Main switch for '72 Wombat 125

[Brian4236]

Hi, everyone. The headlamp on my '72 Wombat does not light. I have tested the light using a 6-volt battery. The light works. I wonder if it's the switch. When I turn the switch (first turn), all of the lights (tail light, speedo, brakes) work as they should. When I turn the switch again, the headlamp does not turn on. I have checked the connections; they all seem to be good. I have not ridden this bike much, but last year when I first noticed a problem with the headlamp it was when I turned the switch once and the lamp would go on (it should go on only after turning the switch to the second position). Now the headlamp just not turn on. It's probably a bad switch, right? Thanks. --Brian

[Dale]

Do you have a toggle switch on the back left side of the headlamp bucket? What position is it in? You would normally want it on AC and with it there you would only have a headlight lit when the key is in the 2nd on position and the engine is running.

[Brian4236]

Yes, there is a toggle switch, which is in the AC position. But the light doesn't work in the AC or DC position.

[Dale]

If it doesn't work with either AC or DC the I would look carefully at the dimmer switch and then the connection between it and the head lamp.

[Brian4236]

I will give that a try and then report back. Thanks.

[Darrell]

Make sure no soldered wire connections have broken off the toggle switch. Vibration seems to break the wires off at the terminals.
If this is your situation then resolder them or reconnect using spade connectors. The latter is more reliable, I think.

[Brian4236]

I checked the connections on the dimmer switch. They look OK.
The toggle switch "DC" and "AC" plate must have been backward (in other words, when the toggle indicated AC I believe it was on DC).
Either way, when the toggle is on "AC" nothing happens when the main switch is on or off with the engine running or not.
With the engine running and the toggle on "DC" the headlamp turns on with the first turn of key in the main switch (and remains on with the second turn of the key). As I understand it, the headlamp should only turn on at the second turn of the switch. Ugh. I am not sure what to do. I hope this makes sense.

[Dale]

It would be correct for your headlamp to work in both key positions while in the DC mode. This is considered the emergency mode of operation so that you have a working light in the event of an engine failure.

Let's focus on the AC operation. It seems like that is where the failure is. You will need the engine to be running and the key to be in the 2nd position. You should then be able to read AC voltage at the green terminal of the AC/DC switch. Don't worry about what the voltage reads but instead look for the presence of voltage. (The voltage will vary with RPM and the meter will jump all over).

Since your lamp works with DC we know the circuit from the center terminal (Brown wire) of the AC/DC switch through the dimmer switch to the lamp is good. So look for the AC at the switch and if not there, start tracing it backwards towards the lighting coil. And yes, this path will take you through the main switch and it is possible that it could be the problem. It is more likely to be a poor connection at a bullet terminal or even a connection at the coil.

[taber hodaka]

And it could be a short somewhere?? --------------Clarence

[Dale]

It could be a short as Clarence pointed out. When working with 46 year old wiring anything is possible. The key is looking for the source of the voltage in question. In this case it is the Yellow wire coming off of the Magneto (lighting coil) and connects to terminal C2 on the main switch. With the switch in the 2nd (Night) position, C2 is connected to terminal HL. It then becomes the green wire that feeds the Emergency Switch. You can look for that AC voltage at any point in this circuit and determine where you have it and where you don't.

Here is a link to the schematic for the 72 Wombat that is located on the Strictly Hodaka website. Don't work in the dark...
https://www.strictlyhodaka.com/v/vspfil ... iagram.jpg

[viclioce]

I feel your pain!!! I’ll have more info for you soon! Victor