This looks like it might be a good preventative fix to do before the
regulator goes bad. Might also be able to use if the regulator goes bad
depending on the state of the diodes (would work great if they are not
shorted. A simple check with an ohm meter would answer that.). In the
regulaor I disected one diode was completely blown away and the other was
shorted out so the answer would probably be NO if you want to try using
after the regulator has gone bad. Also, they used MCR16N SCR's instead of
the TIP154E in the one I looked at so they have changed some parts. Only
the diodes were bad (Lousy installation. Looks like they were soldered to
the copper plate). Sure is a pitty you can't open these up without
destroying them. We could be fixing them for a whole lot less than the $150
for a new one....
Bill
A010
Monowheel Classic
Still Building......
----- Original Message -----
From: "Jan de Jong" <jan.de.jong@xs4all.nl>
Sent: Friday, August 08, 2008 6:20 AM
Subject: Re: Europa-List: Ducatti Rectifier/Regulator
>
> Hi Jos,
>
> I think I found an interesting bit of forum:
> http://www.pilots24.com/pilots24/forum/viewtopic.php?t=7756&sid=542ce097cbdde3a5ceba2e5bd0d71c38
> Scroll down to 40% of the page.
>
> Writer Arrow is convinced that he has found the problem with the
> 912/Ducati regulators, as follows.
> The regulating bridge has 4 elements:
> 2 power diodes MR2510 and 2 thyristors TP154E (obsolete) or 2N6504.
> One diode and one thyristor in series conduct part of one half sinus of
> the alternator output, the other diode and other thyristor in series
> conduct part of the other half sinus of the alternator output.
> The thyristors have TO220AB packaging and are mounted directly to the
> housing.
> The diodes have MICRODE BUTTON CASE 193 leadless packaging and Ducati
> designed a mounting technique: both diodes with their cathodes soldered to
> a small copper sheet, copper sheet mounted to the housing using silicone
> foil heat conducting isolation; wires to the PCB soldered to both anodes
> and the copper sheet.
> Everything potted with a potting compound.
> The problem is that heating/cooling cycles work the electrical connections
> to the diodes loose. The symptoms are as follows: charging ok after
> startup (13.8V), losing it after half an hour, but the warning light stays
> off.
>
> The writer has a diagnostic test using a battery and two 12V lamps to
> check continuity under heating.
>
> The writer has a solution: parallelling the diodes with an external pair.
>
> The writer has notified Rotax and asked them what they had done / were
> doing about the problem (January 2008). The correspondence can be followed
> at:
> http://www.pilots24.com/pilots24/forum/viewtopic.php?p=48297&highlight=#48297
> Scroll 30% down.
> The upshot seems to be that Rotax knows there is a problem but it must be
> because units are operated above 80C. No redesign yet.
>
> By the way, Jos, the MR2510 datasheet shows a forward voltage drop of 0.9
> to 1.0V at 20A, the 2N6504 one of 1.3V at 20A. Your 0.6V is too
> optimistic! Newer parts may be better...
>
> I understand that Schicke and Silent-Hektik make a better product than
> Ducati:
> http://www.schicke-electronic.de/dgr3.htm
> http://www.silent-hektik.com/Duc_R_Duc.htm
>
>
>
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