350 Mk3 Charge Light

[geodoc]

Hello,

I just joined the forum & would like to see if anybody here can make heads or tails out of how this headlight bucket mounted warning light is supposed to work.

I got this bike from a friend to troubleshoot a no-charging situation. The alternator turned out to not be putting out any AC so the owner decided to get an Electrex alternator / reg-rec set-up to fix & maybe get somewhat brighter lights as well. I installed the reg-rec & made the appropriate wiring mods (inc. charge warning light output lead from reg-rec), but noticed that the red warning light that I assumed was a charge light before I took it apart was connected in a way that could not possibly serve that function.

The upper photo is the bike. The bottom image is the wiring diagram I got off the Motoscrubs 'Tech' page. The center image has been modified to show how this warning light is connected on this bike. You can see that its set up so that the ign. 'ON' indicator light (7) is normally just grounded on one end. On this bike instead of going to ground, that end has an additional brown wire that is connected to the 'positive' center connection to the warning light (21). For the life of me I don't see how this could do anything but just stay lit when the ign. sw. is in the 'ON' position and have no charge indication function & this is apparently what it was doing according to the owner. Question is, did a '69 350 Mk3 normally have a charge warning light? The bottom image does not show one present, but is in every other way (well, almost, this bike has a sealed beam in it with no pilot light). Scouring the internet, I can't find a widecase wiring diagram that shows a charge light.

My plan is to find an appropriate warning light with two pig-tails (non LED of course) and connect the reg-rec's charge light output to one side and system voltage off the key switch to the other so it will function as intended, so in some ways the answer to this question will become purely academic, but I'm curious.

Thoughts?

Thanks,

George
Vancouver BC





Std. Widecase wiring with extra warning light (21)



Std. Widecase wiring:



As an aside, I posted the saga of resurrecting a '73 750 GT that I found over on the Bevel Heaven Forum:

http://forum.bevelheaven.com/viewtopic. ... f6340353b1

[ducwiz]

Hi,

DUCATI singles never had a "charge indicator" (= current is produced by the alternator and charging the barrery). The little bulb in the lamp shell was/is always and only an indicator for the ignition switch being turned into the "ON" position. Indeed, this also indicates that some residual battery charge/voltage is present.
This indicator is an original equipment for your early widecase model. Possibly the bulb holder has been exchanged by a previous owner? In case of doubts refer to the parts catalog or user manual.
The modified circuit scheme shows the indicator in series connection with the numberplate/tail-light. This makes no sense for me, as the small indicator bulb prevents the sronger taillight from working as bright as designed. Are you shure you depicted this modification correctlyy?
I presume an Electrex STK-163 http://www.electrexworld.co.uk/cgi-bin/sh000001.pl?WD=ducati&PN=STK%2d163%2ehtml#SID=447?aSTK_2d163 alternator is fitted, together with the appropriate R-R. On the Electrex page you will find a circuit scheme, showing how a true charge (or alternator voltage) indicator has to be connected. Indeed, you need a bulb/holder with 2 ground-free connectors, which sits between the brown R-R terminal and the (switched) output (#7 in your circuit scheme) of the ignition key #10.
This alternate circuit scheme of w/c points ignition models may give more clarity (click to magnify:





cheers Hans

[geodoc]

Hello Hans,

The additional warning light (21) that is shown in my (center) modified illustration is not the tail light wired in series with the ignition switch "ON" indicator light. Light (21) is actually exactly the same as the high beam indicator light & mounted to the left of the light selector switch in the headlight bucket with the high beam indicator light mounted to the right of the switch. I think where I may have caused the confusion is that what I referred to as light (7) / ignition "on" indicator light & at the very top of the illustration is actually 'wire' #7, but the number happens to be right next to the indicator bulb. You're right, the component (7) is indeed the tail light assembly. But yes, the center illustration accurately describes the way that bulb is wired in. Otherwise, as I mentioned in my first post, the wiring diagram accurately depicts the wiring and components as found on this bike, right down to the color codes except for no parking / pilot lamp on account of the sealed beam (as does the wiring diagram you attached in your post).

Later today I'll take a photo of the inside of the headlight bucket to make it more clear how this indicator light is connected and where it's located.

As for finding an accurate depiction of the lighting components and wiring, I'm pretty well limited to what I can find on the web. I do see that on the Motoscrubs 'Tech' page there is a narrow case wiring diagram (http://www.motoscrubs.com/Ducati_Electr ... ematic.jpg) that shows a charge light present. Maybe they dropped that for the wide cases, or only some wide cases, maybe it was added later, maybe it was the dreaded Luigi factor, who knows? Anyway, like I said in my first post & as you pointed out again, my plan is to install a 2 pigtail warning light and wire it up per the Electrex diagram.



GD

Hi,

DUCATI singles never had a "charge indicator" (= current is produced by the alternator and charging the barrery). The little bulb in the lamp shell was/is always and only an indicator for the ignition switch being turned into the "ON" position. Indeed, this also indicates that some residual battery charge/voltage is present.
This indicator is an original equipment for your early widecase model. Possibly the bulb holder has been exchanged by a previous owner? In case of doubts refer to the parts catalog or user manual.
The modified circuit scheme shows the indicator in series connection with the numberplate/tail-light. This makes no sense for me, as the small indicator bulb prevents the sronger taillight from working as bright as designed. Are you shure you depicted this modification correctlyy?
I presume an Electrex STK-163 http://www.electrexworld.co.uk/cgi-bin/sh000001.pl?WD=ducati&PN=STK%2d163%2ehtml#SID=447?aSTK_2d163 alternator is fitted, together with the appropriate R-R. On the Electrex page you will find a circuit scheme, showing how a true charge (or alternator voltage) indicator has to be connected. Indeed, you need a bulb/holder with 2 ground-free connectors, which sits between the brown R-R terminal and the (switched) output (#7 in your circuit scheme) of the ignition key #10.
This alternate circuit scheme of w/c points ignition models may give more clarity (click to magnify:





cheers Hans