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| electronic ignition and tacho signal??? https://ausmini.com/forums/viewtopic.php?f=2&t=99706 |
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| Author: | 68Rusty [ Sat Feb 22, 2020 1:12 pm ] |
| Post subject: | electronic ignition and tacho signal??? |
Hi all, Earlier this year I fitted an accuspark ignition module to my distributor and the car runs very well as a result. I have recently bought a SAAS tacho for the car and having trouble getting it to read properly. I am hoping someone here may have a solution for the issue I a can't solve. Steps I have taken to try get it working correctly, 1. Installed, wired as per wiring instructions, AUX power, Batt constant power, earth, light switch power, green wire neg side coil signal to tacho. (Result tacho reads off the dial) 2. Instructions said if needle reading bounces around try installing a resistor 10K ohm 1/4 inline for the green signal (neg coil side signal to tacho). Tried it, did not help. 3. I noticed that when I hold each end of open wire and become the resistor the tacho sort of works, at least at idle. When the rev come up uncomfortable tingling runs through my fingers. Also when I pinch the wires tightly the resistance seems to drop and the tacho reads too high again. 4. I Tried supplying the power to the electronic ignition module from a different location away from the aux power to the coil to ensure no interfering signal was interrupting the signal, didn't seem to help much. 5. Checked the coil to make sure resistance was measuring correctly on both windings and all checked out correct. Was a little higher across terminals (3.2ohms) as higher performance than std coil. I really cannot figure this out? All other functions on the Tacho are working correctly, it is set to 4cyl. This is the tacho I have purchased https://www.shopsaas.com/saas-tachometer-0-9k-shiftlite-3-1-2-in-dash-black-muscle-sg31642 Tacho install instructions here https://www.shopsaas.com/assets/files/install/MuscleInDashTachFitting.pdf |
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| Author: | hpal [ Sat Feb 22, 2020 8:14 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
No answer for you sorry, but interested to see if my smiths Tacho works ok when I change to electronic ignition. |
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| Author: | drmini in aust [ Sun Feb 23, 2020 3:57 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
Sounds like yours might be faulty, is it still under warranty? I fitted an Autogage tachometer to mine with a similar dizzy module. It went off scale when cranking, but read fine when running. I enquired from Autometer USA, they said this is normal and won't hurt it. However I didn't like it. I fitted a small NC relay in the signal feed from the coil and switched it with the red/white wire from ign switch. |
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| Author: | 68Rusty [ Sun Feb 23, 2020 6:57 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
drmini in aust wrote: Sounds like yours might be faulty, is it still under warranty? It is still under warranty,I fitted an Autogage tachometer to mine with a similar dizzy module. It went off scale when cranking, but read fine when running. I enquired from Autometer USA, they said this is normal and won't hurt it. However I didn't like it. I fitted a small NC relay in the signal feed from the coil and switched it with the red/white wire from ign switch. I have been researching and discovered there are tacho signal filters for both excess noise and voltage. https://www.glowshiftdirect.com/hei-tac ... al-filter/ https://www.autometer.com/tach-filter.html https://wiki.autosportlabs.com/CoilX https://www.maxtow.com/tachometer-signal-filter/ https://shop.classicinstruments.com/sn20 They are only around $20 which seems reasonable. I'm wondering if this will help resolve the issue? Sent from my moto g(6) using Tapatalk |
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| Author: | Convertible Mini [ Sun Feb 23, 2020 4:30 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
Check car wiring for Voltage drops. |
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| Author: | minijcar [ Mon Feb 24, 2020 5:54 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
1N4004 Diode in Series with the signal wire. |
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| Author: | 9YaTaH [ Mon Feb 24, 2020 7:18 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
minijcar wrote: 1N4004 Diode in Series with the signal wire. I assume the diode clips the peaks of the interference?...hmmmm |
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| Author: | minijcar [ Mon Feb 24, 2020 6:30 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
Look at the links 9ytah and the pictures show that a diode is the primary element. You can complicate it if necessary but the first step is a diode followed by a capacitor. The resistor will only be relevant if it is connected between pulse and power to pull up the signal. I’ve suggested something that might help and if it doesn’t won’t hurt. An oscilloscope will tell the story but how many people/ ‘professionals’ are up to giving information at this level. 
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| Author: | 68Rusty [ Mon Feb 24, 2020 7:24 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
Thanks for the feed back, some good ideas me thinks. Next plan of action, - I will will power the distributor off separate battery power to rule out that power/voltage source from the car isn't interrupting or polluting the tach signal. - I have ordered a diode as suggested, seems to make some sense to me, I tried varying resistors on the weekend and none seemed to control the signal any better, getting some consistency on the signal voltage cannot hurt particularly for a $ or less. One of the links mentioned that tacho's with shift lights and programmable rev warnings are particularly fussy when it comes to the tacho signal, so this might be why I am having these issues. - I also tried the RPM tacho on the old dwell meter I have and it reads fine. This would indicate the dizzy signal is ok (not faulty at least), but I am assuming it reads current and not voltage as my new tacho does. |
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| Author: | 9YaTaH [ Tue Feb 25, 2020 8:28 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
minijcar wrote: Look at the links 9ytah and the pictures show that a diode is the primary element. You can complicate it if necessary but the first step is a diode followed by a capacitor. The resistor will only be relevant if it is connected between pulse and power to pull up the signal. I’ve suggested something that might help and if it doesn’t won’t hurt. An oscilloscope will tell the story but how many people/ ‘professionals’ are up to giving information at this level. Hmmmmm...looked through all the links and couldn't see a 1N4004 in series with a signal wire...but its late and I am tired from travelling... |
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| Author: | minijcar [ Wed Feb 26, 2020 5:30 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
9Y the CoilX shows it’s circuit clearly. I nominated the 1N4004 as it is available everywhere and unlike the examples shown is not surface mounted. Easy to solder in series with a wire The others are wrapped in heat shrink but I bet in essence they are the same. Diode and a capacitor plus a little dressing. I can suggest a whole range of signal conditioners. You can see a number of them on my website but ultimately we have had plenty of success with 4 simple components: a diode, a 1k and 4.7k resistor and a couple of green capacitors starting with 0.047uf. Less than a dollar in total. Yesterday it was a Datsun 1600 with a vtec engine and ecu. The signal out of the ecu was below 5 volts amplitude. Common in ls1 engines also. A 1 k resistor from pulse to power to pull the signal up. Fixed. Tacho worky. |
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| Author: | 9YaTaH [ Wed Feb 26, 2020 8:19 am ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
minijcar wrote: 9Y the CoilX shows it’s circuit clearly. I nominated the 1N4004 as it is available everywhere and unlike the examples shown is not surface mounted. Easy to solder in series with a wire The others are wrapped in heat shrink but I bet in essence they are the same. Diode and a capacitor plus a little dressing. I can suggest a whole range of signal conditioners. You can see a number of them on my website but ultimately we have had plenty of success with 4 simple components: a diode, a 1k and 4.7k resistor and a couple of green capacitors starting with 0.047uf. Less than a dollar in total. Yesterday it was a Datsun 1600 with a vtec engine and ecu. The signal out of the ecu was below 5 volts amplitude. Common in ls1 engines also. A 1 k resistor from pulse to power to pull the signal up. Fixed. Tacho worky. Still not sighted! but CoilX say "The raw ignition signal is passed through a diode to prevent negative voltage transients."...Yay! Your 1N4004 advice above is helpful and appreciated  Signed: 9YaTaH ex-Datto 1600 owner, Electronics and Communications Certificated, former Instrument Tradesman 
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| Author: | minijcar [ Wed Feb 26, 2020 4:51 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
https://wiki.autosportlabs.com/File:CoilX_brd.png |
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| Author: | minijcar [ Wed Feb 26, 2020 4:56 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
This circuit is limited to 5volts as a family plc input output so is not really suitable for most Tachometers as it is close to or on the threshold. A pull-up resistor for those that are following this paint drying exercise would give it the extra it needs |
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| Author: | 9YaTaH [ Wed Feb 26, 2020 5:33 pm ] |
| Post subject: | Re: electronic ignition and tacho signal??? |
minijcar wrote: This circuit is limited to 5volts as a family plc input output so is not really suitable for most Tachometers as it is close to or on the threshold. A pull-up resistor for those that are following this paint drying exercise would give it the extra it needs Cheers
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