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https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl >> >> AC Ripple Diode Fault? https://yabb.autonerdz.com/cgi/yabb2//YaBB.pl?num=1407307505 Message started by Olly on Aug 5^th, 2014 at 10:45pm

Title: AC Ripple Diode Fault?
Post by Olly on Aug 5^th, 2014 at 10:45pm

Have a look at some of these captures and let me know your thoughts.

My understanding was, when viewing AC Ripple (apart from the main ripple itself) that any of the sharp long down or upward spikes would indicate a failing or weak diode in the rectifier unit.

Check these captures out and let me know your thoughts. They all came off what appear to be bikes with working charging systems and many of them either very new and/or low milage. I have even found similar captures after replacing rectifiers.

Am i wrong about the diodes or is there some other explanation?

Pics wont attach at the moment, will try and upload them in a bit

Tiger_1050_ac_ripple_good_001.bmp (225 KB | )

Title: Re: AC Ripple Diode Fault?
Post by Olly on Aug 5^th, 2014 at 10:47pm

more pics

Daelim_ac_ripple.bmp (225 KB | )

Yamaha_SRV_ac_ripple.bmp (225 KB | )

Rodney_Mulqueen_-_Daytona_AC_Ripple.bmp (225 KB | )

Title: Re: AC Ripple Diode Fault?
Post by busjockey on Aug 7^th, 2014 at 6:29am

From what I can see Olly that is just noise. The most important thing to look for on ac ripple is the total amplitude. From what I kind see they look fine. If you want to see if you have unwanted noise spikes, put your scope on dc coupling and then look at it again. You usually don't want no more than over a volt of a spike. Try that and repost. :)

Title: Re: AC Ripple Diode Fault?
Post by JNelson on Aug 7^th, 2014 at 6:50pm

I agrees with busjockey, those spikes look like noise.

But that first waveform looks bad to me. Normally I look for evenly spaced humps all fairly uniform and less than 0.3-0.5 volts -ish

Title: Re: AC Ripple Diode Fault?
Post by Olly on Aug 8^th, 2014 at 9:30pm

Thanks for the info. I was starting to wonder why i was getting so many with those spikes on such new bikes.

So secondly is there any way to identify noise over a fault?

And also what could be causing the slightly uneven signal in the first pic?

The battery voltage may have been low ish at the time of test as it was our demonstrator bike which does lots of short journeys and sits around a bit, and i had been doing allot of base tests on it with stop starts.

busjockey wrote on Aug 7^th, 2014 at 6:29am:

If you want to see if you have unwanted noise spikes, put your scope on dc coupling and then look at it again. You usually don't want no more than over a volt of a spike.

If i choose DC coupling i have to have the scale at 5v/div to fit on the screen and i have no zoom function sadly. but i will get a couple of captures and post for reference.

What have you found causes higher than acceptable noise and what symptoms have you experienced?

Thanks for the help :)