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Zapped V12 E-type

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Tullamore

Tullamore

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I took two cars out to a vintage race track this weekend and the alternator on the Jag was overcharging the battery. I had a quick disconnect on the battery and when I disconnected the battery (with the engine running, I had done this before with no problems but I think this time the fan wasn't running to add a good load) I think it sent a voltage spike through the system and zapped something.

The car won't start because it appears there is no spark. Coil is good. Any ideas on what the likely culprit is or how to trouble shoot it?

We had a great time running around though until this happened when we were about to head out.

The video: https://www.youtube.com/watch?v=lnae7yshqt4
 
An unregulated E-Type V12 alternator can easily produce a momentary 60+ volts and 200 amps. The ignition amplifier should be the place to start looking for the lack of spark. Just be glad that is about the only electronic device of that era.
Alan T
 
If you still have the OPUS unit on the car, there is a kit available to fix it. It is sold in the US by XKs Unlimited, and is called the Re Opus. I bought mine thru the UK because XKs was out of stock, but in reality it came from New Zeland. I had no problem with the install, and it even has LEDs to see if it has power, and whether or not the pick up is working. Really easy, and it still looks stock.

Don't be shocked if it took out the voltage regulator also, as it is solid state too.

FWIW, disconnecting the battery of a running car as a diagnostic aid is a bad idea. In a modern car that could cost thou$ands of dollars.
 
I am going to order a new voltage regulator, I think the cause of this mishap. I do still have the OPUS amplifier so I will order the upgrade, it sounds like it would have been a good idea to have replaced already anyways.

Do you think I should order a new ballast unit while I am at it, or should that not have been affected?
 
If you have a shop manual, the ballast is really easy to test. It is just a matter of measuring resistances with an ohm meter. Not likely it got cooked, but who knows?
 
Okay I think I'm in trouble. I think my Opus unit was upgraded at some time before. Instead of the bottom plate held with screws it was rivets. Inside looks very different than the pictures shown in the ReOpus instructions and I have only four wires instead of five of six. My distributor also only has two wires instead of three.

Anyone recognize the components?


IMG_3268.jpg


IMG_3270.jpg


IMG_3273.jpg
 
WOW!! I have never seen that done before. It looks like a nice job though. Which way to go now though.... The "chip" inside the OPUS (with beyrillium warning) is a replaceable part. It is a GM chip, and can be crossed over by a decent parts guy. I am told that genuine GM parts have better dwell curves than cheapo knock offs, but honestly, I have never had the need to check. OR I guess you could try to find an opus pick up, and make it as it was. What is inside your distributor? Do you still have the "rotor" with the 12 metal rods? I am betting that you have an XJS distribtor(or at least the innards) as that would be compatible with the re engineered amp. Man, you just never know what you are going to find on one of these old cars.... I have had great luck with the CEI units over the years, so that is not a bad way to go.
 
Uh, if you dispose of that thing, be sure that the component containing the beryllia is properly disposed of.

Beryllia, AKA beryllium oxide, is a ceramic used occasionally in electronic components as a heat-conductive insulator--conducts heat almost as well as aluminum. If it gets into your lungs, even in minute quantities, you're toast. Usually it's not too much of a problem, since it is a hard solid, but if it gets crushed or ground up, it could be very dangerous.

Beryllium oxide insulators were fairly common in electronics back in the 70s, but dealing with the stuff was such a pain that it has been largely phased out. Other harmless ceramics, such as alumina, are usually good enough.
 
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