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Fitting Omex shift lights - problems


Mrs Kipper

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Tried this at the weekend without success ☹️

 

Car is EU2 1600 K. Spliced into black/white wire into back of rev counter with piggy back spade connector. Connected blue wire from Omex to this. Connected red wire to a power source and the black to earth.

 

Reset Omex as per the instruction to the default setting of 6000 rpm. Started engine and even on tickover at 1000 rpm, the lights were flashing green and any slight increase in revs brought up the red.

 

What have I done wrong *confused* I thought that the unit may not have been set for 4 cylinders but I checked and this was OK.

 

I am going to give Omex a call today but any thoughts 🤔

 

Kipper

 

Fun is not a straight line.

 

Edited by - Kipper on 3 Jul 2006 08:25:32

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Kipper

 

Can you possibly disconnect the black/white lead from the back of the tacho but leave that lead connected to the Omex and try again. It might be that the Omex is loading the tacho.

 

I have designed my own shift lights and I had to take the tacho loading into consideration so I incorporated an extra transistor stage so that the shift lights and the tacho can't "see" each other but both can use the pulses coming along the black'white wire.

 

The other likely cause (although you would need an oscilloscope to see it) is that the pulses coming into the tacho are full of electrical "noise", viz: spikes etc rather than being reasonably clean square-shaped pulses. These spikes are probably large enough to trigger the Omex and so it is counting more pulses than there are in reality. Omex should have designed their circuit to "clean up" these raggedy pulses.

 

What they mean by "RF interference" (RF = Radio Frequency) is probably more likely the spikes above, viz: the Omex is mistakenly counting additional pulses but I don't believe it's RF generated; the circuit design should take care of that and why should your car be more RF prone than any other?

 

I notice you live in Hertfordshire and I'm in Bedfordshire (nr Dunstable) so if you can get over here, I'll put it on my 'scope and we can see what's really happening.

 

Chris

 

2003 1.8K SV 140hp see it here

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Chris

 

Thanks for the reply.

 

The black/white wire goes into the tacho through a connector block so its difficult to disconnect. But as I have spliced into the wire with a piggy bank connector, I suppose I can leave the wire from the tacho free and just have the blue Omex wire connected (If you see what I mean?).

 

I'm sprinting at Pembrey this weekend so I don't think that I will have time to play with the set up again until after this. However, I would be very interested in taking up your offer of coming over to Beds if that isn't going to be too much of a problem for you.

 

 

 

Kipper

 

Fun is not a straight line.

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Kipper

 

I suppose I can leave the wire from the tacho free and just have the blue Omex wire connected (If you see what I mean?).
That's exactly what I mean. Contact me via Blatchat if you do want to come over here sometime.

 

Edited to ask: From where are you taking the +12v and earth connections for the Omex, just in case the supply is very"dirty" at that point?

 

Chris

 

 

2003 1.8K SV 140hp see it here

 

Edited by - Chris W on 4 Jul 2006 11:26:48

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Chris

 

Just for testing purposes, I was taking the live from the live side of the horn button (only because it had spade end connectors) and the earth from the earth lead of the fuse box in the scuttle under the dash.

 

 

 

Kipper

 

Fun is not a straight line.

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Chris

 

The fuse box has a short black wire coming from it (or from around it?) that is fixed directly to the bulkhead with a self tapper. I took this to be an earth for something so connected the Omex earth lead to it.

 

Kipper

 

Fun is not a straight line.

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