At my last event, the tach display on my xg log stopped working. Every other function is normal. Could this be the rpm filter failing? The car has a normal coil with Pertronix ignition.
Thanks for any ideas.
Aim tach display
At my last event, the tach display on my xg log stopped working. Every other function is normal. Could this be the rpm filter failing? The car has a normal coil with Pertronix ignition.
Thanks for any ideas.
If your RPM filter power is connected to the ignition switch, then it failed when you turned off the ignition with the engine running. You need to have the RPM power be the exact same as the XG-Log (either master switched power, or from data system power switch).
The RPM filters can be killed if there is input voltage / current (from the negative side of the coil discharging), while the power to the filter is turned off.
You can be lucky for a while, but eventually it will get every one.
That's interesting. The AIM guys in Lake Elsinore told me that if the power dropped below 9V on start it would probably kill the filter. So I put a big-ass cap and zener diode on it so that it would pump up to no-load voltage before the starter pulls it down. But DOH! I related it to some problem of low voltage within the chip, not lack of power altogether. I have a switch on the amp so I can turn it off if I'm doing extended cranking with the ignition on. I guess I'll have to change that switch to DPST!
The little op amps are only about $1.80 from Digi-key but it takes a talented tech with the right soldering tools to swap them out. I tried to reverse engineer it so that I could build some with full-size parts instead of that surface-mount stuff, but there were a couple of bits I couldn't easily figure out.
and now for something completely different
David is quite humble, not out to shill his products; but if you want to get a consistent and reliable tach signal, the Veracity FF/pinto RPM speed pickup kit works excellent. Just make sure the pickup has adequate clearance from the cap screws on the collar, like I didn't...
https://veracitydata.com/products/ve...cing-products/
Last edited by DanW; 07.27.17 at 1:04 AM. Reason: grammar
“Racing makes heroin addiction look like a vague wish for something salty.” -Peter Egan
Thanks for the input. I will try a new filter and get the veracity set up for the winter re-build.
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