Rectifier

[gapper]

Hello
i am New to the wonderful world of the XS650!
so i just bought this bike and have been going over everything slowly. it seesm to run fine, changed oil and filters, checked Valve"s adjusted can tension. New Battery,

so i noticed it was not starting very well, like battery i low, hmm well only short trips, 7 or 8 blocks to work and back. so i take it out on the Hwy about a 3/4 hr ride.

then this morning ..click, click.. so thro charger on and wham away it goes...

oh oh thinking charging system is pooched. so i do some tests today after i charge battery. follow as much of curly's guide and also my manual to narrow down problem. brush's are ok, voltage is a little lower then battery at alternator, but whe ni go to check the rectifeir as per the manual, i get no continuity from red to white at all, on all three and from wha ti have read is that it has failed.

so i reconect all and figure that i should be able to see what altnator is putting out if i touch the positive wire on it and ground to frame right? so at idle it is putting out 10.5 volts, and at 3000 rpm it is 11.7-12.0 volts. now with a faulty rectifeir should it be reading higher or is that causing some voltage drop?

i think i have gone about this the correct way.

not sure if my signature has this info so will add it as well

1983 XS650sk 26,000 kms
stock bike,

thanks

 

[littlebill31]

Put red from volt meter to red on battery, black to ground on battery.
http://www.xs650.com/forum/showthread.php?t=8838&highlight=rectifier

 

[XSLeo]

Hi,
On your recifier, it is six diodes which are electrical one way valves, they let power flow just one way.
When you test a diode you hook the leads up one way then reverse them. One way will conduct power the other way won't.
I'll post up some references, I hope they come out clear. I scanned them from my factory manual.
One shows the complete wiring for the alternator and the recifier and regulator.
The other shows how the recifier works.
I hope you can read the text.
Leo

 

[gapper]

Thanks
i have figured it out. the regulator, rectifier is pooched. i have order a new one, was going to do the home made one, but getting the parts is tough were i live, abolut an hour and a half to a city that has parts...

i will keep you posted on how it all turns out...

 

[XSLeo]

On the second pic the white wires hook to U, V, W. When AC flows in the white wire one is + one - Then it switchs from that to - + It does this as well as switch the wires that are hooked up. In one phase the AC is on UV the next Phase is VW next is WV.
Lets just use one set of leads. The UV leads. With U+ V- power flows to the junction of diodes D1 and D4 The power can only flow one way, out to the red, around to the black up to diode D5 over and down to the V- wire. Then as the polarity changes U-,V+ it flows up from V+ through D2 to red around to black to D4 to the U- wire. The phase changes Three times per revolution so the + and - switch from the UV to VW to WU wires
In the lower line of pic two you see the fully rectified wave form of just one pair of wires. The other phases start at 1/3 and 2/3 of the way between where the humps touch the line. so from where one hump starts and ends two more start there and match the humps you see. I'm not sure I'm explaining it well. But the three phase alternator put out three times as much power as a single phase. Thats not exactly right, a single phase can put out almost as much, but not as smoothly or at as low an rpm.
I hope you understand this.
On testing you touch the meter red lead to the red wire and the black lead to U, V, W. THen touch the black lead to the red wire and the red lead to the U, V, W. One way will be a very high reading the other a low reading, Using the diode check on your meter about a 500 reading one way, infinite the other. Now do it the same way with the black wire It should read the opposite from the first set of tests.
Leo