Wiring in Digital Speedometer

[Guest]

So my speedometer came in today. I got it wired in and everything works as it should except the tachometer.

So here is the set up. It has a single wire from the speedometer for the tach. It is grounded and powered through the speedometer itself.

I wired it to the white wire for 1/4 coil. So its the signal from the points. The tach reads but it is all over the place and stays around 2k no mater what.

So how am I supposed to wire it. The instructions say to wire it either to the magneto or the rectifier.

Thanks

[posplayr]

I dont know what it is so hard but many aftermarket tachs have issues with reading RPM. Generally a zener diode is best to clamp any of the spikes on the primary voltages which can well exceed 12V.

You might try putting a 10K ohms 1/4 watt resistor in series between the coil and the tech, and a 5V zener between the tach input and tach ground . Zener points up from ground.


You might also try what JohnKat did, Wired it to the sig gen for the OEM ignitor

http://www.thegsresources.com/_forum/showthread.php?230478-Does-anyone-have-experience-with-the-digital-speedometers-Just-have-1-question&p=2164404#post2164404

[John Kat]

I dont know what it is so hard but many aftermarket tachs have issues with reading RPM. Generally a zener diode is best to clamp any of the spikes on the primary voltages which can well exceed 12V.

You might try putting a 10K ohms 1/4 watt resistor in series between the coil and the tech, and a 5V zener between the tach input and tach ground . Zener points up from ground.


You might also try what JohnKat did, Wired it to the sig gen for the OEM ignitor

http://www.thegsresources.com/_forum...04#post2164404

You are definitely right: the voltage on the primary side of the coils can go well above 100 volts during the spikes.
The zener diode route is the way to go if there is no CDI.

[curtie94]

Alright so I tried a 10k ohm resistor but no good. Still does the same.

So are you saying I also need to wire in a zener diode.

The tach is built into the speedo and it is powered and grounded from the speedometer itself. So I only have a single wire for the tach.

So would I solder the zener diode inline with the resistor?

[posplayr]

Alright so I tried a 10k ohm resistor but no good. Still does the same.

So are you saying I also need to wire in a zener diode.

The tach is built into the speedo and it is powered and grounded from the speedometer itself. So I only have a single wire for the tach.

So would I solder the zener diode inline with the resistor?

This:

You might try putting a 10K ohms 1/4 watt resistor in series between the coil and the tech, and a 5V zener between the tach input and tach ground . Zener points up from ground.

means this:

http://i449.photobucket.com/albums/qq215/posplayr/ZENER_PROTECTION_zpssxybvwyw.jpg

[curtie94]

oh that makes sense now. I ordered some zener diodes and I already have the resister installed.

Could I rob a zener diode from a cell phone charger or something?

[posplayr]

oh that makes sense now. I ordered some zener diodes and I already have the resister installed.

Could I rob a zener diode from a cell phone charger or something?

Most stuff these days is surface mount which I assume you wouldn't know what to do with. You also did not mention a zener voltage. They range but you need something 5-12V. You might be hard pressed to recognize a through hole zenero to use, radio shack carried them but there are probbaly other electronics tore that would have them in small packs. You probably want some axial through hole parts.


Did you try the CDI pickup?

[curtie94]

I did read the post but I still wasn't sure. Do you mean to wire the pickup into my tach wire?

[posplayr]

I did read the post but I still wasn't sure. Do you mean to wire the pickup into my tach wire?

I should not have said CDI (I was following JohnKat's terminology hopefully not resulting in any confusion).

What I said before is this(including a link):

You might also try what JohnKat did, Wired it to the sig gen for the OEM ignitor

But now I realize I'm not sure what he did and how he connected to the pickup. He will have to come to his defense to explain what he did, but I can only assume he needed to connect one wire and he picked one of those from the ignition pickup.

What bike are you wiring this to. You have never stated that I can see?

[mikerophone]

What bike are you wiring this to.

This ^ and also, which digital speedo/tach you went with - trailtech or other? Do you have a link/pics/price?

[curtie94]

Well I got it. I actually wired in a different speedometer/tachometer. This one actually has gear position and neutral light. The tach worked great with just the resistor.

The speedometer uses 2 magnets instead of 1 and could tell the tire size by that. So thanks guys for your help. I guess the other cluster was defective.

[posplayr]

Well I got it. I actually wired in a different speedometer/tachometer. This one actually has gear position and neutral light. The tach worked great with just the resistor.

The speedometer uses 2 magnets instead of 1 and could tell the tire size by that. So thanks guys for your help. I guess the other cluster was defective.

I know that it is top secret, but I promise no one else will read this post but me, so post what tachs you are talking about............

[curtie94]

Here is the one that I got working. http://www.ebay.com/itm/201339327407...%3AMEBIDX%3AIT

And this is the first one that I tired that the tach didn't work on.http://www.ebay.com/itm/191562502739...%3AMEBIDX%3AIT

[posplayr]

Did you ever try with the zener? that is really what saves the gauge. The resistor is to limit the current in the zener.

[curtie94]

I can't get any zener's local so I ordered some 5v ones off ebay. should get them in a few days. should I wire one in once I get them?

The only thing with the round speedometer is the gas gauge doesn't work. Is there anything I have to do to get the gas gauge to work?