Volt Meter Wiring

Good day ,
Hopefully you can be of some assistance on my latest problem .
I have had my 1981 Pantah 500 going for over a year now and have had a persistant problem with the battery going flat after about 2 weeks of standing .
On checking I found that even with the ignition switched off there was still a current draw . Upon further investigation I isolated the problem to the Volt meter unit . Comparing the wiring to that of the wiring diagram I found it to be very different .I am planning to put it back to standard but am not sure of the connections on the unit . It is a Ducati Electrotecnica unit with 3 spade terminals marked L , A and B+ . From what I can glean from the diagram one goes to earth , one to the generator light and the other , a double brown to the ignition switch and regulator but I don’t know which terminal is which .
Your assistance on this would be much appreciated .

It sounds like one of the rectifier diodes is bad or going bad and leaking current back. I think Electrex make a replacement unit. If you’re not too bothered about the charging light pretty much any reg/rec will do.

You might have the switched +ve and the battery +ve the wrong way round, I had this on my Darmah, and ‘killed’ 2 batteries before I relaised.
What was happening was, it would charge OK, but there was leakage through from the terminal that should have been the switched one, about 150mA which is enough to drain the battery after a couple of weeks on inactivity.
I will need to look at my reg/rec to give you the correct connections, sounds like the same as my Darmah though?