MEP803a tripping overload fault while other unit chugs along no problems.

I've got one unit that runs fine with two 5400w dryer elements connected in parallel but my other one is tripping the overload circuit within a minute or so of loading it down.

S8 was gritty as **** and presented a volt meter problem when I first got the unit and the unit has had work done on it concerning the the main generator wiring. I cleaned S8 and resolved the volt meter issue but now having issues with the unit holding power under a 3/4 load.

I'll try cleaning S8 again using Deoxit and see where that leads me.

Note: This unit was saturated with gritty dust throughout and required a thorough cleaning and compressed air to even be presentable.

Soak, cycle dozens of times, soak, cycle a dozen times, soak, drink a beer, cycle, soak... that Deoxit is great stuff. Clean until you get tired of cleaning. If it were me, I would also be cleaning all of the terminal board connections in that same rear control area at the same time!

Light in the Dark said:

Soak, cycle dozens of times, soak, cycle a dozen times, soak, drink a beer, cycle, soak... that Deoxit is great stuff. Clean until you get tired of cleaning. If it were me, I would also be cleaning all of the terminal board connections in that same rear control area at the same time!

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Thanks and will do. My wife was going to town and I put four cans of Deoxit on the shopping
list.

The switch might be bad too... but its more likely a corrosion/contamination issue.

Saw several S8's in the big auction site one for 85 smackers. Old style, but still, whats a can of deox cost times how many you have used and figure out how many hours invested in the old switch?

Guyfang said:

Saw several S8's in the big auction site one for 85 smackers. Old style, but still, whats a can of deox cost times how many you have used and figure out how many hours invested in the old switch?

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Yes it reaches a point of diminished returns at some point but I figure it's worth a try considering that a cleaning resolved my volt meter issue a short while ago. I'll try it once more and see what happens then probably go for a new switch.

Update: I used a can of CRC cleaner on the S8 switch and exercised it thoroughly. Hooked up my dryer element loads and tried it again....no dice. Still faulting with an overload fault showing on the fault panel. The ammeter DID start working however but was pegging to the right. I cut the load in half (5400w and it was reading @ 75% load.....which I know is wrong. I shut the set down and could faintly smell electrical burning smell.


I spent the rest of the morning checking the wiring connections point to point according to the schematic. While looking at a connection on the under side of S8 using a mirror and a bright LED Maglight I noticed that the contacts on connection #28 of S8 were burnt to a crisp. Most of one contact was missing, lots of evidence of heating and arching. There's no question that S8 has to be replaced at this point and have a couple coming(Thanks Guyfang for the reference on the bay).

I'll replace S8 when the new one arrives and update further.

Thanks to Light in the Dark and Guyfang for your suggestions.....both were correct.

I wonder if you cleaned out something that was preventing the burn up prior (so the current again flowed properly after cleaning) or if the burn up was present, but its time was just up to be discovered.

Guyfang said:

		S8 Switch Terminals
From	Wire #	Wire #	From
TB3-2	002A	2	43	176C	P6-12
TB3-8	008A	3	44	162B	P6-7
TB3-10	010A	8	45	160B	P6-8
TB3-4	004A	9	46	177B	P6-10
TB4-1	167B	13	47	175B	P6-9
P6-32	179B	14	L1	001A	TB3-1
TB3-6	006A	20	L1	001B	K1-A1
TB3-7	007A	22	L2	002B	K1-B1
TB3-12	012A	26	L3	003A	TB3-3
TB3-5	005A	32	L3	003B	K1-C1
TB3-11	011A	36	L0	006D	TB4-4
TB3-9	009A	38	L0	006B	TB2-L0
TB4-1	167A	41

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TB-3 connection 12 is one leg of a winding used in the 120/240v circuit so that would account for it being overloaded and not being able to carry the full load as only two windings in the generator were active, the third making only
partial or no contact due to the burnt S8 contacts on terminal 28. From the S8 schedule, 120/240 single phase, terminal 28 is active in the circuit along with terminals 26, 25, 21 to L1.

Light in the Dark said:

I wonder if you cleaned out something that was preventing the burn up prior (so the current again flowed properly after cleaning) or if the burn up was present, but its time was just up to be discovered.

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I'm positive that the burnt contact was there all along and causing my fault. The set would run without fault on a lesser load of 5400w. It was difficult if even possible to get the spray under the switch I think my cleaning had little effect on that aspect of it. It did however clean the terminal that enabled the ammeter to work.

Guyfang said:

		S8 Switch Terminals
From	Wire #	Wire #	From
TB3-2	002A	2	43	176C	P6-12
TB3-8	008A	3	44	162B	P6-7
TB3-10	010A	8	45	160B	P6-8
TB3-4	004A	9	46	177B	P6-10
TB4-1	167B	13	47	175B	P6-9
P6-32	179B	14	L1	001A	TB3-1
TB3-6	006A	20	L1	001B	K1-A1
TB3-7	007A	22	L2	002B	K1-B1
TB3-12	012A	26	L3	003A	TB3-3
TB3-5	005A	32	L3	003B	K1-C1
TB3-11	011A	36	L0	006D	TB4-4
TB3-9	009A	38	L0	006B	TB2-L0
TB4-1	167A	41

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Am I missing something? Is one of your columns mislabeled? Is the third column supposed to be "terminal" for S8?

Should have looked like this. For some reason I can not get it to look like it should.View attachment Scan_0001.pdf

Guyfang said:

Should have looked like this. For some reason I can not get it to look like it should.View attachment 724830

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Thanks, I thought I was losing it for a minute! You sent me scouring the schematics for other designations....which isn't a bad thing really.
I think I've narrowed it down to the bad switch....it has seen better days.

I sent you the listing, for when you get the new switch. Never, ever, just mark the wires and disconnect them. If someone else hooked up something wrong, you just repeated his mistake.

Guyfang said:

I sent you the listing, for when you get the new switch. Never, ever, just mark the wires and disconnect them. If someone else hooked up something wrong, you just repeated his mistake.

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Yes I understand that completely and will follow the list. Is that page in a manual or is that of your own design?

There is wiring in the set that has sharpie marker on them but I went through it this morning and cleaned, tightened and verified the connections by the wire numbers and point to point via the schematic. That's when I observed the burnt contacts.

Thanks once again for your assistance!

Something I made up. I am trying to do the whole wire diagram that way.

Guyfang said:

Something I made up. I am trying to do the whole wire diagram that way.

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That would be very helpful to all concerned! I appreciate your efforts very much.

I should not have written "I". Its a "WE" project. Chris Medico is also involved in this project. Its just a very big PITA. Every once in a while I ask a member to check something on a gen set, as I do not have one to look at. So don't be surprised If I ask you!

Guyfang said:

I should not have written "I". Its a "WE" project. Chris Medico is also involved in this project. Its just a very big PITA. Every once in a while I ask a member to check something on a gen set, as I do not have one to look at. So don't be surprised If I ask you!

Click to expand...

No problem, I'd be glad to help if I can, just say the word.