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Discussion Starter #1
Hi all,

Came home with the Alfetta on the back of a tow truck after the RAC man diagnosed a failed ignition coil amplifier.

I can't find anyone so far (Highwood, CA, EB, Alfa Shop, Ignition parts, eBay ) who stocks them and the advice from EB was that they are like hens teeth and rubbish anyway so ditch what I've got and buy a 123 Distributor.

If this is the case then c'est la vie but it's not the £20 fix I was hoping for so does anyone have any other suggestions, can it be bypassed with some other electrical gubbins?

Thanks
 

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Ignition coil amplifier? Is this a standard feature on an Alfetta? Mine has never had one.

Or do you mean the ballast resistor?
 

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Hi all,

Came home with the Alfetta on the back of a tow truck after the RAC man diagnosed a failed ignition coil amplifier.

I can't find anyone so far (Highwood, CA, EB, Alfa Shop, Ignition parts, eBay ) who stocks them and the advice from EB was that they are like hens teeth and rubbish anyway so ditch what I've got and buy a 123 Distributor.

If this is the case then c'est la vie but it's not the £20 fix I was hoping for so does anyone have any other suggestions, can it be bypassed with some other electrical gubbins?

Thanks
Is that the ballast resistor, or is it an after market add on to boost coil performance - either way it can be binned as long as you have a decent / appropriate coil
 

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If it is the part in the above post take the part number and do a Google search using that. When the same part on my 75 2.5 V6 failed the part on that was replaced with a jaguar item. That was 1996 and the Internet was young then and Yahoo was the search engine to use but it saved me a fortune over the Alfa part.
 

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Discussion Starter #6
No it is an amplifier, apparently it's job is turn the coil off and on to fire up the sparks when starting (more info in link) Standard kit on (some?) Alfetta's and S3 and S4 spiders according to CA?? All the suppliers I phoned where familiar with them but no one stocked them.

http://www.205gtidrivers.com/articl...ne-related/what-is-the-ignition-amplifier-r89


There are plenty out there for other cars, mostly more modern 7 pole ones as per link but I can't find one for mine.
 

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Discussion Starter #7 (Edited)
Well it looks like you guys might be right. I've found reference to it on a couple of Ferrari sites where it is referred to as a ballast resistor and a ceramic resistor on another site attached to the original magneti marelli coil.

Cavallino

Magneti Marelli Ignition Coil BZR200A Superpotente

I replaced the original mm coil with an accuspark one a bit ago but didn't touch the thingamebob. With it off the car I've tried starting it but still nothing? There's a spare green wire that did attach to it (the guy at EB referred to it) but I dont know what to do with it. I've tried attaching it to either side of the coil but still nothing.
 

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It's a resistor that connects to a low resistor coil.
During cranking the resistor is bypassed and the coil gets battery voltage to create an extra strong spark.
You have to measure the coil's resistance to know if a resistor is needed.
The green wire belongs on the coil's + side and when attached the car should start.
 

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Discussion Starter #9
Thanks for that, I did connect it to + side with a clip but no joy, it's chucking it down and dark now so I'll try and attach it properly tomorrow.

What sort of resistance should I need, mine is listed as 30hms?
 

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My limited understanding of ballast resistors is thus; they essentially allow a 9v coil to have a "boost" up to battery voltage during starting, to produce a bigger spark. Once the engine starts they regulate the coil supply back to 9v for running.

Bridging a defective resistor will toast your coil, as it'll get 12v all the time.

If you know the resistance of the ballast resistor, you could replace it with a suitable length of resistance wire to recreate it, failing that, you need at 12v feed and a 12v coil to replace the current one.
 

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It is a very long time since I have worked with coils and ballast resistors but most of what has been posted I recall as correct.

However, most that I worked with had either a 3ohm coil with no resistor or a 1.5ohm coil with 1.5ohm resistor. (Does the "15" on your resistor really stand for 1.5ohm?)

Those with the ballast resistor had 12V direct to the coil when the key is in start position but once the key is released to run position the feed to the coil is via the ballast resistor.

There were a few variations where the resistors were 1 ohm and the coil was 2 ohm or similar but they seemed less common.

If you buy a 12V coil the primary winding resistance should be about 3 ohm and you should be able to use that as a direct replacement without refitting the resistor. You might get slightly more wear on your points so make sure the condensor (capacitor) is in good condition and that will make sure points wear is kept to a minimum.

Some believe that using a 6V coil and bypassing the resistor at start is to improve start up spark and some believe it is to reduce points wear. The other reason that is rarely considered is that current draw by the starter when cranking can reduce battery voltage to 10V or less so bypassing the coil resistor when cranking will negate the voltage drop at the coil. So which ever the design reason there are three benefits from one simple design.

However, if you have a good battery and ignition system you should be able to replace the coil with a standard 12V one, feed it with 12V bypassing the resistor and not notice the difference. Obviously with a battery in poor condition and big voltage drops caused by cranking you will get a fail to start sooner than with the resistor design circuit.
 

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No it is an amplifier, apparently it's job is turn the coil off and on to fire up the sparks when starting (more info in link) Standard kit on (some?) Alfetta's and S3 and S4 spiders according to CA?? All the suppliers I phoned where familiar with them but no one stocked them.
I don't remember seeing anything like that on either of my two running cars, or the S4 I broke for spares. I will have a look in my parts stash, though.

The Cavallino part in the link posted above shows a figure of 1.5ohms, which ties in with kandlbarretts post. Could you just buy a 1.5ohm resistor from Maplins - does it have to be a ceramic one?
e.g. http://www.maplin.co.uk/p/metal-film-06w-15-ohm-resistor-m1r5
 

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Discussion Starter #14

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I had a ballast resistor on my S2 but binned it with no ill affects when I bought a new coil - the coil has to be the right one for the ballast resistor otherwise as someone said it will be toast - minis used to have BR's - something to do with providing as much power for sparks as possible when starting but these days with good batteries , starters and sparks is completely unnecessary - your coil should work fine without it as long its the standard 12v one not one designed to work with a BR
 

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So it has - memory is terrible - and to answer your question from 2 years ago Rob, the accuspark conversion worked well but in the end I decided to go for a 123 as my dizzy was a bit worn, not looked back since
 

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I don't remember seeing anything like that on either of my two running cars, or the S4 I broke for spares....
I agree, CA has that wrong, imo. That thing first appeared on a 73 GTV.
The ballast resistor is to protect the points, and neither the injected S3s nor S4s have points....so it'd be a bit useless;)
 

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Commonly known as a condenser - that's telling you Dom!
I'm sticking to oily bits, these elecktricy things confuse me
 
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