nib1980
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| posted on 8/12/06 at 08:56 PM |
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Megajolt Capacitor?
Hi all,
just putting the finishing touches to my megajolt install, and I can't fathom for the life of me why there is a capacitor that seems to be used
in grouding the 12v +ve feed.
Any ideas? is it needed?
Many thanks
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paulf
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| posted on 8/12/06 at 08:58 PM |
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Its not needed its part of the radio suppression in the original fitment.
Paul.
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nib1980
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| posted on 8/12/06 at 09:00 PM |
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excellant
Many thanks Paul.
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Syd Bridge
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| posted on 9/12/06 at 10:19 AM |
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The capacitor would also smooth out any transient 'spikes' in the power supply line.
I'd put it in, even if there was one in the circuitry internally; which there should be anyway.
Cheers,
Syd. 
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Fred W B
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| posted on 9/12/06 at 10:48 AM |
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Found this on the net when I was wiring my ignition
Cheers
Fred W B
Adding a Capacitor:
Here's the part you may have heard of, but never paid much attention to. Adding a capacitor when installing an MSD offers several advantages and
is very benificial to a long lasting ignition. MSD calls it a "Noise Filter," but it is simply just a cap. Typically, these are used to
help filter out any radiated noise from the ignition to your electrical system which can cause some radiated noise through your stereo. For most of us
this won't be a problem. The important thing is that this cap also filters the power going to the MSD. This will prevent power surges and spikes
from damaging the MSD. Things like jump-starting your car are very tough on sensitive parts, but using a cap will provide the protection you need.
At this point, you have the option of either ordering the MSD part (PN 8830), which is what I recommend, or going to your local electronics part store
and picking one up. If you do the latter, you will need one of at least 25,000 microferrad and 16 volts. Anything bigger will be fine, but any larger
than 50,000 microferrads will simply be overkill. Just make sure that it's at least 16 volts and not just a 12 volt cap.
To install the cap, simply run the power lead for the MSD to the positive terminal of the cap. Then run a wire from this same terminal on the cap over
to the battery. At this point you have two options: You can either run the negitive lead from the MSD much the same way - to the cap and then to
ground, or you can simply ground the MSD and then ground the cap - independently. (Both methods are shown below) Either way will work just as well,
just go with whatever install method you think will fit your install best.
Understand that adding the cap may be the one thing that makes the differance between an ignition that lasts the life of the car -vs- one that only
lasts to the end of the year. After having installed around a hundred of these Ignitions, I can assure you it really does make all the difference. The
only two I've ever seen go bad, didn't have a cap installed.
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paulf
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| posted on 9/12/06 at 11:29 AM |
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The one fitted to Fords with edis is about 2 microfard ,it is a square plastic cased one and is usually located near the coil mounting bracket and
connected to the +12v line to the coilpack.I have ran my car for 2 years without one and most other people dont fit one either.The Megajolt has its
own transient and surge protection in the power supply circuit.
It will however do no harm to fit it, but is unlikely to be beneficial.
25000 microfarads is overkill for this type of system but may be required for MSD if it has a high current drain, a small capacitor is sufficent to
filter out high frequency noise and spikes as the battery also smoothes the voltage .
Paul.
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Fred W B
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| posted on 9/12/06 at 12:05 PM |
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quote:
MSD if it has a high current drain,
I don't know what the current drain is, but can tell you that if you let the MSD king lead arc to earth it makes a spark that looks like arc
welding, complete with tracks on the metal part 
Cheers
Fred W B
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