1969 Scrambler electrical issues

[DewCatTea-Bob]

quote= JimF ...
"I would propose to Ted that for diagnostic reasons that he disconnect the wires going from the rectifier/regulator from the battery, "

____ The stock red-wire that physically-connects directly between the battery & the R/R.unit, actually does-not make any ELECTRICAL-connection between those two particular system-components,, cuz the pair of red-terminals located on the outside of the R/R.box are merely-just an EXTERNAL -(only !) direct connection-point between the battery's positive-post wire-lead & the red alt.wire-lead (which is the 'common-circuit' -[NOT an actual 'center-tap', as often assumed], of the two alt.stator-windings).
__ So therefore, disconnecting that mere PHYSICAL-connection between battery & R/R.unit, (which is actually just a direct electrical-connection merely between the battery & alternator only), would actually not make the (seemingly obvious) expected electrical-disconnection (between battery & R/R.box).
(ASSUMING of-course that the battery isn't hooked-up with it's positive & negative poles reversed from the normal NEG.ground-standard. _ [In which case the battery could then possibly short-circuit itself through the alt.winding & rectifier circuit (and possibly blow a low-value 'main-fuse'),, (unless THAT circuit is interrupted [as Jim has suggested doing]).] )


" I believe the consensus is that a load (the battery in this instance) is required to be electrically on the R/R unit to prevent internal damage to its electronics when the engine is rotating so connecting that back up and trying to start the bike would begin to test the ignition circuit. "

____ After realizing that which I've posted above, it should now be understood that the R/R.unit is-NOT actually electrically-connected directly to the battery (on it's positive-side,, [as is the actual-case with the n-c.R/R.unit] ).
However, the R/R.unit does have an electrical-connection to the battery's pos.side (THROUGH the ign.switch, by a brown-wire), only for the sole-purpose of allowing the regulator-circuit to 'sense' the battery's voltage-level,, so that reg.circuit doesn't require any 'load', (as it's an 'input' rather than an 'output').
__ Nor do the two remaining R/R.unit's other connections* require any load !
(* As it's pair of yellow-terminals are actually INputs [for the alternator's two outputs].)
The stock R/R.unit's only 'output' is through it's metal-casing directly to ground, and that pulsating-DC.output doesn't really require any load either.
__ The w-c.type R/R.unit's internal-electronics are pretty-much only at risk just whenever the battery has become disconnected/off-line (or otherwise similarly disfunctional) AFTER the reg.sensor-circuit has already been turned-on FIRST/before-hand, (which thus-then leaves the [rather sensitive] sensor-circuit exposed to the resulting higher-voltages that are no-longer able to be absorbed-down by the battery load-circuit).
And-so normally, that rather delicate regulator-circuit is NORMALLY kept safe from damaging unregulated/high-voltages (from the alternator), since the whole Reg/Rect.unit is normally kept shut-down whenever the battery is-not UP-to it's normal-state -(in which such condition causes the sensor-circuit to "turn-on" & activate the rectifier-circuits), to start-out with.
So this means that the w-c.type R/R.unit effectively protects it's own-self from running with a dead-battery (which can't absorb any excess system-voltage), because it's sensor-circuit needs at-least (I think) 4-volts in order to turn-on & allow rectified-power into the system.
__ So anyone who has hoped to get their stock WideCase-Duke started with a dead-battery, by pushing their Duke down the road in hopes of getting started rather with DC.power produced by it's stock charging-system, would've wasted their time on such an effort !
(But such an effort WILL work okay with a n-c.type R/R.unit, as IT doesn't need to be 'turned-on' by any battery first !)



" in the rare case of a shorted condenser in the ignition circuit,
I would suggest that this rare fault would cause a fuse to blow "

____ Sorry to-say, Jim,, but for the better-sake of others...
__ Firsty, the stock-system has no fuse-circuit at all associated with ANY section of the ign.system,, and secondly, even a fully shorted-out condenser wouldn't make any greater of a 'short-circuit' (in that ign.circuit) than that accomplished by the ign.points (whenever closed-together), anyhow !
So such a "rare fault" would-not blow a (suitably valued) fuse, even if there actually was such fusing located anywhere within the associated battery/ign.system-circuit.


Enlightening-Cheers,
dct.Bob

PS. It seems that every-time I read what I've already written & posted in this post, I then feel the need to alter my previous posted-wording or add more to it.
__ If anyone doesn't clearly understand any wording here-above, then please request improved clarification !

[TedsDucs]

Hey guys - thanks for all the input.

I can officially confirm that I am an idiot. What I thought was a fuse was in fact one of those "festoon" bulbs that sort of look like a fuse. It lights the ignition indicator from inside the headlight shell. I had replaced it with a fuse - Duh! Anyway, got a bulb to replace that, and now no more shorts. The other three fuses in the shell are 25/25/ and 15, as Bob pointed out, and wiring diagram confirms. My master on the battery is a 30. All good. With the battery hooked up, now I have a horn! Bob - good catch - you mentioned I should have a ground from the coil to the headlight - that was hooked up wrong! Fixed that, and now I have a headlight - high and low! The tiny high beam indicator bulb is burned out - trying to find one of them....

On a side note, it appears someone replaced the original headlight reflector assembly with a sealed beam unit - it is a GE 4020 dual-filament bulb, mounted to a rubber flange, which is then mounted to the headlight shell, so I have in effect two chrome mounting rings holding the reflector/beam on - I assume that was from some later model Aprilia headlight - weird.....

Anyway, still tracing the wiring to find see if I have missed anything. Don't have the taillight hooked up, as I am waiting on the fender from the painter. At least I know the bulb is good.....

You guys are awesome! Now on to the ignition circuits......

Thanks, Ted

[DewCatTea-Bob]

[quote="TedsDucs
" What I thought was a fuse was in fact one of those "festoon" bulbs that sort of look like a fuse.
I had replaced it with a fuse
Anyway, got a bulb to replace that, and now no more shorts. "

____ That bulb-holder does appear much like a fuse-holder, and a fuse placed within that location would indeed create a 'short' from the ign.switch power-outlet to ground. _ And-so, since the only other fuse in that circuit is your main-fuse, then those two fuses would be the only ones that could possibly blow. _ But however, your 30-amp main-fuse should-not have ever gotten any chance to blow, because the wrongly-placed 25-amp fuse should've always burned-up before your main-fuse got the chance to.
__ Anyhow, it's a good-thing that you found your own mistake, cuz that particular source for your shorting-issue is one that I wouldn't have soon thought-of to suspect & suggest checking for, (even-though I now recall having ran-into the exact-same happenstance once before), UNLESS you first mentioned that you had 4-fuses inside your headlamp, and/or exactly WHICH of your fuse-locations in the headlamp was blowing, (as THEN I would've realized your shorting-issue right-off-the-bat !).
__ The bulb that actually belongs in that location is meant to light-up only whenever the key-switch is in it's std.ON-position, and it's indicator-lens/warning-light is supposed to stand-for 'GENERAL' - (meaning main-systems are powered-up).



" Bob - good catch - you mentioned I should have a ground from the coil to the headlight - that was hooked up wrong! "

____ It WOULD'VE been a "good catch", if your related connection-error had been the source of your shorting-issue. ...
I had thought that perhaps you may've mistakenly connected the headlamp ground-wire to the ign.coil power-terminal (instead of at it's grounded mounting-bracket), which then could've caused your main-fuse to (rather slowly) blow, after the ign.switch was turned-on. ...
The headlamp ground-wire is actually supposed to be grounded to the ign.coil's BRACKET-MOUNT, as it's function is to make-sure that the headlamp-shell is FULLY grounded, because otherwise the headlight can't be trusted to draw ALL of it's current-demand through just the fork-neck & clutch-cable. - (That's why I mentioned that the main-fuse may blow "rather slowly", cuz the fork-neck's greased ball-bearings can't be trusted to pass sufficient current-flow for the headlight, and therefore possibly also not pass enough current to quickly blow a suitably-larger amp.value main-fuse.)



" Fixed that, and now I have a headlight - high and low! "

____ Even before properly grounding the headlamp's (black) ground-wire (to the main-frame), you still should've had at least some fair amount of lighting from your headlight,, as there also ought to be a short length of 18Ga wire going from the common-post of the headlight-socket to the headlamp's shell/ground, (which ought to have achieved a fairly-adequate main-ground circuit [at least through the clutch-cable, (unless you have too-much paint on your frame's motor-mount points, [in which such case your ign.system may not work well either])] ).



" it appears someone replaced the original headlight reflector assembly with a sealed beam unit - it is a GE 4020 dual-filament bulb, "

____ But that's std.issue for all made-for USA w-c.models ! _ So if you're here in the U.S., then that's probably stock.


" mounted to a rubber flange, which is then mounted to the headlight shell, so I have in effect two chrome mounting rings holding the reflector/beam on - I assume that was from some later model Aprilia headlight - weird..... "

____ Can you post any pix of all those parts (if your Duke is a USA.model) ?



" still tracing the wiring to find see if I have missed anything. "

____ Too-bad that you hadn't sooner let us know, as you began your wiring-project,,
would've been happy to have helped guided you through it, step by step !


Hopeful-Cheers,
DCT-Bob

[TedsDucs]

" it appears someone replaced the original headlight reflector assembly with a sealed beam unit - it is a GE 4020 dual-filament bulb, "

____ But that's std.issue for all made-for USA w-c.models ! _ So if you're here in the U.S., then that's probably stock.


" mounted to a rubber flange, which is then mounted to the headlight shell, so I have in effect two chrome mounting rings holding the reflector/beam on - I assume that was from some later model Aprilia headlight - weird..... "

____ Can you post any pix of all those parts (if your Duke is a USA.model) ?

Attached is a view of the headlight when I got it....Looked online and don't see any images of scramblers that look like that....The more I get into this bike, the more I realize that it was not as "unmolested" as I thought....


Bob - did these bikes come with turn signal prewiring? I have a set of green and blue wires that run from the headlight to near tail, not connected to anything - I assumed they were disconnected turn signals...

Ted, learning every day....

[DewCatTea-Bob]

[quote="TedsDucs
" Attached is a view of the headlight when I got it....Looked online and don't see any images of scramblers that look like that.... "

____ I've never seen any headlamp-ring setup like that on any Duke-model before,
it's not stock ! _ But it looks like it could be a good-fix for some stock headlamp-shells which have lost their original screw-thread fastener-mount.



" did these bikes come with turn signal prewiring? I have a set of green and blue wires that run from the headlight to near tail, not connected to anything - "

____ Yes, most-all w-c.models came stock with that extra pair of colored wires added to the stock wire-harness, (intended for easy installation of optional turnsignal-lamps).



" I assumed they were disconnected turn signals... "

____ It's quite most-likely that no turn-lamps had EVER been installed by ANYone, even-though various turn-lamp kits were available (for 20 to 30 $ back-then).


Duke-Cheers,
-Bob