Transformer of Unknown Rating

We had this old NM-CD AA, AAA, and 9V -All-In-One Battery Charger. Its very old and is currently not anymore working. I wanted to know the rating of the Transformer inside it so i can reuse it for future projects, BUT, there aren't any part numbers or anything written on this transformer.. so how do you find out a rating of a transformer if you only have as far as a multimeter and internet?...

I'm sure this isn't a 220v-110v, but probably to lower voltages.



The two blue thicker wires went straight to 220V AC mains on the charger's design. The PCB beside it was previously connected to it. It only had Resistors, Diodes, and LED's then straight to the AAA, AA, and 9V battery connection.

 

I just did some tests... gladly i'm still alive, nothing burned

Did some continuity tests first which seems ok, except for the blue thick wires which may not be beeping on the tester due to some reistance of the coils- not sure on this part...
Connected the thick blue wires to the 220 ac mains with some aligator clips and hooked my multimeter to the thin wires taking extra caution my skin doesnt touch any of the wires and no short circuits, my results are below:

Thin blue wire & thin black wire = 23V
red & yellow = 7V
Thin blue wire & red = 15V

 

This gives me confidence to test some other transformer i may meet in the future
Sounds dangerous! I like it!