Don't try this with your JimStim...

Building and using the Stimulator to test your Megasquirt

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Don't try this with your JimStim...

Postby DaveEFI » Mon May 18, 2015 5:24 am

Had a V3 board in for repair which had severe damage to the ground tracks. Sorted that, but had it returned saying no spark - it had two coil drivers added for 4 cylinder wasted spark. All I'd previously done is seen the spark outputs working on my JimStim LEDs, when patched up.

So decided to try it using an actual EDIS coil. Knowing these take a lot of current, I fed a temporary heavy ground to MS to prevent routing that current through the JS. And obviously a +12v feed to the coil, both from the same heavy duty power supply as the JS. The driver ouput to the coil I took from the JimStim tag strip.

Didn't work and the JS CPU is now fubar.

I've done much the same before using an ordinary Stim just to provide ignition pulses when testing injector drivers in the workshop. But in this case needed the JS to replicate the 36-1 trigger.

Anyone know why the CPU chip failed?
Rover SD1 3.5 EFI
MS2 V3
EDIS
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Re: Don't try this with your JimStim...

Postby racingmini_mtl » Mon May 18, 2015 8:09 am

If you used the JS to connect to the coil, all the coil current went through its ground plane with flyback, noise and all that. There was likely a lot more than the 3.3V the CPU can handle.

Jean
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racingmini_mtl
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Re: Don't try this with your JimStim...

Postby DaveEFI » Mon May 18, 2015 8:58 am

That does sound the most likely reason. With hindsight, would have made more sense to use a separate power supply for the JS.
Rover SD1 3.5 EFI
MS2 V3
EDIS
Tech Edge O2
London UK.
DaveEFI
Super MS/Extra'er
 
Posts: 2776
Joined: Sun Apr 15, 2012 12:55 am


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