Negative Ground Conversion

JimC said:

If the case of the positive ground device is a conductor and attached to ground and ground has been changed from positive to negative, then the case must be insulated from ground and normal hot lead (now being positive) is attached to the case and the negative terminal of the device attached to ground (which is now negative).

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I need Hobot to translate that one. :mrgreen:

Hence the caveat, Sometimes it's a whole lot easier to just get the correct polarity device.

rick in seattle said:

Bonwit said:

rick in seattle said:

Positive-ground solid-state assimilators are NOT reversible. . .

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My Cool Cat Express SS3AW Assimilator is. Just swap the orange and black leads.
http://coolcatcorp.com/Merchant5/mercha ... gory_Code=

-John[/quote

Negatory, my good man. Mike Frank at CoolCat sells two versions, one each for positive and negative ground systems, respectively. Reversing the polarity of the two wires forward-biases all diodes, sends any transistors into cut-off, and reverses the sense of any comparison of voltages. If it works at all under these conditions, the device is comparing voltages with respect to the "hot" battery point, and not to a common reference, or ground. It is simply not possible for an active device, especially a comparitor, to function under a reversed polarization.

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Thanks for bringing this up. Considering I don't have the foggiest idea how any of this works I'll concede that you know more about it than I do. However, I just received an email from Jack. He said I had ordered the negative ground version which I wired according to instructions I received here. Its worked perfectly with positive ground, so go figure. Anyway, given that mine is really a negative ground box it should be an easy conversion.

-John

Simplest to run a -ground device w/o concern to rest of bike
is just mount it totally electrically isolated from bike and
run proper power leads in and out. GPS velcro'd to a base
or plastic clamps would work.

To switch whole bike using Lucas items require reversing
the zenor 'Diode' and the blue can capacitor leads
as some say its insulation is polarity sensitive, but
may not matter. I'd think the as assimulator would also
need reversal if ya still have one and still want it.

hobot

Simplest to run a -ground device w/o concern to rest of bike
is just mount it totally electrically isolated from bike

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And there's the problem. The Garmin's power adapter plugs into the back of the unit. All is well until you go to un-plug it (say, when you park the bike and want to take the Garmin with you). That bare connector, if allowed to touch the frame will short.

And there's the problem. The Garmin's power adapter plugs into the back of the unit. All is well until you go to un-plug it (say, when you park the bike and want to take the Garmin with you). That bare connector, if allowed to touch the frame will short.

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Why not convert your Norton to negative ground and be done with it? All the electronic gadgetry, LEDs , etc. are negative ground devices. It's just not that complicated to do. The devices that Hobot mentioned are good candidates for replacement (zener & assimalator) with ungrounded devices or outright removal (blue capacitor).

JimC said:

And there's the problem. The Garmin's power adapter plugs into the back of the unit. All is well until you go to un-plug it (say, when you park the bike and want to take the Garmin with you). That bare connector, if allowed to touch the frame will short.

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Why not convert your Norton to negative ground and be done with it? All the electronic gadgetry, LEDs , etc. are negative ground devices. It's just not that complicated to do. The devices that Hobot are good candidates for replacement (zener & assimalator) with ungrounded devices or outright removal (blue capacitor).

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Yep, that's the plan. . . Be done with it!

Thanks

I changed my 850 to negative earth for the sake of being able to use standard LED lamp clusters in the blinkers and tail lights. If not for the desire to do that, I wouldn't have bothered.

For me it was a simple matter of reversing the output wires from my Sparx regulator/rectifier. And of course the battery and electronic ignition wiring. The Zener goes away and so did the blue can. My Sparx unit is mounted in the battery compartment, screwed to the back of the airbox plate.

My only regret is that the ground wires are still all red, and that's now negative. As an EE that just rubs me the wrong way.

My Garmin GPS is powered through a 2 wire cable and doesn't care about ground polarity. The inline fuse would be in the ground side of the wire if the bike was + gnd, but that can be supplimented with a second fuse. That's how mine was wired before I made the swap.

My Cool Cat Express SS3AW Assimilator is. Just swap the orange and black leads.
http://coolcatcorp.com/Merchant5/mercha ... gory_Code=

Negatory, my good man. Mike Frank at CoolCat sells two versions, one each for positive and negative ground systems, respectively. Reversing the polarity of the two wires forward-biases all diodes, sends any transistors into cut-off, and reverses the sense of any comparison of voltages. If it works at all under these conditions, the device is comparing voltages with respect to the "hot" battery point, and not to a common reference, or ground. It is simply not possible for an active device, especially a comparitor, to function under a reversed polarization.

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I beg to differ. I also have a Cool Cat unit. It works fine on positive ground with the leads reversed from the normal Jaguar negative ground configuration. In the reversed mode the RPM needs to be a hair higher (like 1100) for the warning light to go fully out but it is not noticeable in the daytime.

I had mentioned this to Cool Cat when I got it about 2 years ago - in case he wanted to add a note in the instructions - but never got a response of any sort. You would think he would have said something about a different version?

Russ