Topic: 1972 cb750 four electrical gremlins

[catlin]

I have been fixing up a 1972 cb750 four, and decided I could not stand the turn buzzer sound.  I removed the two buzzer wires behind the headlight and somehow in the process disabled my left blinker light.  All other blinker lights work, and I have power at the left blinker light via test light.  When I remove the orange ground light wire and put it to metal, the left blinker works.  The strange thing is that after doing this, my whole blinker system is non-functional for a few minutes.  I turn the system off, and after a few everything works again except for the left blinker.  I know this has to be something to with the ground, but can't figure it out.  Anyone had any similar experiences or advice?

Thanks for the info!

[beemerbum]

Didn't your bike have the cancelling switch?

[HondaMan]

The front turn lamps on the K2 ground thru the chrome headlight mounting ears. This ground connects to the nut on the headlight's mounting bolt: this special nut has a ground tab on it with a Green wire (ground) for the turn lamp. These get crusty/rusty and taking open the headlight can disturb them just enough to make for a poor ground, which then causes intermittent turn signal operation.

So, you've probably awakened the crust monster, and will have to go back inside the headlight bucket and clean up all the connections. Add a drop of oil to them afterward to get another 10-15 years out of them.

[JeffK]

Run a test ground from the chrome stem to any other ground on the bike and if it the blinker starts working again you can be assured it is the ground wire from the stem inside the rats nest. You also may have disconnected the other end of that ground (where it plugs into the wire harness).

Jeff

[catlin]

My bike must be before they had the noise cancellation switch, I don't have that extra button on the left side.  The headlight ground is where I was testing my circuit tester from so i'll take another look.  I made a mistake in my earlier post.  I have two black wires from the left blinker into the headlight harness.  One positive (hooks into solid orange 3 prong) and negative (hooks into orange/white stripe 3 prong).  When I disconnected the black negative from the ground (orange/white stripe) and touched that black wire to the ground on the headlight bolt the blinker lit up.  Unfortunately, it would work for awhile before the whole blinker system would stop functioning.  I'll double check the headlight grounds but feel like they must function okay for all the other lights to work.  I also took off the ground in the left blinker light (the wire braid) and cleaned it.  It must work if the light comes on when I ground the black wire in the headlight harness to a metal post.

Thanks for the information folks.

[PeWe]

It is not difficult if you open a circuit diagram and look how the wires are connected.
The buzzer get 12V from the blinker relay (grey if I remember correctly) and another 12V from the black wires (main power) in headlight bucket. That's why it sounds when the blinker is not lit (12V from both sides). You might have noticed that it start to buzz direct, blinker lit it's silent.

You might have removed buzzer wiring AND the small extension that connect the buzzer in parallel with blinkers? Circuit diagram makes it clear.

My K2 build got a buzzer. (I got a Goldwing version with 3 wires years ago, seller sold it as NOS K6. I checked the Goldwing wiring and saw which wires that do what and connected it. OK)

My K6 had a buzzer but I removed it as one of the first measures when I have just bought the bike dead stock. 18-19 years old can't has such "silly" device

I have been close to death several times due to no buzzer. It is too easy to forget the blinker, ride on a road and a car will just cross it just in front of you. The car driver see that your blinker is on intending to turn so OK for him/her to cross the road.

I spend and have spent many important seconds to verify that blinker is not blinking on my CB750 K6 when riding on a road with a car at next side road wanting to cross it. Look down to pilot lamps/blinkers and up again takes 2-3 important sec.

I'll look for a buzzer to my K6 since it work fine. My K2 has after market switches, left side with buzzer off button when pressed. But blinker switch has not that good center point where it should stop by a small pellet finding an indent. Honda switch is better.

I have already been warned several times this year that blinker is on when it should not.

[bryanj]

You missunderstand the wiring to the light, the one that goes to orange is the 21w blinker, the one to orange/white is the 5w running light and the ONLY ground is via the casing to ear to shell bolt to nut inside then finaly via wire to green loom ground connector

[AwesomeCB]

I have been close to death several times due to no buzzer. It is too easy to forget the blinker, ride on a road and a car will just cross it just in front of you. The car driver see that your blinker is on intending to turn so OK for him/her to cross the road.

The buzzer is as annoying as hell but it works for me. It should be a feature on every bike, with an option for the rider to decide whether to use it and switch it on/off. Never had a buzzer on any of my other bikes and there too many times I could have gotten myself in a world of hurt because I left my blinker on too long.

[catlin]

Thanks all for the reply.  I had a combination of issues once I started really looking at it (partially my stupidity).  Hondaman was correct, the biggest issue I had was that the chrome bolt was a little dirty (didn't appear too bad from outside).  I took it off and wirewheeled it clean.  The intermittent blinker signal issue was due to my old battery.  It had enough juice to operate the running lights, but not the blinker relay.  If I cranked it, the lights would blink fine after the ground cleaning.  I did have the wire diagrams wrong, and someone had been in there before me doing some weird things with T junctions.  I removed those and put them back in the correct location.  Must have been someone who didn't know to clean the grounds. 

As for the buzzer preference, I usually do just fine with the idiot light.  Whatever floats your boat.  I kept the part because I think it is an interesting relic of the past, just like the headlight on/off switch.

So for now, issue is resolved.  Great forum and knowledgeable folks! I'm sure i'll be back with more.