RIGHT (in NORMAL CASES), but we try to search, what is real problem in Your system, so it then needs some other measurements, like current and also insulation. Put ampere meter in 10A scale(not smaler!!!) (in DC surely) between regulator output + terminal and battery + terminal to see, is it really charcing or no. Amperes are now more important, than voltage! Make good connections with meter and start bike to see, is it really charching, or no.

If U use digital meter, check polarity of meter and look, what direction current flow!!!!!. U cant destroy digital meter with wrong polarity in ampre scale, but its important to know current DIRECTION with right poles in meter....

As I told, dont be in any hurry with this !!!!!!! Ask, if You dont understand something. much better that way... take a time......

On the last few days, with a friend of mine mechanic, I tried to solve the problem.
I have replaced those bad regulator's connections (melted) and I kept the connections under the tank which were in good shape.
No matter, I sprayed all the connections (under the dashboard, too) with plentiful dielectric oil.
Finally, today I reassembled the bike and when I started the engine the battery lamp was blinking.
After only few kms, she turned on, but weak and, when I went on the motorway, when I just taken a look to the dashboard, she was fully switched off.
I stopped the engine and started again, but the damned lamp started to work as should.
So, I don't know what I did , I wonder if my work was useful , if she would have turned off by herself , if she'll keep on work as should, etc.
By now, she's off...
Ciao

Cool down little Frankie! I know very well, that fighting with such problems are sometimes very hard (i have to do such every day in my work with electrics...).... I want to give next advice: Put both Ampere meter(in ab.20A scale) to those wires, what are going to battery from regualtor AND also one Voltage meter to battery terminals.... Run bike from idle to higher RPMs(in street) and MAKE NOTES, what is going on.... If battery is in normal condition(!!!! Did U check it in close car battery maintain place?), then starting of bike will take some current from battery=> Voltage goes lower, maybe under 12.5V. When bike reach normal temperature, battery will be charged enough, then voltage should be over 12.5V!!! Then start drive and look then voltage: it should go upper and stay between 12.5-14.7V and current goes whole time lower, when battery charge more and battery voltage goes up to end (ab.14.5V)..... If all function, like shopuld with ampre and volate meters, then You can forget 120% that warning light !!!!! But if it doesnt charge enough(voltage and Ampres), then You have failed regulator..... I know these thiongs are not so simple to understand, but measurements will show what is wrong... As they say in Electrex fault finding diagram, sometimes it needs MORE measurements !!! Only ampere meter and voltage meter will show, is it REALLY charhing, or no. IF NO, then You have to check all connectors and maybe change regulator....

Come to here with Your bike and we put meters to Your bike and "listen" what is going on...

Is your battery 100% ok?

U told, that You cleaned and welded some connectors, are U 100% sure, that ALL was done?

It can also be, that stator have failed, that it dont give enough power(current) to regulator. that can measured by some insulation and resistance measurements....

I am little drunked, so, i cant give full quarantee, what i have written, sorry... Anyway You are welcome to Finland with Your 907 charge problems

At end: If it charge battery, then DONT WORRY about warning light and then that warning light "feed" from regulator have failed......

Take bike to such guy, who have 2 multimeters to put ampere meter(ab. 20A scale) between regulator output and battery PLUS terminal AND voltage meter to battery terminals to see, what is happening in voltage.... that can tell 100% is it charching, or no... very simple...

RED one.

Its coming out from regulator in 2 red wires and in first connector feed only one red to battery PLUS terminal via 30A main fuse located in left side of rear panel. Easiest way to connect Ampere meter is to put it to main fuse(30A) place with some good connections/connectors. That main fuse in just between battery + and regulator output, but U have to be 100% of connection then, cause fuse is not then in its place, so its important to use right scale in meter wire must be connected to right meter poles! If battery is in good charge, then 20A scale in meter can be very good.... Well charged battery would NOT take more, than 20A. So, for ampere meter replace main fuse with A-meter in 20A scale..... Check also, that meter is in DC area. Meter polarity U dont have to think, its not important, cause current dont go back to regulator from battery, only TO battery.

Btw, Yellow wires are coming FROM stator.

Note, these colours are for OEM Ducati regulator.

Now, it's all clear!!!
Sorry, I'm a little bit slow in such things, even if the friend of mine (mechanic) is not too much skillful too... .
Many thanks .
Come there, still great weather to make trips on bike.
Unfortunately, I can't now because of a pain in the shoulder.
Ciao

I pray, that Your shoulder and your 907 recover very soon....

Btw, seems. taht driving season is over now here, cause temperature fall next night first time under 0 Celcius.....

Here the temperature is still about 15/17 C.

Can you believe that on my red 907 the battery light doesn't switch on with the engine off????
GGGGRRRRRRRRRR!!!!!!!!!!!!!!!!!!
Ciao

Check warning light bulb in dashboard ! Take it off and measure with resistance scale in multimeter. If broken, then huge number of ohms, but if its ok, then only very small ohms.