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Mecc Alte Spa Generator

Charlin

Registered
I would have to get the rear bracket off to remove the diode bridges. It's too small on this size head. All I did was remove each lead from the diode one at a time and test. I had to turn the engine over by hand to get to all the leads.

One meter lead on disconnected diode lead, and other meter lead on the diode bridge. All tested good that way.

I found this manual while searching around online. https://www.meccalte.com/downloads/Series_ECP_EN.pdf This is for an ECP, mine is an ECO. If you look at section 9.5.2 mine is the 28 series, but the diode bridge looks like the one beside it, by the 34 series. The directions state how to test the (T30)
diode bridge.

My manual states I have the (T30) diode bridges like shown on the 34 series in the above manual. They look the same anyway. Do you think that test was accurate? I'm starting to think that testing one diode with the other side still connected on the same bridge may have given me a false reading.

I'll upload a picture from my manual and the rear of the machine to give a better idea. My manual also states that I should be getting a high
resistance reading one direction, and a low reading the other direction, which is what I've always been told about testing diodes.

I didn't get that, I got anywhere from .446 to .455 in one direction and nothing in the other. My meter did beep once, which is supposed to
mean a good diode.
Rear_Gen.jpgManual_page.jpg
 

Birken Vogt

Registered
If you are testing any device, leaving only one lead connected will not mess with anything. Your test was likely a good test. My Fluke showed about .480-.500 volts per diode on this unit. But in your picture there it looks like if you remove the 3 screws per bridge they will come right out. Pay attention to the plastic insulating washers on the side screws that you put them back in the right order. Diode plate-washer-terminals-screw head, they are just there to mechanically hold the sides of the plates and provide a handy point to terminate the wires, they are not to be electrically connected to the plate. Even if you don't remove the plates you can still do the tests I described, you can see where the wires dive back in to go to the main rotor for that test and the diode plates themselves are the outputs of the AC exciter windings.
 

Charlin

Registered
Okay, I was finally able to get back to this. First off, do all the wires on each diode pack need to be disconnected at the same time?
I manually turned the engine to line up the top pack, it is easy to get to the whole pack that way. If all the wires need to be disconnected I can
manually turn the engine and get to them.

I did remove the exciter rotor phase wires from all and tested. I tested the resistance between each of those wires, resistance was .06 which
is fine per that info sheet. Did I do that correctly?

I then clipped leads to the exciter rotor wires and put 12 volts to blue-yellow. The meter showed a reading but was not a steady reading
of 12 volts, kinda just bounced around but under a volt. I only touched them for a second. I went around from one to another, black lead
on one rotor phase wire red on another. Was this correct? I did get an arc on the blue-yellow up top when touched with battery.

Now on the rest of that test, you lost me. (Then check the wires that tie all 3 positives and all 3 negatives to the actual red/black (green?) that go up to the main field. I just can't figure that one out. Then test ohms on main field? Where is the main field? You'll have to excuse me, I'm slow learning at
stuff I'm not familiar with. I did end up removing that one diode pack to see what it was like in case I had to remove the rest, now I have to go look
for small brass washers in there I dropped. Thanks for taking the time to help Birken Vogt.
Diode_Pack.jpg
 

Birken Vogt

Registered
All the positives (red) and all the negatives (green or black) from the 3 diode packs are tied together and then they go to a pair of wires that disappear down the center shaft to the main field.

So if you apply battery to those main field wires you should get a similar bounce out of the main output.

When doing the zap test all you need to do is hold DC on for half a second or so. The output metering will bounce once when you apply DC and again when you remove it. If you hold it steady you will see nothing during that time.
 

Charlin

Registered
There are red and green on the diode packs. Do I apply battery to each red and each green one at a time or put all three reds- greens together
and zap?
 

Charlin

Registered
I should have been more specific. Jump all greens together, then jump all reds together, then positive battery to reds, negative battery to greens
then zap? Or zap one diode pack at a time with meter on main output?
 

Birken Vogt

Registered
All the reds and all the greens should be connected together with jumpers already and then go on to the main field so if you just hit them with battery without disconnecting anything it should also be the same. Red is positive and black/green is negative.
 

Charlin

Registered
I got interrupted earlier and just started back on it. I see that they are all connected now. One of the diode packs has red and green connected
on the same side. The other side is only red. Does this sound normal? If red and green are on the same side and red on the other where woukd I connect the negative to zap with battery? I'll upload pictures. Under my thumb are the ring terminals that go on the diode pack.
Red_Green_Diode.jpgRed_Wire_Diode.jpg
 

Birken Vogt

Registered
I don't quite understand the question but on the one I just finished, there was a red and a green jumper with 3 ring terminals each running around to all the positive and negative terminals respectively. And then a larger red and green wire that came off neighboring bridges and disappeared to go the main field on 2 of the screw terminals.
 

Charlin

Registered
On two of the bridges there is a red wire, and a smaller red wire on one side, and a green on the other. On the bridge in the picture above,
there is a red and green wire on one side together, and only a red on the other side. That's what has me confused.
 

Birken Vogt

Registered
You better draw a sketch of how it is laid out because it is hard enough on one of these to see what is going on because everything is so cramped, let alone cell phone pictures over the internet...
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
A red and green wire on the same terminal? That seems suspicious. Has this ever worked since you have had it?
 

Charlin

Registered
A red and green wire on the same terminal? That seems suspicious. Has this ever worked since you have had it?
Yes, I bought it new 15 years ago. It worked fine up until last week. It doesn't have many hours on it at all, and I mean probably less than 50.
I bought it after hurricane season in 04 when my area got nailed 3 times in a row. Three storms like two and three weeks apart. After I bought
it I've been lucky and never really needed it. We've had quite a few hurricanes since, but none have affected me bad.
 

Charlin

Registered
You better draw a sketch of how it is laid out because it is hard enough on one of these to see what is going on because everything is so cramped, let alone cell phone pictures over the internet...
Birken, I don't know if I can draw a sketch of what is in there. It is so tight like you said, I loose track of the wires as they go around that back area.
All I know is that one diode bridge has a red and green wire on one side, and the other two don't. I'll try to use a small mirror to look in there.
Maybe I can see how the wires go around that back end.
 

Birken Vogt

Registered
Your pictures look good, maybe rotate it to 3 different positions where the break between the bridges is up and center and the wires visible and maybe I can interpret if you take 3 pictures of that.
 

Charlin

Registered
I took two of the diode bridges out to see if I could get a better look. What I found, there are two red wires coming from the inside of the
generator. One red has a blue clip on it. That is the one that is on the same diode terminal with the green wire.

The other red wire has a red clip on it marked with a positive plus. So all the greens are jumped together and go up into the generator on
that one red wire with the blue clip, and all the reds are jumped together and go into the generator on the red with a positive.

So I'm assuming that is the +and- I'm am looking for. They just used two reds with those clips instead of different colored wires.
Picture_1_L.jpg
 

Vanman

Subscriber
Last Subscription Date
06/10/2020
Is that one ring terminal in the photo burned where the wire connects to it?
 

Charlin

Registered
No it's black paint. If you look at the picture of the back with the cover off you can see black lines. That is where the paint went through
the louvered cover. I did find a loose ring terminal when I was twisting on the wires. I crimped it tight, I don't know if that would have cause
this problem. I doubt it, but it would be kinda funny if that's all it was.
 

Charlin

Registered
I went ahead and applied 12 volts to those two wires that go into the generator. I did get a pulse on the meter. Now I'm not sure where to
test the ohms on the main field?
 

Birken Vogt

Registered
Well if you have pulsed the exciter stator and gotten pulses out of the exciter rotor, and all the diodes are good, and you have pulsed the main rotor and gotten a pulse out of the main output, then the generator is working, and all you have to do is put it all back together and it will work.

Ha, ha. Problems like this are what make men go bald. Find out where the problem lies and fix it is all I can say...maybe hook it up to one of the $20 SX460s and see if it works on that...I don't know what else to say....
 
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