Trispark/ smiths

Hi all,

So my friend rode 60 miles to my house and we were going to head to the Hansen Dam Norton meet. I Was excited. My mk3 had different ideas.

Would not start. After about an hour of messing about i found out the trispark is dead. I think i know why, but a question to those in the know: i have a smiths electronic tach. It has been great for thousands of miles. I have a dual coil and positive earth.

The ignition wire powers the trispark, and in turn the trispark triggers to neg side pf the coil. I have a very good earth or ground everywhere and voltage is good. The electronic ignition is wired up correctly.

The electronic tacho senses the coil pulse and is correctly connected via red/ blue to the negative side of the coil to sense the revs. This same wire has 12v continuous from electronic tach to coil. This seems very wrong. The smiths gets its operating voltage from another wire. So i am thinking the tacho shorted and back fed down and screwed up the trispark. I removed the red and blue from coil to test, but is too late trispark already dead. I tried triggering the coil and by passing trispark everything and it works.

My question is, should the red and blue wire from smiths electronic tacho have a 12v feed from tach to coil? If so why. Does not make much sense to me.

This is going to cost a lot to fix, so i want to get my facts right before i see about any warranty possibilities, which are probably zero to none.

Cheers
Jerry

It almost seems as though you are mixing up power to the tach and power to the trispark. I would surely keep these power feeds separate and the only thing the tach and the ignition would have in common will be the red/blue wire to the whatever is need to sence the pulse.

Although draw to the tach is minimal, I would think that the tach might fail before the Trispark although the trispark robustness always seems to be in question.

My 72 has always had a 2 position switch with the light switch on the shell and another toggle under the seat for the Mag. The Hunt mag is totally separate from all other electronics. I required a module from Joe Hunt to send the pulse from the mag to the tach and that is the only thing in common between them. I only mention this as an example of to different but related systems.

I don't know if this has anything to do with your issue but thought it may help.

Peter

Hi Pete,

The power to the tach is independent from everything else and i have a fuse for that circuit. The tach has a wire that comes from it (red/blue). It has been ok for 5000 miles. The red and blue wire goes on the coil to sense pulse there. I am seeing 12v from tach to coil on this red blue. As far as i am concerned thats wrong and something shorted in the tach, but i am not 100% I was hoping that some one could confirm that there should not be 12v there from tach. Or if thats how it should be, then maybe the trispark failed.

Cheers
Jerry

Jerry Doe said:

Hi Pete,

The power to the tach is independent from everything else and i have a fuse for that circuit. The tach has a wire that comes from it (red/blue). It has been ok for 5000 miles. The red and blue wire goes on the coil to sense pulse there. I am seeing 12v from tach to coil on this red blue. As far as i am concerned thats wrong and something shorted in the tach, but i am not 100% I was hoping that some one could confirm that there should not be 12v there from tach. Or if thats how it should be, then maybe the trispark failed.

Cheers
Jerry

Click to expand...

When you disconnect this wire from the coil does it still show 12 volts? And is it 12 volts plus or minus? Did it get pinched in the shell? There is no fuse on this wire I assume, so if it got pinched, even inadvertantly, it sure could have done some damage.

The 12 volt continuous wire added to the impulse side is a fix commonly used by hot rod builders experiencing erratic tach movement. Does the 12 volt to the impulse circuit have a resistor in line?
This fix was suggested to me as a fix for my Smiths electronic tach malfunction, however the Smiths had other problems and is currently in the UK being repaired under warranty by Smiths.



Glen

I've just installed a Smiths electronic tach and Tom included a 22.2K (I think) resistor with it to be wired into the red/blue wire that connects to the coil. He said this was to protect the tach from spikes that are produced by the TriSpark.

Do you have a resistor wired in line on the red/blue wire? If not, is it possible that the TriSpark sent a spike to the tach that caused it to malfunction and send voltage back out through the red/blue wire?

The Smiths install leaflet states the red/blue should connect to " switched side of ignition coil"

Yes on red blue to switched side. No to resistor. I checked original paperwork and no resistor was specified and i wasnt sent one. It makes total sense though and i should have thought of that. Looks like i am gonna be more than a few days on this.

So maybe it was supposed to have 12v on blue and red. The plot thickens.. Seems strange. I need to know for sure, does blue red have 12v or not. I asked Tom at smiths usa...

Cheers and thaks for the feedback

Jerry

I think you are on to the cause Jerry... The coil's low voltage circuit is triggered by the ignition module so How could the tach sensor wire attached to the low voltage circuit have any voltage of it's own on it when it's sending the ignition voltage pulses to the tachometer ?... I think your suspicion that the tach is shorted will be confirmed.

I wonder if you could protect your ignition circuitry with a diode or something like that... if indeed your tach has a short that will kill your next ignition module...

I just checked. With power to the tach, but the engine not running, there is 0v on the red/blue wire on my bike.

Thanks very much for confirming. That means my smiths gauge failed. Now i have some direction.

Maybe put another mechanical tach on instead and replace trispark, i suppose.. Thinking.........

Jerry , my mistake, didn't read your info thoroughly. You and Steelcap are correct, there should not be 12 volt continuous on the impulse wire if the tach is wired up as per Smiths. The diagram I posted is a fix for lumpy digital tachs of all sorts, of course with this fix in place you would have 12 volt continuous with key on.
But not with your setup.


Glen

Jerry,
As far as the Trispark goes, does yours have the test button on it and if so have you tried the tests they suggest? I had one that wouldn't fire but showed good when testing, but would malfunction shortly after putting back in bike...Sent to Trispark and it tested bad trigger circuit..

Hi Bill,

Yes mine does have the test button. It's as dead as a DoeDoe. I am still waiting to hear back from Tom, but I doubt I am covered by warranty as its been over a year with approx 5000 miles. Basically the electronic Tacho failed and took out the Trispark with it. I think the coil is ok. Its looking like this is going to cost me just under $600 for a new Tacho and Trispark. At least it happened in my garage and not out on the road.

Maybe I should go back to points and put a mechanical Tacho back on (joking..).

Jerry

The Trispark has a 3 year warranty and can probably be taken care of by the vendor you purchased from...If not contact Steve Kelly and he would definitely help you out...I actually ordered a spare unit to carry with me...I told Steve I liked the ignition but am a little hesitant about trusting it without a spare...He gave me a deal on the spare and I feel safer now using the Trispark...

Jerry Doe said:

Hi all,

So my friend rode 60 miles to my house and we were going to head to the Hansen Dam Norton meet. I Was excited. My mk3 had different ideas.

Would not start. After about an hour of messing about i found out the trispark is dead. I think i know why, but a question to those in the know: i have a smiths electronic tach. It has been great for thousands of miles. I have a dual coil and positive earth.

The ignition wire powers the trispark, and in turn the trispark triggers to neg side pf the coil. I have a very good earth or ground everywhere and voltage is good. The electronic ignition is wired up correctly.

The electronic tacho senses the coil pulse and is correctly connected via red/ blue to the negative side of the coil to sense the revs. This same wire has 12v continuous from electronic tach to coil. This seems very wrong. The smiths gets its operating voltage from another wire. So i am thinking the tacho shorted and back fed down and screwed up the trispark. I removed the red and blue from coil to test, but is too late trispark already dead. I tried triggering the coil and by passing trispark everything and it works.

My question is, should the red and blue wire from smiths electronic tacho have a 12v feed from tach to coil? If so why. Does not make much sense to me.

This is going to cost a lot to fix, so i want to get my facts right before i see about any warranty possibilities, which are probably zero to none.

Cheers
Jerry

Click to expand...

Hi Jerry,

There is no voltage in the red/blue wire from the tach. The tach is a read only instrument that picks up the pulses from the ignition system.
It would be pretty impossible for the tach to take out an ignition system as far as I can tell. Think about it. Has anyone ever heard of a tach on their new motorcycle or car taking out their ignition system on their bike or car? It simply picks up the pulses and converts it to a gauge you can see.
Here is a more likely scenario. The TriSpark more than likely took out the gauge and somehow shorted out the board allowing a voltage reading
on the pick up wire. The TriSpark is a great ignition system and I have one myself on my street Norton. But...Smiths did a bunch of testing on all the aftermarket ignition systems out there and found that the TriSpark is prone to sending out occasional voltage spikes. This seems to have little or no effect generally on the bike but has caused some issues on some of the electronic tachs. So they recommended installing a 22 kilo ohm .5 watt resistor on any motorcycle running a TriSpark. This came to light not long ago so I found an electronic supplier and started now supplying one along with a piece of shrink tube with any bike with running the TriSpark at no charge. According to Smiths in the UK, this cured the issue. Again, I want to emphasize the TriSpark is a great ignition system, just install a resistor if running the Smiths electronic tach. If you bought a tach from me and are running the TriSpark, let me know and I'll send you a resistor at no charge.

Cheers,

Tom Kullen
tom@smithsgaugesusa.com
http://www.smithsgaugesusa.com

Hi all,

A quick update. I talked with Matt and he is sending me a new Trispark under warranty. I also talked with Tom about the tacho and he thinks the Trispark might have taken out the Tacho. Tom recommends adding a resistor on the blue and red wire to the Tacho. I did not have a resistor as it was not sent with one. So if you have smiths electronic Tacho and Trispark I would add a resistor if you don't have one.

All for now
Cheers

Thanks Tom,

Looks like I missed your post. It does make far more sense that the Trispark took out the Tacho now you mention it. I am very happy with the Smiths gauges. Second best mod I did to my bike (best was hydraulic clutch).

I will send you my old Tacho when I get it off so you can have a look. Appreciate the help,

Cheers
Jerry

worntorn said:

The 12 volt continuous wire added to the impulse side is a fix commonly used by hot rod builders experiencing erratic tach movement. Does the 12 volt to the impulse circuit have a resistor in line?
This fix was suggested to me as a fix for my Smiths electronic tach malfunction, however the Smiths had other problems and is currently in the UK being repaired under warranty by Smiths.

Glen

Click to expand...

Hi Glen,

If I'm reading your wiring diagram correctly, your showing 12 volts wired directly into your signal input wire. There should never be power hooked to the wire picking up pulses. These are signal only wires. The same goes for the white/black wire that gives you the option of picking up the pulses from an ignition with a built in ECU. If you put 12 volt power directly into either one of these signal only wires you would probably blow the input. Your tach had both the inputs blown so this might be the reason? Either way Smiths is repairing the gauge under warranty. The resistor goes inline on the signal wire (red/blue) not the 12 volt hot lead as indicted on your schematic. Resistor according to the engineers at Smiths should be 22 Kilo-ohm 0.5 watt not .25 watt. It is supposed to halve the dissipated power to the built in resistor on the tach board. This will raise the input voltage threshold from 8.0 volts to 10.volts.

Cheers,

Tom Kullen
tom@smithsgaugesusa.com
http://www.smithsgaugesusa.com

Hi Tom

My tach quit while riding, not during testing.

This was a fix for lumpy operation suggested to me by a hotrod builder friend who installs a lot of Dakota Digital, Autometer and other electronic tachs in his customer's cars.
I tried all of the things you suggested, but never did get around to trying this. I wondered about the 12 volts continuous, but he claims no problems. Also, the diagram shown is a fix for shaky needle function, but I had perfect needle function for two weeks, then basically no needle function after the problem arose, so it seemed unlikely to work.
Lots of car tachs wired up that way though. You'll note the diagram is from Street and Performance. They sell Autometer and other Digital Electronic tachs and instruments.
Glen