monty348 Posted November 11, 2014 Author Report Share Posted November 11, 2014 I had one Ducati unit fail and the fan stopped working but the engine ran. Replaced it and a few years later it failed with no spark. There were burnt marks on the epoxy in different places. Right now I'm running my bike with the first failed unit but using a battery to run the fan. When you replaced the diode, did you have a spark but no fan or no spark? There was no spark before replacing the diode. Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 11, 2014 Report Share Posted November 11, 2014 Guessing but here goes anyway. The electronics in the CDI almost certainly work at about 5 volts DC. To save having to have a second rectifier for the CDI electronics it could be that they use the DC from the fan rectifier and reduce the voltage. This would explain why no spark if no rectifier even though the power for the ignition is generated separate to the power for fan / horn / lights. 1 Quote Link to comment Share on other sites More sharing options...
steve_earle Posted November 12, 2014 Report Share Posted November 12, 2014 I think I see how this system works now, So could this be done: Stator output passed through a bridge rectifier and routed to 2 regulators 5v and 12v, Odviously they will need a heatsink bracket making up, then the 12v routed to fan and 5v routed to cdi. There are a few ways to wire it with the same result. https://www.coolcomponents.co.uk/voltage-regulator-5v.html?gclid=Cj0KEQiAp4yjBRCE_enjmpug944BEiQATCpLvWmmOCE5enpV743B61c1hbLuOCKKnWUjdorDb4S1QcAaAvHx8P8HAQ http://www.ebay.co.uk/itm/like/130948535760?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0 http://www.ebay.co.uk/itm/like/141316793337? limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0 Does this look possible? Quote Link to comment Share on other sites More sharing options...
dadof2 Posted November 12, 2014 Report Share Posted November 12, 2014 For the low cost its worth a try, nothing ventured, nothing gained as they say. Quote Link to comment Share on other sites More sharing options...
monty348 Posted November 13, 2014 Author Report Share Posted November 13, 2014 For the low cost its worth a try, nothing ventured, nothing gained as they say. I'm certainly not qualified to comment on a work around to replace the Ducati unit but will say that I "think" it's possible the rectifier may also have an effect on ignition timing. Quote Link to comment Share on other sites More sharing options...
steve_earle Posted November 13, 2014 Report Share Posted November 13, 2014 The rectifier only converts the ac current from the stator to a dc current to power fan and dc electrics. Definatly not to do with ignition timing, The Cdi will pick up a timing pulse from either a hall sensor or alternating poles of the coils shorting north to south to simulate a gap at tdc. The cdi then uses this info to determine the spark time and will advance it depending on engine revs. Quote Link to comment Share on other sites More sharing options...
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