Current Draw of Original Dinoplex

You could, but you shouldn't. The MSD box has two power leads; one that should have power "all the time" and the other that is switched. The large RED wire can be easily connected to the B+ terminal on a nearby alternator (which is always hot). There's no need to run to the starter...

The smaller MSD power wire would then connect back to the OE switched lead.

David

 

It took me a long time, before I even noticed where my hidden MSD-6 was located, by the p.o.

 

I seperated the original 2 yellow wires and thought its a walk in the park to put them back when I switch back to my upgraded dinoplex paperweight. Its no biggie, we wont tell anyone what you did . I think in the boxer repair thread I showed my MSD install on my boxer.

 

I'm running the same unit (MSD 7AL-2) in my Boxer. I believe that the current draw specs they gave you are for an 8-cylinder car, running at 6,000 RPM.) I suspect that the 12-cylinder car will draw more current, as she's "sparking" more...and potentially, reving higher.

If you need the "special" electrical connectors, male or female, for the OE Ferrari connector, let me know and I'll drop a couple in the mail.

Also, I think you'll find that you'll get better results by not using the Magnetti Marelli coil, but that's another subject of controversy...

Good luck on the claim that they "remove the potting". I'm working with another Electrical Enginner here on some 308 spark boxes...and despite numerous effort, we've had little luck removing that stuff without further damaging the circuit board.

Regards.
David

 

Good day,

If this company just "repairs" the originals without any type of re-design of the input circuitry, then I do not think that this would be the best option... From what I have heard and read, the original Dinoplex's are very sensitive to voltage fluctuations and at times die in these condition(s). So if you run the battery down, use a battery tender, or even "boost" the battery you run the risk of frying your Dinoplex.... so if you do decide to pursue this $850 repair, you may wish to ask for a multiple discount, as the probability that you will need to do this again is a real possibility.

As for your MSD issue with separating the two joined (at the crimp connector) wires... again not a big issue. So, at some point if you remove the MSD and re-install your Dinoplex all you will need to do is "re-crimp" the two wires you separated and re-install them within the original OEM wire housing. In my case, I made a mating connector for the OEM housing and so I left the original OEM housing in its place and wired (most of) the MSD signals to my fabricated housing. The remaining MSD wires (the separated wire, +12V, and Ground) were wired separately. I then mounted the MSD to a back-plate I made and then mounted this to the original Dinoplex mounting studs... As a result, I can remove my MSD and re-install my Dinoplex without any indication that the MSD was ever installed in a handful of minutes... maybe 15 or so because of the cramped space where the Dinplex/MSD is/was installed.

Cheers,

Sam

 

According to the MSD installation manual, do NOT connect the power lead to the alternator. My mechanic ran the lead
to the starter motor, when he installed the unit on my 512BBi.

-------------------------------------------------------------------------------
This wire connects directly to the battery positive (+) terminal or to
a positive battery junction or the positive side of the starter solenoid.
Note: Never connect the alternator.
--------------------------------------------------------------------------------
http://www.msdignition.com/uploadedFiles/MSDIgnitioncom/Products/Ignitions/6420_instructions.pdf

 

Interesting, in that the B+ terminal gets it's feed directly from the battery...and has been connected that way for over 20 years. As I recall, that's either an #8 or #10 wire. I wonder what they're thinking...

 

Hi,

this is not a really helpful advice as you already have a MSD 7AL-2 but i would recommend using the MSD 6AL-2 for the boxer instead. The MSD 7 series is for high compression/turbo engines and develops much more ignition energy (and draws more power) than required for the Boxer. As with any MSD CDI, take care that you use helical wound ignition cables and keep a healthy distance between the ignition cables to avoid 'crosstalk' which can lead to unwanted sparks at cylinders in the compression phase (e.g. knocking).

The AEC 104 is encased in cured epoxy, it is quite difficult to get to the components, you can either
dissolve the epoxy with a (quite unhealthy) methylene chloride/acetic acid mix, heat it to >300C or spend some time with a dremel. No fun. I have done this to a given extent with a AEC 103 but need to invest much more time to get to a state when i can do a full circuit diagram.
It would be easier to get rid of the epoxy core and replace the circuit with a MSD 6AL-2 or Mallory Hyfire 6 PCB - both should fit but need a 6 pin connector instead of the original 4 pin connector.

2dinos, here is a good explanation from the MSD website how to apply the diode to the regulator circuit in general (your regulator will have a different pinout, let me know your Boxer model and year and i can look for a circuit diagram): http://www.msdignition.com/page.aspx?id=3296

As David already mentioned, the Magneti Marelli coil has different characteristics and is not really build to handle the higher current of the MSD CDI. A MSD Blaster 2 might be a good choice and does not look too different. The correct coils are 'e-coil' transformers and look really out of place.

Best,
Adrian

www.dinoplex.org

 

Good day,

I suspect that the issue of why they want you to connect at the Starter as opposed to the Alternator has to do with the Inductance of the wiring.

Let me explain...I suspect that the wiring size to the Alternator is of a higher gauge (i.e smaller diameter wire) (and may even be a longer wire length) than the Starter wire... which would make sense as the Starter draws a lot more current that what the Alternator produces and so the starter wire needs to have a much lower resistance (i.e. lower gauge or thicker wire) so that resistive losses are minimized. So, because of the wiring size (and most likely length) of the Alternator wiring, the Alternator wiring Inductance will be higher (maybe 2 times or more) than that of the Starter Wire. Why is Inductance of a concern? Well, in brief, the higher the wire Inductance the more time it will take for a given amount of current to flow through this wire ... How does this affect the MSD?... well, I imagine that the MSD's current requirement is not a static/constant amount but goes from some low/nominal amount to a peak (6-7 Amps so I have heard) and so having a delay in the MSD in getting this high current surge will have an effect on its operation...i.e. perhaps lower output discharge or even a delay firing... both of which would affect how your car will run.

As always, there are always parasitic components (in this case Inductance) to electrical wires that can cause problems in certain scenarios (in this case the periodic current surges of the MSD).

Here ends the lesson (taken from Sean Connery in the Untouchables)

Cheers,

Sam

 

Here's a response from an MSD tech that I found on their forum, regarding the power lead connections.

"The alternator produces a lot of electrical noise and can affect the charging circuit for the MSD box. It may also be producing a power spike that can damage the MSD box as well. This is why we also recommend connecting the Heavy Red wire of the MSD box directly to the battery pos terminal. This allows the battery to act as a filter to absorb most of the electrical noise produced by the alternator.

Before installing another MSD box I would suggest having the charging system checked to make sure it is not producing any power spikes (this is something that cannot be seen with a volt meter or test light)."

 

Interesting, particularly considering that the B+ lead on the alternator connects directly to the battery (thru the ammeter shunt). I fail to see how the battery "acts as a filter" regarding spikes, as the B+ and primary positive lead share the same connection. I guess I'll have to scope both these connections...and look for noise.

Thanks for the info...

David

 

Good day David,

Connection at the Battery will be the best location, as this has the least impedance to ground and therefore less inductance, etc which will result in a much smaller "spike" or electrical noise.

Although a wire connected to the battery is the same electrical potential, parasitic elements of the wire (capacitance and inductance) become an issue with certain types of electrical signals. If the signals were DC then the parasitic components of the wire can be ignored and so your comment would be correct . Remember that the MSD is a switching capacitive electronic device so that it actually causes a AC signal (varying current draw) from the battery. This AC signal, depending upon its magnitude and frequency, will cause these parasitic components of the wire (capacitance and inductance) to be present and thus potentially cause issues (electrical noise, potential difference between each end of the wire, Electromagnetic Interference/EMI, etc).

The bottom line is that a wire has some very interesting properties/characteristic once it is subjected to an AC signal... At DC, then ohm's law simply applies, but as the frequency (and edge rates) of the signal increases, some very nasty properties start to develop...You should see the stuff that I have to deal with my high frequency designs...

Cheers,

Sam

 

Sam,

I guess I never really gave much thought to the AC current switching component within the MSD unit...although I am aware of the AC noise on the alternator output. It's really not a big deal to cleanly tie the unit to the battery or the starter terminal. Thanks for your thoughts on this subject.


David

 

I, too, have heard of this problem. Yet, I have never experienced this with my BB/MSD set-up.

 

I had run-on issues on two british cars from the early seventies with external regulator, newer cars with integrated regulator did not seem to exhibit this behaviour. My assumption is that the alternator bulb just functions as a resistor in line, allowing a small voltage to activate the MSD via the smaller red cable (ignition key).
A quick fix would be to use a relay which is activated by the +12 feed via the ignition key and then switches (forwards) the +12v to the smaller red cable. No idea why MSD did not do this as default.

 

Good day David,

You are very welcome!

Cheers,

Sam

 

Good day,

I, too, have (thankfully) never experienced this problem.

For me, I do not like adding components whether it be a relay, diode, etc to fix something without knowing why the issue occurs and how the "fix" is supposed to cure it...Although the suggested additions are fairly innocuous, at times adding items without knowledge of the problem can cause other unforeseen issues. That being said, I know that what I am about to say does not help 2dinos right now, but sometime this Spring I will be analyzing the MSD unit in order to retrofit it into the Dinoplex for Paul and myself (and probably Angelo too )... At that time I will take a look at the MSD circuitry to see how or why their circuitry would allow for a "run-on" condition. Consequently, I will report back what I find.

Cheers,

Sam

 

Good day Adrian,

Not to defend MSD, but there could be a multitude of reasons why they did not do this. There could be electrical issues that we are unaware of, lack of physical area (volume if one includes height) for the relay, relay reliability and longevity, assembly issues (a number of relays have to be hand-assembled as opposed to automated assembly), cost, etc? We just do not know. It is possible that using the relay may only benefit a limited number of vehicles and so burdening the product with potentially increased cost may be unwarranted. Or, as you have suggested, it is possible that they never thought that it was necessary... perhaps their future versions will have this?

At times designers make the (hopefully) best product they can given time, effort, $$$. There are always trade-offs with product design and so only after they received end-customer feedback and/or real-world feedback (failures, etc) use will they know if the decisions they made were correct... hence version 2 (or 3, 4, 5 ...) of products .

Cheers,

Sam