No headlight, taillight or dash

[mousewheels]

But you will have to try a little harder to get me to understand that last paragraph.

--- Last paragraph Lunytune was asking about---
Note how the stator output for the headlight goes to the regulator. I've suspect that connection leads to an internal voltage 'clamp'. So at peak stator voltage {high rpm, low battery charge current required etc}, the lamps can be protected. If that part of the regulator is bad, *or* the ground for the regulator is compromised, the clamping function could be disabled, or weak. At that point, Hitting the break lever could make the AC lights (HL/tail and dash) dimmer, because the brake light increases the load on the stator.

Hmm.. lets try it this way:
The voltage output of the AC side of the stator is variable based upon engine rpm:

• At idle, the light is dim
• At low speeds it gets brighter
• Mid riding speed it's up to full intensity
• High speed - don't want to overvoltage the bulb

Unlike the DC side, which rectifies AC to DC, then to a regulator section in series with the battery, the AC side has the stator coil dumping whatever it makes at the lamps. The regulator cannot act like a valve to limit what comes *out* of the stator. So the regulator pin for the Lights must functionally puts a 'load' on the output when the voltage is higher than preferred for long bulb life. It cannot dump energy to the battery side, or else it would override the regulator function, effectively overcharging the battery. Plus it would need to be rectified. The other possible path for regulation, is to dump current into the regulator ground pin. Acting like a dummy load, it drags the output down when needed.

Now if the ground pin is opened, or the circuitry in the regulator is 'open' on the AC stator side, it cannon dump energy at all. The stator output is free to be higher than good for bulb light at high rpm.

When you find that volt meter, and are doing the intermittent connection tests, you could connect it to the headlamp and ride around. You can then tell if the voltage is limited to what you feel reasonable for a 12v bulb. I'm not saying blown bulbs on your scooter was caused the circuitry being described, this is an observation of what should be taking place and a way to verify operation.

A regulator like that gets stressed if normal circuit loads are removed, it must waste power as heat to keep the voltage in check. There is something of interest in the Dio electrical diagram. There is a Hi/Low beam switch for the light, and an additional switch to turn the lights Off. When you trace the switch in the "Off" position, it switches in a resistor, to simulate the load of a headlamp. That keeps the regulator from getting hotter than normal.

When you see how Honda took care that the regulator is not stressed when the light is intentionally turned off, it makes one start thinking if a headlight bulb goes out, replacement is a good idea rather than riding w/o the lamp on.

[Lunytune]

Acting like a dummy load, it drags the output down when needed.

What does this "clamp" look like, where is it located and how does it know when the stator is overcharging (too much voltage for lightbulb health)?

There is a Hi/Low beam switch for the light, and an additional switch to turn the lights Off. When you trace the switch in the "Off" position, it switches in a resistor, to simulate the load of a headlamp

The Manual we found (Eliteguy) is obviously Canadian, as noted by the language translation problems. I do not find any kind of "off" switch on my JDM.

You are giving me ideas to play with, such as maybe an extra light, like a small fog light or running lights to add to the circuitry, to add some load to the stator. Only problem with that is, it would also add load to low RPM and cause even dimmer light at low RPM.

[mousewheels]

What does this "clamp" look like, where is it located

If it is present, it is inside the regulator block.

Electrically, there's many ways to design a circuit that will detect a voltage above a threshold, then apply a load as required. A simple circuit is shown in the schematic below. Protecting light bulbs is less fussy that a critical supply on most electronic equipment.

how does it know when the stator is overcharging (too much voltage for lightbulb health)?

Suppose there was a pump on the tailshaft of your transmission. Pressure output is proportional to output rotation speed. Tied to the pump is a small spool valve, and a calibrated spring. When the tailshaft gets to a designed in speed (thus pressure) it pushes the spool valve far enough a port is opened. Now fluid can flow into a larger piston, extending it and delivering a large force to lock up a clutch.

Well in the circuit below, the 'zener diode' works like the spool valve and calibrated spring. A designer just picks a value that 'opens' (conducts current) at a design point desired. For the sake of simplicity, we'll neglect base-emitter voltage drop on the transistor.

Assume the designer selects a 15v zener as the designed regulating point. At the zener starts letting current flow. Current flow occurs in both R1 and R2. Current through R2 also flows through the PNP transistor. Base current is amplified by the "PNP" transistor, kind of like that piston in the transmission.

As voltages below 15v, the zener flows no current, so there is no load on the stator. So at idle, low speeds etc the regulator wastes no power. The circuit is monitoring for a rise above the calibrated voltage of 15v, at which point it will load the stator output, by sending current from the output back to ground.

[Bear45-70]

Mouse, if you are not a teacher you should be. You explanations are concise, to the point and totally informative. I enjoy reading they even though I already know most of this stuff.

[Lunytune]

Since scooters are notorious (IMO) for not having enough taillight, I had already bought a light which will mount perfectly in the license plate holes (this is Missouri, no tags on 50 scoots). I wasn't sure which scoot I would do first, but since the Dio taillight is stator driven, I think I will put it on to see how it effects the voltage.

[mousewheels]

Mouse, if you are not a teacher you should be. You explanations are concise, to the point and totally informative. I enjoy reading they even though I already know most of this stuff.

Thanks Bear!

Since scooters are notorious (IMO) for not having enough taillight, I had already bought a light which will mount perfectly in the license plate holes (this is Missouri, no tags on 50 scoots). I wasn't sure which scoot I would do first, but since the Dio taillight is stator driven, I think I will put it on to see how it effects the voltage.

Ok - I know your meter is missing. Good discussion. I was talking about this because you had replaced your headlamp not that long ago. I don''t believe anything you did would create as short a life as the bulb gave you.

On my side, I will get some hardware together to test a regulator. Conditions will simulate stator output greater than what would be good for the lamps - over 14.5 v or so. And report back to your thread.

[mousewheels]

Lunytune,
Here's an update for testing the regulator. Testing below confirmed the regulator applies a load to the stator to keep voltage from climbing with RPM. I do keep an open mind for your theory a voltage spike caused by a loose battery connection blowing lamps.

What is shown here is a clamping action the regulator provides to protect your lamps. Consistent with our earlier discussion, if the regulator ground connection is lost, lamp protection could be lost.

To All:
Troubleshooting the headlight circuit can be done with a DMM. There's no need to dive in further unless interested.

Test Circuit

1. The test circuit uses a a variable AC supply and resistance to simulate the stator coil.
2. A simplification of the regulator inputs was made - connection of the Headlight and Charge coil wires (Yellow and White) were made common.

Monitoring points, and lamps are placed in places where they can demonstrate regulator functionality. Monitoring points will show the regulator action, 12v test lamps show a headlamp would be protected by the regulator action.

Scope Photo 1
The scope traces are as follows:
Top trace: Variable AC Supply voltage output
Bottom trace: Voltage across the light bub

Two Fluke True RMS bench meters are used. The top meter is measuring the variable AC supply, Bottom is the voltage on the Lamp.
RMS measurement is basically the equivalent DC voltage of the waveform.

Discussion: Oscilloscope waveforms show high peak to peak readings. Looking the bottom waveform (the headlamp voltage) 43.10v peak-peak looks like a sure bulb killer. The 12v test lamp did not blow and the meters show the voltage to be within expectations. Difference is peak-peak (scope) vs RMS (DMM) voltage.

The lower trace has been marked up to show the portions of the AC waveform that drive the lamp. When those two segments are averaged, the result is the 11.8v the DMM reads.

Scope Photo 2
In this part of the test, the variable AC supply has been turned down, simulating a low speed operation. Note the AC input has dropped from 22.6v to 13.5 (on the upper DMM's in each picture). The lower DMM is showing the voltage at the 'headlight' to be 12.3 v.

Conclusion:
Over a 13.5 to 22.6 volt input range, the headlight voltage barely sees a change.

[Bear45-70]

Lunytune,
Here's an update for testing the regulator. Testing below confirmed the regulator applies a load to the stator to keep voltage from climbing with RPM. I do keep an open mind for your theory a voltage spike caused by a loose battery connection blowing lamps.

What is shown here is a clamping action the regulator provides to protect your lamps. Consistent with our earlier discussion, if the regulator ground connection is lost, lamp protection could be lost.

To All:
Troubleshooting the headlight circuit can be done with a DMM. There's no need to dive in further unless interested.

Test Circuit

1. The test circuit uses a a variable AC supply and resistance to simulate the stator coil.
2. A simplification of the regulator inputs was made - connection of the Headlight and Charge coil wires (Yellow and White) were made common.

Monitoring points, and lamps are placed in places where they can demonstrate regulator functionality. Monitoring points will show the regulator action, 12v test lamps show a headlamp would be protected by the regulator action.

Scope Photo 1
The scope traces are as follows:
Top trace: Variable AC Supply voltage output
Bottom trace: Voltage across the light bub

Two Fluke True RMS bench meters are used. The top meter is measuring the variable AC supply, Bottom is the voltage on the Lamp.
RMS measurement is basically the equivalent DC voltage of the waveform.

Discussion: Oscilloscope waveforms show high peak to peak readings. Looking the bottom waveform (the headlamp voltage) 43.10v peak-peak looks like a sure bulb killer. The 12v test lamp did not blow and the meters show the voltage to be within expectations. Difference is peak-peak (scope) vs RMS (DMM) voltage.

The lower trace has been marked up to show the portions of the AC waveform that drive the lamp. When those two segments are averaged, the result is the 11.8v the DMM reads.

Scope Photo 2
In this part of the test, the variable AC supply has been turned down, simulating a low speed operation. Note the AC input has dropped from 22.6v to 13.5 (on the upper DMM's in each picture). The lower DMM is showing the voltage at the 'headlight' to be 12.3 v.

Conclusion:
Over a 13.5 to 22.6 volt input range, the headlight voltage barely sees a change.

Mouse, Someday I wanna see your test bench.