Part substitution

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hardline
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Part substitution

Post by hardline »

My PWM IAC Mosfet failed about a week ago. Looks like it is stuck on, as the IAC gets warm fast and it idled at 4500 RPM. I am currently running with the idle set screw run in all the way for cold idle, but I idle at about 1600 RPM warm. I have a few spare IGBTs laying around and was wondering if I could use an IGBT in place of the MOSFET on that circuit.
trakkies
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Re: Part substitution

Post by trakkies »

The only MOSFETs I'm aware of are the two injector drivers. Can you give more details?
Dave P, London UK.
Rover V-8
MSII V3
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hardline
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Re: Part substitution

Post by hardline »

Matt Cramer
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Re: Part substitution

Post by Matt Cramer »

That's a power darlington. I suspect an IGBT could work here as long as it can trigger off a 5 volt input. Some can't.
trakkies
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Re: Part substitution

Post by trakkies »

As Matt says a Darlington pair (effectively two transistors in one case.) They are cheap as chips on Ebay. Cheaper than an IGBT.
Was it correctly mounted on a heat-sink? Without one it could overheat and fail. If you're not using the ignition driver (Q16) remove it and mount the TIP 120 there. Otherwise fix it to the case. For either, using a mounting kit which insulates it.
Dave P, London UK.
Rover V-8
MSII V3
EDIS
Tech Edge Wideband
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