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where is the ballast resistor?


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Some may remember me from my recent GT6 days - well, I sold that cos my wife found it too uncomfortable.....so I bought a spitfire 1500 instead. And yes, wife did test it and said it was OK! Anyway, this car had, until today, a 40 odd year old sparkrite "electronic" ignition system. I've removed that, because it just didn't work properly, to be replaced with an accuspark module. However, this car should have a ballasted ignition system, and does have the appropriate (very old) Lucas DLB102 coil, but I cannot for the life of me find a ballast resistor. I would assume that it should be in close proximity to the coil, or at least in the engine compartment. Am I looking in the wrong place?

And while I'm here, the ignition light doesn't go out. I've removed the plug from the back of the alternator, and checked the voltage on the middle terminal, that goes to the battery (with the engine running, even I'm not that dim). I tested the voltage from that terminal to earth, and it registers about 0.5 volts!! Am I doing the wrong test, or does that mean that the almost new alternator is dead.

would appreciate  any help

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There is a special high resistance wire  which I believe is pink/white that runs from the ignition switch to the coil.  There is no separate ballast resistor.

I was told never to run the alternator without the connection to the battery or the electronics may be damaged.  Both large terminals should be at battery voltage.  The smaller terminal should be at basically 0 volts but rise to 12 volts as the alternator charges the battery. 

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well a dlb 102 is  a 1.5ohm coil for a ballasted system   if its now running on 12v you double the current and can blow electronic units 

or if points the added current will burn points  and blow condensers and fail rotors as your HT is also doubled up  

 

as Graham says  agree youre looking for a dull white/pink wire and it should have a boost link yellow/black? frm starter solenoid to the coil + ve

the alternator should not be run disconnected , and the small terminal feeds the voltage to the ignition warning lamp if this is disconnected nothing works 

or if it does it will be uncontrolled    .

pete

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Please correct me if I'm wrong if using electronic Ignition (Accuspark or Magnetronic) you need the full 12 volts ie a 12v (3ohm) coil and a 12v ignition feed to the coil, the ballasted 6v pink white/wire needs disconnecting and replacing with ign 12v.

Well that's what my Vitesse, Spit Mk2, original 12v systems and Sprint old 6v ballasted system bypassed with 12v and 3ohm Bosch coil operate at.

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Alternatively, keep the 6volt ballasted system and run a separate switched 12 volt supply, from a green or white wire, to the electronic module.  That is how my Pertronix system works.  I have also included an in-line 5 amp fuse tucked up behind the dash.  Removal of the fuse then immobilises the car, just remember to replace the fuse before trying to drive off otherwise you can be sat there for ages wondering why it will not start. (How do I know?)

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Ford ran a Similar "resistance wire" system too back when. The "Ballast Resister" was often JUST the running supply wire connecting the Coil to the system There being a separate wire from the "Start" terminal to supply 12V during Cranking. . I replaced one or 2 on  Early Anglia`s and Other Fords, they seemed to degrade quickly.

Pete

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9 hours ago, Peter Truman said:

Please correct me if I'm wrong if using electronic Ignition (Accuspark or Magnetronic) you need the full 12 volts ie a 12v (3ohm) coil and a 12v ignition feed to the coil, the ballasted 6v pink white/wire needs disconnecting and replacing with ign 12v.

Not always. I have an Aldon aka Pertronix and it is specifically for a ballasted system. 1.5 ohm coil, 12 volt start, 6 volt running.

Doug

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Don't bin the alternator, it could be fine.

If you completely disconnect an alternator then there will be no current going TO the alternator, from the battery via the ignition warning light, to energise the field coils. Hence no magnetism, so no generation of volts or amps.  That's a simplification but it'll do. Just as well really as an energised alternator running with no load can self destruct pretty instantly.

One option for a basic test of an alternator is:

1) Measure battery voltage with ignition off. Should 12.something volts. 12.6 for example

2) Start car, warm up,  and run at a slightly fast idle. Measure voltage across battery again. Should be significantly higher than previous figure, say 14.4volts.

With few exceptions an alternator that passes that test is fine.

C

 

 

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Doug your right I've just re-read the Lumenition Magnetronic instructions, where the ignition supply to the coil thro the ballast wire can be connected to the coil via ballast and non-resisted ie full 12volts to the ignition module, so the 1.5 ohm coil can still be used. 

Thinking back I couldn't be bothered trying to find the 12volt ign supply in the Sprints wiring loom before the ballast wire so I took the easy way out and disconnected/bypassed the ballast and replaced the nom 6 volt coil with a 12volt 3 ohm as I'd read somewhere the 12v supply gave improved ignition, spark and better performance?? The 6v or 1.5ohm coil was failing anyway leaking oil.

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OK, thanks for replies. I will check pink/white wire (a bit embarrassed that I didn't know about that). I intended to get an accuspark electronic module specifically for the ballasted system anyway, I think all I need to do is confirm the ballast wire. It had been running OK on my test drive, and driving it home. The only difference was the sparkrite piggyback electronic system, which I have now removed.  Alternator - well I had done the voltage across the battery test, and it showed only 12.75 volts. but it looks like a new alternator, so I couldn't convince myself that it  was toast? If there is a problem in the wiring, presumably that would fail that test as well?

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For the alternator is the plug not of the two part type?  You have a 'body' plastic block that the wires/connectors clip into and plugs into the alternator, then a separate plastic 'cap' that snaps over the back of the 'body' piece, then finally a wire retaining clip attached to the alternator flips up over both and into a groove in the 'cap' to stop anything falling out.

Given that you should be able to unclip the wire retaining clip and pop off the cover, leaving the 'body' block in situ/wires connected and access the connectors with your multimeter probes - remembering that it could be chucking out quite a big current.

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Couple of things?. Easy enough to measure the Voltage, even across the battery, Static and running voltages should be noticably different, anything close(ish) to 14V is OK. However if you want to measure the Current (Amps) you will likely need a Hefty calibrated  "Shunt" in parallel with the sort of DIY meters on the market, very few will handle more than 10amps . I "fried" an "industrial" strength "AVO" meter once in ignorance of that fact. There was time when the Regulators in the back of Alternators where replacable. Lucas Agents could do it.

Pete

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The first thing I tried was  measuring the across-battery voltages, static and running, and its too low (12.7), but, as above, I cannot quite convince myself that a brand new-looking alternator should have failed, so I was wondering if it's possible to check the wiring, in case there is a break/earth somewhere. Is it simply a case of disconnecting the plug and measuring the resistance between the end of the charging lead and the battery? Can't believe it's that simple!

And, of course, if the alternator is toast, what's the cause (apart from if it's a cheap chinese one!)

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1 hour ago, Doctor slow said:

And, of course, if the alternator is toast, what's the cause (apart from if it's a cheap chinese one!)

Connecting the battery terminals back to front will fry one instantly.

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Ashamed to say been there done that, got the Nobel prize for it. On a midget where battery is hidden behind the heater. In the dark put battery in the wrong way round, then connected it. Lot of light suddenly.

So, if there are no other causes, do I bite the bullet and get a new alternator

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6 hours ago, Doctor slow said:

OK, thanks for replies. I will check pink/white wire (a bit embarrassed that I didn't know about that). I intended to get an accuspark electronic module specifically for the ballasted system anyway, I think all I need to do is confirm the ballast wire.

I've just spent the morning fitting Accuspark to one of the most... interesting... Spitfires that's graced my door in an age. I'm assuming from the butchery of the loom that it's been converted from ballast to non-ballast (see photo) but now I've to run out and confirm that the module the driver supplied is indeed non-ballast; he may have ordered it by supplying the car details rather than any knowledge of the actual situation.

A64CC8DE-AD17-49FA-A44C-8753B6CB0A2F_1_105_c.jpg.5f6030063229b1a4087fb025db0640a9.jpg

I've just been to the Accuspark website; the kit I have is marked 'Kit 5' on the box but the website says that's for 24v Landrovers...

If it's 5J for the Spitfire 1500 then it's listed as 'ballast'. Now I don't know whether to leave it, as it's been fitted this morning, or revert to points until I'm sure it won't get fried. Any ideas?

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2 hours ago, Doctor slow said:

Ashamed to say been there done that, got the Nobel prize for it. On a midget where battery is hidden behind the heater. In the dark put battery in the wrong way round, then connected it. Lot of light suddenly.

So, if there are no other causes, do I bite the bullet and get a new alternator

What is the Alternator make?. I know that Regulators are available for Some (Bosch for one) and Assuming the Coils have`nt fried. They are relatively Cheap?. "Mistakes" often only affect the regulator. Worth a thought?.

Pete

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