Mudbogger sent me his Honda tach.

Haven't been able to get inside ityet. But here's some photos as is.

This got a bit wet and muddy inside at some point.

More to come as I crack into it.


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Hondaline Tach repair
Hondaline Tach rebuild
Hondaline Tach inside

I have one with a busted needle...I couldnt figure out how to get it open with out a big hammer so I quit

It was easier to get into then first thought.
I cut the outer ring and peeled it back.

The entire inside was coated with mud. And the magnetic damening had
crud in the magnets, Possibly making it stick?

The PC Board had a little residue other than mud on it.

The rear has a lot of wholes t allow more dirt back in.

The lens will need to be glued back on since the metal ring is not reinstallable. These are made to go together and never apart.

The bolts I mentioned need isolating are not a big deal after all.
Just meter mounts, not conductors.

Hi Mass great stuff, thanks for the time and effort.The tach according to the old owner would work after it"warmed up" as he called it, I never had it running long enough to see if it indeed would work after "warming up" but he swore it did.Can the tach be waterproofed in a fashion that will allow me to use it?Is the mud/water damage so severe that it may be too far gone on the magnetics?

I took some close up shots of the electronics.

For the most part this is boring. How ever if I can disclose the design and help others debug or fix there tachs then its a win win.

BTW this is pre scrubbing the dirt and reflowing the solder.

From the close ups I see how I need to reflow the solder on some of these pads. Those alone may be the problem.

I also noticed the tach's power is diode protected. that's good to know: If it gets wired backwards it doesn't burn just blows the diode.

I've yet to put a meter lead on so this subject so we'll see what follows.

more

Finally got a chance to try the tach on my Pilot.

I retouched the solder spots that were crappy looking.
Looks like it did the trick. A little cleaning and a few dabs of solder.

Next step is to get it back together.

Thanks again Mass for everything-I don't no how you did it, but I am so thankful!!!!

Finally got to reassembling the Tach.

We used black silicone

One coat and let it dry then we can glue the lens to the seal.

May still need to figure out an out seal. I was thinking compression like thick electrical tape.

Mass can you describe in greater detail how the tach hooks up to the Pilot wiring. Is it getting its signal from the stator output or from the firing of the spark plug. If it is getting its signal from the stator that would mean it would not matter if the tach was designed for a 2 stroke or 4 stroke.


How many wires are there and where do they hook up (pictures showing the hook up so I could look at my wiring would be great).

Thanks
Doug

The one I had on my Pilot ran in a series with the ignition coil..

I sure can.

The Honda tach has three wires for the Tach operation and 2 wires for its night lamp.

Tach Wires
Green : Chassis Ground
Black : +12 Volts DC (switched)
Black Yellow : This signal is FROM the CDI (Capacitor Discharge Ignition). And TO the Ignition coil This is an Active HIGH signal I believe. Meaning it pulses Positive electrical signals to the ignition coil to excite into a high voltage.

Warning there is also another Back Yellow on the FL400R Harness FROM the 'pulser' in the stator area TO the CDI (Capacitor Discharge Ignition). DO NOT use this signal wire.

When I field tested the Tach for Mud I built a real simple harness. I'll take a pic after this message.

I connected it directly to the battery with green and black.

Black Yellow wires in Parellel with the Black/Yellow into ignition coil. A simple Y connetion off of it and into the tach.

So its getting its tach signal rateoff of how often the spark is excited by the ignition coil.

The circuit inside the tach:
Is a Frequency to DC voltage converter. What that means is the higher the frequency the more DC voltage it creates. The frequency is how fast the coil is being told to spark. The DC voltage is to drive the meter to display the value. The meter takes very small voltages to react from 0 to full.

I did not attempt to determine the field resistance of the meter and calculate the voltage range of the tach meter. I got his tach working and didn't want to risk breaking it.

How ever I am curious of the CDI (Capacitor Discharge Ignition) to ignition coil signal. I'll attempt to put a O'Scope on it and grab a pic. Hopefully it doesn't pookkaboom my scope....

Hmm a 2 stroke versus a 4 stroke tach..... Would dividing the 4 stroke tach values in half = the 2 stroke values? If so then a simple divide by 2 circuit may be the trick. Meaning a 2 stroke tach could work on a 4 stroke... To go the other way is more tricky. Its not as easy to do a multiply by 2.

And the Night lamp wires to Brown and Green.
That would be running lights and ground respectively.

a few mo pics.

This wire harness is really just three wires with crimp connectors on each end.

The spade connector is a male and a female crimp. So it works nice inline.
This connects at the coil to get at the Blk/Yel line.

Thanks for the info on how this is hooking up. Most "modern" small Engine tachs now determine RMP based on the Hz from the stator, this way it doesnt matter if it is 2 stroke, 4 stroke, 1 cyl or 10. You only need to know how many poles are on the rotor (flywheel in the Pilots case), which should be 6 or 12 (every 30 or 60 degrees) to detemine the RMP based on the Hz of the stator output signal.

In looking at the wiring diagram for the Pilot you will see a yellow wire coming from alternator (a single phase of the stator) going to the CDI (Capacitor Discharge Ignition). Why are they taking an AC signal the CDI (Capacitor Discharge Ignition)? The only reason I can think of would be to determine the RMP of the motor (( Internal Combustion Engine ? )).

Is it possible AC signal going to the CDI (Capacitor Discharge Ignition) is just being passed through the CDI (Capacitor Discharge Ignition) to the tach you are hooking up?

I'm sure it is passing thru. I see that signal as the power generation side of the CDI (Capacitor Discharge Ignition). And the CDI (Capacitor Discharge Ignition) uses this lead to generate the power to the Igintion coil.

Since we know the CDIs can rev limit.
And also I've heard do timing adjustments then that tells me the CDI (Capacitor Discharge Ignition) take s in the two signals. Then adjusts 'when' to send a clean pulse with power to the Ignition coil at the right timing. The ignition coil is only a Step Up trasnformer with the secondary winding going thru the spark plug.

OK end of project.

Reglued the lens and gasket on.
And wrapped it with 3M tape.

Mud: I'll ship it out tomorrow or Saturday.

Thanks Mass and Kathy for the great work, I do apprec it!!!

Bravo !

Boy too bad you cant find a LARGE hunk of heat shrink tubing you could put that around the outside and shrink it down...