Thread: TT350 Not XT350
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Old 02-15-2013, 05:10 AM   #125
Gnarly Adventurer
Joined: Jul 2010
Location: Queensland Australia
Oddometer: 141
Originally Posted by pigeyes View Post
Righto, any of you blokes got a coded wiring diagram for these tt ( and/or XT) things.
currently putting blinkers on 2 of our 350's and the yankee diagram isn't compatible.
So if any one can steer me in the right direction for info.... greatly appreciated, got it almost sussed
but just like to check.Appears to be individual rectifier and regulator so may have to let some of the smoke out to find
where I need to connect things... beaudy eh!
I've got a very basic wiring diagram for a TT350S that has no DC circuits.

The TT350 I've been working on is plated as a 1999 but the VIN number says its a 1994. The magneto leads are the standard white/red and black and brown into the CDI module plus the yellow for the lights. The yellow becomes yellow/red and runs up into the light switch where it is voltage regulated to 12V AC when the lights are switched on - makes sense to keep the bulbs surviving.

The added bonus in my case is the presence of an additional white magneto power lead. This little critter is provided for the DC requirements of horn, indicators, brake and instrument panel lights. The white lead also runs up into the light switch and is not voltage regulated with lights on (Yellow/red is switched in at this time) but is voltage regulated to 12V AC with lights off.

The standard wiring connects the white circuit to a basic rectifier (25mm x 25mm x 6mm thick) with 2 terminals - white one side and red the other. This is the way Yamaha produce a very rough 6V DC on the red circuit for indicators, horn, brake lights and instrument lights PLUS charge a tiny 6V lead acid battery. The low weight of a smaller battery seems to be the only positive result of the 6V option.

The big problem is when the white circuit is unregulated (lights on) there can be more than 20V AC in this circuit which when it is halved by the standard basic rectifier, produces ~ 10 V DC - this is not good for 6V bulbs, indicator senders and very small 6V batteries.

I've ditched the 6V DC setup and used a bridge rectifier to produce DC at a nominal 12V DC. The component is rated to 400V and 35amps and cost the princely sum of $AU 5 from Jaycar (everything electronic store) The rectifier has 4 terminals with white to the AC marked terminal and the second black magneto return lead diagonally opposite. DC positive is marked with DC negative diagonally opposite.

The 12V+ DC circuit now runs the horn, indicators, brake light and tail light. I tried a 12V car horn but it didn't fly so I went back to the original 6V horn and it tolerates the additional voltage - should be adequate for registration purposes.

I initially had a reasonably large 100V DC capacitor wired into the DC circuit but have deleted it - it's just not needed nor is a battery.

There is the issue of the headlight dimming significantly at low revs due to it's AC source off the magneto. It's entirely possible to fix this by converting the yellow/red AC circuit into DC with another bridge rectifier and using a large capacitor to store charge for use at low revs. I've opted to see if I can live with the variations in headlight brightness for the time being - I'm sick of working on the thing - it's time it was ridden.

Lenz1 screwed with this post 02-15-2013 at 04:34 PM
Lenz1 is offline   Reply With Quote