regulator rectifier

I would like to upgrade the reg/rec on my 77 with a new solid state device and happen to have an extra for a Ducati 996. I "think" it is simply a matter of changing the brush as shown at the beginning of this thread, but the Duc wiring diagram is slightly different. Any advice?

78410d1287388745-relays-question-996-wiring.jpg
 
Thanks. What is the difference between PMA and ours? I.e. Why won't it work?

PMA alternators,use a regulator, that controls output voltage by shunting excessive current to ground. It has no means to control the current flow to an electromagnetic rotor that is used on an XS650.

The rotors in the stock XS650 alternator have no magnetism, until a DC current flows through the rotor windings. The required current comes from a regulator via the brushes.
The DUC regulator is not designed to sense voltage and supply current to rotor windings. Therefore it can't control the rotor on an XS650.

Review the first of this thread. It talks about using a VR-115 regulator and a 3 phase rectifier. Many of us have used these components for years, and they work very well.
They are simple to install, inexpensive, and will do an excellent job for you on a 1977.
 
Thank you again. So it seems the PMA setup strictly regulates/modifies the rough, uncontrolled output that magnets and a coil generate (output filter). In comparison, the XS setup first needs power to charge the coil, so it generates it from the brushes and gets regulated on the way in (input filter). If I have that right, in order to use the Duc Reg/Rec, I would still need this input voltage and filter, so I would end up with 2 regulators and 1 rectifiers. Now I can understand why people either upgrade the electronics as mentioned in the first posts or simply swap the whole system to the PMA-style charging system. I may just leave it as is for now since I still have lots of work and $$$ to spend getting it back on the road with its new sidecar.
 
You can't mix PMA components with electromagnet type alternators. They live in different worlds.

So, you cannot use the DUC rec/reg with the stock alternator.

If your stock alternator is working, just keep using it. The stock rectifier and regulator that you have on your bike are both very rugged and have survived quite well over the years. However, they are both of older design and are somewhat crude compared to more modern units. You can continue to use the stock rec. and reg. if you wish, as long as they fully charge your battery. To fully charge your battery, you need to see 14.1 volts at the battery terminals, when you rev up the engine to approximately 3000 rpm.

If you don't see 14.1 volts, then the simple inexpensive option is to change over to a VR-115 and a new 3 phase rectifier, which will make the charging system work 100%.
 
Hello all,

A question I have about my XS2 manufactured 8/71 pic below.

Attached to my battery box is the regulator on top what is the other unit below the regulator? My service manual does not show detailed pictures for this. The top unit is the regulator right?
regulator.png


Now I do not have the rectifier attached below the box like the newer bikes and wonder if this is my rectifier?
rectifier.png


Thanks for the help..
 
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