Older RDAC XB not reading RPM

[aelsaadany]

Hi everyone,

I have a project that came with Odyssey and RDAC XB. I installed everything and the RDAC works fine with the other sensors except the RPM. I installed UMA sensor with slick mag and tried all the settings with and without ballast jumpers and no luck. Every time I try to test by tuning the started there is 0 RPM reading. I hope somone can shed some light on what can be the cause and if anyone experienced the same issue. Thank you in advance

[rainier]

The UMA sensors output a pulse which a voltage equivalent of the supply voltage (usually 12V) - so that is an ideal signal and easy to use with any of our RDACs. Ballast is not used (that would almost short the signal to ground). If there is no indication chances are there is no pulse either. In this case verify this by using a volt meter connected to the RPM signal line and ground. Leave the mags off (shorted) and start the engine - you should be able to clearly see the meter indicate the pulse - it works better with one of the old needle based meters (but almost impossible to find now) but even the digital ones should show you some activity - some of the digital meters have a little bar to emulate the needle which can be helpful.

[aelsaadany]

Thank you Rainier. So far I tested by turning the prob by hand and the voltmeter indicates between 0-12v on each turn. I read through the forum and almost exhausted all the options.
I also tested with 10k and 22k resistors with no luck. I rechecked all the wiring and even added a heavier Guage ground from the engine block to the buss bar for connected next to the rdac and still no luck. Is there a way to may be test the port on the RDAC to see if it's may be faulty? Or could it be something else?

[rainier]

If you get a solid pulse like that the RDAC should not have any issue at all. If it does not indicate - can you check the number of pulses per revolution setup in your instrument to make sure it is not set to some very high number that is not realistic.
If that does not change anything we would have to assume that the RPM input on the RDAC is damaged.