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Location:
Newcastle
Registered:
July 2003
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jaycar digital tacho problem
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Tue, 01 November 2005 03:47
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this arvo i whipped up a jaycar digitial tacho kit for the corona. the thing sounds like a tractor regardless of how much gas you give it so hence putting the tacho in it.
ive got it all together it powers up no problem.
when i hook it to the car it is giving the correct voltages to the PIC +5V on 4&14. nothing smokes. nothing gets hot.
when i hook the signal wire to the negative side of the coil the car refuses to start.
i disconncted it starts ok, touched the signal wire to the coil.. instantly stalls.
any thoughts... ?
oh and its a 1X engine in an XT130 corona/.
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Location:
Adelaide
Registered:
July 2004
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 08:09
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+ve charge going through tacho onto -ve on coil? maybe wrong wire your hooking or something within the unit itself is crossed
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Location:
Newcastle
Registered:
July 2003
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 08:46
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my flat mate just gave me a hand and we gave it another shot.
i thought perhaps the tach was sucking too much energy from the coil so i placed a resistor inline with the input to the tach.
at first i tried 500kOhms. it ran fine but gave no signal on the tach. i stepped down in values until i got to about 400Ohms. then i got a signal on the tach (too high a reading though) and the car ran.. any lower resistance and the car stalled.
when the car is running without the tach connected i put the multimeter from the -ve of the coil to the chasis. it was measuring between 300-400hz when idling.
any thoughts ?>
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Location:
Newcastle
Registered:
July 2003
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 11:04
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any thoughts people ?!?!?
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I Supported Toymods
Location:
Glenmore Park, NSW
Registered:
March 2004
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 11:28
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you running a ballast resistor?
if not may be why your needing to add resistance? i dunno shot in the dark here.
too high a reading? prob just have to set the buttons right.
have built and installed this on a 2t but found the readout to be too slow. improved accuracy of readings though.
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Location:
Newcastle
Registered:
July 2003
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 11:31
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i have set the buttons to configure it for a 4 cyl engine and it hasnt made a difference..
i havent got any resistorin there atm. there is what looks like a large ceramic resitor connected to the +ve of the coil however.
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Location:
Perth
Registered:
June 2003
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 12:38
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check for shorts on the coil- line on your tacho, the only thing to stop the engine from working would be if the coil- was being held at a constant voltage.
the ballast resistor in the coil+ shouldnt have an effect on the tacho.
hope that helps man, unfortunately i havent built a PIC based tacho, so i cant help much beyond that.
Rudi
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Location:
perth
Registered:
June 2005
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Re: jaycar digital tacho problem
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Tue, 01 November 2005 15:28
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man if u ask me, i would never buy a digital tach... cars got one, safc got one eboost got one - their all fucked should have bought a analoge one - at least u dont have to stare at it to see whats happening. id get one from a wrecker if moneys the problem
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