Can You Burn Out a Tachometer?

Garrett Bernhagen /

Purchased one of those ungodly expensive tachs from treat land a while back for use on my magnum. Wired it once and it kind of worked but now it doesn't seem to do anything anymore; tried a few different wiring methods and now I'm afraid I ruined it. Is that something that can happen?

Re: Can You Burn Out a Tachometer?

From your experience it definitely is something that can happen . ;)

Re: Can You Burn Out a Tachometer?

Garrett Bernhagen /

Thanks for the input, haha

Re: Can You Burn Out a Tachometer?

Does that tach have a battery for any reason ?

Re: Can You Burn Out a Tachometer?

How many RPMs are you revving to burn out a tach? You must be flying...

Re: Can You Burn Out a Tachometer?

Garrett Bernhagen /

this tachometer works like a voltage meter. it has no cables or anything that run to the wheels, it measures the current from the headlight wire and interprets it as an RPM reading. I am wondering if I sent the wrong kind of voltage to it and burned it out or if it was just defective from treatland to begin with. I have no knowledge of how common this style of tachometer is and what sensitivities it has to being wired improperly so I am looking for some advice if any others have had experience with this either in mopeds or on other vehicles.

Re: Can You Burn Out a Tachometer?

Dirty30 Dillon /

> Garrett Bernhagen Wrote:

> -------------------------------------------------------

> this tachometer works like a voltage meter. it has no cables or anything

> that run to the wheels, it measures the current from the headlight wire

> and interprets it as an RPM reading. I am wondering if I sent the wrong

> kind of voltage to it and burned it out or if it was just defective from

> treatland to begin with. I have no knowledge of how common this style of

> tachometer is and what sensitivities it has to being wired improperly so

> I am looking for some advice if any others have had experience with this

> either in mopeds or on other vehicles.

You have to link the Tach you are talking about.

No tach that I know of pull signal off of the headlight, that doesn't make any logical sense as they almost always pull pulse from the HT coil plug wire via inductance on the outside of the jacket.

If you are feeding it VAC directly into that signal wire, you have fried it and you'll have to buy a new one.

Re: Can You Burn Out a Tachometer?

On mine you just stick the open wire near the plug wire. Doesn't physically wire up to anything.

Re: Can You Burn Out a Tachometer?

Woah yeah...It measures rpm man you connect it to the ignition circuit not the light circuit. You probably fried the coil inside.

It measures pulses not voltage, the low current pulses energise a coil. That coil creates a magnetic field which produces a force upon a ferrite bead attached mechanically to the needle. The more pulses the more it can move the bead, overcoming the force of the spring and in turn the needle moves farther up the dial. (edited)

Re: Can You Burn Out a Tachometer?

> Garrett Bernhagen Wrote:

> -------------------------------------------------------

> this tachometer works like a voltage meter. it has no cables or anything

> that run to the wheels, it measures the current from the headlight wire

> and interprets it as an RPM reading. I am wondering if I sent the wrong

> kind of voltage to it and burned it out or if it was just defective from

> treatland to begin with. I have no knowledge of how common this style of

> tachometer is and what sensitivities it has to being wired improperly so

> I am looking for some advice if any others have had experience with this

> either in mopeds or on other vehicles.

That like, can't be right. Every other tach out there is fed off the ignition wire for a reason. Think about it, it would have to be specifically tuned to every single stator out there if it measured the current to the headlight, no 2 bikes are the same. Even then, it's not a reliable method at all. Finally, you would have to have the tach wired in series, not parallel, if it ran that way; meaning you would have had to cut your headlight wire in half and wire the tach in the missing portion of wire.

In conclusion, you have it hooked up wrong, it should feed off the ignition coil. Pulses/second give RPM ez pz can't fuck it up no tuning to each stator that way

Re: Can You Burn Out a Tachometer?

> Aaron Blair Wrote:

> -------------------------------------------------------

> Woah yeah...It measures rpm man you connect it to the ignition circuit

> not the light circuit. You probably fried the coil inside.

>

> It measures pulses not voltage, the low current pulses energise a coil.

> That coil creates a magnetic field which produces a force upon a ferrite

> bead attached mechanically to the needle. The more pulses the more it

> can move the bead, overcoming the force of the spring and in turn the

> needle moves farther up the dial.

haha ouch. Most likely what happened.

I believe hes referencing the trail tech vapor. I've just installed and routed the temp sensor, the wheel speed sensor and now doing the tachometer.

Wish it was just wrapped around the spark plug wire. I'd love a more solid connection. I'll tape it, but a connector woulda been nice. (edited)

Re: Can You Burn Out a Tachometer?

Garrett Bernhagen /

Tachometer from Treatland

This is the tachometer. I reached out to others on the forum that have an LTD and had it wired the way I tried it. (see attached image)

On the LTD, the yellow wire is the wire to the headlight to my knowledge. That was the + end of the tach, and the brown wire is - ground, which goes to the frame. I did the same for mine where green was - and black was + and it worked at first up to about 500 rpm and then stopped working forever.

image2.jpeg

Re: Can You Burn Out a Tachometer?

Dirty30 Dillon /

yeah, sounds like you burned it up. im guessing the lite green is signal and needs to pull from the ht coil pulse.

i will look at my puch monza this weekend to see how the tach is wired.

Re: Can You Burn Out a Tachometer?

If it's a VDO you can get it repaired.

Re: Can You Burn Out a Tachometer?

Ohh yeah, looks like you accidentally hooked signal up to the bikes lighting circuit instead of the ignition.

It's an easy mistake to make tho. Some old analog tachs could use the light coil as a signal as long as it wasn't rectified. Those interpreted the AC flipping as a signal. Easy way to fell the difference is that those only have two connections. As the light bulb is powered from the same source so it doesn't need three.

If you want to actually test it to see, grab a multimeter and connect it between the signal wire and ground. Set it to continuity/or ohms if yours doesn't have continuity.if you get a value it might not be fried, could just be frozen... Open circuit and it's toast. Burned up a turn in the magnet wire.... (edited)

Re: Can You Burn Out a Tachometer?

Can verify that both Ltd tachs and laguna tachs pull the signal from the lighting coil.

Re: Can You Burn Out a Tachometer?

OP you ever get this working? I just bought the same one for my Ltd

Re: Can You Burn Out a Tachometer?

Re: Can You Burn Out a Tachometer?

I set up a tach on my slex and it is really easy. It just needs ac power and frame ground. I just spliced the red into my lights (I recommend a fuse) and grounded the black it a the ground terminal on my triple tree. Very accurate.

Re: Can You Burn Out a Tachometer?

Thanks Daniel, that’s straight forward enough. Still weird that this seems like a pretty not common setup for a tach...

To be honest I got the tach to “complete” my Ltd so it’s definitely more for looks to me. That and my plastic insert is kinda broken 😑

Re: Can You Burn Out a Tachometer?

Coming back to this because I got it working today.

Yes, it does work by going off the light coil. I spliced into the yellow wiring used for the headlight to the little green wire, and grounded the little back wire. This initially didn't work but I came across the listing on JMPB parts that explained that the housing needs to be grounded too.

https://www.jmpbparts.com/tachometer-vdo-replica-60mm-puch-monza.html

so I ended up doing that and it works! Only problem I'm facing now is it seems to read about 50% of what the real RPM should be. At full speed its reading like 4200 rpm when im doing at 8500.

Re: Can You Burn Out a Tachometer?

You have to use the adjuster screw to dial in the rpms. Look in the rest of the pictures on jmpb, they show you the one to turn, i don’t remember which way to send it, but it’s pretty obvious once you start messing with it. (edited)

Re: Can You Burn Out a Tachometer?

Oddly enough I looked and it seems like mine doesn’t have the adjuster .... I wonder if I’m meant to open it up somehow to get to some type of adjustment? Anyone know if I can crank this open somehow? It has the screws at the bottom ... (edited)

B431BEA9-D8CC-461F-A34C-68853EFE62F1.jpeg

Re: Can You Burn Out a Tachometer?

Hey I got it open. No screw where that thing would be but what’s this plastic looking screw with white goop?

Edit: I yolod and tried screwing it back and forth, breaking it free from the goop. It can only go so far left and right so this very may well be it, I can’t test with the bike on until tomorrow though! (edited)

84CABF26-D996-4C31-97D2-4741FA7990B5.jpeg

Re: Can You Burn Out a Tachometer?

Success! Turn that bad boi all the way to the left and its about perfect. There definitely is room for fine tuning it if you probably wanted to cut out a hole in the housing but all the way left seems pretty good.

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