the weather here (Mid-Atlantic). It has been raining on and off for a half a month now. When I am at home it rains, when at work sometimes it is OK.
They are predicting rain again for a third week.
My wife is asking when I am going to get the generators working and out of the way, so that I can get on more important matters (like her honey-do list).
However after the power losses we had this past winter during big snow storms she very is supportive.

I have the parts I need (I think). The V5 varistors just came in.
I may have to wait for Friday or the weekend before I can resume.
Hopefully with some (good?) news.
 
K

kb3bf

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first attempt to start the 2nd MEP.

Guyfang,

I took advantage of a couple hours of dry weather and added the last of the missing parts to the second MEP I got mid April.
So far that includes the new V5 varistor, the two 1N5406 diodes above it (on the power resistor strip), the two 1N5406 on the front panel (S1 and S5), and the 1N5406 on the terminal strip in the back compartment (5 missing diodes).
I added the 5 missing relays and S14, the Freq. Trip Switch.
I also added a new CB1 and the 30A fuse below it, and checked and reconnected the AC Voltage Regulator which luckily was not removed.

These repairs restored some functions to the front panel, but not all. I now hear the relay for the glow plugs and the Aux pump click(ing). Before it was nothing. The front panel light comes on (when switched on), but there's no power to the shutoff solenoid and main fuel pump. I can start the engine if I manually move the shutoff solenoid forward and power the main fuel pump separately.

My next step is to make sure S1 has all the voltages at the common pins, but it got dark, I could not see the pin numbers and of course it started to drizzle again. As you can see S1 is the plastic round type. Next time I am going to try to find the common pins and see what voltages are present.

This is better than expected, as the 2nd MEP was expected to be for spare parts only since I didn't think the engine would work once it had water in it. Both MEPs are 1994 vintage and have 1200hrs and 14hrs (second MEP).

Anything comes to mind?
 

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K

kb3bf

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A couple more images of the second MEP.

A pair of Ku-band dishes help keep the rainwater out of the two MEPs while repairs are ongoing.
While i replaced a lot of rusty screws with new SS ones, I got a lot more to replace.
It drives me crazy to see all the rusty hardware everywhere. I can't believe the PM did not specify SS hardware.
The new V5 varistor is now installed.
I already found two wasp nests in the MEPs so I work with a can of wasp killer next to me.
 

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K

kb3bf

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I have the diagnostic connector pinouts, and the S1 schematic details, and I am going to Kinko's to see if they can print a decent schematic.
My printer s...s big time in quality.
 
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