Need help 003a in previously perfect condition stopped producing power.

[storeman]

Guys,
Electronics is my admitted weak suit (among others). By way of background, I bought a laundry unit early this year which had been in storage and contained a mep-003A with only 54 original hours, 1991 model on a 1991 laundry unit. Generator ran like a dream until the day SS website went down.

On that day I installed a battery isolator switch to the negative battery cable, patterning it off the unit I removed the switch from (which still runs great). In the process of installing the switch I arc'd the negative cable twice to the hold down frame (tiny sparks). On completion of switch installation I restarted the unit and no power. Did the following per TM:

(1) Isolate the trouble to generator or regulator.
Discomect the voltage regulator at the exciter (wires
P67C16 at TB3-5 and P60E16 at TB3-6). Connect a 12
volt battery in place of the regulator with the (+)
terminal to TB3-6 and (-) terminal to TB3-5. Run the
engine with the battery in place of the voltage regulator.
If there is output now, the voltage regulator is
bad. If there is no output, the main alternator is bad.

No power off the 12 volt battery, so....if TM is to be believed, my AC VR is fine but my little shorts killed the main alternator (gen head). I have had similar arcs in the past with no effect. I hate to tear into the diodes and other fearful areas. 10 amp fuse is fine on the DC side in case you wonder and should have no effect anyway.

I then removed the switch and returned the unit to original configuration. No change, still no juice.

Does anyone have any suggestions? I can't see how this experience could have caused damage anywhere except possibly the AC VR. I am not too hot on the idea of testing it either but will do whatever unless someone raises their hand.

Thanks in advance for the sage advice which I'm sure will spew forth. Golly, I'm glad this board is back up! Cheers Patracy!

Jerry

 

[Isaac-1]

Where are you checking for power, have you manually tripped and reset all breakers?

Ike

ps particularly try tripping and resetting the AC push to reset breaker by the front panel outlet

 

[storeman]

Ike,
Was watching gauges and tried convenience plug after resetting it. I reset the main breaker but it shouldn't have impact on convenience plug. Did not try the lugs. All meters working before the incident. Thanks.
Jerry

 

[storeman]

bump

 

[dangier]

Jerry, may just have been a coincidence that something died the same time. You tried a 12v battery on the exciter. How about taking an ohm reading on the exciter wires through the gen head. You worked with the wiring, there may be a loose connection that comes and goes. I can't imagine your work as described burning out the gen head.
I accidentally hooked up booster cables up backwards and all it did (other than sparks), was to blow the dc reg fuse.
David

 

[storeman]

David,
I'll try that as soon as possible. Wife has me all wrapped up in a 70th b-day celebration Saturday which I didn't ask for.

I also can't visualize my actions on the battery disconnect switch doing any significant damage. Thanks.
Jerry

 

[dangier]

Jerry

Happy Birthday!!

I couldn't resist......

David

 

[gimpyrobb]

Speaking of all wrapped up...

 

[kipman]

Gimp, looks DH is staring at the present.

 

[jbk]

i would meter the a/c output lugs. just to see if its just the gauges. if you lose that ground strap for the control box you will lose all but your dc gauge.

 

[Jimc]

hmmm, i highly doubt a little arc is going to fry the gen end. its something else. other than the simple things like breakers, etc its hard for me to give advice on the electrical side of things without it in front of me. maybe some of the other guys will chime in


happy birthday!

 

[aheilmann68]

I had my positive line from the batteries decide to contact the frame and everything stopped especially the fuel pumps. Turns out the ground strap that is right under the control panel cooked and lost continuity dropping my ground. I also had a field flashing issue and had the a-4 diodes cook. I traced back to them when I was able to flash the field with 12v

 

[n1oty]

Jerry,

Are you getting 24 volts DC on the separate cannon plug going to the field flash diodes???

John

 

[Jimc]

i wouldnt doubt for a minute that there was a poor ground somewhere and the arc finally did it in completely. continuity through all the cases, components and framework on these generators are very important. usually all the nuts and star washers are so rusty and corroded on every one i have ever seen that problems seem inevitable. going back to my rebuild threads, this is why i replace about every nut bot and washer with new and use copper never seize on everything.

hey not for nothin jerry but when you were messin with your batteries, there is a ground cable that runs from the batteries over to the slave connector and down to the split bolt on the frame for the ground. did you hook that back up? if you dont have a ground going from the batteries down to the actual skid strange things will happen.

 

[storeman]

Thanks to all.

JBK (Jim) DC gauge is working. I haven't had time to follow through on the other recommendations, but will.

Jimc, You may have just hit on it. As I recall, on that infamous day, I made a few other changes on my to-do list to comply with a long list of things I'd been noting from the board and my own observations. When is comes to electricity, I often get it wrong.

I've long been operating these units on 4 wires with 1 each to L1 and 3 and the neutral and ground to L0. Never had an issue. That day, in addition to installing the battery isolator switch, I removed the ground to frame by cutting the wire which (as I understood it) was recommended and taped it off. I ran the ground wire from the house connection to the frame as I understood to be correct. Apparently I misunderstood the many postings on that subject.

Do I need to reconstruct what I cut? If so, no problem, I think. What did I miss on the correct ground and neutral house connection issue? I'm sure my generator ground wire is attached to the frame and to the house ground.

BTW: Also did the same with the 002A and it is working.

Jerry

 

[Jimc]

ok from my understanding when connecting a gen to a house, the house/panel is already grounded so you do not install a grounding rod or anything like that on the gen side because you would then have a double ground. the gen should pickup the ground through L0, the 4th wire through your plug to the house. the gen would need its own ground when used as a stand alone unit like a job site/field use or something like that. now on the gen you have a ground from your batteries going to the starter then another going up front under the control box to the frame/slave connector. that needs to be in place or many things wont work....usually. this is because there may not be a good ground from the starter to the eng block. there is usually enough resistance there to cause an issue but could depend on the starter. i know i dont have good continuity from the ground stud on any of my starters to the starter case. if that is poor or non existent then the block is the same and that follows through the ground strap and into the frame. so.... the only way the skid or any of the case grounded components that bolt to the skid, like fuel pumps get their ground is through that wire from the batt neg to the ground stud/split bolt under the control box. you can also add a jumper from the starter ground stud to the block. this will work as well. you can easily take a multimeter and put it on continuity and check from the neg batt post to the eng, skid, all control cases, etc to see if your grounds are good or have continuity through all the gen components.

 

[Munchies]

You did what we were talking about regarding the neutral?
Yes, and to confirm.
1. Remove the large diameter cable that comes from the re connection box to the back of the ground terminal (1/2'' deep well socket here). Tape it up.
2. l1 and l3 are your two 120v legs as always.
3. l0 is your NEUTRAL..... Only the neutral.
4. Ground to ground.

 

[Chainbreaker]

Also, for peace of mind it would not hurt to open up your inlet box (assuming you are using one) and verify your gnd connection is solid . My inlet box had a wire nut from house gnd wire to pig tail into connector. I opted to eliminate wire nut and change it to hook up via the gnd lug already present inside inlet box as that is a more secure gnd connection. I also used contact cleaner on all the male terminals at connector. In this configuration you are extremely dependent on good ground connections all the way from chassis to house gnd.

Remember that if you do any offline testing (not powering house) to remain plugged into house (breaker off) or you lose your chassis gnd. Not good! Otherwise you would need to revert back to a SDS (self derived system) configuration with a driven gnd rod and genset neutral reconnected when testing if necessary to be disconnected from house.

 

[Munchies]

You have another reconnection box you can swap over? Pretty quick swap, four bolts, and 3 amphenol connectors.

 

[storeman]

Munchies, I wish I did have another but will get to the troubleshooting suggestions after the weekend.
Jerry