direct replacement 6 Volt rectifier for Monza

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el_guru
Posts: 24
Joined: Thu Jun 23, 2011 12:10 am

Re: direct replacement 6 Volt rectifier for Monza

Postby el_guru » Sat Feb 10, 2018 10:13 pm

Saga continues.....

Thanks again Hans for that info... I'm not giving up on this now its got me vexed... :D

pulled the regulator apart.
IMG_2279.JPG

There is continuity between the centre lead and each respective diode in one direction only which would imply that they are ok.?
There another 2 other components hiding under the black sheathing behind the 2 main diodes.?
IMG_2283.jpg

The 27ohm resistor has obviously got very hot in the past but is reading 28-29 ohms so probably also ok.?
IMG_2278.jpg


the link to the rebuild section of the regulator is very useful in how to pull the thing apart. However of very limited use as the regulator was ok in the article but in the write up doesn't define what ok actually is.?? :cry:
Last edited by el_guru on Sat Feb 10, 2018 10:17 pm, edited 1 time in total.

ducwiz
Posts: 222
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: direct replacement 6 Volt rectifier for Monza

Postby ducwiz » Sat Feb 10, 2018 10:17 pm

Guys,

I'm not a n/c specialist and do not own one, have only worked on friend's bikes, but on a lot of the electrics and differentt charging systems. However, I'm a curious person, always willing to learn. So, I just surfed a bit through the web and finally found this: http://www.regulatorrectifier.com/catalog/1965-1967-ducati-250-monza-regulator-rectifier
Seems a bit strange, no postal address or owner name, but online since 2004. It might be the R-R el_guru is searching for.
Does anybody know this company?

Jordan, I see a risk in running the bike without a regulator, with a rectifier only. OK, if the headlight is always kept switched on and you sum up all power loads in the system (back light, ignition, intermittend stop light), only a small fraction of the alternator power (60 watts max.) is remaining for battery charging, maybe less than 1 Amp charge current. But, this not always guaranteed, and if the (already fully charged) battery is then overcharged anyhow, acid may spill over the bike's parts and will produce a lot of ugly corrosion or damage. So, I personally would never dispense with a R-R.

Hans

EDIT: ah, wasn't fast enough ... Seems your big diodes are OK, they block in one direction but pass current in the opposite way - typical diode behaviour. What about the small ones (they are supposedly hidden in that ugly braided shield tubes, must also have a commen lead and two single ends)?
Last edited by ducwiz on Sat Feb 10, 2018 10:31 pm, edited 1 time in total.

el_guru
Posts: 24
Joined: Thu Jun 23, 2011 12:10 am

Re: direct replacement 6 Volt rectifier for Monza

Postby el_guru » Sat Feb 10, 2018 10:22 pm

Hans,

it looks exactly the same as the one Guzzino sells. I emailed them for some further info.

http://www.guzzino.com/noname3.html

Meanwhile I am determined to get my original regulator back working.

Jordan
Posts: 751
Joined: Fri Dec 24, 2010 11:29 am

Re: direct replacement 6 Volt rectifier for Monza

Postby Jordan » Sat Feb 10, 2018 10:33 pm

Hello Hans,

I understand your concern about unregulated charging systems not being ideal.
But, there are instances of that being the standard arrangement on production machines.
For example, Honda CB72/77, which had an otherwise comprehensive electrical system including starter motor.
Also several dual purpose on/off road bikes relied on the "balanced system" of charging.

ducwiz
Posts: 222
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: direct replacement 6 Volt rectifier for Monza

Postby ducwiz » Sat Feb 10, 2018 10:41 pm

Indeed, this item looks the same. But their explanation is wrong/misleading: The Monza/Mach1 alternator is not a single phase machine, it has 2 phases as well, like the widecase 90W alternator. The difference is: The monza version has it's center tap grounded locally on the stator plate and thus only 2 wires, while the w/c version has the center tap routed outwards as a third (red) wire, forming the +-output. You can check this in the el. schematics from the workshop manual. Here, the mentioned ground connection is visible.
I presume this R-R is of the shunt regulating type (shorting the staor winding in order to bypass excess current), while the w/c R-R is a series type, which disconnects the stator from the system in case of overvoltage.

Hans

el_guru
Posts: 24
Joined: Thu Jun 23, 2011 12:10 am

Re: direct replacement 6 Volt rectifier for Monza

Postby el_guru » Sat Feb 10, 2018 10:51 pm

all diodes seem to be ok.... only work in one direction.

BUT.....

there is a lead from the capacitor broken off from the nearby stud, hopefully that will get the whole thing working again.
IMG_20180210_224214784 copy.jpg



FINALLY IT LIVES.....!!!!

7.5 ish volts across the battery. Thanks again for all your help.

JimF
Site Admin
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Re: direct replacement 6 Volt rectifier for Monza

Postby JimF » Sun Feb 11, 2018 12:51 am

A friend of the forum named Robert Ostman was kind enough to point out some mistakes I made when I created a schematic for the regulator. I believe Robert's schematic changes to be accurate and an improvement on what I had done and I thank him for his contribution as it will benefit us all.

You will see the Ostman revised schematic has replaced the original on this page:

http://www.motoscrubs.com/Ducati_Electr ... ulator.gif

At one time long ago I recall coming to the conclusion after some circuit analysis that the chokes served as a crude but effective voltage regulator as it was created from an era likely before the advent of semiconductor voltage regulators.

I should have written down the theory of operation as I understood it back in 2004 but I failed to do so, and now I haven't thought about it for 14 years and would have to go back to it again with an older and slower brain.

In the meantime, here is a website page that offers an explanation of the circuit function of the regulator.

http://mbvmc.org/restore/ducati/ducati%20regulator.html

Jim

Ventodue
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Location: Montpellier, France

Re: direct replacement 6 Volt rectifier for Monza

Postby Ventodue » Sun Feb 11, 2018 11:27 am

JimF wrote: At one time long ago I recall coming to the conclusion after some circuit analysis that the chokes served as a crude but effective voltage regulator as it was created from an era likely before the advent of semiconductor voltage regulators.

Check, Jim. That's what I thought, too (see my earlier post). If not, someone needs to explain the function of those coils ;) :)

P.s. I quote Jim Downey's article: "As current passes through coils L1 and L3, a magnetic field is induced in L2 which, through a saturation principle, keeps the voltage output near 6 volts".

ranton_rambler
Posts: 69
Joined: Sun Jun 04, 2017 11:33 am
Location: Stafford UK

Re: direct replacement 6 Volt rectifier for Monza

Postby ranton_rambler » Sun Feb 11, 2018 2:29 pm

I've got the same reg/rec with my 175, but the diodes conduct in both directions so I'll probably replace it with a modern alternative.
Anyone know the stator coil resistance? I believe I have the 60W alternator.
Ian

ducwiz
Posts: 222
Joined: Tue May 22, 2012 12:52 pm
Location: near Frankfurt, Germany

Re: direct replacement 6 Volt rectifier for Monza

Postby ducwiz » Sun Feb 11, 2018 3:10 pm

The 60W alternator:

Image

The grounded centert tap mentioned in my earlier posting is clearly visible as a solder lug on the stator plate, and as a small triangle in the schematics drawing.

And here are the the instruction how to modify the 60W stator for the application of the new electronic regulator of the w/c singles:

Image Image

Hans


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