MEP 802a/803a reliability in the field

[Guyfang]

Dusting off an old thread here and I've made good progress on this list of spares.

My question is for Guyfang. What part are you referencing with item 2 of your list "plastic relay"? Is this the relay socket that the wires connect to and the relays plug in to?

Thanks,

-Craig

Roger. They can be bought on line, or, bought from SS member Kurt Klopp, cheaper.

 

[kloppk]

I believe Guy's post mentioning "Plastic Relay" was referring to the relay common to the row of relays behind the control panel.
Specifically K12, K15, K16, K19 & K20
They are all KUP-14D15-24 Potter & Brumfield relays
S14 is the oddball Frequency Trip Switch (of which you have 2 heading your way)

 

[cbisson]

I believe Guy's post mentioning "Plastic Relay" was referring to the relay common to the row of relays behind the control panel.
Specifically K12, K15, K16, K19 & K20
They are all KUP-14D15-24 Potter & Brumfield relays
S14 is the oddball Frequency Trip Switch (of which you have 2 heading your way)
View attachment 823009

Thank you Kurt. I received the 2 S14 trip switches yesterday. I will acquire a couple of the KUP-14D15-24 Potter & Brumfield relays and add them to the spares stash. You don't happen to know the function of each of them off the top of your head do you? Is their a supplier you'd recommend for the relays?

Thank you again for making these quality and affordable OE replacements. I already have a spare A1 but plan to add one of your replacement VRs for the ability to function with defective quad windings.

 

[kloppk]

Here is an updated picture with the function labelled on top of each relay.
S14 is the Frequency Trip Switch. Responsible for sensing when engine RPM > 900 RPM. Causes K16 to open and close.
K12 is the Fault relay. It activates if the sets Fault Monitor detects a fault. Causes set to shut down if it trips.
K15 is the Field Flash relay. When active it causes the sets generator head to be flashed.
K16 is the Crank disconnect relay. This disables the starter once the engine RPM is > 900 RPM. It also enables field flashing.
K19 is the Fuel Level Relay. This trips when the fuel level drops really low causing the set to shut down.
K20 is the Oil Pressure (OP) relay. It closes when there is sufficient oil pressure. If the OP drops too low it trips causing the set to shut down.

K20 is the only "acitve" relay once the set has started and is running.
All the other relays are inactive once the set has started and is running.

I buy a bulk of my parts from DigiKey. Link to relay available at Digikey: Relay on DigiKey
There are many other parts suppliers that it can be purchased from too.

Used ones are available on ebay for a little less money.

I have plenty of the Voltage Regulators when you decide you'd like to add one to your spares kit.

 

[cbisson]

Here is an updated picture with the function labelled on top of each relay.
S14 is the Frequency Trip Switch. Responsible for sensing when engine RPM > 900 RPM. Causes K16 to open and close.
K12 is the Fault relay. It activates if the sets Fault Monitor detects a fault. Causes set to shut down if it trips.
K15 is the Field Flash relay. When active it causes the sets generator head to be flashed.
K16 is the Crank disconnect relay. This disables the starter once the engine RPM is > 900 RPM. It also enables field flashing.
K19 is the Fuel Level Relay. This trips when the fuel level drops really low causing the set to shut down.
K20 is the Oil Pressure (OP) relay. It closes when there is sufficient oil pressure. If the OP drops too low it trips causing the set to shut down.

K20 is the only "acitve" relay once the set has started and is running.
All the other relays are inactive once the set has started and is running.

I buy a bulk of my parts from DigiKey. Link to relay available at Digikey: Relay on DigiKey
There are many other parts suppliers that it can be purchased from too.

Used ones are available on ebay for a little less money.

I have plenty of the Voltage Regulators when you decide you'd like to add one to your spares kit.
View attachment 823047

Thanks again for the detailed response.

-Craig

 

[cbisson]

One time I was to be inspected, by the Brigade IG. Inspector General. One of the big no, no's is "Excess". It took two trips with an M35 truck to haul off all my "Nice to have" stuff.

1 ea. A1 Volt reg
1 ea. Plastic relay
1 ea. 24 volt alternator
1 ea. K4
1 ea. K1
1 ea. K2
1 ea. K8
1 ea. S14
1 ea. A9
Diodes for the main gen
1 ea. LOP
1 ea. Engine over temp switch
1 ea. MPU
1 ea. Water pump and gaskets
1 ea. set of injector pumps and injectors
1 ea. Starter
1 ea. E1 and E2 fuel pump
1 ea. package of both fuses needed.
And what you already have. If I looked long enough at this screen, the list would grow. Some things I did not add, as anyone who is a competent mechanic, should be able to hay seed fix. Like the throttle cable, or defective S17. Things like that.

I'm looking through the wiring diagrams, the -24P, etc and I can't find anywhere that directly cross references a component designation (K4) to a part number. I get the description from the wiring diagram like "overvoltage relay" but I can't translate that description to a part number. The descriptions in the -24P in many cases are generic such as "electromagnetic relay". Is there anywhere that directly cross references the wiring diagram references to a part number such as K4 = overvoltage relay = part #

Thanks

 

[kloppk]

K4 is the Overvoltage Relay. It's actually one of the black box's bolted down behind the control panel. It's the first black box to the left of S14.

... Is there anywhere that directly cross references the wiring diagram references to a part number such as K4 = overvoltage relay = part #

Not that I'm aware of. Sometimes you have to piece the info together using the -24 and -24P.
There is a table in the -24 in the schematics that does indicate K4 is the Overvoltage relay.
In the -24 removing K4 it indicates.. "Tag and disconnect overvoltage relay (30, Figure 2-11) electrical leads."
If you go to figure 2-11 item 30 you can see what part in the diagram is K4.
From there you can go to the -24P, look at the corresponding parts diagram, locate the same box and then scroll down to the parts table to get the PN.
If you search the -24P with that PN you'll then get the NSN number.

It looks like this...

 

[Guyfang]

K4 is the Overvoltage Relay. It's actually one of the black box's bolted down behind the control panel. It's the first black box to the left of S14.


Not that I'm aware of. Sometimes you have to piece the info together using the -24 and -24P.
There is a table in the -24 in the schematics that does indicate K4 is the Overvoltage relay.
In the -24 removing K4 it indicates.. "Tag and disconnect overvoltage relay (30, Figure 2-11) electrical leads."
If you go to figure 2-11 item 30 you can see what part in the diagram is K4.
From there you can go to the -24P, look at the corresponding parts diagram, locate the same box and then scroll down to the parts table to get the PN.
If you search the -24P with that PN you'll then get the NSN number.

It looks like this...
View attachment 823138

Here are a few other helpful hints. When you open your control panel and look at the K4, its marked with the part #88-21139. Open the -24P. Go to the rear of the TM. Go to the Cross Reference Indexes National Stock Number Index, Section IV. Its listed in alpha numerical sequence. Scan down until you see part #88-21139. Look to the right. It tells you Figure number and Item number. In this case, Figure #8, item #5. Simple. It also tells you the NSN as well as the FSCM, (supplier of that item)

Now lets say you have the -24P in front of you. If you go to the CROSS-REFERENCE INDEXES
FIGURE AND ITEM NUMBER INDEX, Section IV, it is listed by the figure # and then Item #. It gives you the same info as the above listed reference.

Now, lets say you are holding a K4 in your hand. The part number is not viable. BUT, lets say its new, in the box. You have an NSN. Go to the CROSS REFERENCE INDEXES NATIONAL STOCK NUMBER INDEX, Section IV. It lists all the NSN's (in NIN sequence, that means you ignore the first 4 numbers) and, you guessed it, the figure # and Item # are listed there!

You are of course right. That info should be listed next to the parts call out listing, next to the figure. And in fact, it is in SOME books, for SOME equipment. That's the problem when you have 6 different commands writing the TM's. Everyone thinks their way is best. The info is there, you just need to look closer in the books. I quickly decided to make a list for each gen set. List all that kind of info. AND, when a change came out, I could change my list ASAP. The Military changes TM's almost as often as we have world killer asteroid strikes. AND, I can add sub part # and sub NSN's to my list. Some parts have from 2-50 sub numbers.

Attached is a parts listing for most of the stuff I found that I needed mostly, for the MEP-803A. If you take a look, there is much more info then it seems at first.

 

[cbisson]

K4 is the Overvoltage Relay. It's actually one of the black box's bolted down behind the control panel. It's the first black box to the left of S14.


Not that I'm aware of. Sometimes you have to piece the info together using the -24 and -24P.
There is a table in the -24 in the schematics that does indicate K4 is the Overvoltage relay.
In the -24 removing K4 it indicates.. "Tag and disconnect overvoltage relay (30, Figure 2-11) electrical leads."
If you go to figure 2-11 item 30 you can see what part in the diagram is K4.
From there you can go to the -24P, look at the corresponding parts diagram, locate the same box and then scroll down to the parts table to get the PN.
If you search the -24P with that PN you'll then get the NSN number.

It looks like this...
View attachment 823138

Thank you Kurt, I have been using the method you've described..... was just hoping that there was a cross reference that I hadn't found.

 

[cbisson]

Here are a few other helpful hints. When you open your control panel and look at the K4, its marked with the part #88-21139. Open the -24P. Go to the rear of the TM. Go to the Cross Reference Indexes National Stock Number Index, Section IV. Its listed in alpha numerical sequence. Scan down until you see part #88-21139. Look to the right. It tells you Figure number and Item number. In this case, Figure #8, item #5. Simple. It also tells you the NSN as well as the FSCM, (supplier of that item)

Now lets say you have the -24P in front of you. If you go to the CROSS-REFERENCE INDEXES
FIGURE AND ITEM NUMBER INDEX, Section IV, it is listed by the figure # and then Item #. It gives you the same info as the above listed reference.

Now, lets say you are holding a K4 in your hand. The part number is not viable. BUT, lets say its new, in the box. You have an NSN. Go to the CROSS REFERENCE INDEXES NATIONAL STOCK NUMBER INDEX, Section IV. It lists all the NSN's (in NIN sequence, that means you ignore the first 4 numbers) and, you guessed it, the figure # and Item # are listed there!

You are of course right. That info should be listed next to the parts call out listing, next to the figure. And in fact, it is in SOME books, for SOME equipment. That's the problem when you have 6 different commands writing the TM's. Everyone thinks their way is best. The info is there, you just need to look closer in the books. I quickly decided to make a list for each gen set. List all that kind of info. AND, when a change came out, I could change my list ASAP. The Military changes TM's almost as often as we have world killer asteroid strikes. AND, I can add sub part # and sub NSN's to my list. Some parts have from 2-50 sub numbers.

Attached is a parts listing for most of the stuff I found that I needed mostly, for the MEP-803A. If you take a look, there is much more info then it seems at first.

Guyfang, once again you have hit it out of the park!!!! This is perfect and represents a lot of work. Thank you!! I will be sure to verify, since this is specific to the 803, that the parts are in fact common to the 802. I suspect that most parts are common, but some will certainly be model specific.

 

[Guyfang]

99.95% are the same. Do look at this attachment if you want to compare. You may also find parts that are the same, but have another NSN or part#.